ALBERT

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 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 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: Forests, Vol. 9, Pages 584: The Concept of Landscape Structure, Forest Continuum and Connectivity as a Support in Urban Forest Management and Landscape Planning Forests doi: 10.3390/f9100584 Authors: Janez Pirnat David Hladnik Close-to-nature urban forests and remnants of natural vegetation represent an important opportunity for urban residents to experience daily perception of and access to the natural environment. Despite there being a high percentage of forest cover (59%) and a favorable structure of the prevailing forested landscapes in Slovenia, urban expansion and infrastructure-driven development has severely weakened the connectivity and conservation of urban and suburban forests. The majority of urban settlements lie within walking distance of the surrounding forests (<1 km). However, only close-to-nature forests with relatively low silvicultural inputs offer ecosystem services sufficient to fulfil the supply and demand of the expanding urban population. In order to estimate the conservation of forests in the open space of Slovenian settlements, we used a spatial model of landscape structure and forest connectivity. The model can be enhanced with patterns of corridors and stepping stones of natural vegetation in the landscape matrix to provide support in the decision-making process of landscape planning and the conservation of urban and suburban forests.

Description: Forests, Vol. 9, Pages 585: Optimizing the Location of Biomass Energy Facilities by Integrating Multi-Criteria Analysis (MCA) and Geographical Information Systems (GIS) Forests doi: 10.3390/f9100585 Authors: Heesung Woo Mauricio Acuna Martin Moroni Mohammad Sadegh Taskhiri Paul Turner Internationally forest biomass is considered to be a valuable renewable energy feedstock. However, utilization of forest harvesting residues is challenging because they are highly varied, generally of low quality and usually widely distributed across timber harvesting sites. Factors related to the collection, processing and transport impose constraints on the economic viability of residue utilization operations and impact their supply from dispersed feedstock locations. To optimize decision-making about suitable locations for biomass energy plants intending to use forest residues, it is essential to factor in these supply chain considerations. This study conducted in Tasmania, Australia presents an investigation into the integration of Multi-criteria analysis (MCA) and Geographical Information systems (GIS) to identify optimal locations for prospective biomass power plants. The amount of forest harvesting biomass residues was estimated based on a non-industrial private native resource model in Tasmania (NIPNF). The integration of MCA and a GIS model, including a supply chain cost analysis, allowed the identification and analysis of optimal candidate locations that balanced economic, environmental, and social criteria within the biomass supply. The study results confirm that resource availability, land use and supply chain cost data can be integrated and mapped using GIS to facilitate the determination of different sustainable criteria weightings, and to ultimately generate optimal candidate locations for biomass energy plants. It is anticipated that this paper will make a contribution to current scientific knowledge by presenting innovative approaches for the sustainable utilization of forest harvest residues as a resource for the generation of bioenergy in Tasmania.