ALBERT

Description: Forests, Vol. 9, Pages 581: Effect of Vegetation Management and Site Conditions on Volume, Biomass and Leaf Area Allometry of Four Coniferous Species in the Pacific Northwest United States Forests doi: 10.3390/f9090581 Authors: Carlos A. Gonzalez-Benecke Herman N. Flamenco Maxwell G. Wightman Allometric equations are useful tools for calculating tree and stand-level attributes, such as above-ground biomass or stem volume, using simple measurements that can be obtained from stand inventory data. These equations tend to be species-specific and can be affected by site conditions and silvicultural treatments. Forest vegetation management treatments (VM) are an important component of reforestation programs in the Pacific Northwest of the United States; however, no study has investigated the impact of these treatments on crop tree allometry. In this study we assessed the long-term effects of two contrasting VM treatments on the allometry of sixteen-year-old Douglas-fir, western hemlock, western redcedar, and grand fir trees growing in Oregon’s central Coast Range (CR) and fifteen-year-old Douglas-fir and western redcedar trees growing in Oregon’s Cascade foothills (CF). The VM treatments included a control which received only a pre-planting herbicide application and a VM treatment consisting of five consecutive years of vegetation control after planting. The equations developed in this study were species-specific and were not affected by VM with the exception of western redcedar foliage biomass. For western redcedar, tress of similar diameter had more foliage biomass when growing on plots without VM after planting. The allometry of Douglas-fir and western redcedar was also found to be affected by site, such that trees of similar diameter and height had larger stem volume when growing at the CR site than the CF site. This difference in stem volume was found to be the result of differences in stem tapering. There was a strong relationship between stand basal area and leaf area index that was the same for all species tested and was unaffected by site. The equations presented in this study are useful for calculating stem volume, leaf area and individual tree and component biomass for stands of the studied species that are of similar age.

Description: Forests, Vol. 9, Pages 589: Assessing the Progress of REDD+ Projects towards the Sustainable Development Goals Forests doi: 10.3390/f9100589 Authors: Charlotte Milbank David Coomes Bhaskar Vira Almost a decade since the establishment of Reducing Emissions from Deforestation and Degradation (REDD+), this study investigates the extent to which REDD+ projects are delivering on the promise of co-benefits and the elusive ‘triple-win’ for climate, biodiversity, and local communities. The Climate, Community and Biodiversity Alliance (CCB) is among several leading REDD+ certification standards that are designed to support the delivery of social and environmental co-benefits, and ‘socially-just’ carbon. This study uses an in-depth content analysis of 25 subnational REDD+ project documents to assess the extent to which REDD+ project objectives align with Sustainable Development Goals (SDG) targets, and evaluates the reporting of progress towards meeting these objectives. Currently the CCB standards address a relatively small subset of SDG targets. Despite this, we find that REDD+ projects aspire to work on a much broader set of SDG target objectives, thus going beyond what the CCB Standards require for REDD+ validation. However, although reviewed REDD+ projects have these aspirations, very few are actively monitoring impact against the goals. There is a gap between aspiration and reported progress at the goal level, and for each project: on average, only a third of SDGs that are being targeted by REDD+ projects are showing ‘improvement’. The analysis shows which global goals are most frequently targeted, and which are the least. It also allows an analysis of which projects are following through most effectively in terms of monitoring progress towards the SDGs. This assessment provides insights into the priorities of REDD+ project proponents, suggesting that REDD+ has unfulfilled potential to elicit positive change in relation to the SDGs. Our analysis also shows that there is considerable potential for the safeguarding bodies to do more to ensure that real improvements are made, and reported against, aligning REDD+ projects more strongly with global development agendas.

Description: Forests, Vol. 9, Pages 587: Tree- and Stand-Level Biomass Estimation in a Larix decidua Mill. Chronosequence Forests doi: 10.3390/f9100587 Authors: Andrzej M. Jagodziński Marcin K. Dyderski Kamil Gęsikiewicz Paweł Horodecki Carbon pool assessments in forests is one of the most important tasks of forest ecology. Despite the wide cultivation range, and economical and traditional importance, the aboveground biomass of European larch (Larix decidua Mill.) stands is poorly characterized. To increase knowledge about forest biomass accumulation and to provide a set of tools for aboveground biomass estimation, we studied a chronosequence of 12 larch forest stands (7–120 years old). From these stands, we measured the biomass of 96 sample trees ranging from 1.9 to 57.9 cm in diameter at breast height. We provided age-specific and generalized allometric equations, biomass conversion and expansion factors (BCEFs) and biomass models based on forest stand characteristics. Aboveground biomass of stands ranged from 4.46 (7-year-old forest stand) to 445.76 Mg ha−1 (106-year-old). Stand biomass increased with increasing stand age, basal area, mean diameter, height and total stem volume and decreased with increasing density. BCEFs of the aboveground biomass and stem were almost constant (mean BCEFs of 0.4688 and 0.3833 Mg m−3, respectively). Our generalized models at the tree and stand level had lower bias in predicting the biomass of the forest stands studied, than other published models. The set of tools provided fills the gap in biomass estimation caused by the low number of studies on larch biomass, which allows for better estimation of forest carbon pools.

Description: Forests, Vol. 9, Pages 588: Relationships between Tree Vigor Indices and a Tree Classification System Based upon Apparent Stem Defects in Northern Hardwood Stands Forests doi: 10.3390/f9100588 Authors: Edouard Moreau Steve Bédard Guillaume Moreau David Pothier Many northern hardwood stands include several low-vigor trees as a result of past management. To restore these degraded stands, partial cuts are applied with partly validated tree classification systems that are based upon apparent stem defects. We sampled 214 sugar maple (Acer saccharum Marsh.) and 84 yellow birch (Betula alleghaniensis Britt.) trees from six sites covering the northern hardwood forest zone of the Province of Quebec, Canada. We evaluated their vigor with a four-class system, and quantified the growth efficiency index and several indices that were based solely upon radial growth. The growth efficiency index increased non-significantly with increasing tree vigor class. The five-year basal area increment (BAI-1-5) was significantly different between the lowest and highest tree vigor classes. Yet, temporal changes in BAI-1-5 helped classify correctly only 16% of high-vigor trees that became poorly vigorous 8–10 years later. Overall, these results suggest that the tree classification system is weakly related to actual tree vigor and its application likely generates few significant gains in future stand vigor. Modifying and simplifying the tree vigor system must be considered to facilitate the tree marking process that is required to improve the vigor of degraded stands.

Description: Forests, Vol. 9, Pages 590: Influential Actors’ Perceptions of Facilitators and Instruments for Solving Future Forest Land-Use Disputes in Europe Forests doi: 10.3390/f9100590 Authors: Peter K. Aurenhammer Špela Ščap Nike Krajnc Jorge Olivar Pablo Sabin Sílvia Nobre Francesco Romagnoli Despite strong expectations regarding the role that forestry, with its multitude of potential benefits, could and should play in the ‘bio-economy’, little research has been done on the actual perceptions of influential actors on how to best address future forest land-use disputes. We want to shed light on whether and in which contexts expectations regarding the bio-economy, e.g., the strong role of markets, are likely. The paper analyses influential actors’ core values and beliefs about the primary facilitators and the most appropriate instruments for resolving disputes over future forest land use. We used Social Network Analysis-based sampling and a quantitative semi-structured questionnaire, which included a preference analysis with twelve items covering broad issues and disputes related to future forest land use, to identify actors’ beliefs about and preferences for facilitators and policy instruments within key issues for future land use. The respondents were asked to identify one of five ‘primary facilitators’ (state, market, society, individual citizens/owners, leave it to nature) and distribute six points to a maximum of three preferred instruments (eight items, covering a broad set of instruments, from dictates or bans to awareness raising). The results are based on the perceptions of the influential or most important actors from various innovative government and private forest initiatives in Bavaria (Germany), Slovenia, Castilla y León (Spain), Nordeste (Portugal), and Latvia (481 actor responses, 109 initiatives). The initiatives included participatory mountain forest initiatives, forest intervention zones, afforestation projects, forest owner associations, and model forest and labelling initiatives. The results provide insight into the similarities and differences between European countries and actor groups regarding the preferred facilitators and instruments for solving future forest problems. In light of disagreement in the literature on the role of the state or markets in future forest land use and the bio-economy, our results show that the market and its instruments are considered to play a dominant role in wood mobilisation. With respect to all other issues (socio-ecological, societal, other), the state or other institutions and their instruments gain priority. The state is considered to play a stronger role in developing new markets, e.g., for energy transition or new uses of wood, contrary to liberal market expectations. Ecological and social problems are considered to be outside of the market domain. Here, the state is called in, e.g., to steer recreational issues, the provision of ecosystem services, or the improvement of the protective function. The clearest preference across all regions is for the state to secure the provision of ecosystem services, in contrast to calls for future markets to regulate this field.

Description: Forests, Vol. 9, Pages 591: Productivity, Costs, and Selected Environmental Impacts of Remote-Controlled Mini Forestry Crawlers Forests doi: 10.3390/f9100591 Authors: Ferréol Berendt Mathieu Fortin Christian Suchomel Janine Schweier An effective way to reduce off-road traffic in forests is to implement greater distances between skid trails. However, this implies that trees beyond the boom reach of the harvester need to be felled motor manually before being winched to the skid trail, for example using a remote-controlled mini forestry crawler (MFC). They are only a few local studies which have evaluated the performance of such MFCs. The use of MFCs for wood extraction operations in mixed soft- and hardwood stands is presented in this study conducted in Southwestern Germany. The aim of this study was to analyze the productivity, costs, and selected environmental impacts of mini forestry crawlers during winching operations through a time study. Using statistical regression, time consumption was analyzed in order to determine significant explanatory variables. Environmental impacts were evaluated using the life cycle assessment (LCA) methodology with Umberto software. The mean net cycle time was 4.82 min and the net productivity rate was 7.77 m3 by productive machine hour (PMH0). Explanatory variables which significantly affected the net cycle time were the winched volume, the number of trees per load, and winching distance. Environmental analysis showed that inputs of fossil energy were mostly due to diesel and lubricant consumption. Raw materials for machine manufacture and maintenance showed the highest impact in human toxicity potential category. The MFCs showed good environmental performances, but the harvesting system should become more productive in order to be more cost effective.

Description: Future Internet, Vol. 10, Pages 93: Proactive Caching at the Edge Leveraging Influential User Detection in Cellular D2D Networks Future Internet doi: 10.3390/fi10100093 Authors: Anwar Said Syed Waqas Haider Shah Hasan Farooq Adnan Noor Mian Ali Imran Jon Crowcroft Caching close to users in a radio access network (RAN) has been identified as a promising method to reduce a backhaul traffic load and minimize latency in 5G and beyond. In this paper, we investigate a novel community detection inspired by a proactive caching scheme for device-to-device (D2D) enabled networks. The proposed scheme builds on the idea that content generated/accessed by influential users is more probable to become popular and thus can be exploited for pro-caching. We use a Clustering Coefficient based Genetic Algorithm (CC-GA) for community detection to discover a group of cellular users present in close vicinity. We then use an Eigenvector Centrality measure to identify the influential users with respect to the community structure, and the content associated to it is then used for pro-active caching using D2D communications. The numerical results show that, compared to reactive caching, where historically popular content is cached, depending on cache size, load and number of requests, up to 30% more users can be satisfied using a proposed scheme while achieving significant reduction in backhaul traffic load.

Description: Future Internet, Vol. 10, Pages 92: Occlusion-Aware Unsupervised Learning of Monocular Depth, Optical Flow and Camera Pose with Geometric Constraints Future Internet doi: 10.3390/fi10100092 Authors: Qianru Teng Yimin Chen Chen Huang We present an occlusion-aware unsupervised neural network for jointly learning three low-level vision tasks from monocular videos: depth, optical flow, and camera motion. The system consists of three different predicting sub-networks simultaneously coupled by combined loss terms and is capable of computing each task independently on test samples. Geometric constraints extracted from scene geometry which have traditionally been used in bundle adjustment or pose-graph optimization are formed as various self-supervisory signals during our end-to-end learning approach. Different from prior works, our image reconstruction loss also takes account of optical flow. Moreover, we impose novel 3D flow consistency constraints over the predictions of all the three tasks. By explicitly modeling occlusion and taking utilization of both 2D and 3D geometry relationships, abundant geometric constraints are formed over estimated outputs, enabling the system to capture both low-level representations and high-level cues to infer thinner scene structures. Empirical evaluation on the KITTI dataset demonstrates the effectiveness and improvement of our approach: (1) monocular depth estimation outperforms state-of-the-art unsupervised methods and is comparable to stereo supervised ones; (2) optical flow prediction ranks top among prior works and even beats supervised and traditional ones especially in non-occluded regions; (3) pose estimation outperforms established SLAM systems under comparable input settings with a reasonable margin.

Description: Forests, Vol. 9, Pages 592: Strategies for Climate-Smart Forest Management in Austria Forests doi: 10.3390/f9100592 Authors: Robert Jandl Thomas Ledermann Georg Kindermann Alexandra Freudenschuss Thomas Gschwantner Peter Weiss We simulated Austrian forests under different sustainable management scenarios. A reference scenario was compared to scenarios focusing on the provision of bioenergy, enhancing the delivery of wood products, and reduced harvesting rates. The standing stock of the stem biomass, carbon in stems, and the soil carbon pool were calculated for the period 2010–2100. We used the forest growth model Câldis and the soil carbon model Yasso07. The wood demand of all scenarios could be satisfied within the simulation period. The reference scenario led to a small decrease of the stem biomass. Scenarios aiming at a supply of more timber decreased the standing stock to a greater extent. Emphasizing the production of bioenergy was successful for several decades but ultimately exhausted the available resources for fuel wood. Lower harvesting rates reduced the standing stock of coniferous and increased the standing stock of deciduous forests. The soil carbon pool was marginally changed by different management strategies. We conclude that the production of long-living wood products is the preferred implementation of climate-smart forestry. The accumulation of carbon in the standing biomass is risky in the case of disturbances. The production of bioenergy is suitable as a byproduct of high value forest products.

Description: Forests, Vol. 9, Pages 593: Macronutrient Stocks in Scots Pine Stands of Different Densities Forests doi: 10.3390/f9100593 Authors: Andrzej Węgiel Ernest Bielinis Krzysztof Polowy A positive nutrient balance is crucial to sustaining forest productivity. Differences in stand densities usually mean different aboveground biomass stocks and different proportions of tree compartments. These differences can be reflected in the different macronutrient stocks between stands of different densities, because various tree compartments have different element concentrations. In this study, 82-year-old stands of Scots pine were compared, and specifically, the concentrations of the elements in tree compartments and the amounts of macronutrients in aboveground biomass were compared. The nutrients considered in this study were nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur. A positive correlation between stand density and the level of stored macronutrients was found for nitrogen, phosphorus, and potassium. This result means that forest managers can influence nutrient balances by regulating stand densities or by harvesting methods (SOH: stem-only harvesting or WTH: whole-tree harvesting).

Description: Forests, Vol. 9, Pages 594: Screening Potential Bioenergy Production of Tree Species in Degraded and Marginal Land in the Tropics Forests doi: 10.3390/f9100594 Authors: Nils Borchard Medha Bulusu Ann-Michelle Hartwig Matthias Ulrich Soo Min Lee Himlal Baral Bioenergy can produce at least 25% of the global energy demand to combat climate change through reducing emissions in the energy sector. However, information on the bioenergy production potential of woody species and their suitability for silviculture on various soils in the humid tropics is limited. This review aims to identify tree species suitable for bioenergy production under these conditions. Data were compiled from 241 publications and nine freely available databases to assess environmental and silvicultural information on tropical tree species. Energy outputs were derived from the estimated productivity of the reviewed species and ranged from 0.2 to 24.0 Mg biomass ha−1 yr−1, 0.1 to 9.0 Mg bio-oil ha−1 yr−1, and 0.2 to 20.0 Mg sugar ha−1 yr−1, equivalent to an energy yield between 2 and 444 GJ ha−1 yr−1. As such, these bioenergy yields are within the range reported for the lignocellulosic biomass of energy crops cultivated in Europe, the USA, and Brazil. Our review identified some high-yielding species (e.g., Dyera polyphylla (Miq.) Steenis, Metroxylon sagu (Rottb.), Pongamia pinnata (L.)) and leguminous species that could be beneficial in mixed stands (e.g., Elaeis oleifera (Kunth) and Pongamia pinnata) or are suitable species to grow on wet or re-wetted peatland (Dyera polyphylla). However, there are limitations to cultivate woody bioenergy species on wet peatland. Sustainable methods for managing and harvesting forests, particularly on wet or re-wetted peatland, need to be developed.

Description: Forests, Vol. 9, Pages 583: An Integer Linear Programming Model to Select and Temporally Allocate Resources for Fighting Forest Fires Forests doi: 10.3390/f9100583 Authors: Jorge Rodríguez-Veiga María José Ginzo-Villamayor Balbina Casas-Méndez Optimal planning of the amount and type of resources needed for extinguishing a forest fire is a task that has been addressed in the literature, using models obtained from operational research. In this study, a general integer linear programming model is proposed, which addresses the allocation of resources in different time periods during the planning period for extinguishing a fire, and with the goal of meeting Spanish regulations for the non-negligence of fronts and periods of rest for pilots and brigades. A computer program and interface were developed using the R language. By means of an example using historical data, we illustrate the model at work and its exact resolution. Then, we carry out a simulation study to analyze the obtained objective functions and resolution times. Our simulation study shows that an exact solution can be obtained very quickly without requiring heuristic algorithms, provided that the planning period does not exceed five hours.

Description: Forests, Vol. 9, Pages 484: Fungal Frequency and Mite Load Trends Interact with a Declining Mountain Pine Beetle Population Forests doi: 10.3390/f9080484 Authors: Javier E. Mercado Beatriz Ortiz-Santana Shannon L. Kay The mite and fungal biota associated with the mountain pine beetle (MPB) (Dendroctonus ponderosae Hopk.) may not be stable throughout an irruptive event. In congeneric beetles, variations in the frequency of their associated organisms affect population trends and similar effects may occur in MPB. We studied fungi and mite trends in a declining irruptive MPB population as it attacked three different pine hosts in the Colorado Front Range. During the study, we found two new associates including one biologically relevant mite and one beneficial blue-stain fungus. Fungi hyperphoretic on mites were also documented. This included beneficial and potentially detrimental species to the MPB. The frequency of several organisms varied between some years or pine hosts but not within male or female beetles. A large increase of Trichouropoda sp. and T. ips mites trended inversely with the declining beetle population, while a decrease in the beneficial blue-stain fungi trended similarly to the declining beetle population. We discuss the interactions and potential effects of phoretic biota in relation to (1) the MPB associates’ population trends, (2) the MPB incursions into cooler areas, and (3) the redundancy of blue-stain fungi carried by the MPB holobiont. These findings increase our knowledge of the mechanisms that influence MPB populations.

Description: Future Internet, Vol. 10, Pages 76: SCADA System Testbed for Cybersecurity Research Using Machine Learning Approach Future Internet doi: 10.3390/fi10080076 Authors: Marcio Andrey Teixeira Tara Salman Maede Zolanvari Raj Jain Nader Meskin Mohammed Samaka This paper presents the development of a Supervisory Control and Data Acquisition (SCADA) system testbed used for cybersecurity research. The testbed consists of a water storage tank’s control system, which is a stage in the process of water treatment and distribution. Sophisticated cyber-attacks were conducted against the testbed. During the attacks, the network traffic was captured, and features were extracted from the traffic to build a dataset for training and testing different machine learning algorithms. Five traditional machine learning algorithms were trained to detect the attacks: Random Forest, Decision Tree, Logistic Regression, Naïve Bayes and KNN. Then, the trained machine learning models were built and deployed in the network, where new tests were made using online network traffic. The performance obtained during the training and testing of the machine learning models was compared to the performance obtained during the online deployment of these models in the network. The results show the efficiency of the machine learning models in detecting the attacks in real time. The testbed provides a good understanding of the effects and consequences of attacks on real SCADA environments.

Description: Future Internet, Vol. 10, Pages 78: Smart Collection of Real-Time Vehicular Mobility Traces Future Internet doi: 10.3390/fi10080078 Authors: Nisrine Ibadah Khalid Minaoui Mohammed Rziza Mohammed Oumsis César Benavente-Peces Mobility trace techniques makes possible drawing the behaviors of real-life movement which shape wireless networks mobility whereabouts. In our investigation, several trace mobility models have been collected after the devices’ deployment. The main issue of this classical procedure is that it produces uncompleted records due to several unpredictable problems occurring during the deployment phase. In this paper, we propose a new procedure aimed at collecting traces while deployment phase failures are avoided, which improves the reliability of data. The introduced procedure makes possible the complete generation of traces with a minimum amount of damage without the need to recover mobile devices or lose them, as it is the case in previous mobility traces techniques. Based on detecting and correcting all accidental issues in real time, the proposed trace scanning offers a set of relevant information about the vehicle status which was collected during seven months. Furthermore, the proposed procedure could be applied to generate vehicular traces. Likewise, it is suitable to record/generate human and animal traces. The research outcomes demonstrate the effectiveness and robustness of the smart collection algorithm based on the proposed trace mobility model.

Description: Future Internet, Vol. 10, Pages 77: Motives for Instagram Use and Topics of Interest among Young Adults Future Internet doi: 10.3390/fi10080077 Authors: Yi-Ting Huang Sheng-Fang Su Instagram is currently the most popular social media app among young people around the world. More than 70% of people between the ages of 12 and 24 are Instagram users. The research framework of this study was constructed based on smartphone addiction and the uses and gratifications theory. We used 27 question items divided into five factors, namely social interaction, documentation, diversion, self-promotion, and creativity, to investigate the motives for Instagram use and topics of interest among university students in Taiwan. A total of 307 valid questionnaires were obtained. The results revealed that on the whole, the motives for Instagram use were mostly to look at posts, particularly involving social interaction and diversion motives. The level of agreement expressed toward motives for creating posts was lower. Gender, professional training background, and level of addiction to Instagram all exert influence on motives for Instagram use. Over half of the students majoring in design followed artisans and celebrities (including designers), and female students noticed ads on Instagram more than male students did.

Description: Forests, Vol. 9, Pages 485: Developing and Field Testing a Tool Designed to Operationalize a Multitreatment Approach in Hardwood-Dominated Stands in Eastern Canada Forests doi: 10.3390/f9080485 Authors: Eric R. Labelle Gaetan Pelletier Michel Soucy Variations in species composition, diameter and height distributions, and quality make the management of hardwood-dominated stands difficult, particularly when considering mechanized forest operations. This study aimed to develop and field test a tool designed to improve the feasibility of forest operations in heterogeneous forest stands in Eastern Canada. To address inherent stand variability, a multitreatment approach was selected using conventional forest inventory (one inventory plot per hectare) and a silvicultural treatment decision key as main inputs. The Excel-based spreadsheet in combination with an ArcGIS model, referred to as the Multitreatment Planning Tool (MTPT), allowed to build operational maps identifying the type and spatial extent of silvicultural treatments to be performed. Once uploaded to positioning systems in harvesting machines, the operators were provided guidance on the silvicultural treatment to be performed and the location of the suggested machine trails. Field results obtained from nine harvest blocks (over 300 ha treated in total) showed the potential of using the MTPT until more mature and higher resolution-enhanced inventories become mainstream. Machine operators and operational managers both appreciated the straightforward and flexible method. Additional testing and refinement of the method is necessary, particularly when considering re-entry scheduling.

Description: Forests, Vol. 9, Pages 483: Impacts of a High Nitrogen Load on Foliar Nutrient Status, N Metabolism, and Photosynthetic Capacity in a Cupressus lusitanica Mill. Plantation Forests doi: 10.3390/f9080483 Authors: Ruirui Li Yi Lu Fuxu Wan Yiming Wang Xiaocheng Pan At present, anthropogenic nitrogen deposition has dramatically increased worldwide and has shown negative impacts on temperate/boreal forest ecosystems. However, it remains unclear how an elevated N load affects plant growth in the relatively N-rich subtropical forests of Southern China. To address this question, a study was conducted in a six-year-old Cupressus lusitanica Mill. plantation at the Scientific Research and Teaching Base of Nanjing Forestry University, with N addition levels of N0 (0 kg ha−1 year−1), N1 (24 kg ha−1 year−1), N2 (48 kg ha−1 year−1), N3 (72 kg ha−1 year−1), N4 (96 kg ha−1 year−1), and N5 (120 kg ha−1 year−1). Leaf physiological traits associated with foliar nutrient status, photosynthetic capacity, pigment, and N metabolites were measured. The results showed that (1) N addition led to significant effects on foliar N, but had no marked effects on K concentration. Furthermore, remarkable increases of leaf physiological traits including foliar P, Ca, Mg, and Mn concentration; photosynthetic capacity; pigment; and N metabolites were always observed under low and middle-N supply. (2) High N supply notably decreased foliar P, Ca, and Mg concentration, but increased foliar Mn content. Regarding the chlorophyll, photosynthetic capacity, and N metabolites, marked declines were also observed under high N inputs. (3) Redundancy analysis showed that the net photosynthesis rate was positively correlated with foliar N, P, Ca, Mg, and Mn concentration; the Mn/Mg ratio; and concentrations of chlorophyll and N metabolites, while the net photosynthesis rate was negatively correlated with foliar K concentration and N/P ratios. These findings suggest that excess N inputs can promote nutrient imbalances and inhibit the photosynthetic capacity of Cupressus lusitanica Mill., indicating that high N deposition could threaten plant growth in tropical forests in the future. Meanwhile, further study is merited to track the effects of high N deposition on the relationship between foliar Mn accumulation and photosynthesis in Cupressus lusitanica Mill.

Description: Forests, Vol. 9, Pages 488: Influence of Natural and Artificial Weathering on the Colour Change of Different Wood and Wood-Based Materials Forests doi: 10.3390/f9080488 Authors: Davor Kržišnik Boštjan Lesar Nejc Thaler Miha Humar The importance of the aesthetic performance of wood is increasing and the colour is one of the most important parameters of aesthetics, hence the colour stability of twelve different wood-based materials was evaluated by several in-service and laboratory tests. The wood used for wooden façades and decking belongs to a group of severely exposed surfaces. Discolouration of wood in such applications is a long-known phenomenon, which is a result of different biotic and abiotic causes. The ongoing in-service trial started in October 2013, whilst a laboratory test mimicking seasonal exposure was performed in parallel. Samples were exposed to blue stain fungi (Aureobasidium pullulans and Dothichiza pithyophila) in a laboratory test according to the EN 152 procedure. Afterwards, the same samples were artificially weathered and re-exposed to the same blue stain fungi for the second time. The purpose of this experiment was to investigate the synergistic effect of weathering and staining. The broader aim of the study was to determine the correlation factors between artificial and natural weathering and to compare laboratory and field test data of fungal disfigurement of various bio-based materials. During the four years of exposure, the most prominent colour changes were determined on decking. Respective changes on the façade elements were significantly less prominent, being the lest evident on the south and east façade. The results showed that there are positive correlations between natural weathering and the combination of artificial weathering and blue staining. Hence, the artificial weathering of wood-based materials in the laboratory should consist of two steps, blue staining and artificial weathering, in order to simulate colour changes.

Description: Forests, Vol. 9, Pages 489: Sustainability of Forest Cover under Climate Change on the Temperate-Continental Xeric Limits Forests doi: 10.3390/f9080489 Authors: Csaba Mátyás Imre Berki András Bidló György Csóka Kornél Czimber Ernő Führer Borbála Gálos Zoltán Gribovszki Gábor Illés Anikó Hirka Zoltán Somogyi Climate change particularly threatens the xeric limits of temperate-continental forests. In Hungary, annual temperatures have increased by 1.2 °C–1.8 °C in the last 30 years and the frequency of extreme droughts has grown. With the aim to gain stand-level prospects of sustainability, we have used local forest site variables to identify and project effects of recent and expected changes of climate. We have used a climatic descriptor (FAI index) to compare trends estimated from forest datasets with climatological projections; this is likely for the first time such a comparison has been made. Four independent approaches confirmed the near-linear decline of growth and vitality with increasing hot droughts in summer, using sessile oak as model species. The correlation between droughts and the expansion of pest and disease damages was also found to be significant. Projections of expected changes of main site factors predict a dramatic rise of future drought frequency and, consequently, a substantial shift of forest climate classes, especially at low elevation. Excess water-dependent lowland forests may lose supply from groundwater, which may change vegetation cover and soil development processes. The overall change of site conditions not only causes economic losses, but also challenges long-term sustainability of forest cover at the xeric limits.

Description: Future Internet, Vol. 10, Pages 79: Queue Spillover Management in a Connected Vehicle Environment Future Internet doi: 10.3390/fi10080079 Authors: Chuanxiang Ren Wenbo Zhang Lingqiao Qin Bo Sun To alleviate the queue spillovers at intersections of urban roads during rush hours, a solution to the cross-spill problem based on vehicle networking technologies is proposed. This involves using connected vehicle technology, to realize the interactive information on vehicle and intersection signal control. The maximum control distance between intersections is determined by how vehicles are controlled and would travel in that connected environment. A method of calculating overflow tendency towards intersection queuing is also proposed, based on the maximum phase control distance. By this method, the intersection overflow is identified, and then the signal phases are re-optimized according to the requirements of different phases. Finally, overflow prevention control was also performed in this study. The VISSIM simulation results show that the method can better prevent the overflow of queues at intersections.

Description: Forests, Vol. 9, Pages 486: Effects of Narrow Linear Disturbances on Light and Wind Patterns in Fragmented Boreal Forests in Northeastern Alberta Forests doi: 10.3390/f9080486 Authors: Eleanor R. Stern Federico Riva Scott E. Nielsen Forest fragmentation threatens forest biodiversity and ecosystem function. One of the concerns relates to increases in edge effects, which among other things affects the forest microclimate that influences the distribution and behavior of species. In Alberta, Canada, boreal anthropogenic disturbances from in situ oil exploration are increasing forest fragmentation, especially in the form of exploratory well pads and seismic lines (i.e., linear forest clearings created during the exploration phase of oil extraction). Dissection of these forests by seismic lines has the potential to change local patterns in wind and light, and thus may alter forest communities. Although alterations of these abiotic conditions are likely, the magnitude of these changes is unknown, particularly the effects of changes in the width and orientation of linear disturbances. Here we investigated changes in light and wind on seismic lines compared to that of adjacent undisturbed forests and nearby cleared openings. Specifically, we examined how seismic line characteristics (i.e., line direction, line width, and adjacent canopy height) altered local responses in these abiotic conditions. Generalized Linear Mixed Effect models predicted a 2-fold increase in average light intensity and maximum wind speeds, and a 4-fold increase in average wind speeds on seismic lines compared to adjacent forests. These changes did not approach the conditions in large openings, which compared to forests had a 3-fold increase in average light intensity, a 16-fold increase in average wind speeds, and a 4-fold increase in maximum wind speeds. Line width and orientation interacted with adjacent forest height altering the abiotic environment with wider lines having a 3-fold increase on maximum wind speed. We conclude that even localized, narrow (<10-m wide) forest disturbances associated with oil sands exploration alter forest microclimatic conditions. Recent changes in practices that reduce line width as well as promoting tree regeneration, will minimize the environmental effects of these anthropogenic disturbances.

Description: Forests, Vol. 9, Pages 490: Determinants of Above-Ground Biomass and Its Spatial Variability in a Temperate Forest Managed for Timber Production Forests doi: 10.3390/f9080490 Authors: María de los Ángeles Soriano-Luna Gregorio Ángeles-Pérez Mario Guevara Richard Birdsey Yude Pan Humberto Vaquera-Huerta José René Valdez-Lazalde Kristofer D. Johnson Rodrigo Vargas The proper estimation of above-ground biomass (AGB) stocks of managed forests is a prerequisite to quantifying their role in climate change mitigation. The aim of this study was to analyze the spatial variability of AGB and its uncertainty between actively managed pine and unmanaged pine-oak reference forests in central Mexico. To investigate the determinants of AGB, we analyzed variables related to forest management, stand structure, topography, and climate. We developed linear (LM), generalized additive (GAM), and Random Forest (RF) empirical models to derive spatially explicit estimates and their uncertainty, and compared them. AGB was strongly influenced by forest management, as LiDAR-derived stand structure and stand age explained 80.9% to 89.8% of its spatial variability. The spatial heterogeneity of AGB varied positively with stand structural complexity and age in the managed forests. The type of predictive model had an impact on estimates of total AGB in our study site, which varied by as much as 19%. AGB densities varied from 0 to 492 ± 17 Mg ha−1 and the highest values were predicted by GAM. Uncertainty was not spatially homogeneously distributed and was higher with higher AGB values. Spatially explicit AGB estimates and their association with management and other variables in the study site can assist forest managers in planning thinning and harvesting schedules that would maximize carbon stocks on the landscape while continuing to provide timber and other ecosystem services. Our study represents an advancement toward the development of efficient strategies to spatially estimate AGB stocks and their uncertainty, as the GAM approach was used for the first time with improved results for such a purpose.

Description: Algorithms, Vol. 11, Pages 123: Time Series Forecasting Using a Two-Level Multi-Objective Genetic Algorithm: A Case Study of Maintenance Cost Data for Tunnel Fans Algorithms doi: 10.3390/a11080123 Authors: Yamur K. Al-Douri Hussan Hamodi Jan Lundberg The aim of this study has been to develop a novel two-level multi-objective genetic algorithm (GA) to optimize time series forecasting data for fans used in road tunnels by the Swedish Transport Administration (Trafikverket). Level 1 is for the process of forecasting time series cost data, while level 2 evaluates the forecasting. Level 1 implements either a multi-objective GA based on the ARIMA model or a multi-objective GA based on the dynamic regression model. Level 2 utilises a multi-objective GA based on different forecasting error rates to identify a proper forecasting. Our method is compared with using the ARIMA model only. The results show the drawbacks of time series forecasting using only the ARIMA model. In addition, the results of the two-level model show the drawbacks of forecasting using a multi-objective GA based on the dynamic regression model. A multi-objective GA based on the ARIMA model produces better forecasting results. In level 2, five forecasting accuracy functions help in selecting the best forecasting. Selecting a proper methodology for forecasting is based on the averages of the forecasted data, the historical data, the actual data and the polynomial trends. The forecasted data can be used for life cycle cost (LCC) analysis.

Description: Algorithms, Vol. 11, Pages 127: Application of Angle Related Cost Function Optimization for Dynamic Path Planning Algorithm Algorithms doi: 10.3390/a11080127 Authors: Mingbin Zeng Xu Yang Mengxing Wang Bangjiang Xu In recent years, Intelligent Transportation Systems (ITS) have developed a lot. More and more sensors and communication technologies (e.g., cloud computing) are being integrated into cars, which opens up a new design space for vehicular-based applications. In this paper, we present the Spatial Optimized Dynamic Path Planning algorithm. Our contributions are, firstly, to enhance the effective of loading mechanism for road maps by dividing the connected sub-net, and building a spatial index; and secondly, to enhance the effect of the dynamic path planning by optimizing the search direction. We use the real road network and real-time traffic flow data of Karamay city to simulate the effect of our algorithm. Experiments show that our Spatial Optimized Dynamic Path Planning algorithm can significantly reduce the time complexity, and is better suited for use as a real-time navigation system. The algorithm can achieve superior real-time performance and obtain the optimal solution in dynamic path planning.

Description: Forests, Vol. 9, Pages 500: Taylor’s Power Law for Leaf Bilateral Symmetry Forests doi: 10.3390/f9080500 Authors: Ping Wang David A. Ratkowsky Xiao Xiao Xiaojing Yu Jialu Su Lifang Zhang Peijian Shi Leaf shape and symmetry is of interest because of the importance of leaves in photosynthesis. Recently, a novel method was proposed to measure the extent of bilateral symmetry in leaves in which a leaf was divided into left and right sides by a straight line through the leaf apex and base, and a number of equidistant strips were drawn perpendicular to the straight line to generate an equivalent number of differences in area between the left and right parts. These areal differences are the basis for a measure of leaf bilateral symmetry, which was then examined to see how well it follows Taylor’s power law (TPL) using three classes of plants, namely, 10 geographical populations of Parrotia subaequalis (H.T. Chang) R.M. Hao et H.T. Wei, 10 species of Bambusoideae, and 10 species of Rosaceae. The measure of bilateral symmetry followed TPL for a single species or for a class of closely related species. The estimate of the exponent of TPL for bamboo plants was significantly larger than for the dicotyledonous trees, but its goodness of fit was the best among the three classes of plants. The heterogeneity of light falling on branches and leaves due to above-ground architectural patterns is an important contributor to leaf asymmetry.

Description: Forests, Vol. 9, Pages 499: Ecological Factors Affecting White Pine, Red Oak, Bitternut Hickory and Black Walnut Underplanting Success in a Northern Temperate Post-Agricultural Forest Forests doi: 10.3390/f9080499 Authors: Benoit Truax Daniel Gagnon Julien Fortier France Lambert Marc-Antoine Pétrin This study took place in southern Québec (Canada) where young stands of white ash and grey birch have been underplanted with white pine, red oak, bitternut hickory and black walnut. The establishment success of white pine and red oak was measured with and without tree shelters (to protect from deer). Ecological factors affecting the height growth of the four species were also measured for protected trees. After 6 years, the survival and total height of unprotected oak was 29% and 44.3 cm vs. 80.5% and 138.5 cm for protected oak. White pine was less affected by browsing (survival of 79.5 and 93.5%; height of 138.5 and 217.9 cm for unprotected vs. protected pine). Height of white pine was higher in the grey birch stands, while height of all hardwoods was higher in the white ash stands, which had better soil drainage, higher fertility, and an understory dominated by Rubus species. Total height of all hardwoods was significantly (p < 0.05) correlated with Rubus cover and with soil fertility. Pine and walnut height were strongly correlated (p < 0.001) to shelterwood structure (canopy openness or total basal area). Pine was less sensitive to variations in shelterwood characteristics, while black walnut showed high sensitivity. This study provides evidence that underplanting is suitable for black walnut assisted migration northward and for bitternut hickory restoration, despite soil conditions that were less favorable than in bottomland habitats mainly supporting these species in eastern Canada. Tree shelters offering protection from deer browsing and species-specific site selection are recommended for underplanting in the southern Québec region.

Description: Algorithms, Vol. 11, Pages 129: The Fast Detection and Identification Algorithm of Optical Fiber Intrusion Signals Algorithms doi: 10.3390/a11090129 Authors: Zhiyong Sheng Dandan Qu Yuan Zhang Dan Yang With the continuous development of optical fiber sensing technology, the Optical Fiber Pre-Warning System (OFPS) has been widely used in various fields. The OFPS identifies the type of intrusion based on the detected vibration signal to monitor the surrounding environment. Aiming at the real-time requirements of OFPS, this paper presents a fast algorithm to accelerate the detection and recognition processing of optical fiber intrusion signals. The algorithm is implemented in an embedded system that is composed of a digital signal processor (DSP). The processing flow is divided into two parts. First, the dislocation processing method is adopted for the sum processing of original signals, which effectively improves the real-time performance. The filtered signals are divided into two parts and are parallel processed by two DSP boards to save time. Then, the data is input into the identification module for feature extraction and classification. Experiments show that the algorithm can effectively detect and identify the optical fiber intrusion signals. At the same time, it accelerates the processing speed and meets the real-time requirements of OFPS for detection and identification.

Description: Forests, Vol. 9, Pages 510: Exogenous Oxalic Acid and Citric Acid Improve Lead (Pb) Tolerance of Larix olgensis A. Henry Seedlings Forests doi: 10.3390/f9090510 Authors: JinFeng Song Daniel Markewitz Shaoping Wu Ying Sang Chengwei Duan XiaoYang Cui We investigated the beneficial role of different concentrations of exogenous oxalic acid (OA) or citric acid (CA) for improving Pb tolerance and mitigating Pb-induced physiological toxicity in Changbai larch (Larix olgensis A. Henry) seedlings in northeast China. The seedlings were exposed to 100 mg·kg−1 Pb in soil alone or in combination with OA or CA irrigation for 10, 20, or 30 days. Pb-induced damage in L. olgensis was evident from elevated lipid peroxidation that significantly inhibited plant growth. Malondialdehyde (MDA) contents also increased in the presence of elevated Pb; however, superoxide dismutase (SOD) and peroxidase (POD) activities, as well as proline and pigment contents, all decreased. The damage increased in controls over the application periods. Pb contents in fine roots and leaves generally decreased with low-concentration organic acids (<1.0 mmol·L−1), but often increased at 5.0 and 10.0 mmol·L−1. Alternatively, when Pb-stressed plants were exposed to an organic acid (especially 5.0 or 10.0 mmol·L−1 for 10 days), the damage, as indicated by the physiological parameters, was reversed, and plant growth was promoted; CA was more effective in inducing these changes than OA. Therefore, exogenous organic acids have the potential to alleviate Pb-induced oxidative injuries, and can improve the tolerance of L. olgensis seedlings to Pb stress. Under lower OA and CA concentrations, the detoxification mechanism appears to be an external resistance mechanism; however, under higher concentrations (5.0–10.0 mmol·L−1) internal resistance mechanisms appear dominant. It is also possible that the two mechanisms work in tandem.

Description: Forests, Vol. 9, Pages 515: 25 Years of Criteria and Indicators for Sustainable Forest Management: Why Some Intergovernmental C&I Processes Flourished While Others Faded Forests doi: 10.3390/f9090515 Authors: Stefanie Linser Bernhard Wolfslehner Fady Asmar Simon R. J. Bridge David Gritten Vicente Guadalupe Mostafa Jafari Steven Johnson Pablo Laclau Guy Robertson The use of criteria and indicators (C&I) for data collection, monitoring, assessing and reporting on sustainable forest management (SFM) has been growing since the Earth Summit in 1992, supported by eleven intergovernmental, regional and international forest-related C&I processes. The initial effort led to varying levels of implementation across countries. Several processes never went much beyond the adoption of a first set of C&I while others have made substantial progress. In recent years, interest in C&I for SFM has again increased. In light of the Sustainable Development Goals and emerging global challenges the contribution of C&I to monitor, assess and report on forest conditions and trends is increasingly important. We compare and analyse the structure, activities and progress of the intergovernmental C&I processes. The work is based on document analysis and questionnaires sent to the secretariats of the processes and C&I experts. We found many similarities but also major differences in the structure and content of the C&I sets. The results provide a context for discussing and understanding why some of the C&I processes are successful in their work while others have stalled. Finally, we propose the required ingredients for success for the future activities of the forest-related intergovernmental C&I processes.

Description: Forests, Vol. 9, Pages 516: Variation of Traits on Seeds and Germination Derived from the Hybridization between the Sections Tacamahaca and Aigeiros of the Genus Populus Forests doi: 10.3390/f9090516 Authors: Jialei Zhu Ju Tian Jun Wang Shuijing Nie Poplar is an important research organism, and species in sections Tacamahaca and Aigeiros, have advantages in terms of stress resistance, ease of propagation, and fast growth. Poplar species are widely distributed and well-adapted in the world, presenting a large potential for genetic improvement. Hybridization between different species allows us to generate offspring with a unique combinations of traits. This approach has a huge potential for breeding new poplar varieties that could aid in controlling desertification in the arid and semi-arid zones of the “Three-North” in China. In this study, we carried out a cross test scheme with nine female and thirteen male poplar trees. A total of 105,401 seeds were collected from 117 crosses. Flowering phenology and seed maturation differences of the hybrid progeny were monitored in greenhouses. For male trees, Populus deltoides had the longest flowering time. For female trees, Populus pseudo-simonii showed the longest seed maturity time. The number of carpals and ovules were not the same in different females. Meanwhile, three carpals were found in P. pseudo-simonii. A highly significant positive correlation was found between the seed size and the Thousand Kernel Weight, as well as the seedling cotyledon length. During seed germination, non-radicle and non-hypocotyl seedlings were observed. We also observed a number of cotyledon variants, including single and fused cotyledons, two cotyledons with one cotyledon cracking into two parts, three cotyledons, as well as four cotyledons. These results lay a favorable foundation for combining the research between the sections Tacamahaca and Aigeiros in future work.

Description: Forests, Vol. 9, Pages 517: Fine Root Dynamics in Three Forest Types with Different Origins in a Subalpine Region of the Eastern Qinghai-Tibetan Plateau Forests doi: 10.3390/f9090517 Authors: Shun Liu Da Luo Hongguo Yang Zuomin Shi Qianli Liu Li Zhang Ying Kang Fine roots play a crucial role in plant survival potential and biogeochemical cycles of forest ecosystems. Subalpine areas of the Eastern Qinghai-Tibetan Plateau have experienced different forest re-establishment methods after clear-cutting primary forest. However, little is known about fine root dynamics of these forests originating from artificial, natural and their combined processes. Here, we determined fine root traits (biomass, production and turnover rate) of three subalpine forest types, i.e., Picea asperata Mast. plantation forest (artificial planting, PF), natural secondary forest (natural without assisted regeneration, NF) and P. asperata broadleaved mixed forest (natural regeneration after artificial planting, MF) composed of planted P. asperata and naturally regenerated native broadleaved species. At the soil depth of 0–30 cm, fine root biomass was the highest in PF and fine root production was the highest in NF, and both were the lowest in MF. Fine root dynamics of the three forest types tended to decrease with soil depth, with larger variations in PF. Fine root biomass and production were the highest in PF in 0–10 cm soil layer but were not significantly different among forest types in the lower soil layers. There were positive correlations between these parameters and aboveground biomass across forest types in soil layer of 0–10 cm, but not in the lower soil layers. Fine root turnover rate was generally higher in mixed forests than in monocultures at all soil depths. In conclusion, the natural regeneration procedure after clear-cutting in the subalpine region of western Sichuan seems to be superior from the perspective of fine root dynamics.

Description: Forests, Vol. 9, Pages 518: Estimation and Uncertainty of the Mixing Effects on Scots Pine—European Beech Productivity from National Forest Inventories Data Forests doi: 10.3390/f9090518 Authors: Sonia Condés Hubert Sterba Ana Aguirre Kamil Bielak Andrés Bravo-Oviedo Lluís Coll Maciej Pach Hans Pretzsch Patrick Vallet Miren del Río An increasing amount of research is focusing on comparing productivity in monospecific versus mixed stands, although it is difficult to reach a general consensus as mixing effects differ both in sign (over-yielding or under-yielding) and magnitude depending on species composition as well as on site and stand conditions. While long-term experimental plots provide the best option for disentangling the mixing effects, these datasets are not available for all the existing mixtures nor do they cover large gradients of site factors. The objective of this study was to evaluate the effects and uncertainties of tree species mixing on the productivity of Scots pine–European beech stands along the gradient of site conditions in Europe, using models developed from National and Regional Forest Inventory data. We found a positive effect of pine on beech basal area growth, which was slightly greater for the more humid sites. In contrast, beech negatively affected pine basal area growth, although the effects switched to positive in the more humid sites. However, the uncertainty analysis revealed that the effect on pine at mid- and more humid sites was not-significant. Our results agree with studies developed from a European transect of temporal triplets in the same pine–beech mixtures, confirming the suitability of these datasets and methodology for evaluating mixing effects at large scale.

Description: Forests, Vol. 9, Pages 526: Mobility Range of a Cable Skidder for Timber Extraction on Sloped Terrain Forests doi: 10.3390/f9090526 Authors: Andreja Đuka Tomislav Poršinsky Tibor Pentek Zdravko Pandur Dinko Vusić Ivica Papa The use of forestry vehicles in mechanised harvesting systems is still the most effective way of timber procurement, and forestry vehicles need to have high mobility to face various terrain conditions. This research gives boundaries of planning timber extraction on sloped terrain with a cable skidder, considering terrain parameters (slope, direction of skidding, cone index), vehicle technical characteristics and load size (5 different loads) relying on sustainability and eco-efficiency. Skidder mobility model was based on connecting two systems: vehicle-terrain (load distribution) and wheel-soil (skidder traction performance) with two mobility parameters: (1) maximal slope during uphill timber extraction by a cable skidder based on its traction performance (gradeability), and (2) maximal slope during downhill timber extraction by a cable skidder when thrust force is equal to zero. Results showed mobility ranges of an empty skidder for slopes between −50% and +80%, skidder with 1 tonne load between −26% and +63%, skidder with 2 tonne load between −30% and +51%, skidder with 3 tonne load between −34% and +39%, skidder with 4 tonne load between −35% and +30% and skidder with 5 tonne load between −41% and +11%.These results serve to improve our understanding of safer, more efficient timber extraction methods on sloped terrain.

Description: Forests, Vol. 9, Pages 527: Quantifying the Effects of Wood Moisture and Temperature Variation on Time-of-Flight Acoustic Velocity Measures within Standing Red Pine and Jack Pine Trees Forests doi: 10.3390/f9090527 Authors: Peter F. Newton The relationship between the dynamic modulus of elasticity (me) of xylem tissue and acoustic velocity (vd) has been established for a number of commercially-important coniferous species, including red pine (Pinus resinosa Ait.) and jack pine (Pinus banksiana Lamb.). However, vd has been shown to vary systematically with xylem temperature (tx) and moisture (mx) for some species, and hence when the calibrated me–vd relationships are used outside of the range of conditions under which they were parameterized, erroneous predictions may arise. Consequently, the objectives of this study were (1) to investigate the significance of tx and mx effects on vd measurements within standing red pine and jack pine trees, and (2), given (1), to develop correction equations for standardizing vd measurements to referenced tx and mx conditions if warranted. Analytically, based on a temporal replicated sampling design, 26 mature red pine and 36 semi-mature jack pine trees growing in managed plantations located within central Ontario, Canada (Kirkwood Forest, Great Lakes—St. Lawrence Forest Region), were continuously measured for vd, tx, and mx during the spring-to-autumn seasonal periods in 2016 (red pine) and 2017 (jack pine). A total of 6 measurement events per species occurred at approximately 4–8 week intervals in which a total of 624 red pine and 864 jack pine cardinal-specific (north, east, south, and west) breast-height acoustic velocity, xylem temperature, and xylem moisture measurements were obtained: Yielding a total of 156 red pine and 216 jack pine mean tree-based values available for analysis. Over the sampling periods, (1) mean tree xylem temperatures ranged from a minimum of 3 °C to a maximum of 31 °C (mean = 19.2 °C) in red pine and from a minimum of 0 °C to a maximum of 27 °C (mean = 16.5 °C) in jack pine, and (2) mean tree xylem moistures ranged from a minimum 31% to a maximum of 45% (mean = 38.6%) in red pine and from a minimum 25% to a maximum of 50% (mean = 38.8%) in jack pine. Graphical examination of the moisture effect on the vd and tx relationship by tree and species revealed inversely proportional, linear-like trends at lower moisture levels and directly-proportional, linear-like trends at higher moisture levels where the effect was more evident for red pine than for jack pine. In order to describe this multivariate relationship, species-specific, two-level hierarchical, mixed-effects linear models inclusive of random and fixed effects were specified and subsequently parameterized. The first-level model described the tree-specific vd–tx relationship deploying a simple linear regression specification, whereas the second-level model expressed the first-level parameter estimates as a linear function of seasonal mean tree moisture. The resultant statistically-validated, parameterized regression models, for which 64% (red pine) and 90% (jack pine) of the vd variation was explained, indicated that the vd–tx relationship varied systematically with seasonal mean moisture level in red pine but not so in jack pine. More precisely, in red pine, vd declined with increasing tx at lower moisture levels (<38%), but increased with increasing tx at higher moisture levels (>38%). Conversely, although vd declined with increasing tx in jack pine, the relationship was unaffected by changes in seasonal mean tree moisture levels. Consequently, based on the final hierarchical model specifications, correction equations for adjusting observed vd values to standardized temperature (20 °C) and moisture conditions (40% for red pine) were developed for each species. Across the range of temperatures (≈5 °C–30 °C) and mean moisture levels (≈30–45%) examined, these equations generated a mean absolute vd adjustment of approximately 0.12 km/s for red pine and 0.04 km/s for jack pine. However, based on the corresponding relative magnitude of these adjustments which account for the narrow species-specific vd sample ranges observed (0.80 and 0.85 km/s for red pine and jack pine, respectively), the standardization of vd estimates could be of operational significance when acoustic sampling during periods in which xylem temperature and moisture levels approach the extremities of their spring-to-autumn seasonal ranges. Overall, the results of this empirical-based assessment, which confirmed the presence of temperature and moisture induced variation in acoustic velocity measures within standing red pine and jack pine trees, were largely in accordance with expectation. The subsequent provision of species-specific correction functions for adjusting observed vd sample values to corresponding equivalents referenced to standardized temperature and moisture conditions could assist in mitigating the consequences of environmental variability when acoustic sampling.

Description: Forests, Vol. 9, Pages 524: Drought Sensitiveness on Forest Growth in Peninsular Spain and the Balearic Islands Forests doi: 10.3390/f9090524 Authors: Marina Peña-Gallardo Sergio M. Vicente-Serrano J. Julio Camarero Antonio Gazol Raúl Sánchez-Salguero Fernando Domínguez-Castro Ahmed El Kenawy Santiago Beguería-Portugés Emilia Gutiérrez Martin de Luis Gabriel Sangüesa-Barreda Klemen Novak Vicente Rozas Pedro A. Tíscar Juan C. Linares Edurne Martínez del Castillo Montserrat Ribas Matamoros Ignacio García-González Fernando Silla Álvaro Camisón Mar Génova José M. Olano Luis A. Longares Andrea Hevia J. Diego Galván Drought is one of the key natural hazards impacting net primary production and tree growth in forest ecosystems. Nonetheless, tree species show different responses to drought events, which make it difficult to adopt fixed tools for monitoring drought impacts under contrasting environmental and climatic conditions. In this study, we assess the response of forest growth and a satellite proxy of the net primary production (NPP) to drought in peninsular Spain and the Balearic Islands, a region characterized by complex climatological, topographical, and environmental characteristics. Herein, we employed three different indicators based on in situ measurements and satellite image-derived vegetation information (i.e., tree-ring width, maximum annual greenness, and an indicator of NPP). We used seven different climate drought indices to assess drought impacts on the tree variables analyzed. The selected drought indices include four versions of the Palmer Drought Severity Index (PDSI, Palmer Hydrological Drought Index (PHDI), Z-index, and Palmer Modified Drought Index (PMDI)) and three multi-scalar indices (Standardized Precipitation Evapotranspiration Index (SPEI), Standardized Precipitation Index (SPI), and Standardized Precipitation Drought Index (SPDI)). Our results suggest that—irrespective of drought index and tree species—tree-ring width shows a stronger response to interannual variability of drought, compared to the greenness and the NPP. In comparison to other drought indices (e.g., PDSI), and our results demonstrate that multi-scalar drought indices (e.g., SPI, SPEI) are more advantageous in monitoring drought impacts on tree-ring growth, maximum greenness, and NPP. This finding suggests that multi-scalar indices are more appropriate for monitoring and modelling forest drought in peninsular Spain and the Balearic Islands.

Description: Forests, Vol. 9, Pages 525: Effects of Stand Structure, Browsing, and Biophysical Conditions on Regeneration Following Mountain Pine Beetle in Mixed Lodgepole Pine and Aspen Forests of the Southern Rockies Forests doi: 10.3390/f9090525 Authors: Kristen A. Pelz Frederick W. Smith Aspen (Populus tremuloides) and lodgepole pine (Pinus contorta var. latifolia) co-occur in the southern Rocky Mountains (USA), where mountain pine beetle (MPB, Dendroctonus ponderosae) has caused extensive lodgepole pine mortality since the late 1990s. Both species excel in post-disturbance high-light environments, but lodgepole pine has generally been thought to establish poorly on undisturbed seedbeds, and aspen suckering may be inhibited by intact aspen overstory. We ask whether lodgepole pine and aspen will regenerate in sufficient quantities to revegetate these forests. We visited a random sample of aspen and lodgepole pine stands across the affected landscape in northern Colorado and southern Wyoming to measure regeneration and overstory mortality. Lodgepole pine regeneration is occurring in 85% of stands, and most stands have >550 stems ha−1. The median aspen sucker density was 6175 stems ha−1. Surprisingly, neither lodgepole pine nor aspen regeneration density was related to overstory mortality level. Animal damage is currently affecting aspen in these forests. Over 50% of stands had damage to 60% or more of their suckers, but 30% of stands had <20% of their stems damaged. Browsed stems were significantly shorter for their ages and were shorter than the 2.5-m height threshold for possible elk browsing. However, the results suggest that sufficient quantities of down lodgepole pine may protect aspen from damage and allow aspen to successfully recruit to the overstory. Multiple regression analysis showed that down lodgepole pine basal area, followed by browsing pressure, were the most important predictors of sucker height and the proportion of suckers browsed. Although 15% of stands had no lodgepole pine regeneration, aspen and lodgepole pine forests are generally regenerating despite animal browsing on aspen. This study is the first to present a regional perspective on regeneration in MPB-affected lodgepole pine and aspen forests, and overall, intervention does not seem necessary to ensure a mix of both species in the future.

Description: Forests, Vol. 9, Pages 528: Drought Influence on Forest Plantations in Zululand, South Africa, Using MODIS Time Series and Climate Data Forests doi: 10.3390/f9090528 Authors: Sifiso Xulu Kabir Peerbhay Michael Gebreslasie Riyad Ismail South Africa has a long history of recurrent droughts that have adversely affected its economic performance. The recent 2015 drought has been declared the most serious in 26 years and impaired key agricultural sectors including the forestry sector. Research on the forests’ responses to drought is therefore essential for management planning and monitoring. The effects of the latest drought on the forests in South Africa have not been studied and are uncertain. The study reported here addresses this gap by using Moderate Resolution Imaging Spectroradiometer (MODIS)-derived normalized difference vegetation index (NDVI) and precipitation data retrieved and processed using the JavaScript code editor in the Google Earth Engine (GEE) and the corresponding normalized difference infrared index (NDII), Palmer drought severity index (PDSI), and El Niño time series data for KwaMbonambi, northern Zululand, between 2002 and 2016. The NDVI and NDII time series were decomposed using the Breaks for Additive Seasonal and Trend (BFAST) method to establish the trend and seasonal variation. Multiple linear regression and Mann–Kendall tests were applied to determine the association of the NDVI and NDII with the climate variables. Plantation trees displayed high NDVI values (0.74–0.78) from 2002 to 2013; then, they decreased sharply to 0.64 in 2015. The Mann–Kendall trend test confirmed a negative significant (p = 0.000353) trend between 2014 and 2015. This pattern was associated with a precipitation deficit and low NDII values during a strong El Niño phase. The PDSI (−2.6) values indicated severe drought conditions. The greening decreased in 2015, with some forest remnants showing resistance, implying that the tree species had varying sensitivity to drought. We found that the plantation trees suffered drought stress during 2015, although it seems that the trees began to recover, as the NDVI signals rose in 2016. Overall, these results demonstrated the effective use of the NDVI- and NDII-derived MODIS data coupled with climatic variables to provide insights into the influence of drought on plantation trees in the study area.

Description: Algorithms, Vol. 11, Pages 130: Numerical Modeling of Wave Disturbances in the Process of Ship Movement Control Algorithms doi: 10.3390/a11090130 Authors: Piotr Borkowski The article presents a numerical model of sea wave generation as an implementation of the stochastic process with a spectrum of wave angular velocity. Based on the wave spectrum, a forming filter is determined, and its input is fed with white noise. The resulting signal added to the angular speed of a ship represents disturbances acting on the ship’s hull as a result of wave impact. The model was used for simulation tests of the influence of disturbances on the course stabilization system of the ship.

Description: Forests, Vol. 9, Pages 533: Rethinking Fuelwood: People, Policy and the Anatomy of a Charcoal Supply Chain in a Decentralizing Peru Forests doi: 10.3390/f9090533 Authors: Aoife Bennett Peter Cronkleton Mary Menton Yadvinder Malhi In Peru, as in many developing countries, charcoal is an important source of fuel. We examine the commercial charcoal commodity chain from its production in Ucayali, in the Peruvian Amazon, to its sale in the national market. Using a mixed-methods approach, we look at the actors involved in the commodity chain and their relationships, including the distribution of benefits along the chain. We outline the obstacles and opportunities for a more equitable charcoal supply chain within a multi-level governance context. The results show that charcoal provides an important livelihood for most of the actors along the supply chain, including rural poor and women. We find that the decentralisation process in Peru has implications for the formalisation of charcoal supply chains, a traditionally informal, particularly related to multi-level institutional obstacles to equitable commerce. This results in inequity in the supply chain, which persecutes the poorest participants and supports the most powerful actors.

Description: Forests, Vol. 9, Pages 531: Intersectoral and Intermunicipal Cooperation as a Tool for Supporting Local Economic Development: Prospects for the Forest and Wood-Based Sector in Poland Forests doi: 10.3390/f9090531 Authors: Leszek Wanat Tomasz Potkański Jan Chudobiecki Elżbieta Mikołajczak Katarzyna Mydlarz Intersectoral and intermunicipal cooperation are still underdeveloped spheres of public and economic development policies. This also applies to the natural economy to a large extent. Scientific discussions are invariably focused on pro-competitive activities, the economic efficiency of which is not always sufficient. In this paper the authors attempt to identify factors leading to cooperation between local government authorities and economic entities focusing on the forestry and wood-based sector in Poland. These processes were analyzed within the framework of the Spatial Economics and New Institutional Economy, both in the theoretical and practical context. The aim of the research was to identify the ability to create intersectoral and intermunicipal partnerships in already existing and newly established functional areas, as this may determine the development of the forestry and wood-based industry.

Description: Algorithms, Vol. 11, Pages 132: Study of Precipitation Forecast Based on Deep Belief Networks Algorithms doi: 10.3390/a11090132 Authors: Jinglin Du Yayun Liu Zhijun Liu Due to the impact of weather forecasting on global human life, and to better reflect the current trend of weather changes, it is necessary to conduct research about the prediction of precipitation and provide timely and complete precipitation information for climate prediction and early warning decisions to avoid serious meteorological disasters. For the precipitation prediction problem in the era of climate big data, we propose a new method based on deep learning. In this paper, we will apply deep belief networks in weather precipitation forecasting. Deep belief networks transform the feature representation of data in the original space into a new feature space, with semantic features to improve the predictive performance. The experimental results show, compared with other forecasting methods, the feasibility of deep belief networks in the field of weather forecasting.

Description: Forests, Vol. 9, Pages 540: Influence of Natural and Anthropogenic Linear Canopy Openings on Forest Structural Patterns Investigated Using LiDAR Forests doi: 10.3390/f9090540 Authors: Udayalakshmi Vepakomma Daniel D. Kneeshaw Louis De Grandpré In much of the commercial boreal forest, dense road networks and energy corridors have been developed to access natural resources with unintended and poorly understood effects on surrounding forest structure. In this study, we compare the effects of anthropogenic and natural linear openings on surrounding forest conditions in black spruce stands (gap fraction, tree and sapling height, and density). Forest structure within a 100 m band around the edges of anthropogenic (roads and power lines), natural linear openings (streams), and a reference black spruce forest was measured by identifying individual stems and canopy gaps on recent high density airborne LiDAR canopy height models. CUSUM curves were used to assess the distance of edge influence. Forests surrounding anthropogenic openings were found to be gappier, less dense, and have smaller trees than those around natural openings. Forests were denser around natural and anthropogenic linear openings than in the reference forest with edge effects observed up to 24–75 m and 18–54 m, respectively, into the forest. A high density of saplings in the gappier forests surrounding anthropogenic openings may eventually lead to a higher forest biomass in the zone area surrounding roads as is currently observed around natural openings.

Description: Algorithms, Vol. 11, Pages 131: An efficient algorithm to determine probabilistic bisimulation Algorithms doi: 10.3390/a11090131 Authors: J.F. Groote H.J. Rivera Verduzco E.P. de Vink We provide an algorithm to efficiently compute bisimulation for probabilistic labeled transition systems, featuring non-deterministic choice as well as discrete probabilistic choice. The algorithm is linear in the number of transitions and logarithmic in the number of states, distinguishing both action states and probabilistic states, and the transitions between them. The algorithm improves upon the proposed complexity bounds of the best algorithm addressing the same purpose so far by Baier, Engelen and Majster-Cederbaum (Journal of Computer and System Sciences 60:187–231, 2000). In addition, experimentally, on various benchmarks, our algorithm performs rather well; even on relatively small transition systems, a performance gain of a factor 10,000 can be achieved.

Description: Forests, Vol. 9, Pages 542: Forest Carbon Sequestration, Pathogens and the Costs of the EU’s 2050 Climate Targets Forests doi: 10.3390/f9090542 Authors: Ing-Marie Gren Abenezer Aklilu Katarina Elofsson Carbon sequestration is suggested as a low-cost option for climate change mitigation, the functioning of which can be threatened by pathogen infestation. This study calculates the effects of infectious pathogens on the cost of achieving the EU’s 2050 climate targets by combining the so-called production function method with the replacement cost method. Pathogens are then assumed to affect carbon sink enhancement through the impact on productivity of forest land, and carbon sequestration is valued as the replacement for costly reductions in emissions from fossil fuels for reaching the EU’s 2050 climate targets. To this end, we have constructed a numerical dynamic optimization model with a logistic forest growth function, a simple allometric representation of the spread of pathogens in forests, and reductions in emissions from fossil fuels. The results show that the annual value of forest carbon sequestration ranges between approximately 6.4 and 14.9 billion Euros, depending on the impact and dispersal of pathogens. Relatively large values are obtained for countries with large emissions from fossil fuels, e.g., Germany, France, Spain and Italy, which also face costs of pathogen together with countries with large forest area, such as Romania.

Description: Forests, Vol. 9, Pages 543: Erratum: Drössler, L., et al. Over- and Underyielding in Time and Space in Experiments with Mixed Stands of Scots Pine and Norway Spruce. Forests 2018, 9, 495. Forests doi: 10.3390/f9090543 Authors: Forests Editorial Office After publication of the research paper [1], the Forests editorial office noticed errors and wish to make the following corrections.[...]

Description: Forests, Vol. 9, Pages 546: Effect of Stem Diameter, Genetics, and Wood Properties on Stem Cracking in Norway Spruce Forests doi: 10.3390/f9090546 Authors: Pauls Zeltiņš Juris Katrevičs Arnis Gailis Tiit Maaten Endijs Bāders Āris Jansons The choice of seed material (genetics) is one of the tools that can improve adaptation to the changing climate. Insufficient adaptation can result in a number of potential risks, including stem cracking. The goal of this study is to assess the influence of genetics and wood properties on stem cracking in Norway spruce (Picea abies Karst). The study was conducted on a 35-year-old provenance trial in Eastern Latvia. Stem cracks were assessed using a six-score scale. Tree-ring parameters, i.e., latewood proportion, maximum and mean density, mean earlywood, and latewood density were analysed. The overall incidence of stem cracking was 23.5%, varying between 0% and 79% at a family mean level. Heritability of stem cracking was low, ca., two times lower than for the diameter at breast height (DBH): h2 = 0.09 and 0.21, respectively. There were non-significant family and provenance effects on the occurrence of stem cracks, and weak family mean correlations between DBH, and the proportion of trees with any stem cracks or severe stem cracks. Overall, larger trees were more prone to cracking irrespective of provenance or family. Cracked trees had lower wood density parameters than unaffected trees, yet the latewood proportion was similar. Silvicultural treatments or selection to improve wood density could be suggested to reduce the risk of stem cracking.

Description: Forests, Vol. 9, Pages 547: Theory-of-Change Development for the Evaluation of Forest Stewardship Council Certification of Sustained Timber Yields from Natural Forests in Indonesia Forests doi: 10.3390/f9090547 Authors: Claudia Romero Francis E. Putz To illustrate the importance of theories-of-change (ToCs) for evaluation of conservation interventions, we consider the global ToC from the Forest Stewardship Council (FSC) and then develop a more explicit ToC focused on the sustained timber yield (STY) aspiration for natural forest management in Indonesia. We use these ToCs to consider certification implementation processes vis-à-vis indicators for STY extracted from FSC’s Indonesian Stewardship Standard that mentions STY explicitly in 45 and implicitly in 21 of 237 indicators. Analysis of 38 audit reports about 23 enterprises (2001–2017) revealed that only 77 of 504 major non-conformities assigned by auditors addressed STY. This apparent lack of attention to STY is surprising given the exhaustion of timber stocks in many production forests and the closure of many forest enterprises over the past two decades, but our ToC reveals numerous unsatisfied and unsatisfiable assumptions in certification that preclude detection of unsustainable harvests. Furthermore, compliance with governmental regulations on harvest intensities does not allow full timber recovery. To sustain yields, logging intensities need to be reduced and/or silvicultural treatments applied to increase yields, both of which reduce short-term profits. Declining yields might be accepted if the capacity of logged forests to grow timber is not impaired, but forest abandonment due to timber stock depletion is worrisome if it fosters illegal forest conversion.

Description: Future Internet, Vol. 10, Pages 87: Log Likelihood Ratio Based Relay Selection Scheme for Amplify and Forward Relaying with Three State Markov Channel Future Internet doi: 10.3390/fi10090087 Authors: Manish Sahajwani Alok Jain Radheyshyam Gamad This paper presents log likelihood ratio (LLR) based relay selection scheme for a cooperative amplify and forward relaying system. To evaluate the performance of the aforementioned system model, a three state Markov chain based fading environment has been presented to toggle among Rayleigh, Rician, and Nakagami-m fading environment. A simulation is carried out while assuming that there is no possibility of direct transmission from the source and destination terminal. Simulation results on the basis of Bit Error Rate (BER), Instantaneous Channel Capacity, and Outage probability have been presented and compared for different cases. In each case, the best performance of the proposed algorithm is obtained with a Binary Phase Shift Keying (BPSK) modulation scheme.

Description: Algorithms, Vol. 11, Pages 136: Mixed Order Fractional Observers for Minimal Realizations of Linear Time-Invariant Systems Algorithms doi: 10.3390/a11090136 Authors: Manuel A. Duarte-Mermoud Javier A. Gallegos Norelys Aguila-Camacho Rafael Castro-Linares Adaptive and non-adaptive minimal realization (MR) fractional order observers (FOO) for linear time-invariant systems (LTIS) of a possibly different derivation order (mixed order observers, MOO) are studied in this paper. Conditions on the convergence and robustness are provided using a general framework which allows observing systems defined with any type of fractional order derivative (FOD). A qualitative discussion is presented to show that the derivation orders of the observer structure and for the parameter adjustment are relevant degrees of freedom for performance optimization. A control problem is developed to illustrate the application of the proposed observers.

Description: Forests, Vol. 9, Pages 552: Subwatershed-Level Lodgepole Pine Attributes Associated with a Mountain Pine Beetle Outbreak Forests doi: 10.3390/f9090552 Authors: Howard Williams Sharon M. Hood Christopher R. Keyes Joel M. Egan José Negrón Mountain pine beetle (Dendroctonus ponderosae Hopkins; MPB) is an aggressive bark beetle that attacks numerous Pinus spp. and causes extensive mortality in lodgepole pine (Pinus contorta Douglas ex Loudon; LPP) forests in the western United States and Canada. We used pre-outbreak LPP attributes, cumulative MPB attack severity, and areal extent of mortality data to identify subwatershed-scale forest attributes associated with severe MPB-caused tree mortality that occurred across the Northern Rockies, USA from 1999–2014. We upscaled stand-level data to the subwatershed scale to allow identification of large LPP areas vulnerable to MPB. The highest mortality occurred in subwatersheds where LPP mean basal area was greater than 11.5 m2 ha−1 and LPP quadratic mean diameter was greater than or equal to 18 cm. A coarse assessment of federally-owned LPP-dominated forestland in the analysis area indicated about 42% could potentially be silviculturally treated. Silvicultural management may be a suitable option for many LPP forests, and our hazard model can be used to identify subwatersheds with LPP attributes associated with high susceptibility to MPB across landscape spatial scales. Identifying highly susceptible subwatersheds can help prioritize general areas for potential treatments, especially where spatially extensive areas of contiguous, highly susceptible LPP occur.

Description: Forests, Vol. 9, Pages 559: Effect of Species Complementarity on Financial Return in Mixed Stands of European Beech and Scots Pine in Northern Spain Forests doi: 10.3390/f9090559 Authors: Fernando García-Robredo The research on mixed-species forestry has rapidly increased in recent decades because there is a growing interest in these types of stands for environmental reasons. Their positive influence on ecosystem biodiversity, stability and resilience, as well as their role in the new challenge brought up by the adaptation to global change, have been the object of many research works. However, the economic implications of mixed-species forest management have not deserved the same attention. The objective of this work is to study the effect of species interactions on productivity, and to economically assess this effect. This research is focused on the analysis of financial return and risk in even aged mixed stands of Pinus sylvestris and Fagus sylvatica in Northern Spain. Growth and yield projections for monospecific and mixed stands of Scots pine and European beech were made by means of a previous model developed from a set of the Spanish National Forest Inventory plots in the region of Navarre. Data from yield tables for both species were used. The effect of species proportion on total stand yield was assessed and transgressive overyielding was found for some mixing ratios. A data series on average stumpage price for both species in Spain over a 29-year period was compiled and the joint probability distribution of price data was used to generate 500 price scenarios. Different management alternatives based on species proportion and rotation age were considered and evaluated in terms of profitability and risk. Some management recommendations can be derived from the results obtained, which point at an optimum mixing ratio from 30% to 40% Scots pine and 70% to 60% European beech.

Description: Algorithms, Vol. 11, Pages 138: Are Markets Truly Efficient? Experiments Using Deep Learning Algorithms for Market Movement Prediction Algorithms doi: 10.3390/a11090138 Authors: Sanjiv Das Karthik Mokashi Robbie Culkin We examine the use of deep learning (neural networks) to predict the movement of the S&P 500 Index using past returns of all the stocks in the index. Our analysis finds that the future direction of the S&P 500 index can be weakly predicted by the prior movements of the underlying stocks in the index, but not strongly enough to reject market efficiency. Decomposition of the prediction error indicates that most of the lack of predictability comes from randomness and only a little from nonstationarity. We believe this is the first test of S&P 500 market efficiency that uses a very large information set, and it extends the domain of weak-form market efficiency tests.

Description: Forests, Vol. 9, Pages 568: EU Legislation on Forest Plant Health: An Overview with a Focus on Fusarium circinatum Forests doi: 10.3390/f9090568 Authors: Anna Maria Vettraino Roel Potting Rosa Raposo The increase in arrivals of new forest pests highlights the need for effective phytosanitary legislation and measures. This paper introduces legislation targeted at prevention and management of potential introductions of forest pests and pathogens. An overview is given on plant health regulations on global and regional level with detailed information on the situation in the European Union (EU). The current and new European legislation is discussed, and a particular focus is given on eradication and contingency plans for Fusarium circinatum. We identified key aspects relevant for the improvement of the efficacy of measures aimed to prevent alien pests.

Description: Forests, Vol. 9, Pages 573: Assessing the Spatial and Spatio-Temporal Distribution of Forest Species via Bayesian Hierarchical Modeling Forests doi: 10.3390/f9090573 Authors: Óscar Rodríguez de Rivera Antonio López-Quílez Marta Blangiardo Climatic change is expected to affect forest development in the short term, as well as the spatial distribution of species in the long term. Species distribution models are potentially useful tools for guiding species choices in reforestation and forest management prescriptions to address climate change. The aim of this study is to build spatial and spatio-temporal models to predict the distribution of four different species present in the Spanish Forest Inventory. We have compared the different models and showed how accounting for dependencies in space and time affect the relationship between species and environmental variables.

Description: Algorithms, Vol. 11, Pages 140: Complexity of Hamiltonian Cycle Reconfiguration Algorithms doi: 10.3390/a11090140 Authors: Asahi Takaoka The Hamiltonian cycle reconfiguration problem asks, given two Hamiltonian cycles C 0 and C t of a graph G, whether there is a sequence of Hamiltonian cycles C 0 , C 1 , … , C t such that C i can be obtained from C i − 1 by a switch for each i with 1 ≤ i ≤ t , where a switch is the replacement of a pair of edges u v and w z on a Hamiltonian cycle with the edges u w and v z of G, given that u w and v z did not appear on the cycle. We show that the Hamiltonian cycle reconfiguration problem is PSPACE-complete, settling an open question posed by Ito et al. (2011) and van den Heuvel (2013). More precisely, we show that the Hamiltonian cycle reconfiguration problem is PSPACE-complete for chordal bipartite graphs, strongly chordal split graphs, and bipartite graphs with maximum degree 6. Bipartite permutation graphs form a proper subclass of chordal bipartite graphs, and unit interval graphs form a proper subclass of strongly chordal graphs. On the positive side, we show that, for any two Hamiltonian cycles of a bipartite permutation graph and a unit interval graph, there is a sequence of switches transforming one cycle to the other, and such a sequence can be obtained in linear time.

Description: Algorithms, Vol. 11, Pages 141: Generalized Paxos Made Byzantine (and Less Complex) Algorithms doi: 10.3390/a11090141 Authors: Miguel Pires Srivatsan Ravi Rodrigo Rodrigues One of the most recent members of the Paxos family of protocols is Generalized Paxos. This variant of Paxos has the characteristic that it departs from the original specification of consensus, allowing for a weaker safety condition where different processes can have a different views on a sequence being agreed upon. However, much like the original Paxos counterpart, Generalized Paxos does not have a simple implementation. Furthermore, with the recent practical adoption of Byzantine fault tolerant protocols in the context of blockchain protocols, it is timely and important to understand how Generalized Paxos can be implemented in the Byzantine model. In this paper, we make two main contributions. First, we attempt to provide a simpler description of Generalized Paxos, based on a simpler specification and the pseudocode for a solution that can be readily implemented. Second, we extend the protocol to the Byzantine fault model, and provide the respective correctness proof.

Description: Forests, Vol. 9, Pages 578: 25 Years of Criteria and Indicators for Sustainable Forest Management: How Intergovernmental C&I Processes Have Made a Difference Forests doi: 10.3390/f9090578 Authors: Stefanie Linser Bernhard Wolfslehner Simon R. J. Bridge David Gritten Steven Johnson Tim Payn Kit Prins Rastislav Raši Guy Robertson Growing concern about forest degradation and loss, combined with the political impetus supplied by the Earth Summit in 1992, led to the establishment of eleven intergovernmental, regional, and international forest-related processes focused on the use of criteria and indicators (C&I) for sustainable forest management (SFM). Up to 171 countries have participated in these processes to apply C&I frameworks as a tool for data collection, monitoring, assessment, and reporting on SFM and on achieving various forest-related UN Sustainable Development Goals. Based on an expert survey and literature analysis we identify six interlinked impact domains of C&I efforts: (1) enhanced discourse and understanding of SFM; (2) shaped and focused engagement of science in SFM; (3) improved monitoring and reporting on SFM to facilitate transparency and evidence-based decision-making; (4) strengthened forest management practices; (5) facilitated assessment of progress towards SFM goals; and (6) improved forest-related dialog and communication. We conclude that the 25-year history of C&I work in forestry has had significant positive impacts, though challenges do remain for the implementation of C&I and progress towards SFM. The work should be continued and carried over to other sectors to advance sustainability goals more broadly.

Description: Forests, Vol. 9, Pages 576: Effect of Rotation Age and Thinning Regime on Visual and Structural Lumber Grades of Douglas-Fir Logs Forests doi: 10.3390/f9090576 Authors: Eini C. Lowell Eric C. Turnblom Jeff M. Comnick CL Huang Douglas-fir, the most important timber species in the Pacific Northwest, US (PNW), has high stiffness and strength. Growing it in plantations on short rotations since the 1980s has led to concerns about the impact of juvenile/mature wood proportion on wood properties. Lumber recovered from four sites in a thinning trial in the PNW was analyzed for relationships between thinning regime and lumber grade yield. Linear mixed-effects models were developed for understanding how rotation age and thinning affect the lumber grade yield. Log small-end diameter was overall the most important for describing the presence of an appearance grade, generally exhibiting an indirect relationship with the lower quality grades. Stand Quadratic Mean Diameter (QMD) was found to be the next most uniformly important predictor, its influence (positive or negative) depending on the lumber grade. For quantity within a grade, as log small-end diameter increased, the quantity of the highest grade increased, while decreasing the quantity of the lower grades differentially. Other tree and stand attributes were of varying importance among grades, including stand density, tree height, and stand slope, but logically depicted the tradeoffs or rebalancing among the grades as the tree and stand characteristics change. Structural lumber grade presence was described best by acoustic wave flight time, log position (decreasing presence in upper logs), and an increasing presence with rotation age. A smaller set of variables proved useful for describing quantity within a structural grade. Forest managers can use these results in planning to best capture value in harvesting, allowing them to direct raw materials (logs) to appropriate manufacturing facilities given market demand.

Description: Algorithms, Vol. 11, Pages 51: A Crowd Cooperative Spectrum Sensing Algorithm Using a Non-Ideal Channel Algorithms doi: 10.3390/a11040051 Authors: Xinxin Lv Qi Zhu Spectrum sensing is the prerequisite of the realization of cognitive radio. So it is a significant part of cognitive radio. In order to stimulate the SUs to sense the spectrum, we combine the incentive mechanism of crowd-sensing with cooperative spectrum sensing effectively, and put forward a crowd cooperative spectrum sensing algorithm with optimal utility of secondary users (SUs) under non-ideal channel which we define SUs’ utility expectation functions related to rewards, sensing time and transmission power. Then, we construct the optimization problem of maximizing the utilities of SUs by optimizing the sensing time and the transmission power, and prove that this problem is a convex optimization problem. The optimal sensing time and transmission power are obtained by using the Karush-Kuhn-Tucker (KKT) conditions. The numerical simulation results show that the spectrum detection performance of algorithm, which we put forward, is improved.

Description: Algorithms, Vol. 11, Pages 54: Dual Market Facility Network Design under Bounded Rationality Algorithms doi: 10.3390/a11040054 Authors: D. G. Mogale Geet Lahoti Shashi Bhushan Jha Manish Shukla Narasimha Kamath Manoj Kumar Tiwari A number of markets, geographically separated, with different demand characteristics for different products that share a common component, are analyzed. This common component can either be manufactured locally in each of the markets or transported between the markets to fulfill the demand. However, final assemblies are localized to the respective markets. The decision making challenge is whether to manufacture the common component centrally or locally. To formulate the underlying setting, a newsvendor modeling based approach is considered. The developed model is solved using Frank-Wolfe linearization technique along with Benders’ decomposition method. Further, the propensity of decision makers in each market to make suboptimal decisions leading to bounded rationality is considered. The results obtained for both the cases are compared.

Description: Future Internet, Vol. 10, Pages 36: Dynamic Linked Data: A SPARQL Event Processing Architecture Future Internet doi: 10.3390/fi10040036 Authors: Luca Roffia Paolo Azzoni Cristiano Aguzzi Fabio Viola Francesco Antoniazzi Tullio Salmon Cinotti This paper presents a decentralized Web-based architecture designed to support the development of distributed, dynamic, context-aware and interoperable services and applications. The architecture enables the detection and notification of changes over the Web of Data by means of a content-based publish-subscribe mechanism where the W3C SPARQL 1.1 Update and Query languages are fully supported and used respectively by publishers and subscribers. The architecture is built on top of the W3C SPARQL 1.1 Protocol and introduces the SPARQL 1.1 Secure Event protocol and the SPARQL 1.1 Subscribe Language as a means for conveying and expressing subscription requests and notifications. The reference implementation of the architecture offers to developers a design pattern for a modular, scalable and effective application development.

Description: Forests, Vol. 9, Pages 221: Interaction between Ailanthus altissima and Native Robinia pseudoacacia in Early Succession: Implications for Forest Management Forests doi: 10.3390/f9040221 Authors: Erik T. Nilsen Cynthia D. Huebner David E. Carr Zhe Bao The goal of this study was to discover the nature and intensity of the interaction between an exotic invader Ailanthus altissima (Mill.) Swingle and its coexisting native Robinia pseudoacacia L. and consider management implications. The study occurred in the Mid-Appalachian region of the eastern United States. Ailanthus altissima can have a strong negative influence on community diversity and succession due to its allelopathic nature while R. pseudoacacia can have a positive effect on community diversity and succession because of its ability to fix nitrogen. How these trees interact and the influence of the interaction on succession will have important implications for forests in many regions of the world. An additive-replacement series common garden experiment was established to identify the type and extent of interactions between these trees over a three-year period. Both A. altissima and R. pseudoacacia grown in monoculture were inhibited by intraspecific competition. In the first year, A. altissima grown with R. pseudoacacia tended to be larger than A. altissima in monoculture, suggesting that R. pseudoacacia may facilitate the growth of A. altissima at the seedling stage. After the second year, R. pseudoacacia growth decreased as the proportion of coexisting A. altissima increased, indicating inhibition of R. pseudoacacia by A. altissima even though the R. pseudoacacia plants were much larger aboveground than the A. altissima plants. In early successional sites A. altissima should be removed, particularly in the presence of R. pseudoacacia in order to promote long-term community succession.

Description: Forests, Vol. 9, Pages 223: Sustainable Forest Bioenergy Development Strategies in Indochina: Collaborative Effort to Establish Regional Policies Forests doi: 10.3390/f9040223 Authors: Viktor J. Bruckman Maliwan Haruthaithanasan Raymond O. Miller Toru Terada Anna-Katharina Brenner Florian Kraxner David Flaspohler We conducted a feasibility study in Indochina (Cambodia, Laos, Myanmar, Thailand, and Vietnam) with the aim of promoting biomass and bioenergy markets, technology transfer, rural development, and income generation. Policy development is guided by the International Union of Forest Research Institutions (IUFRO) Task Force “Sustainable Forest Bioenergy Network”. In this paper, we highlight the achievements up to now and present results of a multi-stakeholder questionnaire in combination with a quantitative analysis of the National Bioenergy Development Plans (NBDPs). We found a gap between official documents and working group assessments. NBDPs are focused on the market development, technology transfer, and funding possibilities of a regional bioenergy strategy, while the respondents of a questionnaire (working groups) favored more altruistic goals, i.e., sustainable resource management, environmental protection and climate change mitigation, generation of rural income, and community involvement, etc. We therefore suggest the following measures to ensure regulations that support the original aims of the network (climate change mitigation, poverty alleviation, sustainable resource use, and diversification of energy generation): (i) Consideration of science-based evidence for drafting bioenergy policies, particularly in the field of biomass production and harvesting; (ii) invitation of stakeholders representing rural communities to participate in this process; (iii) development of sustainability criteria; (iv) feedback cycles ensuring more intensive discussion of policy drafts; (v) association of an international board of experts to provide scientifically sound feedback and input; and (vi) establishment of a local demonstration region, containing various steps in the biomass/bioenergy supply chain including transboundary collaboration in the ACMECS region.

Description: Forests, Vol. 9, Pages 222: First-Year Vitality of Reforestation Plantings in Response to Herbivore Exclusion on Reclaimed Appalachian Surface-Mined Land Forests doi: 10.3390/f9040222 Authors: Zachary J. Hackworth John M. Lhotka John J. Cox Christopher D. Barton Matthew T. Springer Conventional Appalachian surface-mine reclamation techniques repress natural forest regeneration, and tree plantings are often necessary for reforestation. Reclaimed Appalachian surface mines harbor a suite of mammal herbivores that forage on recently planted seedlings. Anecdotal reports across Appalachia have implicated herbivory in the hindrance and failure of reforestation efforts, yet empirical evaluation of herbivory impacts on planted seedling vitality in this region remains relatively uninitiated. First growing-season survival, height growth, and mammal herbivory damage of black locust (Robinia pseudoacacia L.), shortleaf pine (Pinus echinata Mill.), and white oak (Quercus alba L.) are presented in response to varying intensities of herbivore exclusion. Seedling survival was generally high, and height growth was positive for all species. The highest herbivory incidence of all tree species was observed in treatments offering no herbivore exclusion. While seedling protectors lowered herbivory incidence compared with no exclusion, full exclusion treatments resulted in the greatest reduction of herbivore damage. Although herbivory from rabbits, small mammals, and domestic animals was observed, cervids (deer and elk) were responsible for 95.8% of all damaged seedlings. This study indicates that cervids forage heavily on planted seedlings during the first growing-season, but exclusion is effective at reducing herbivory.

Description: Forests, Vol. 9, Pages 225: A Participatory Approach to Evaluating Strategies for Forest Carbon Mitigation in British Columbia Forests doi: 10.3390/f9040225 Authors: Guillaume Peterson St-Laurent George Hoberg Stephen R. J. Sheppard To be successful, actions for mitigating climate change in the forest and forest sector will not only need to be informed by the best available science, but will also require strong public and/or political acceptability. This paper presents the results of a novel analytical-deliberative engagement process that brings together stakeholders and Indigenous Peoples in participatory workshops in the interior and coastal regions of British Columbia (BC) to evaluate a set of potential forest carbon mitigation alternatives. In particular, this study examines what objectives are prioritized by stakeholders and Indigenous Peoples when discussing forest carbon mitigation in BC’s forests, as well as the perceived effectiveness of, and levels of support for, six forest-based carbon mitigation strategies. We start by describing the methodological framework involving two series of workshops. We then describe the results from the first round of workshops where participants identified 11 objectives that can be classified into four categories: biophysical, economic, social, and procedural. Afterwards, we discuss the second series of workshops, which allowed participants to evaluate six climate change mitigation strategies against the objectives previously identified, and highlight geographical differences, if any, between BC’s coastal and interior regions. Our results effectively illustrate the potential and efficacy of our novel methodology in informing a variety of stakeholders in different regions, and generating consistent results with a surprising degree of consensus on both key objectives and preference for mitigation alternatives. We conclude with policy recommendations on how to consider various management objectives during the design and implementation of forest carbon mitigation strategies.

Description: Forests, Vol. 9, Pages 224: The Impact of Green Space Layouts on Microclimate and Air Quality in Residential Districts of Nanjing, China Forests doi: 10.3390/f9040224 Authors: Liyan Rui Riccardo Buccolieri Zhi Gao Wowo Ding Jialei Shen This study numerically investigates the influence of different vegetation types and layouts on microclimate and air quality in residential districts based on the morphology and green layout of Nanjing, China. Simulations were performed using Computational Fluid Dynamics and the microclimate model ENVI-met. Four green indices, i.e., the green cover ratio, the grass and shrub cover ratio, the ecological landscaping plot ratio and the landscaping isolation index, were combined to evaluate thermal and wind fields, as well as air quality in district models. Results show that under the same green cover ratio (i.e., the same quantity of all types of vegetation), the reduction of grass and shrub cover ratio (i.e., the quantity of grass and shrubs), replaced by trees, has an impact, even though small, on thermal comfort, wind speed and air pollution, and increases the leisure space for occupants. When trees are present, a low ecological landscaping plot ratio (which expresses the weight of carbon dioxide absorption and is larger in the presence of trees) is preferable due to a lower blocking effect on wind and pollutant dispersion. In conjunction with a low landscaping plot ratio, a high landscaping isolation index (which means a distributed structure of vegetation) enhances the capability of local cooling and the general thermal comfort, decreasing the average temperature up to about 0.5 °C and the average predicted mean vote (PMV) up to about 20% compared with the non-green scenario. This paper shows that the relationship vegetation-microclimate-air quality should be analyzed taking into account not only the total area covered by vegetation but also its layout and degree of aggregation.

Description: Algorithms, Vol. 11, Pages 52: Introduction to Reconfiguration Algorithms doi: 10.3390/a11040052 Authors: Naomi Nishimura Reconfiguration is concerned with relationships among solutions to a problem instance, where the reconfiguration of one solution to another is a sequence of steps such that each step produces an intermediate feasible solution. The solution space can be represented as a reconfiguration graph, where two vertices representing solutions are adjacent if one can be formed from the other in a single step. Work in the area encompasses both structural questions (Is the reconfiguration graph connected?) and algorithmic ones (How can one find the shortest sequence of steps between two solutions?) This survey discusses techniques, results, and future directions in the area.

Description: Forests, Vol. 9, Pages 229: Effects of Near Natural Forest Management on Soil Greenhouse Gas Flux in Pinus massoniana (Lamb.) and Cunninghamia lanceolata (Lamb.) Hook. Plantations Forests doi: 10.3390/f9050229 Authors: Angang Ming Yujing Yang Shirong Liu Hui Wang Yuanfa Li Hua Li You Nong Daoxiong Cai Hongyan Jia Yi Tao Dongjing Sun Greenhouse gases are the main cause of global warming, and forest soil plays an important role in greenhouse gas flux. Near natural forest management is one of the most promising options for improving the function of forests as carbon sinks. However, its effects on greenhouse gas emissions are not yet clear. It is therefore necessary to characterise the effects of near natural forest management on greenhouse gas emissions and soil carbon management in plantation ecosystems. We analysed the influence of near natural management on the flux of three major greenhouse gases (carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O)) in Pinus massoniana Lamb. and Cunninghamia lanceolata (Lamb.) Hook. plantations. The average emission rates of CO2 and N2O in the near natural plantations were higher than those in the corresponding unimproved pure plantations of P. massoniana and C. lanceolata, and the average absorption rate of CH4 in the pure plantations was lower than that in the near natural plantations. The differences in the CO2 emission rates between plantations could be explained by differences in the C:N ratio of the fine roots. The differences in the N2O emission rates could be attributed to differences in soil available N content and the C:N ratio of leaf litter, while the differences in CH4 uptake rate could be explained by differences in the C:N ratio of leaf litter only. Near natural forest management negatively affected the soil greenhouse gas emissions in P. massoniana and C. lanceolata plantations. The potential impact of greenhouse gas flux should be considered when selecting tree species for enrichment planting.

Description: Forests, Vol. 9, Pages 231: National REDD+ Implications for Tenured Indigenous Communities in Guyana, and Communities’ Impact on Forest Carbon Stocks Forests doi: 10.3390/f9050231 Authors: Han Overman Nathalie Butt Anthony R. Cummings Jeffrey B. Luzar José M. V. Fragoso Early project-level initiatives of ‘reducing emissions from deforestation and forest degradation’ (REDD+) have left a negative impression among many forest-dependent peoples (FDP) across the tropics. As countries move towards national-level implementation and results-based payments, it is timely to analyze the effects of ‘national REDD+’ on FDP. We use Guyana’s technically approved United Nations Forest Reference Emission Level (FREL) submission and Opt-In Mechanism to assess how fifteen indigenous communities with tenured forestland may financially benefit from national REDD+, and evaluate whether, and to what extent, Guyana forms a best-case scenario. In addition, we provide a first-time assessment whether field estimates of the average carbon density of mature forests managed by fifteen forest-dependent communities (beyond rotational farming lands) equals that of nearby unmanaged mature forest, as this could affect REDD+ payment levels. We conclude that, notwithstanding some pending issues, Guyana’s national REDD+ program could be very beneficial for FDP, even under a modest United States (US) $5 unit carbon price. We present economic evidence to support forest governance change domestically in sovereign developing countries that may ease FDP tenure and national REDD+ implementation. The average carbon density was locally substantially less in FDP-managed forest, but had little effect on the overall carbon stock of the titled forest area, and is considered modest when incorporating ecological and socioeconomic attributes. Partnerships with FDP when combined with advances in remote sensing could have potential for economic monitoring of forest emissions across the tropics.

Description: Forests, Vol. 9, Pages 235: Chainsaw-Carved Cavities Better Mimic the Thermal Properties of Natural Tree Hollows than Nest Boxes and Log Hollows Forests doi: 10.3390/f9050235 Authors: Stephen R. Griffiths Pia E. Lentini Kristin Semmens Simon J. Watson Linda F. Lumsden Kylie A. Robert The creation of supplementary habitats that effectively mimic the physical and thermal characteristics of natural tree hollows should be a key priority for landscape restoration and biodiversity offset programs. Here, we compare the thermal profiles of natural tree hollows with three types of artificial hollows designed for small marsupial gliders and tree-roosting insectivorous bats: (1) ‘chainsaw hollows’ carved directly into the trunks and branches of live trees, (2) ‘log hollows’, and (3) plywood nest boxes. Chainsaw hollows had thermal profiles that were similar to natural tree hollows: they were consistently warmer than ambient conditions at night, while remaining cooler than ambient during the day. In contrast, glider and bat boxes had the opposite pattern of heating and cooling, being slightly cooler than ambient at night and substantially hotter during the day. Glider log hollows had greater variation in internal temperatures compared to natural hollows and chainsaw hollows, but fluctuated less than glider boxes. Our results provide the first empirical evidence that artificial hollows carved directly into live trees can produce thermally stable supplementary habitats that could potentially buffer hollow-dependent fauna from weather extremes; whereas, poorly insulated plywood nest boxes produce lower-quality thermal environments. Together these findings provide positive impetus for stakeholders involved in conservation management and biodiversity offset programs to consider trialing chainsaw hollows in situations where target fauna require well-insulated supplementary habitats.

Description: Forests, Vol. 9, Pages 243: Composition and Structure of Forest Fire Refugia: What Are the Ecosystem Legacies across Burned Landscapes? Forests doi: 10.3390/f9050243 Authors: Garrett Meigs Meg Krawchuk Locations within forest fires that remain unburned or burn at low severity—known as fire refugia—are important components of contemporary burn mosaics, but their composition and structure at regional scales are poorly understood. Focusing on recent, large wildfires across the US Pacific Northwest (Oregon and Washington), our research objectives are to (1) classify fire refugia and burn severity based on relativized spectral change in Landsat time series; (2) quantify the pre-fire composition and structure of mapped fire refugia; (3) in forested areas, assess the relative abundance of fire refugia and other burn severity classes across forest composition and structure types. We analyzed a random sample of 99 recent fires in forest-dominated landscapes from 2004 to 2015 that collectively encompassed 612,629 ha. Across the region, fire refugia extent was substantial but variable from year to year, with an annual mean of 38% of fire extent and range of 15–60%. Overall, 85% of total fire extent was forested, with the other 15% being non-forest. In comparison, 31% of fire refugia extent was non-forest prior to the most recent fire, highlighting that mapped refugia do not necessarily contain tree-based ecosystem legacies. The most prevalent non-forest cover types in refugia were vegetated: shrub (40%), herbaceous (33%), and crops (18%). In forested areas, the relative abundance of fire refugia varied widely among pre-fire forest types (20–70%) and structural conditions (23–55%). Consistent with fire regime theory, fire refugia and high burn severity areas were inversely proportional. Our findings underscore that researchers, managers, and other stakeholders should interpret burn severity maps through the lens of pre-fire land cover, especially given the increasing importance of fire and fire refugia under global change.

Description: Forests, Vol. 9, Pages 242: Long-Term Effect of Prescribed Burning Regimes and Logging on Coarse Woody Debris in South-Eastern Australia Forests doi: 10.3390/f9050242 Authors: Mitchell G. Stares Luke Collins Bradley Law Kristine French Coarse woody debris (CWD) is vital within forest ecosystems for an array of fauna. Forest management practices, such as prescribed burning and logging, influence the creation or loss of CWD. We examined the effect of long-term prescribed burning and logging on (i) the abundance of hollow-bearing CWD, (ii) the volume of CWD in different decay classes, (iii) the probability of hollow presence, and (iv) the size of hollows at a long-term (28 years) experimental site. Volume of CWD in moderate and advanced stages of decomposition decreased with increasing fire frequency while moderately decomposed material was higher in logged plots. The likelihood of a hollow being present increased with diameter and decreased when CWD was extensively charred. Hollow size was smaller when material was externally charred but larger when charring affected a pre-existing hollow. Increases in moderately decayed CWD reflect a pulse input of unmerchantable timber following the one-off logging event 28 years ago, though future loss of mature trees may lead to reduced input rates of woody debris in the future. Charring effects on hollow formation, increasing hollow size but decreasing overall presence, demonstrate the complex effect of fire on this resource. Our research highlights the need to develop a fundamental understanding of CWD input and loss dynamics in response to fire and logging in order to predict changes to this resource under a broad range of management scenarios.

Description: Future Internet, Vol. 10, Pages 38: MinHash-Based Fuzzy Keyword Search of Encrypted Data across Multiple Cloud Servers Future Internet doi: 10.3390/fi10050038 Authors: He Wu Zhu Pathan To enhance the efficiency of data searching, most data owners store their data files in different cloud servers in the form of cipher-text. Thus, efficient search using fuzzy keywords becomes a critical issue in such a cloud computing environment. This paper proposes a method that aims at improving the efficiency of cipher-text retrieval and lowering storage overhead for fuzzy keyword search. In contrast to traditional approaches, the proposed method can reduce the complexity of Min-Hash-based fuzzy keyword search by using Min-Hash fingerprints to avoid the need to construct the fuzzy keyword set. The method will utilize Jaccard similarity to rank the results of retrieval, thus reducing the amount of calculation for similarity and saving a lot of time and space overhead. The method will also take consideration of multiple user queries through re-encryption technology and update user permissions dynamically. Security analysis demonstrates that the method can provide better privacy preservation and experimental results show that efficiency of cipher-text using the proposed method can improve the retrieval time and lower storage overhead as well.

Description: Algorithms, Vol. 11, Pages 60: Vessel Traffic Risk Assessment Based on Uncertainty Analysis in the Risk Matrix Algorithms doi: 10.3390/a11050060 Authors: Molin Sun Zhongyi Zheng Uncertainty analysis is considered to be a necessary step in the process of vessel traffic risk assessment. The purpose of this study is to propose the uncertainty analysis algorithm which can be used to investigate the reliability of the risk assessment result. Probability and possibility distributions are used to quantify the two types of uncertainty identified in the risk assessment process. In addition, the algorithm for appropriate time window selection is chosen by considering the uncertainty of vessel traffic accident occurrence and the variation trend of the vessel traffic risk caused by maritime rules becoming operative. Vessel traffic accident data from the United Kingdom’s marine accident investigation branch are used for the case study. Based on a comparison with the common method of estimating the vessel traffic risk and the algorithm for uncertainty quantification without considering the time window selection, the availability of the proposed algorithms is verified, which can provide guidance for vessel traffic risk management.

Description: Algorithms, Vol. 11, Pages 58: Computing Fault-Containment Times of Self-Stabilizing Algorithms Using Lumped Markov Chains Algorithms doi: 10.3390/a11050058 Authors: Volker Turau The analysis of self-stabilizing algorithms is often limited to the worst case stabilization time starting from an arbitrary state, i.e., a state resulting from a sequence of faults. Considering the fact that these algorithms are intended to provide fault tolerance in the long run, this is not the most relevant metric. A common situation is that a running system is an a legitimate state when hit by a single fault. This event has a much higher probability than multiple concurrent faults. Therefore, the worst case time to recover from a single fault is more relevant than the recovery time from a large number of faults. This paper presents techniques to derive upper bounds for the mean time to recover from a single fault for self-stabilizing algorithms based on Markov chains in combination with lumping. To illustrate the applicability of the techniques they are applied to a new self-stabilizing coloring algorithm.

Description: Algorithms, Vol. 11, Pages 59: Decision-Making Approach Based on Neutrosophic Rough Information Algorithms doi: 10.3390/a11050059 Authors: Muhammad Akram Nabeela Ishfaq Sidra Sayed Florentin Smarandache Rough set theory and neutrosophic set theory are mathematical models to deal with incomplete and vague information. These two theories can be combined into a framework for modeling and processing incomplete information in information systems. Thus, the neutrosophic rough set hybrid model gives more precision, flexibility and compatibility to the system as compared to the classic and fuzzy models. In this research study, we develop neutrosophic rough digraphs based on the neutrosophic rough hybrid model. Moreover, we discuss regular neutrosophic rough digraphs, and we solve decision-making problems by using our proposed hybrid model. Finally, we give a comparison analysis of two hybrid models, namely, neutrosophic rough digraphs and rough neutrosophic digraphs.

Description: Forests, Vol. 9, Pages 245: Effects of Management Practices and Topography on Ectomycorrhizal Fungi of Maritime Pine during Seedling Recruitment Forests doi: 10.3390/f9050245 Authors: Arthur Guignabert Florian Delerue Maya Gonzalez Laurent Augusto Mark R. Bakker Symbiosis with ectomycorrhizal (ECM) fungi can be important for regeneration success. In a context of increasing regeneration failures in the coastal forest of maritime pine in Southwest France, we tried to identity whether differences in ECM communities could partly explain the variation of regeneration success and how they are influenced by forest practices and stand characteristics. In particular, we focused on the effects of harvesting methods (comparing mature forest with seed-tree regeneration and clear-cuts) and topography (bottom-, mid-, and top positions). Five field trials (two in regeneration failure areas and three in successful areas) were used to sample 450 one-year-old seedlings. Assessments of ECM of seedling nutrient concentrations and of seedling growth based on exploration types were made. ECM root colonisation was similar in all harvesting treatments, suggesting that enough inoculum remained alive after logging. Harvesting-induced effects modifying soil properties and light availability respectively impacted ECM composition and seedling growth. Topography-induced variations in water and nutrient availability led to changes in ECM composition, but had little impact on seedling growth. Contact, short-distance, and long-distance exploration types improved the nutritional status of seedlings (Ca, K, and N), showing that mycorrhization could play an important role in seedling vitality. However, neither ECM root colonisation nor exploration types could be related to regeneration failures.

Description: Algorithms, Vol. 11, Pages 63: The Supplier Selection of the Marine Rescue Equipment Based on the Analytic Hierarchy Process (AHP)-Limited Diversity Factors Method Algorithms doi: 10.3390/a11050063 Authors: Minghui Shao Yan Song Biao Wu Yanjie Chang Supplier selection is an important decision-making link in bidding activity. When overall scores of several suppliers are similar, it is hard to obtain an accurate ranking of these suppliers. Applying the Diversity Factors Method (Diversity Factors Method, DFM) may lead to over correction of weights, which would degrade the capability of indexes to reflect the importance. A Limited Diversity Factors Method (Limited Diversity Factors Method, LDFM) based on entropy is presented in this paper in order to adjust the weights, in order to relieve the over correction in DFM and to improve the capability of identification of indexes in supplier selection. An example of salvage ship bidding demonstrates the advantages of the LDFM, in which the raking of overall scores of suppliers is more accurate.

Description: Forests, Vol. 9, Pages 249: Changes in Soil Enzyme Activities and Microbial Biomass after Revegetation in the Three Gorges Reservoir, China Forests doi: 10.3390/f9050249 Authors: Qingshui Ren Hong Song Zhongxun Yuan Xilu Ni Changxiao Li Soil enzymes and microbes are central to the decomposition of plant and microbial detritus, and play important roles in carbon, nitrogen, and phosphorus biogeochemistry cycling at the ecosystem level. In the present study, we characterized the soil enzyme activity and microbial biomass in revegetated (with Taxodium distichum (L.) Rich. and Cynodon dactylon (L.) Pers.) versus unplanted soil in the riparian zone of the Three Gorges Dam Reservoir (TGDR), in order to quantify the effect of revegetation on the edaphic microenvironment after water flooding in situ. After revegetation, the soil physical and chemical properties in revegetated soil showed significant differences to those in unplanted soil. The microbial biomass carbon and phosphorus in soils of T. distichum were significantly higher than those in C. dactylon and unplanted soils, respectively. The microbial biomass nitrogen in revegetated T. distichum and C. dactylon soils was significantly increased by 273% and 203%, respectively. The enzyme activities of T. distichum and C. dactylon soils displayed no significant difference between each other, but exhibited a great increase compared to those of the unplanted soil. Elements ratio (except C/N (S)) did not vary significantly between T. distichum and C. dactylon soils; meanwhile, a strong community-level elemental homeostasis in the revegetated soils was found. The correlation analyses demonstrated that only microbial biomass carbon and phosphorus had a significantly positive relationship with soil enzyme activities. After revegetation, both soil enzyme activities and microbial biomasses were relatively stable in the T. distichum and C. dactylon soils, with the wooded soil being more superior. The higher enzyme activities and microbial biomasses demonstrate the C, N, and P cycling and the maintenance of soil quality in the riparian zone of the TGDR.

Description: Forests, Vol. 9, Pages 248: Species- and Elevation-Dependent Growth Responses to Climate Warming of Mountain Forests in the Qinling Mountains, Central China Forests doi: 10.3390/f9050248 Authors: Bo Liu Eryuan Liang Kang Liu J. Julio Camarero Climate warming is significantly affecting the composition and function of forest ecosystems. However, the forest responses to climate change in sub-humid and temperate areas are understudied compared with cold and semi-arid areas. Here, we investigate the radial-growth responses of two subalpine conifer species along an elevational gradient located in the Qinling Mountains, a sub-humid and temperate area situated in central China. Three sites dominated by larch (Larix chinensis Beissn.) and two other sites dominated by fir (Abies fargesii Franch.) located at different elevations were sampled. L. chinensis at a higher elevation showed more common and stronger climatic signals than A. fargesii at a lower elevation. The radial growth of L. chinensis was limited by low pre-growing season temperatures and showed an increasing growth trend in the last few years. On the other hand, A. fargesii growth was limited by summer water shortage and it was characterized by a declining trend in the most recent decade. Consequently, L. chinensis would benefit from climate warming, whereas A. fargesii could be regarded as a vulnerable tree species to warming-induced drought stress.

Description: Algorithms, Vol. 11, Pages 66: Single Machine Scheduling Problem with Interval Processing Times and Total Completion Time Objective Algorithms doi: 10.3390/a11050066 Authors: Yuri N. Sotskov Natalja G. Egorova We consider a single machine scheduling problem with uncertain durations of the given jobs. The objective function is minimizing the sum of the job completion times. We apply the stability approach to the considered uncertain scheduling problem using a relative perimeter of the optimality box as a stability measure of the optimal job permutation. We investigated properties of the optimality box and developed algorithms for constructing job permutations that have the largest relative perimeters of the optimality box. Computational results for constructing such permutations showed that they provided the average error less than 0 . 74 % for the solved uncertain problems.

Description: Algorithms, Vol. 11, Pages 65: Control Strategy of Speed Servo Systems Based on Deep Reinforcement Learning Algorithms doi: 10.3390/a11050065 Authors: Pengzhan Chen Zhiqiang He Chuanxi Chen Jiahong Xu We developed a novel control strategy of speed servo systems based on deep reinforcement learning. The control parameters of speed servo systems are difficult to regulate for practical applications, and problems of moment disturbance and inertia mutation occur during the operation process. A class of reinforcement learning agents for speed servo systems is designed based on the deep deterministic policy gradient algorithm. The agents are trained by a significant number of system data. After learning completion, they can automatically adjust the control parameters of servo systems and compensate for current online. Consequently, a servo system can always maintain good control performance. Numerous experiments are conducted to verify the proposed control strategy. Results show that the proposed method can achieve proportional–integral–derivative automatic tuning and effectively overcome the effects of inertia mutation and torque disturbance.

Description: Forests, Vol. 9, Pages 255: Perceptions on the Importance of Forest Sector Innovations: Biofuels, Biomaterials, or Niche Products? Forests doi: 10.3390/f9050255 Authors: T. Stern L. Ranacher C. Mair S. Berghäll K. Lähtinen M. Forsblom A. Toppinen New innovations are called for to renew the European forest sector into bioeconomy. However, little research exists on how the industry innovativeness is publicly perceived. Using data collected with an online questionnaire in four European countries, we investigate perceptions related to forest sector innovations on 13 current and new bioeconomy-related products and services. Altogether, 218 valid responses were received in 2015, and the data were analysed using descriptive statistics, performance-importance analysis, and Gartner’s innovation hype cycle. Based on our results, the respondents were in the strongest agreement that the forest sector has since the year 2000 has produced innovations related to wood building systems, construction materials, and wood composites. In the next 15 years, they foresaw a decline in innovations related to biofuels and paper products. The European forest sector also has future potential in wood construction, which is likely related to international policy targets related to carbon mitigation and capture. The observed variation in perceptions among the respondents on forest sector innovativeness calls for strengthening industry R&D, as well as by improving societal awareness of ongoing innovation projects by developing better communication.

Description: Forests, Vol. 9, Pages 254: Forest Biomass Policy in Minnesota: Supply Chain Perspectives on Barriers to Bioenergy Development Forests doi: 10.3390/f9050254 Authors: Laura Eaton Carleton Dennis Becker Forest biomass used for heating, electricity, and biofuel production is a source of energy that could reduce the dependence on energy imports while reinvesting domestically. Using the appropriate scale and technology, the US state of Minnesota is poised for increased forest bioenergy production due to the large existing forest products industry. Forest bioenergy investments have been slow to materialize despite state and federal incentives, and this research aims to determine what barriers there are to bioenergy development from the perspective of supply-chain actors by applying theories of natural resource governance. Findings from interviews include the need to create an equitable playing field in terms of energy subsidies and integrate forest bioenergy production with bio-based markets, including traditional forest product markets. Additionally, interviews indicate poor coordination and shared responsibility among state agencies, industry associations, and nonprofit organizations, resulting in a fragmented policy system. Principles to guide enabling forest bioenergy development are identified and discussed in the context of the study findings.

Description: Future Internet, Vol. 10, Pages 42: Test Bed of Semantic Interaction of Smart Objects in the Web of Things Future Internet doi: 10.3390/fi10050042 Authors: Santiago Guerrero-Narváez Miguel-Ángel Niño-Zambrano Dalila-Jhoana Riobamba-Calvache Gustavo-Adolfo Ramírez-González Semantic interaction in the Internet of Things (IoT) is an important concept within current IoT development, given that smart things require further autonomy with greater processing, storage, and communication capacities. The problem is now becoming one of how to get these things to interact and collaborate with each other; to form intelligent environments amongst themselves and thus generate better services for users. This article explores a solution approach that consists in providing collaborative behavior to smart things, through the incorporation of an ontology and an architecture. It makes possible things that can communicate and collaborate with each other, allowing the generation of new services of interaction according to user needs. For this task, a real test bed of smart things was created, in which the proposed solution was deployed (Smart Room). Finally, it was concluded that the creation of these types of test bed is feasible, taking into account that response times and the information delivered by the different managed processes are acceptable. New challenges were encountered, however, such as problems of critical region in test beds with conflicting services and management of multiple users.

Description: Forests, Vol. 9, Pages 259: Assessing Climate Change Impact on Forest Habitat Suitability and Diversity in the Korean Peninsula Forests doi: 10.3390/f9050259 Authors: Chul-Hee Lim Somin Yoo Yuyoung Choi Seong Woo Jeon Yowhan Son Woo-Kyun Lee Habitat changes in temperate forests are more vulnerable to climate change than tropical or boreal forests. This study assessed forest habitat suitability and diversity to determine the impact of climate change on the Korean Peninsula. We used the MaxEnt (Maximum Entropy) species distribution model, three key climate indices, and two representative climate change scenarios, using short and long-term data. Two of the three key climate indices related to temperature were more capricious than the precipitation-related index in the future. In the baseline prediction, both statistical and qualitative validation using the actual vegetation map showed excellent results. Regarding forest habitat suitability, northward migration and substantial increase were definitely distinctive in warm temperate evergreen forest. On the other hand, subalpine forest areas decreased significantly due to climate change; the suitable area for Representative Concentration Pathways (RCP) 8.5 2070s decreased by more than half. With regard to forest habitat diversity, regions with high diversity declined due to climate change. In the RCP 8.5 scenario, areas where all three forest types are suitable no longer appeared; however, in the case of RCP 4.5 2050s, suitable areas for two forest types increased, which implies climate change is not only negative in terms of diversity. As this negative prediction of future change is discouraging, active mitigation and adaptation are required to prevent these changes. The sustainability of future ecosystems is still dependent on our efforts.

Description: Forests, Vol. 9, Pages 260: Fog Water Is Important in Maintaining the Water Budgets of Vascular Epiphytes in an Asian Tropical Karst Forests during the Dry Season Forests doi: 10.3390/f9050260 Authors: Yi Wu Liang Song Wenyao Liu Wenjie Liu Su Li Peili Fu Youxin Shen Junen Wu Pingyuan Wang Quan Chen Huazheng Lu Fog may be an important source of water for forest vascular epiphytes on trees, because they lack direct access to sources of soil water, but little is known about the water use proportions from various sources and potential water uptake pathways in epiphytes. Here, we analyzed leaf carbon isotope ratios as a measure of water use efficiency (WUE), proportions of fog, rain, and soil water use, and foliar water uptake (FWU) in species of epiphyte and their host trees in a tropical karst dwarf forest in China during the dry season. We found that the WUE, as represented by leaf δ13C, was generally enriched in the epiphyte species compared to their host trees. Epiphytes used substantial proportions of fog water, whereas water use in the host trees was dominated by soil water. The leaves of epiphytes and host trees absorbed water following immersion in water for 3 h and FWU possibly related to foliar epicuticular structures, such as fungal endophytes. Our results show a divergence of water use strategies between epiphytes and their hosts and highlight the importance of fog water for epiphytes during the dry season and under a climate change scenario with a reduced occurrence of fog events.

Description: Algorithms, Vol. 11, Pages 71: Improving Monarch Butterfly Optimization Algorithm with Self-Adaptive Population Algorithms doi: 10.3390/a11050071 Authors: Hui Hu Zhaoquan Cai Song Hu Yingxue Cai Jia Chen Sibo Huang Inspired by the migration behavior of monarch butterflies in nature, Wang et al. proposed a novel, promising, intelligent swarm-based algorithm, monarch butterfly optimization (MBO), for tackling global optimization problems. In the basic MBO algorithm, the butterflies in land 1 (subpopulation 1) and land 2 (subpopulation 2) are calculated according to the parameter p, which is unchanged during the entire optimization process. In our present work, a self-adaptive strategy is introduced to dynamically adjust the butterflies in land 1 and 2. Accordingly, the population size in subpopulation 1 and 2 are dynamically changed as the algorithm evolves in a linear way. After introducing the concept of a self-adaptive strategy, an improved MBO algorithm, called monarch butterfly optimization with self-adaptive population (SPMBO), is put forward. In SPMBO, only generated individuals who are better than before can be accepted as new individuals for the next generations in the migration operation. Finally, the proposed SPMBO algorithm is benchmarked by thirteen standard test functions with dimensions of 30 and 60. The experimental results indicate that the search ability of the proposed SPMBO approach significantly outperforms the basic MBO algorithm on most test functions. This also implies the self-adaptive strategy is an effective way to improve the performance of the basic MBO algorithm.

Description: Forests, Vol. 9, Pages 272: Spatio-Temporal Patterns of Urban Forest Basal Area under China’s Rapid Urban Expansion and Greening: Implications for Urban Green Infrastructure Management Forests doi: 10.3390/f9050272 Authors: Zhibin Ren Xingyuan He Haifeng Zheng Hongxu Wei Urban forest (UF) basal area is an important parameter of UF structures, which can influence the functions of the UF ecosystem. However, the spatio-temporal pattern of the basal area in a given UF in regions under rapid urbanization and greening is still not well documented. Our study explores the potential of estimating spatio-temporal UF basal area by using Thematic Mapper (TM) imagery. In our study, the predicting model was established to produce spatiotemporal maps of the urban forest basal area index in Changchun, China for the years 1984, 1995, 2005, and 2014. Our results showed that urban forests became more and more fragmented due to rapid urbanization from 1984 to 1995. Along with rapid urban greening after 1995, urban forest patches became larger and larger, creating a more homogeneous landscape. Urban forest and its basal area in the whole study area increased gradually from 1984 to 2014, especially in the outer belts of the city with urban sprawl. UF basal area was 27.3 × 103 m2, 41.3 × 103 m2, 45.8 × 103 m2, and 65.1 × 103 m2 of the entire study area for the year 1984, 1995, 2005, and 2014, respectively. The class distribution of the UF basal area index was skewed toward low values across all four years. In contrast, the frequency of a higher UF basal area index increased gradually from 1984 to 2014. Besides, the UF basal area index showed a decreasing trend along the gradient from suburban areas to urban center areas. Our results demonstrate the capability of TM remote sensing for understanding spatio-temporal changing patterns of UF basal area under China’s rapid urban expansion and greening.

Description: Algorithms, Vol. 11, Pages 75: A New Oren–Nayar Shape-from-Shading Approach for 3D Reconstruction Using High-Order Godunov-Based Scheme Algorithms doi: 10.3390/a11050075 Authors: Guohui Wang Yuanbo Chu 3D shape reconstruction from images has been an important topic in the field of robot vision. Shape-From-Shading (SFS) is a classical method for determining the shape of a 3D surface from a one intensity image. The Lambertian reflectance is a fundamental assumption in conventional SFS approaches. Unfortunately, when applied to characterize the reflection attribute of the diffuse reflection, the Lambertian model is tested to be inexact. In this paper, we present a new SFS approach for 3D reconstruction of diffuse surfaces whose reflection attribute is approximated by the Oren–Nayar reflection model. The partial differential Image Irradiance Equation (IIR) is set up with this model under a single distant point light source and an orthographic camera projection whose direction coincides with the light source. Then, the IIR is converted into an eikonal equation by solving a quadratic equation that includes the 3D surface shape. The viscosity solution of the resulting eikonal equation is approximated by using the high-order Godunov-based scheme that is accelerated by means of an alternating sweeping strategy. We conduct the experiments on synthetic and real-world images, and the experimental results illustrate the effectiveness of the presented approach.

Description: Forests, Vol. 9, Pages 277: The Application of Two Approaches Using GIS Technology Implementation in Forest Road Network Planning in an Italian Mountain Setting Forests doi: 10.3390/f9050277 Authors: Rodolfo Picchio Giuseppe Pignatti Enrico Marchi Francesco Latterini Mirko Benanchi Cristiano Foderi Rachele Venanzi Stefano Verani A well-planned forest road network is essential for meeting the goal of sustainable forest management. Forest roads play a key role in commercial purposes, fire prevention, and recreational activities. The aim of this work was to apply precision forestry in the analysis of the forest network of two forest ownerships in Tuscany. A proposal was formulated based on the information obtained regarding future forest road construction. This proposal takes into consideration technical effectiveness and environmental sustainability, with particular attention paid to low-impact logging. Two systems were tested so as to gain a better comprehension of different technical approaches. One system was reported by other researchers and the other was developed by the authors of this paper. The aim was to provide a valid instrument and possible alternative for forest managers involved in decision making. This study highlights the importance of precision forestry, even on a small-scale technical application level in forest road planning, thus helping managers and owners during the decision-making process in forestry operations.

Description: Forests, Vol. 9, Pages 278: Short-Term Vegetation Responses Following Windthrow Disturbance on Preserved Forest Lands Forests doi: 10.3390/f9050278 Authors: Douglas R. Manning Margot W. Kaye Stephanie J. Perles David A. Mortensen Invasive exotic plants pose a serious threat to the ecological integrity of forests in the eastern United States. Presence and expansion of these plants are closely associated with human-caused disturbances. Land preservation to exclude human-caused disturbances could protect against invasions, yet natural disturbances persist. We ask if windthrow forest disturbances in preserved National Park lands facilitate exotic species invasions. We hypothesized that exotic plant expansion is positively correlated with forest canopy disturbance from windthrow and proximity of disturbed area to forest edge. Pre and post-disturbance data from National Park Service long-term vegetation monitoring were used to analyze exotic plant richness and abundance in four National Park Service units affected by 2012 severe storms. No significant difference in exotic plant richness or cover occurred between disturbed (n = 18) and undisturbed plots (n = 262) over three years following disturbance. Exotic plant cover prior to disturbance was positively correlated with the amount of nearby linear edge habitat, but there were no significant correlations between edge and change in exotic plant cover following disturbance. Lack of increase in exotic plants after windthrow disturbance suggests that land preservation provides short-term resistance to invasion.

Description: Forests, Vol. 9, Pages 279: Tree Vitality Assessment in Urban Landscapes Forests doi: 10.3390/f9050279 Authors: David Callow Peter May Denise M. Johnstone The recent prolonged drought in Melbourne, Australia has had a deleterious effect on the urban forest, resulting in the premature decline of many mature trees and a consequent decline in the environmental services that trees are able to provide to urban residents. Measuring the severity of tree stress and defoliation due to various climatic factors is essential to the ongoing delivery of environmental services such as shade and carbon sequestration. This study evaluates two methods to assess the vitality of drought stressed Elm trees within an inner-city environment—bark chlorophyll fluorescence measured on large branches and an urban visual vitality index. Study species were Ulmus procera Salisb. (English Elm) and Ulmus × hollandica (Dutch Elm), which are important character and shade tree species for Melbourne. Relationships were identified between leaf water potential and the urban visual vitality index and between leaf water potential and bark chlorophyll fluorescence measured on large branches, indicating that these methods could be used to assess the effect of long-term drought and other stressors on urban trees.

Description: Forests, Vol. 9, Pages 282: Invasive Species May Disrupt Protected Area Networks: Insights from the Pine Wood Nematode Spread in Portugal Forests doi: 10.3390/f9050282 Authors: Begoña de la Fuente Pieter S. A. Beck The expansion of invasive alien species is considered a major threat to forest ecosystems and biodiversity. Their potential impacts range from local changes in species composition to wider-scale effects on forest habitat and landscape functioning, although the latter has been relatively little explored in the literature. Here, we assessed the impact of an invasive forest pest, the pine wood nematode (PWN), in the Natura 2000 network of protected areas (PAs) in Portugal, the first European country in which PWN was reported. We considered the impacts of the pest’s spread (up to 2016) on individual PAs, in terms of the fraction of their coniferous forest infected, and on the corridors between PAs, which were mapped and prioritized through least-cost path modelling, geographic information system analysis, and the graph-based probability of connectivity metric. We found that PWN by 2016 had spread into 49% of the Portuguese Natura 2000 coniferous forest habitat, while it had invaded 68% of the coniferous forests that form the priority corridors between the PAs. These impacts are likely to be aggravated in the next years, given the pace of PWN expansion and the predicted rates of natural spread to new areas in Portugal and, increasingly likely, in Spain. Our results suggest that the connectivity of PA systems may be significantly disrupted by alien species, and that spatially prioritized control measures can help mitigate the impacts of invasive species on the coherence and functionality of protected area networks such as Natura 2000.

Description: Forests, Vol. 9, Pages 280: Evaluation of Salvage Logging Productivity and Costs in Windthrown Norway Spruce-Dominated Forests Forests doi: 10.3390/f9050280 Authors: Kalle Kärhä Tuomas Anttonen Asko Poikela Teijo Palander Ari Laurén Heli Peltola Yrjö Nuutinen Different abiotic and biotic disturbances are expected to become more common in the future due to a warming climate. Globally, post-disturbance salvage logging is becoming more predominant to recover economic value from timber in disturbed forests. This study collected comparative time-study data and analyzed the productivity of cutting for windfalls in clear cuttings and determined the cutting costs of windfalls. Furthermore, the logging (i.e., cutting and forwarding) costs of wind-damaged trees and those of undamaged standing Norway spruce (Picea abies (L.) Karst.) trees in clear cuts were calculated in Finland. The results revealed that the cutting productivity of windfalls was 19–33% lower than that of undamaged stems. The cutting costs of windthrown stems with a volume of 0.3–1.5 m3 were 35–64% higher and the logging costs of windfalls were 10–30% higher than those of undamaged standing stems. The study provided new understanding regarding the productivity and costs of salvage logging operations under Finnish conditions. Even if the logging of windfalls is expensive and laborious, salvage logging operations are important for forest stands and their health to minimize post-disaster damage outbreaks in coniferous forests, such as the damage caused by bark beetles—mainly Ips typographus L.

Description: Forests, Vol. 9, Pages 290: Soil Chemical Attributes, Biometric Characteristics, and Concentrations of N and P in Leaves and Litter Affected by Fertilization and the Number of Sprouts per the Eucalyptus L’Hér. Strain in the Brazilian Cerrado Forests doi: 10.3390/f9060290 Authors: Natasha M. I. Godoi Sabrina N. dos S. Araújo Salatiér Buzetti Rodolfo de N. Gazola Thiago de S. Celestrino Alexandre C. da Silva Thiago A. R. Nogueira Marcelo C. M. Teixeira Filho Given the lack of recommendations for the fertilization of Eucalyptus clones in the second production cycle, the effects of fertilizer rates and the number of sprouts per strain in terms of the soil chemical attributes, biometric characteristics, and the concentrations of N and P in the leaves and in the litter of Eucalyptus L’Hér. in the Brazilian Cerrado were evaluated. The experimental design was a randomized block with four replicates, arranged in a 2 × 4 factorial scheme: one or two sprouts per strain; four fertilizer rates (0, 50, 100, or 200% of 200 kg ha−1 of the formula 06-30-06 + 1.5% Cu + 1% Zn) applied immediately after sprout definition. The option of one sprout per strain yielded higher contents of organic matter (K, S, B, and Mn) in the 0.20–0.40-m layer, the leaf chlorophyll index, the diameter at breast height, and the height of the Eucalyptus 44 months after the definition of sprouts. However, N and P leaf concentrations and the wood volume did not differ as a function of the sprout numbers. The fertilizer dosage did not influence the wood volume, even in sandy soil with low fertility. Approximately 86% of the wood volume was obtained from the supply of soil and root nutrient reserves and 14% of this productivity is due to fertilization minerals. The adequate fertilization in the first cycle of the Eucalyptus supplies almost the entire nutritional demand of the forest in the second production cycle.

Description: Forests, Vol. 9, Pages 291: Automatic Detection of Single Trees in Airborne Laser Scanning Data through Gradient Orientation Clustering Forests doi: 10.3390/f9060291 Authors: Tianyang Dong Qizheng Zhou Sibin Gao Ying Shen Currently, existing methods for single-tree detection based on airborne laser scanning (ALS) data usually require some thresholds and parameters to be set manually. Manually setting threshold or parameters is laborious and time-consuming, and for dense forests, the high commission and omission rate make most existing single-tree detection techniques inefficient. As a solution to these problems, this paper proposed an automatic single-tree detection method in ALS data through gradient orientation clustering (GOC). In this method, the rasterized Canopy Height Model (CHM) was derived from ALS data using surface interpolation. Then, potential trees were assumed as approximate conical shapes and extracted based on the GOC. Finally, trees were identified from the potential trees based on the compactness of the crown shape. This method used the gradient orientation information of rasterized CHM, thus increasing the generalization of single-tree detection method. In order to verify the validity and practicability of the proposed method, twelve 1256 m2 circular study plots of different forest types were selected from the benchmark dataset (NEWFOR), and the results from nine different methods were presented and compared for these study plots. Among nine methods, the proposed method had the highest root mean square matching score (RMS_M = 43). Moreover, the proposed method had excellent detection (M > 47) in both single-layer coniferous and single-layered mixed stands.

Description: Forests, Vol. 9, Pages 287: Comparison of Whole-Tree Wood Property Maps for 13- and 22-Year-Old Loblolly Pine Forests doi: 10.3390/f9060287 Authors: Laurence Schimleck Finto Antony Christian Mora Joseph Dahlen Maps developed using Akima’s interpolation method were used to compare patterns of within-tree variation for Pinus taeda L. (loblolly pine) wood properties in plantation-grown trees aged 13 and 22 years. Air-dry density, microfibril angle (MFA) and modulus of elasticity (MOE) maps represented the average of 18 sampled trees in each age class. Near infrared (NIR) spectroscopy models calibrated using SilviScan provided data for the analysis. Zones of high density, low MFA and high MOE wood increased markedly in size in maps of the older trees. The proportion of wood meeting the visually graded No. 1 (11 GPa) and No. 2 (9.7 GPa) MOE design values for southern pine lumber increased from 44 to 74% and from 58 to 83% respectively demonstrating the impact of age on end-product quality. Air-dry density increased from pith to bark at all heights but lacked a significant trend vertically, while radial and longitudinal trends were observed for MFA and MOE. Changes were consistent with the asymptotic progression of properties associated with full maturity in older trees.

Description: Forests, Vol. 9, Pages 295: Allometric Equations for Predicting Culm Surface Area of Three Bamboo Species (Phyllostachys spp.) Forests doi: 10.3390/f9060295 Authors: Akio Inoue Yoshiyuki Miyazawa Motohiro Sato Hiroyuki Shima It is strongly debated whether bamboo forest ecosystems are a carbon sink or a carbon source because of insufficient knowledge regarding carbon loss via CO2 emissions from these forests. The surface area (S) of bamboo culms (stems) is important for estimating culm respiration, a major component of carbon cycling in bamboo forests. However, few studies have attempted to formulate predictive equations for S. In this study, we developed allometric equations for predicting S in three bamboo species grown in Kyushu Island, western Japan: Phyllostachys pubescens Mazel ex Houz., P. bambusoides Sieb. et Zucc. and P. nigra var. henonis. We used a power equation between S and diameter at breast height (D) and a linear equation between S and D × total culm length (H). The results indicated that P. bambusoides and P. nigra shared common site-independent equations. In contrast, P. pubescens required species-specific equations due to interspecific variation in culm slenderness and tapering. We also found that D was a better predictive variable than DH when quantifying S because of its satisfactory predictive performance and simplicity. These findings will be beneficial for evaluating the contribution of bamboo forest ecosystems to carbon cycling.