ALBERT

Beschreibung: Deciduous seasonal forests (DSFs) have a peculiar floristic composition, with species capable of surviving periods of high water deficit in a year. Our goal was to demonstrate that abiotic filters lead to the assembly of two DSF communities that have high floristic dissimilarity. For this, we characterized the environment of the areas and used the community-weighted mean (CWM), functional richness (FRic) and functional dispersion (FDis) indices for regional recognition of functional patterns. The local assessment of assembly rules was carried out using null models. We found differences in the FRic and FDis between the areas, which was attributed to the different floristic influences exercised on the communities. However, in both, the typical attributes of dry formations were dominant (CWM), indicating that, on the regional scale of study, the dry season acts as a filter in the composition of species in the communities. On a local scale, stochastic dispersion was identified as the most influential mechanism in the assembly of communities. We conclude that deterministic and stochastic processes act in the assembly of the studied communities, and the proportion of each of these depends on the scale, with abiotic filtration predominating on a regional scale and stochastic dispersion events on a local scale. Study Implications With the expansion of agriculture and climate change, tropical dry biomes, such as deciduous seasonal forests, are rapidly changing. In this study, we contribute to the recognition of functional standards and community assembly of this vegetation type to assist in management planning, restoration, and conservation. Understanding the different processes involved in building a community is crucial for anticipating how communities will behave under future environmental scenarios.

Beschreibung: Quantification of soil organic carbon (SOC) stocks in different land uses holds vital significance because of its implications regarding carbon sequestration as the largest terrestrial carbon pool. The current study was conducted to quantify and compare SOC stocks in forest land, agricultural land, and barren land-use categories in the subtropical ecosystems of the Himalayan foothills in Kashmir. Results showed the highest SOC value in the forest soil (75 ± 11.1 Mg C ha−1) followed by agricultural soil (58 ± 7.0 Mg C ha−1) and barren land (44 ± 6.5 Mg C ha−1). SOC stocks in different land uses showed broad variations with values as high as 106 ± 11.3 Mg C ha−1 (forest soils) and as low as 14.1 ± 7.1 Mg C ha−1 (barren land). The forest SOC values responded significantly to species composition with the highest values in Pinus roxburghii Sarg. pure stands as compared with broad leaved forests. Multivariate ordination analyses revealed that the variations in SOC stocks were significantly correlated with vegetation type, altitude, and soil bulk density. The study has identified anthropogenic disturbances as a major factor deteriorating local SOC stocks and recommends immediate soil restoration efforts to enhance the ecological significance of soils as vital regional carbon sinks. Study Implications The current study was designed to investigate the soil organic carbon (SOC) levels in different land uses of the Kashmir Himalayas, Pakistan. Results revealed forest soils as the major carbon sinks of the region, attributed to diverse species composition having a significant quantity of organic residues, followed by agricultural soils. Barren land-use class exhibited the lowest SOC values due to minimum vegetation cover, erosion, and degradation. Significant correlations of SOC stocks with geographical and edaphic variables were identified by multivariate ordination analysis in the investigated land-use classes. Results validate the significance of forests in enhancing SOC stocks, demanding forest restoration in the area by controlling the forest losses as well as afforestation. This article provides vital information required for better understanding of SOC stocks in different land-use classes in the subtropical ecosystems of the Kashmir region.

Beschreibung: Considerable genetic differences in loblolly pine (Pinus taeda L.) exist for growth, stem form, and wood quality traits that influence biomass/biofuel production. By planting genetically superior trees with desirable biomass/biofuel traits, it is possible to substantially increase the amount of biomass and potential sawtimber trees produced from plantations. Ten of the fastest growing loblolly pine families from two provenances, Atlantic Coastal Plain and Piedmont, were tested for their biomass potential in North Carolina on a Piedmont site. At this northern Piedmont site at age six years, there were no provenance differences for biomass production or for trees with sawtimber potential. Variation in volume and sawtimber potential was significant at the family level. For biomass plantations, risks can be mitigated because of shorter rotation length, allowing for a higher-risk seed lot to capture greater gains in terms of volume. For a longer-rotation sawtimber stand, a more conservative family deployment strategy should be considered to maintain stem quality at the end of the rotation. Understanding the different seed source families and harvest regimes is essential to ensure profitable returns from pine plantations. Study Implications Landowners in the southeastern United States have more choices than ever before regarding the choice of genetic stock of loblolly pine seedlings they plant, and the family selection should reflect the stand management objectives with regard to growth, stem form, and wood quality traits. In a biomass/biofuel production regime, planting families from nonlocal seed sources for increased growth can potentially increase the amount of biomass and sawtimber produced from the plantation, although risks such as increased susceptibility to winter storm damage must be considered. For biomass plantations, with shorter rotation lengths, risks can be reduced allowing for a higher-risk genotype to capture the greater gains in volume. For a sawtimber stand, genotype selections should be more conservative to ensure stem quality at the end of the rotation. Understanding different genotypes and harvest regimes is essential to maximize profit from plantations.

Beschreibung: We analyse the effects of the Deep and Comprehensive Free Trade Area between the European Union (EU) and Ukraine on the world’s sunflower complex markets. We develop a spatial equilibrium model that incorporates the vertical and horizontal links between the primary commodity (seeds) and two final by-products (oil and meal). Our empirical analysis covers eight regions—the leading producers and consumers in the sunflower complex. This agreement causes EU’s sunflower oil price to decrease by USD 17.42 per metric ton, benefiting EU’s consumers by USD 81.4 million. However, EU’s total net welfare decreases by USD 10.3 million, while Ukraine’s increases by USD 32.7 million.

Beschreibung: Plants from arid environments display covarying traits to survive or resist drought. Plant drought resistance and ability to survive long periods of low soil water availability should involve leaf phenology coordination with leaf and stem functional traits related to water status. This study tested correlations between phenology and functional traits involved in plant water status regulation in 10 Sonoran Desert tree species with contrasting phenology. Species seasonal variation in plant water status was defined by calculating their relative positions along the iso/anisohydric regulation continuum based on their hydroscape areas (HA)—a metric derived from the relationship between predawn and midday water potentials—and stomatal and hydraulic traits. Additionally, functional traits associated with plant water status regulation, including lamina vessel hydraulic diameter (DHL), stem-specific density (SSD), and leaf mass per area (LMA) were quantified per species. To characterize leaf phenology, leaf longevity (LL) and canopy foliage duration (FD) were determined. HA was strongly correlated with FD but not with LL; HA was significantly associated with SSD and leaf hydraulic traits (DHL, LMA) but not with stem hydraulic traits (vulnerability index, relative conductivity); and FD was strongly correlated with LMA and SSD. Leaf physiological characteristics affected leaf phenology when it was described as canopy foliage duration, better than when described as leaf longevity. Stem and leaf structure and hydraulic functions were not only relevant for categorizing species along the iso/anisohydric continuum but also allowed identifying different strategies of desert trees within the ‘fast–slow’ plant economics spectrum. The results in this study pinpoint the set of evolutionary pressures that shape the Sonoran Desert Scrub physiognomy.

Beschreibung: Concerns about long-term pollinator declines have made assessing bee communities a priority in nonagricultural ecosystems, including managed forests. We assessed wild bee communities in Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) stands one to 15 years after clearcut harvest in western Oregon, USA, testing the hypothesis that bee diversity would be high initially and then decline with time-dependent reductions in floral resources. We captured 2,009 individual bees that represented 67 distinct species/morphospecies in 20 genera and five families. Asymptotic estimators of bee diversity representing Shannon and Simpson diversity were greater in communities during the second half of the early seral period, indicating older early seral stands were less diverse and contained more common and dominant bee species. In addition, observed species richness and bee abundance peaked at approximately three years postharvest and declined thereafter by 20% and 30% per year, respectively. Because floral resources declined in concert with reductions in bee diversity as stands aged, food appears to be a key driver of forest bee communities. Our results indicate that postharvest Douglas-fir stands supported a diversity of bees, including important crop pollinators, but their value to bees was restricted to a relatively short window at the beginning of the early seral period.

Beschreibung: Simultaneous spikes in global prices of many agricultural commodities in recent years have induced an interest in quantifying the degree of synchronisation of these movements. We suggest a conceptual framework explaining why temporally varying price synchronisation may happen and propose the concordance index for the empirical measurement of the incidence, symmetry and permanence of synchronisation. We establish that the index generates insights into time series dynamics which are complementary to those obtained from cointegration analysis. We illustrate the approach with an application for the co-movement in cyclical components of pig and cattle prices in three Latin American countries. The findings reveal moderate synchronisation levels which show asymmetric instabilities.

Beschreibung: This article examines and analyses the environmental civil public interest litigation system in the protection of climate change in China through two cases, the All-China Environment Protection Federation v Zhenhua Co, Ltd for air pollution and Friends of Nature v State Grid Gansu Electric Power Corporation for full-purchase of all on-grid power produced by renewable energy.

Beschreibung: Credit markets are key instruments by which liquidity-constrained smallholder farmers may finance productive investments. However, the documented low demand and uptake of agricultural credit by smallholder farmers in sub-Saharan Africa pose challenges for energizing rural transformation in the region. In this paper, we investigate the impact of rainfall uncertainty—a major source of production risk—on the uptake of credit by rural farm households in Ethiopia. We further examine whether rainfall uncertainty explains credit rationing among those households not participating in rural credit markets. We find that rainfall variability discourages the uptake of agricultural credit. We also find that rainfall variability is associated with credit risk rationing, expressed as low demand for agricultural credit. We show that our findings are robust to alternative ways of constructing rainfall variability (inter-annual or inter-seasonal) and a battery of robustness checks. For instance, we show that rainfall variability is a strong predictor of credit uptake in rural areas while less relevant in urban areas. We also document heterogeneous responses to rainfall variability; those households living in the arid and semi-arid lands of Ethiopia, which are believed to be more vulnerable to recurrent weather shocks, are more responsive to rainfall variability in terms of reduced uptake of agricultural credit. Our results highlight the impacts of uninsured production risk on the demand for agricultural credit and hence smallholder agricultural investments. Our findings suggest the importance of interventions aimed at relaxing smallholders’ credit rationing while also reducing their production risk.

Beschreibung: Drought negatively impacts growth and productivity of plants, particularly in arid and semi-arid regions. Although drought events can take place in summer and winter, differences on the impact of drought on physiological processes between seasons are largely unknown. The aim of this study was to elucidate metabolic strategies of date palms in response to drought in summer and winter season. To identify such differences, we exposed date palm seedlings to a drought-recovery regime, both in simulated summer and winter climate. Leaf hydration, carbon discrimination (∆13C), primary and secondary metabolite composition and contents were analyzed. Depending on season, drought differently affected physiological and biochemical traits of the leaves. In summer, drought induced significantly decreased leaf hydration, concentrations of ascorbate, most sugars, primary and secondary organic acids, as well as phenolic compounds, while thiol, amino acid, raffinose and individual fatty acid contents were increased compared to well-watered plants. In winter, drought had no effect on leaf hydration, ascorbate and fatty acids contents, but resulted in increased foliar thiol and amino acid levels as observed in summer. Compared to winter, foliar traits of plants exposed to drought in summer only partly recovered after re-watering. Memory effects on water relations, primary and secondary metabolites seem to prepare foliar traits of date palms for repeated drought events in summer. Apparently, a well-orchestrated metabolic network, including the anti-oxidative system, compatible solutes accumulation and osmotic adjustment, and maintenance of cell membrane stability strongly reduces the susceptibility of date palms to drought. These mechanisms of drought compensation may be more frequently required in summer.

Beschreibung: The impact of the European Union common agricultural policy direct payments on land prices has received substantial attention in recent years, leading to heterogeneous evidence of capitalisation for both coupled and decoupled payments. In this paper, we provide an extensive review of the empirical works addressing this issue econometrically and compare their results through a Bayesian meta-regression model, focussing on the impact of decoupling and its implementation schemes. We find that the introduction of decoupled payments increased the capitalisation rate, although the extent of this increment hinges on the implementation scheme adopted by the member state.

Beschreibung: Viable farm households contribute to the resilience of agricultural and food systems. Farm income is a policy-relevant proxy for this viability. Here, we address three key aspects of farm income: first, the income issue, focusing on (average) income levels; second, the variability issue, focusing on income risks faced by farmers; and third, the inequality issue, focusing on the heterogeneity and (in-)equalities of farm incomes. This special issue presents new perspectives on measurement, modelling, development and policies related to the income of farm families in Europe, especially in the light of increasing complexity of farms and policies and risk exposure.

Beschreibung: This article will focus on price review clauses in Asian LNG markets from the point of view of price review arbitration and the jurisdiction of the tribunal. The basic conclusion reach is that there is no simple answer but that various considerations speak in favour of establishing the jurisdiction of arbitral tribunals in respect of gas prices. The background to the article is a number of gas price arbitrations that have been initiated in Asian markets and the assumption that these early cases will be followed by many more. One of the questions raised in this context is jurisdiction of the tribunal.

Beschreibung: Predicting tree frost tolerance is critical to select adapted species according to both the current and predicted future climate. The relative change in water to carbohydrate ratio is a relevant trait to predict frost acclimation in branches from many tree species. The objective of this study is to demonstrate the interspecific genericity of this approach across nine tree species. In the studied angiosperm species, frost hardiness dynamics were best correlated to a decrease in water content at the early stage of acclimation (summer and early autumn). Subsequently, frost hardiness dynamics were more tightly correlated to soluble carbohydrate contents until spring growth resumption. Based on different model formalisms, we predicted frost hardiness at different clade levels (angiosperms, family, genus and species) with high to moderate accuracy (1.5–6.0°C RMSE) and robustness (2.8–6.1°C RMSEP). The TOT model, taking all soluble carbohydrate and polyols into account, was more effective and adapted for large scale studies aiming to explore frost hardiness across a wide range of species. The ISC model taking the individual contribution of each soluble carbohydrate molecule into account was more efficient at finer scale such as family or species. The ISC model performance also suggests that the role of solutes cannot be reduced to a 'bulk' osmotic effect as could be computed if all of them were located in a single, common, compartment. This study provides sets of parameters to predict frost hardiness in a wide range of species, and clues in targeting specific carbohydrate molecules to improve frost hardiness.

Beschreibung: In 2017, the Energy Charter Treaty (ECT) began a modernization process aimed at updating, clarifying, and modernizing a number of provisions of the Treaty. Considering the scope of application of the Treaty—cooperation in energy trade, transit, and investment—there is hardly any doubt that the modernization kicked off in 2017 offers a springboard for constructive reform and a unique opportunity to bring the Treaty closer in line with the objectives of the Paris Agreement. Although none of the items selected by the Energy Charter Conference and open for discussion and reform mention climate change or clean energy, a careful analysis of the relevant practice in both treaty drafting and adjudication can provide valuable insights as to how to steer the discussions on some of the existing items in a climate-friendly direction. The purpose of this article is to rely on this relevant practice to explore promising avenues to ‘retool’ the Treaty for climate change mitigation, in other words, to imagine a Treaty that would better reflect climate change concerns and clean energy transition goals.

Beschreibung: Mastic trees (Pistacia lentiscus L.) are dioecious perennial plants highly adapted to Mediterranean climates but display a high sensitivity to winter periods. In order to understand how sex, leaf phenology and ecological context could condition sensitivity to winter and associated mechanisms to acclimate to these conditions, photoinhibition and photo-oxidative stress markers were examined in mastic trees (Pistacia lentiscus L.) from a natural population growing in the Garraf Natural Park for a consecutive 12-month period (seasonal study), as well as in three populations naturally growing in the Montseny Natural Park, including the highest altitudes described for this species, during winter (altitudinal study). Results from these studies indicate that both the winter period and higher elevation influenced the degree of photoinhibition, but this was not conditioned by sex. In fact, winter photoinhibition occurred transiently even though it was accompanied by enhanced chlorophyll loss and malondialdehyde contents. Stress acclimation was achieved through biochemical adjustments in chloroplasts, characterized by anthocyanin shielding, increased de-epoxidation state of the xanthophyll cycle as well as tocopherol accumulation, and phenological adaptations, the latter allowing a complete resetting of the physiological performance of leaves. Moreover, although females showed higher lipid peroxidation than males during the coldest winter months, at the highest elevation and during flowering in spring, this oxidative stress was mild and transient with no negative consequences for the physiology of plants. It is concluded that evergreen mastic trees acclimate to winter conditions and higher elevations by activation of antioxidant defenses together with phenological adjustments, altogether playing a crucial role in plant survival. Sexual dimorphism in mastic trees appears as a relevant factor when considering sensitivity to photo-oxidative stress in winter and altitudinal conditions.

Beschreibung: Longleaf pine (LLP) (Pinus palustris Mill.) is well known for its role in supporting healthy ecosystems in the southeastern (SE) United States (US). The decline of LLP forest ecosystems has led to a consensus among stakeholders that restoration efforts are needed. However, there is still a lack of robust understanding of the utilization of nonmarket ecosystem services of LLP forests. These challenges have presented major barriers to landowner acceptance of subsidized LLP restoration programs. Understanding the tradeoffs between forest ecosystem services is critical to restoring LLP in the SE US. This study employs the best-worst choice (BWC) method to assess public preferences toward hypothetical LLP restoration programs that consider ecosystem services such as recreation, timber production, carbon sequestration, water yield, and wildlife diversity. We surveyed a representative sample of n = 953 respondents from Alabama, Mississippi, Georgia, and Florida, and results showed that residents in all four states are willing to pay for LLP restoration, with the highest average willingness to pay (WTP) for forest recreation ($20.39), followed by red-cockaded woodpecker (RCW) conservation ($13.37) and carbon sequestration ($13.32). This research provides important public preference information on ecosystem services that is critical in forming sustainable LLP restoration programs. Study Implications This study is useful from a policy assessment perspective for evaluating benefits and costs of LLP restoration programs in the SE US, for informing program design, and understanding tradeoffs between LLP ecosystem services. The public plays an important role in influencing environmental policy choices, including LLP restoration programs.

Beschreibung: The continuously increasing atmospheric carbon dioxide concentration ([CO2]) has substantial effects on plant growth, and on the composition and structure of forests. However, how plants respond to elevated [CO2] (e[CO2]) under intra- and interspecific competition has been largely overlooked. In this study, we employed Abies faxoniana and Picea purpurea seedlings to explore the effects of e[CO2] (700 ppm) and plant–plant competition on plant growth, physiological and morphological traits, and leaf ultrastructure. We found that e[CO2] stimulated plant growth, photosynthesis and nonstructural carbohydrates (NSC), affected morphological traits and leaf ultrastructure, and enhanced water and nitrogen use efficiencies in A. faxoniana and P. purpurea. Under interspecific competition and e[CO2], P. purpurea showed a higher biomass accumulation, photosynthetic capacity and rate of ectomycorrhizal infection, and higher water and nitrogen use efficiencies compared with A. faxoniana. However, under intraspecific competition and e[CO2], the two conifers showed no differences in biomass accumulation, photosynthetic capacity, and water and nitrogen use efficiencies. In addition, under interspecific competition and e[CO2], A. faxoniana exhibited higher NSC levels in leaves as well as more frequent and greater starch granules, which may indicate carbohydrate limitation. Consequently, we concluded that under interspecific competition, P. purpurea possesses a positive growth and adjustment strategy (e.g., a higher photosynthetic capacity and rate of ectomycorrhizal infection, and higher water and nitrogen use efficiencies), while A. faxoniana likely suffers from carbohydrate limitation to cope with rising [CO2]. Our study highlights that plant–plant competition should be taken into consideration when assessing the impact of rising [CO2] on the plant growth and physiological performance.

Beschreibung: During the Covid-19 pandemic companies have declared force majeure on contracts across the energy value chain. LNG Sales and Purchase Agreements (SPAs) are no exception. Courts in several jurisdictions have declared Covid-19 a force majeure event. Governments have issued guidelines on managing Covid-related contract disputes. The stage is set for high-value litigation turning on the validity of force majeure clauses. The purpose of this article is to help make sense of these developments. It will review the theory and application of the law of force majeure and, through comparison of six published LNG SPAs, ‘stress test’ current force majeure provisions. The article will consider how contractual risk is presently allocated in these model contracts, what drafting modifications might be applied to improve coverage, align with current case law, better reflect the market environment, and ensure contractual stability under Covid-19 conditions. The focus is on English law, given that this is the lex fori in the majority of the published contracts.

Beschreibung: Environmental models are ubiquitous in assessing the environmental impacts of planned projects. Modelling is an inferential process and includes various mechanisms to address the uncertainty of the outcome. In this article, we acknowledge the continuum of uncertainty assessments and identify the legal mechanisms with which Finnish judicial review—characterised by broad scope of review and in-house expert judges—has encountered model uncertainty. Closely examining 10 waters-related cases heard by the Supreme Administrative Court of Finland, we explain the porous yet substantial boundary between science and law revealed by the cases. The cases demonstrate the elegance with which courts can strike a balance between the contingent precautionary principle, gradually decreasing scientific uncertainty, and the procedural constraints under which they operate. We conclude by analysing the traces towards reciprocality and adaptivity the cases reveal, encouraged by the iterative modelling mechanism and challenged by the constitutional restrictions on the scope of review.

Beschreibung: Stand improvement (SI) has been widely accepted as an effective forest management tool. Yet most studies on its economic feasibility for nonindustrial private forest (NIPF) landowners are outdated and focus on the single stand level. The objective of this study was to conduct an economic assessment of SI’s effects and feasibility in hardwood stands for a case study in the White River Basin in Indiana. It is shown that SI could make these forests more productive and sustainable than the prevalent “hands-off” practice by enhancing the timber value of the residual stand (TV), generating regular timber income, and to some degree, reversing the decline in oak dominance. On average, a 25% increment in the TV could be achieved. Although costly for some NIPFs, once combined with voluntary financial incentive programs, SI could meet landowners’ demands for low-cost, high-return investment options. In particular, participation in the Environmental Quality Incentive Program could, on average, increase the net present value of timber income from thinning activities by nearly $1,600 per hectare over the course of 30 years. The spatial analysis revealed that there existed considerable spatial heterogeneity in SI benefits and impacts, suggesting that public incentive programs should be spatially targeted to achieve greater efficiency. Study Implications This study found that stand improvement (SI) could significantly improve the timber value of forestland in the central hardwood region. Participation in voluntary conservation programs, such as the Environmental Quality Incentive Program, could alleviate part of the SI cost thus making it an attractive investment opportunity for private landowners. For the study region, the White River Basin in Indiana, the results suggested that there existed substantial variations in SI’s effectiveness across space. This implied that program administrators of voluntary incentives could improve the efficiency of public funds allocation by considering this spatial variation when evaluating landowners’ applications for incentives.

Beschreibung: This article theoretically and empirically disentangles the effects of maximum residue limits (MRLs) for pesticides on production, export supply and import demand. We adopt a modelling approach based on the costs and benefits associated with food safety standards and use our theoretical framework to assess the empirical net effects of MRLs for pesticides on African mango production and trade with Organisation for Economic Co-operation and Development (OECD) member countries. On the one hand, we theoretically highlight that for a given production technology and a level of elasticity of production costs with respect to the MRL gap, producers will likely (probability and quantity) produce standard-compliant products if they are able to completely pass through the standard-compliance costs to the unit price they receive from exporters; otherwise, they will exit standard-compliant products market. On the other hand, we theoretically show that the net effects of the MRL gap on bilateral trade can be positive, zero or negative depending on the effects of consumers’ perceived quality (positive), trade costs (negative) and standard-compliant production cost (negative). We use a cross-sectional data set for 12 African countries that produced and exported MRL-compliant mangoes to 31 OECD countries in 2016. On the one hand, we find that the net effect of MRLs is positive for the level of standard-compliant mango production and negative for the probability of producing. On the other hand, they are positive in mango trade between African and OECD member countries. Our results highlight that the tightening or imposition of strict MRLs for pesticides in developed countries may be trade promoting, while they severely impede production in African countries.

Beschreibung: It has been posited that US national forest administration is undergoing a governance transition characterized by an increase in the involvement and influence of non-state actors. One example of this new form of national forest governance is the use of multi-stakeholder collaborative efforts for planning and implementing projects. This has raised normative and positive questions about the value and effectiveness of such efforts and how they compare with more traditional public involvement and planning processes. This study attempts to address the latter questions by analyzing project-level planning and implementation data while comparing collaborative and traditional projects on a suite of metrics related to pace, scale, complexity, and legal outcomes. We used administrative data from the USDA Forest Service to conduct a quantitative analysis of projects over a 14-year period. We found that collaboratively developed projects were larger and more complex than traditional projects and were associated with greater planning efficiency. This analysis responds to the need to systematically assess the impact of collaborative governance and contributes to existing theories of governance, organizational learning, and policy implementation.

Beschreibung: We use a business management game to investigate how a pesticide tax and a green nudge affect crop, tillage and pesticide decisions for a virtual farm. Results from German farmers reveal that both policies can reduce pesticide applications. The pesticide tax involves a substantial profit loss. Unlike in the green nudge scenario, participants under pesticide tax adjust their cropping and tillage strategies. We compare farmers’ decisions to those made by a mathematical programming model. Assuming profit maximisation would overestimate farmers’ response to the tax and underestimate the effectiveness of the nudge.

Beschreibung: Partial harvesting (here defined as removal of ≤50% of preharvest volume) is the predominant silvicultural scheme applied to hardwood forest types in the eastern United States. Future stand conditions are largely reliant on trees retained after harvest, so their mortality because of harvesting activity damage should be minimized or taken into account when planning. We quantify partially harvested stand characteristics and postharvest mortality using data from 32,057 forested conditions, 366,953 trees with a diameter at breast height (dbh) ≥ 2.5 cm, of which 4,469 trees were cut and used in partially harvested stands. On average 23.3% of stand volume was selectively harvested with an additional 2.5% of volume lost to harvesting-caused mortality. Of the trees killed by logging activity in harvested stands, 90.7% were under 28 cm dbh. The likelihood of mortality was 1.31 times higher (95% CI of 1.20 to 1.44) for trees retained in stands that had undergone partial harvesting than for trees growing in unharvested stands. Commercial species had lower odds of mortality (0.88 times) in harvested stands than noncommercial species. Residual trees in harvested stands on private lands had a higher probability of mortality (1.23 times) than those on harvested public lands.

Beschreibung: Distribution of tree diameters in a stand is characterized using models that predict diameter moments and/or percentiles in conjunction with a mathematical system to recover the parameters of an assumed statistical distribution. Studies have compared Weibull diameter distribution recovery systems but arrived at different conclusions regarding the best approach for recovering a stand’s diameter distribution from predicted stand-level statistics. We assessed the effects of sample plot size and diameter moments/percentiles prediction models on the accuracy of three approaches used in recovering Weibull distribution parameters—method of moments, percentile method, and moments-percentile hybrid method. Data from five plot sizes, four of which were virtually created from existing larger plots, from unthinned loblolly pine (Pinus taeda) plantations, were used to fit moments/percentile prediction models and to evaluate the accuracy of the diameter distribution recovered using three approaches. Both plot size and prediction model form affected the accuracy of the recovery approaches as indicated by the changes in their ranking from one plot size to another for the same model form. The method of moments approach ranked best when the evaluation error index did not account for tree stumpage value, but the moments-percentile hybrid approach ranked best when stumpage value was considered. Study Implications Diameter distribution recovery techniques make it possible to disaggregate trees per unit area, predicted by the whole stand growth and yield models, into diameter and utilization product classes. Thus, the techniques provide insights into stand structure, which can guide management decisions such as thinning and selection harvesting. The techniques are also used to generate yield tables by product class, which are important inputs into harvest scheduling optimization programs. An accurate diameter recovery technique is therefore critical to forest management and planning. Based on the findings of this study, the best approach of developing a diameter distribution recovery system for unthinned loblolly pine plantations would be to use the hybrid approach, with tree diameter data collected from plots of at least one-tenth hectare. The well-known (and, most likely, widely used) method of moments approach may not be the best choice. For predicting stand diameter moments and order statistics used in a diameter distribution recovery system, it would be best to use a linear additive model that incorporates a measure of stand density, such as relative spacing and/or number of trees per unit area, and a measure of the stand’s stage of development, such as dominant height and/or age.

Beschreibung: Following harvests by even-aged methods in mixed-hardwood forests, desirable oak (Quercus spp. L.) reproduction can be quickly overtopped by shade-intolerant pioneer species. In a long-term, operational-scale study of uneven-aged management by group selection, we inventoried 10- and 20-year-old reproduction following two harvest entries in a mature, dry-mesic southern Appalachian upland hardwood stand. Our study objectives included evaluating the species composition and structure of reproduction in relation to opening size (0.05 ha to 0.41 ha), position in openings (center or edge), uneven-aged diameter structure, and evidence supporting the delayed oak dominance hypothesis. Opening size had no effect on reproduction from either entry. After 10 years (but not 20) yellow-poplar (Liriodendron tulipifera L.) stem density and basal area were greater in opening centers; oaks were greater at edges. Position did not affect red maple (Acer rubrum L.) or other tolerant species. Diversity significantly increased between 10 and 20 years, suggesting evidence supporting the delayed oak dominance hypothesis. Early results from this study suggest that small openings can be used to regenerate desirable midtolerant and intolerant species in Appalachian mixed-hardwood stands on intermediate quality sites where uneven-aged stand structure is important for timber management and other goals such as visual appearance and early successional habitat. Study Implications Periodic harvests of small groups (0.05 to 0.41 ha) of mature trees in dry-mesic Appalachian oak-dominated, mixed-hardwood stands, followed by site preparation and competition release treatments to control undesirable shade tolerant species, can result in openings stocked with desirable shade midtolerant and intolerant reproduction after 20 years. Centers of openings will be dominated by yellow-poplar, but oak reproduction can be most prevalent around the periphery. Group selection is a flexible method of uneven-aged management that can be used to meet regeneration objectives and related goals such as early successional habitat and visual quality.

Beschreibung: The number of mills and employees in Oregon’s sawmill sector has continuously declined from 2003 to 2017, but the amount of lumber produced has stabilized in recent years. In this study, the performance of individual sawmills is evaluated by applying data envelopment analysis on a unique dataset for 146 mills over four survey years of 2003, 2008, 2013, and 2017. The scale efficiency of these mills is generally high, but their overall technical efficiency is only 85%. In 2017, the most efficient mills as a group used 14% fewer employees, processed 18% more sawlogs, and produced 32% more lumber than an average mill in Oregon. Across the four survey years, productivity growth over time is small at only 0.14% per year, and most of the growth can be attributed to changes in technology. The catch-up effect by individual mills is actually negative at −0.07% per year. These findings reveal that the growth of production efficiency in Oregon’s sawmill sector has been slow, and the direction for future improvement relies on better management of operations and resources by individual mills.

Beschreibung: Oak-pine (Quercus L. - Pinus L.) forest communities on low ridges in the southern Appalachian Mountains are losing diversity as mature pitch (P. rigida Mill.) and shortleaf (P. echinata Mill.) pines die and do not regenerate under a hardwood canopy. Restoration of biodiversity by planting pine seedlings is well known, but little is known regarding whether the configuration of planted seedlings affects growth and subsequent size (diameter at breast height, dbh) as trees age. The purpose of this study was to test the hypothesis that pines growing in groups of two or more trees respond with increased growth (expressed by dbh) to intraspecific competition with other pines compared to single trees subjected only to interspecific competition with surrounding hardwoods. For 13-year-old pitch and shortleaf pines, trees were larger in dbh when occurring in groups than trees occurring singly. Regression indicated that intraspecific competition accounted for 16% of the dbh variation of pitch pine and 29% for shortleaf pine. This study originated from chance observations in a small study of pine restoration. If a designed study confirms these results, resource managers could restore biodiversity with reduced site disturbance and establishment costs by planting pine seedlings in small groups rather than rows.

Beschreibung: A 41-year-old bottomland hardwood plantation experiment located in southeastern Arkansas was revisited in 2017 to evaluate basal area increment (BAI) of four oak species [cherrybark oak (Quercus pagoda Raf.), swamp chestnut oak (Q. michauxii Nutt.), Nuttall oak (Q. texana Buckl.), and water oak (Q. nigra L.)] planted in monoculture in relation with species, spacing, thinning, and neighborhood competition. Species had a significant effect on BAI (P = 0.04), with cherrybark oak and Nuttall oak demonstrating the greatest (21.5 ± 2.5 cm2 year−1) and lowest (12.7 ± 2.9 cm2 year−1) growth rates, respectively, whereas BAI declined significantly with increasing competition (P = 0.03). However, rates of growth decline with competition did not differ between species (P 〉 0.05 for competition × species term), and thinning and spacing treatments had no effect on BAI (P 〉 0.05). We recommend that repetitive thinning, rather than a single thinning, would be appropriate to maintain a positive impact on oak growth. Managing stand density would not only provide opportunities for improving timber production, but also would enhance ecological benefits (e.g., wildlife habitat) through diversification of structure within monoculture plantations. Study Implications: This research supports the general concept that stand density management may effectively alleviate tree-level stresses on bottomland oak species related to intra-specific competition while improving their growth. In particular, repeated thinning could help reduce growth stagnation and maintain tree-level vigor. Repeated tending entries would also create multiple opportunities to simultaneously improve timber production and enhance ecological benefits in bottomland oak monocultures. Finally, the findings of this study confirm the importance of correctly matching species to site when artificially regenerating bottomland oaks.

Beschreibung: The most important climatic variable influencing growth and survival of loblolly pine is the yearly average minimum winter temperature (MWT) at the seed source origin, and it is used to guide the transfer of improved seed lots throughout the species’ distribution. This study presents a novel approach for the assessment of freeze-induced damage and prediction of MWT at seed source origin of loblolly pine seedlings using hyperspectral imaging. A population comprising 98 seed lots representing a wide range of MWT at seed source origin was subjected to an artificial freeze event. The visual assessment of freeze damage and MWT were evaluated at the family level and modeled with hyperspectral image data combined with chemometric techniques. Hyperspectral scanning of the seedlings was conducted prior to the freeze event and on four occasions periodically after the freeze. A significant relationship (R2 = 0.33; p 〈 .001) between freeze damage and MWT was observed. Prediction accuracies of freeze damage and MWT based on hyperspectral data varied among seedling portions (full-length, top, middle, and bottom portion of aboveground material) and scanning dates. Models based on the top portion were the most predictive of both freeze damage and MWT. The highest prediction accuracy of MWT [RPD (ratio of prediction to deviation) = 2.12, R2 = 0.78] was achieved using hyperspectral data obtained prior to the freeze event. Adoption of this assessment method would greatly facilitate the characterization and deployment of well-adapted loblolly pine families across the landscape. Study Implications Cold hardiness is the most important adaptability trait for deployment of loblolly pine in the southeastern United States, and average annual minimum winter temperature (MWT) at the seed source is the present-day standard indicator of cold-hardiness. Advanced generation families are deployed to cold hardiness zones based on the average MWTs of the seed source locations of their founding ancestors, which may become unreliable as breeding cycles progress and the number of ancestors increase. This study demonstrates that hyperspectral imaging promises as a rapid, nondestructive and objective tool for the assessment of cold hardiness of loblolly pine seedlings and the prediction of MWT of origin.

Beschreibung: Large multiobjective forest monitoring efforts such as the USDA’s Forest Inventory and Analysis Program and other National Forest Inventory (NFI) systems are usually described to the public in terms of the relationship of their sample designs to the land base of interest. Sometimes the third dimension of time is included in the description of the sample design. Additionally, there is a tendency to favor descriptions that arguably support design-based views of the used estimation systems. The accompanying justification usually relies on an assumption that design-based estimators are “objective,” whereas model-based estimators are “subjective.” This article posits that this argument misses the mark because design-based estimation begins with the assumption that a probability sample exists and that the sample observations have been obtained without error. In most large sampling efforts, it is known that violations of the sample design not only might, but will, occur. Additionally, some objectives in a multiobjective inventory require estimation of attributes of tangentially related populations. Here we unify estimation methods into an overall theoretical framework, or “wrapper” model, that allows for the recognition, acknowledgement, and accounting for nonsampling errors and imperfect sample frames into estimation systems capable of combining all observations available to analysts of these large inventory systems. Study Implications This study describes a theoretical framework, named a “wrapper” model, that gives developers of national forest inventory and monitoring systems a more complete way to describe the assumptions and information sources contributing to the outputs from those systems. Rather than the usual description of the outputs in terms of the sample design and corresponding estimation system, these elements are recognized simply as (albeit major) components within the wrapper model.

Beschreibung: Small-tree development affects future stand dynamics and dictates many ecological processes within a site. Accurately representing this critical component of stand development is important for evaluating treatment alternatives from fuel hazard reduction to harvest scheduling. As with all forest growth, competition with other vegetation is known to regulate small-tree growth dynamics. This study uses three Nelder plots with 45 years of ponderosa pine growth to understand competition effects on seedling growth and evaluate the Forest Vegetation Simulator (FVS) Central Rockies (CR) variant’s ability to represent these dynamics. Removal of herbaceous competition before planting increased tree diameters by 50–135% and height by 35–75% across a planting density gradient at age 12. However, by age 45, the effect of herbaceous competition on tree size was no longer evident. Instead, trees at the lowest planting density had diameters 2.5–3 times larger than the most densely grown trees. Forest Vegetation Simulator (FVS) simulations underpredicted diameter at breast height (dbh) by 35–50% and 0–35% for 12 and 45-year-old trees, respectively. There was an underprediction bias of 15–20% for heights at age 12 and overpredictions of 5–10% at age 45. Continuous underprediction of dbh will affect the reliability of modeled fuel treatment longevity and sustainable harvest scheduling. Study Implications: Management and modeling of small-tree growth can affect decision-making for a range of activities, from assessing fuel treatment effectiveness to sustainable harvest scheduling. Effective small-tree density management can increase tree diameters at age 45 by 2.5–3 times the diameter of unthinned sites. FVS-CR underpredicted age 12 heights by 0–45% and age 45 diameters by 0–35% as a function of planting density, suggesting that the model fails to capture the intensity or timing of density-induced competition. These underpredictions will inflate the length of time fuel treatments remain effective and decrease projected sustainable harvest levels supported by responsible management.

Beschreibung: This study employed stochastic frontier analysis to determine the effects of forest ownership and management on the technical efficiency of water production from longleaf pine forests in the southern United States. Data at the forest-plot level were obtained from the Forest Inventory Analysis, climatic models, and water supply relationships. Results showed that the provision of water was inefficient and significantly different between public and private ownership. Longleaf pine forests under public ownership were modestly more efficient (2.2%–1.5%) in the production of water than private longleaf pine forests. Forest management had a negative impact on the efficiency in water production for privately and publicly owned longleaf pine forests. If 1 hectare of longleaf pine supplied on average 5,000 cubic meters of water per year, the production of water on public and private lands would be reduced to 4,960 and 4,800 cubic meters per year, respectively, with forest management. Efficiency in water supply was found to decline over time in both types of forest ownership.

Beschreibung: This study attempts to understand the climatic resilience of two forest types of central India—that is, Tectona grandis (Teak) forest of Satpura Tiger Reserve and Shorea robusta (Sal) forest of Kanha Tiger Reserve—using normalized difference vegetation index (NDVI), enhanced vegetation index (EVI) extracted from MODIS, and climate variable data sets at highest spatial and temporal scales. Teak and Sal forests within the core area of the selected tiger reserves represent the least anthropogenic disturbances, and therefore, the observed changes in NDVI and EVI over the past 16 years could be analyzed in the context of climate change. The correlation analysis between climatic variables (minimum temperature, maximum temperature, mean temperature, and total annual rainfall) and forest response indicators (NDVI/EVI) at seasonal and annual scales revealed that Teak and Sal forests are more sensitive to change in past temperature as compared with rainfall. Also, the changes in NDVI and EVI of Sal forest are correlated more to minimum temperature, and that of Teak forest to maximum temperature. The analysis of sapling girth class of Sal and Teak further revealed that Sal as compared with Teak is more affected because of the changing climate variables of the recent past. The findings of the study will help manage forests more efficiently in the context of changing climate.

Beschreibung: In this article, we present a model and estimates of US import demand for softwood plywood from Brazil, Canada, Chile, and China using a cointegration framework. We find evidence of long-run cointegration for time series variables in US import demand functions from Brazil, Canada, and China but not from Chile. The short-run own price elasticity estimates of US import demand from Brazil, Canada, Chile, and China are at –0.53, –0.80, –0.82, and –0.91, respectively. The estimates of long-run price elasticity suggest that US import demand for softwood plywood from the three countries is more sensitive to softwood plywood price change.

Beschreibung: Alaska forest managers seek information on how timber harvesting practices change the creation of postharvest woody residues. To predict residue volumes, researchers investigated how residue ratios—growing-stock residue volume per mill-delivered volume—related to readily available data on logging site and tree attributes in Alaska. Residue ratios were not related to logging site-level variables but were related to individual tree variables with predictive models. Ratios varied widely by tree species and were predicted to increase with larger stump height and larger small-end used diameters and decline exponentially with increasing diameter breast height (dbh) to approximately 25 inches. Ratios were then predicted to increase progressively in larger dbh trees. Results from this study update previous findings in other US Northwest states and can be used to produce or improve residue prediction tools for Alaska land managers.

Beschreibung: The Canary Islands, an archipelago east of Morocco's Atlantic coast, present steep altitudinal gradients covering various climatic zones from hot deserts to subalpine Mediterranean, passing through fog-influenced cloud forests. Unlike the majority of the Canarian flora, Pinus canariensis grow along most of these gradients, allowing the study of plant functioning in contrasting ecosystems. Here we assess the water sources (precipitation, fog) of P. canariensis and its physiological behavior in its different natural environments. We analyzed carbon and oxygen isotope ratios of water and organics from atmosphere, soil and different plant organs and tissues (including 10-year annual time series of tree-ring cellulose) of six sites from 480 to 1990 m asl on the Canary island La Palma. We found a decreasing δ18O trend in source water that was overridden by an increasing δ18O trend in needle water, leaf assimilates and tree-ring cellulose with increasing altitude, suggesting site-specific tree physiological responses to relative humidity. Fog-influenced and fog-free sites showed similar δ13C values, suggesting photosynthetic activity to be limited by stomatal closure and irradiance at certain periods. Besides, we observed an 18O-depletion (fog-free and timberline sites) and 13C-depletion (fog-influenced and fog-free sites) in latewood compared to earlywood caused by seasonal differences in: (i) water uptake (i.e., deeper ground water during summer drought, fog water frequency and interception) and (ii) meteorological conditions (stem radial growth and latewood δ18O correlated with winter precipitation). In addition, we found evidence for foliar water uptake and strong isotopic gradients along the pine needle axis in water and assimilates. These gradients are likely the reason for an unexpected underestimation of pine needle water δ18O when applying standard leaf water δ18O models. Our results indicate that soil water availability and air humidity conditions are the main drivers of the physiological behavior of pine along the Canary Island's altitudinal gradients.

Beschreibung: Tetrastigma hemsleyanum is a liana plant with promising medicinal and ornamental values. Its calabash-shaped roots (CRs) are served as a traditional Chinese herb. However, it takes a long growth period to form CRs. In the present study, three types of architectural roots, including fine roots (FRs), bar-shaped roots (BRs) and CRs, were employed as materials, and the characteristics of histo-anatomy and digital RNA-seq transcriptome profiles were analyzed. Among the three types of roots, the vascular bundles in FRs were intact, while some of the vascular bundles degenerated in BRs, and only few traces of vascular bundles existed in CRs. Meanwhile, no obvious cell inclusions were found in the cytoplasm of FRs, while a few inclusions were found in BRs, and abundant inclusions were detected in CRs, which might be the main source of medicinal components in roots. The transcriptome profiles and qRT-PCR validation indicated that seven up-regulated genes encoding xyloglucan glycosyltransferase, ACC oxidase, CYP711A1, SHORT-ROOT transcript factor, galacturonosyltransferas, WAT1 and WRKY, and two down-regulated genes encoded LRR receptor-like serine/threonine-protein kinase and CYP83B1, were probably involved in the formation and development of CRs. Besides, GO terms of intrinsic component of membrane, integral component of membrane, cell periphery, membrane part, plasma membrane, membrane, intrinsic component of plasma membrane, cellular chemical homeostasis, and plasma membrane part were probably related to the formation of CRs. KEGG pathways related to the development of CRs probably included MAPK signaling pathway-plant, plant hormone signal transduction, and circadian rhythm-plant. Our finding suggested a probable mode for the formation of CRs.

Beschreibung: The mountain birch (Betula pubescens var. pumila (L.)) forest in the Subarctic is periodically exposed to insect outbreaks, which are expected to intensify due to climate change. To mitigate abiotic and biotic stresses, plants have evolved chemical defenses, including volatile organic compounds (VOCs) and non-volatile specialized compounds (NVSCs). Constitutive and induced production of these compounds, however, are poorly studied in Subarctic populations of mountain birch. Here, we assessed the joint effects of insect herbivory, elevation, and season on foliar VOC emissions and NVSC contents of mountain birch. VOCs were sampled in situ by an enclosure technique and analyzed by gas chromatography–mass spectrometry. NVSCs were analyzed by liquid chromatography–mass spectrometry using an untargeted approach. At low elevation, experimental herbivory by winter moth larvae (Operophtera brumata) increased emissions of monoterpenes and homoterpenes over the three-week feeding period, and sesquiterpenes and green leaf volatile in the end of the feeding period. At high elevation, however, herbivory augmented only homoterpene emissions. The more pronounced herbivory effects at low elevation were likely due to higher herbivory intensity. Of the individual compounds, linalool, ocimene, 4,8-dimethylnona-1,3,7-triene, 2-methyl butanenitrile, and benzyl nitrile were among the most responsive compounds in herbivory treatments. Herbivory also altered foliar NVSC profiles at both low and high elevations, with the most responsive compounds likely belonging to fatty acyl glycosides and terpene glycosides. Additionally, VOC emissions from non-infested branches were higher at high than low elevation, particularly during the early season, which was mainly driven by phenological differences. VOC emissions varied substantially over the season, largely reflecting the seasonal variations in temperature and light levels. Our results suggest that if insect herbivory pressure continues to rise in the mountain birch forest with ongoing climate change, it will significantly increase VOC emissions with important consequences for local trophic interactions and climate.

Beschreibung: This paper examines how differences in motivation in terms of use and non-use values affect the choice of animal welfare improvement practices. The application is focused on Swedish dairy farmers’ preferences for different flooring systems’ attributes. Using multiple indicators and multiple causes and hybrid latent class models, the findings demonstrate that dairy farmers who favour flooring solutions that enhance farm animal welfare are motivated by a complex set of both use values relating to internal and external pressures and non-use values linked to animal freedom, ethical codes of farmers and building business-to-customer relationships. The findings imply that measures to stimulate more uptake of animal welfare improvement practices can be better targeted by using insights into motivational constructs of farmers and by adopting policy communication that captures the whole breadth of use and non-use motivational constructs held by farmers.

Beschreibung: Ground-level ozone (O3) pollution affects the plant carbon and water balance, but the relative contributions of impaired photosynthesis and the loss of stomatal functioning to the O3-induced reductions in water use efficiency (WUE) remain unclear. We combined the leaf stable dual isotopic signatures of carbon (δ13C) and oxygen (δ18O) with related instantaneous gas exchange performance to determine the effects of O3 dose on the net photosynthetic rate (An), stomatal conductance (gs) and intrinsic WUE (iWUE = An/gs) in four tree species (one being a hybrid) exposed to five O3 levels. The iWUE declined for each step increase in O3 level, reflecting progressive loss of the coupling between leaf carbon gain and water loss. In ambient compared to charcoal-filtered air, the decreased iWUE was associated with reductions in both An and gs (i.e., decreased δ13C and increased δ18O). In elevated O3 treatments, however, the iWUE declines were caused by reduced An at constant or increased gs. The results show that the dual isotope approach provides a robust way to gather time-integrated information on how O3 pollution affects leaf gas exchange. Our study highlights that O3-induced decoupling between photosynthesis and stomatal regulation causes large and progressive declines in the WUE of forest trees, demonstrating the need for incorporating this, hitherto unaccounted, effect into vegetation models.

Beschreibung: Under the mean-variance efficiency framework, we investigate the role of timberland asset in a mixed-asset portfolio in the United States. Starting from a single period (quarterly) view, we first reveal the crucial role of serial correlation in defining an asset’s financial performance. Accordingly, we modify return, volatility, and correlation for multiyear horizons to account for the nature of long-term investments. Our results show that, although timberland is persistent in all portfolios, private-equity timberland can be substituted by other liquid assets, including public-equity timberland, as the lengthening holding period substantially reduces their volatilities. We conclude that private-equity timberland is a risk diversifier regardless of the length of the investment horizon, whereas public-equity timberland becomes a suitable diversifier only for long-term investors with high risk tolerance. Study Implications: Serial correlation influences an asset’s return, risk, and correlation with other assets as the investment horizon lengthens. Volatilities of large-cap stocks and public timber real estate investment trusts decay significantly when the holding period is longer than three years. Therefore, these liquid assets become more efficient in the long run. Regardless of the length of the investment horizon, private-equity timberland acts as a risk diversifier in a mixed-asset portfolio, whereas public-equity timberland is a suitable diversifier only for high risk, long-term investors.

Beschreibung: The Cutting Methods Study at the Ford Forest in the Upper Peninsula of Michigan, USA, was established in 1956 and has been maintained continuously on a 10 year cycle. Methods consist of three diameter limits (DL; 13, 30, and 41 cm), single-tree selection to three residual basal area limits (STS; 11, 16, and 21 m2ha−1), and light improvement (LI) focused on improving tree grade. Long-term results show that the 41 cm DL produced the greatest managed forest value and cumulative sawlog production, followed by the STS to 11 m2ha−1 residual basal area. STS treatments and LI were uniformly superior at improving standing tree grade. In contrast, treatments that emphasize removal of large diameter trees while retaining moderate residual basal area (the 41 cm DL and 11 m2ha−1 STS) produced the largest harvest volumes of high-grade sawlogs, driving financial performance. Stand density has declined in all treatments except the 30 and 41 cm DL, where it has increased, and these two treatments have larger abundance of saplings and poles. Alternative partial cutting methods such as selection to lower residual basal areas and medium-intensity diameter-limit cuts thus may provide greater financial returns and higher average quality, and could have implications on regeneration and long-term sustainability. Study Implications: Long-term comparison of alternative partial cutting practices in northern hardwoods in the Upper Peninsula of Michigan over 60 years reveals that Arbogast-based single-tree selection is inferior using financial and volume yield criteria. Alternatives that remove more of the larger trees appear over time to increase regeneration and harvested tree quality, which in turn drives financial performance. However, treatments with extremely high volume removals perform poorly against all others, and have few, if any, redeeming financial, silvicultural, or ecological qualities.

Beschreibung: The population of Andaman padauk (Pterocarpus dalbergioides Roxb.), an endemic ornamental timber species, is fast depleting in the Andaman Islands. Afforestation through seedlings is hindered by low germination and high mortality rates. This study attempts to assess the efficacy of clonal propagation methods to hasten mass multiplication by trying out different combinations of growth hormones, concentration, and dipping duration in semi-hardwood stem cuttings and different combinations of growth hormone concentration and substrate in air layering. Dipping the cuttings in indole-3-butyric acid (IBA) 1,500 ppm for 24 hours and spraying the modified stem-cut layers with IBA 2,000 ppm and binding with top soil and decomposed coir dust turned out to be the best treatment combination for cutting and air layering, respectively. Among the considered factors, the concentration of growth hormone is crucial for cutting, as the performance is enhanced with concentration under a given growth hormone and dipping duration. Similarly, the substrate is crucial for air layering, as modified stem-cut air layers bound with top soil and decomposed coir dust not only achieve the best performance, but also catalyze IBA for further improvement when other substrates remain unresponsive. Successful outcome of both clonal propagation techniques gives hope for disseminating the species across the tropics at global level. Study Implications: Low germination and high mortality render propagation of Pterocarpus dalbergioides through seeds inefficient. This study has revealed an optimal combination of growth hormone and its concentration, dipping duration, and substrate to efficiently propagate this tree through stem cutting and air layering. The findings will help disseminate the highly valuable yet endangered timber species not only in its natural habitat of Andaman Islands but across the globe where there are favorable climatic conditions. As all the species under the pantropical Pterocarpus genus share similar growth and reproductive traits, the optimized treatment combination will be applicable to other species whose existence is threatened in their habitat.

Beschreibung: On 22 December 2020, the Norwegian Supreme Court ruled on its first climate case. It dealt with the claim that petroleum licences, issued by the Norwegian government, violate the ‘right to a healthy environment’ as contained in the Norwegian Constitution. The Court rejected the claim and found that the constitutional protection of the environment applies not as a right but as a substantive limit to governmental action, and only in very limited circumstances. Rather than taking the opportunity to give guidance on this constitutional provision, the Court provided a judgment that aligned law with the current politics in favour of continuous petroleum extraction on Norwegian territory.

Beschreibung: We tested the efficacy of a range of herbicides to see if they might be potential substitutes for the use of propyzamide or glyphosate to control grass weed species that, if left unchecked, often outcompete recently planted trees in UK forests. Applications of 0.45kg a.i. ha−1 cycloxydim in late April–early May gave good control of wood small reed (Calamagrostis epigejos (L.) Roth), Yorkshire fog (Holcus lanatus L.), and wavy hair grass (Deschampsia flexuosa (L.) Trin.)) for at least 12 weeks after application. When coupled with a sequential application of 0.15kg a.i. ha−1 propaquizafop made 5 weeks later, purple moor grass (Molinia caerulea (L.) Moench) was controlled for at least 21 weeks. Sequential applications of 0.45 kg a.i. ha−1 cycloxydim in October, then 0.45 kg a.i. ha−1 cycloxydim in late April, was the most effective treatment for minimizing competition from purple moor grass, wood small reed or wavy hair grass and equally effective as propyzamide on Yorkshire fog. The herbicides carbetamide, clethodim, clodinafop-propargyl and fenoxaprop-p-ethyl were not as effective as cycloxydim. We conclude that cycloxydim is effective on a broader range of grass weeds than previously thought. Cycloxydim and propaquizafop are both highly selective and unlike the broad-spectrum herbicide glyphosate will not harm young trees, even if they are oversprayed when in active growth. If applied at the correct time of year, cycloxydim is likely to be as effective as glyphosate on most grasses, and for wood small reed, purple moor grass and wavy hair grass considerably more effective than propyzamide. A sequential application of cycloxydim or possibly propaquizafop in the autumn, followed by a second spray in late April of the following spring, is likely to be the most effective means of maximizing tree growth and survival in grass dominated new planting or restock sites in UK forests.

Beschreibung: Resprouting plants are distributed in many vegetation communities worldwide. With increasing resprout age post-severe-disturbance, new stems grow rapidly at their early age, and decrease in their growth with gradually decreasing water status thereafter. However, there is little knowledge about how stem hydraulic strategies and anatomical traits vary post-disturbance. In this study, the stem water potential (Ψstem), maximum stem hydraulic conductivity (Kstem-max), water potential at 50% loss of hydraulic conductivity (Kstem  P50), and anatomical traits of Caragana korshinkii resprouts were measured during a 1- to 13-year post-disturbance period. We found that the Kstem-max decreased with resprout age from 1-year-old resprouts (84.2 mol m−1 s−1 MPa−1) to 13-year-old resprouts (54.2 mol m−1 s−1 MPa−1) as a result of decreases in the aperture fraction (Fap) and the sum of aperture area on per unit intervessel wall area (Aap). The Kstem  P50 of the resprouts decreased from 1-year-old resprouts (−1.8 MPa) to 13-year-old resprouts (−2.9 MPa) as a result of increases in vessel implosion resistance (t/b)2, wood density (WD), vessel grouping index (GI), and decreases in Fap, and Aap. These shifts in hydraulic structure and function resulted in an age-based divergence in hydraulic strategies i.e., a change from an acquisitive strategy to a conservative strategy, with increasing resprout age post-disturbance.

Beschreibung: The contribution of amino acids (AAs) to soil nitrogen (N) fluxes is higher than previously thought. The fact that AA uptake is pivotal for N nutrition in boreal ecosystems highlights plant AA transporters as key components of the N cycle. At the same time, very little is known about AA transport and respective transporters in trees. Tree genomes may contain 13 or more genes encoding the lysine histidine transporter (LHT) family proteins, and this complicates the study of their significance for tree N-use efficiency. With the strategy of obtaining a tool to study N-use efficiency, our aim was to identify and characterize a relevant AA transporter in hybrid aspen (Populus tremula L. x tremuloides Michx.). We identified PtrLHT1.2, the closest homolog of Arabidopsis thaliana (L.) Heynh AtLHT1, which is expressed in leaves, stems and roots. Complementation of a yeast AA uptake mutant verified the function of PtrLHT1.2 as an AA transporter. Furthermore, PtrLHT1.2 was able to fully complement the phenotypes of the Arabidopsis AA uptake mutant lht1 aap5, including early leaf senescence-like phenotype, reduced growth, decreased plant N levels and reduced root AA uptake. Amino acid uptake studies finally showed that PtrLHT1.2 is a high affinity transporter for neutral and acidic AAs. Thus, we identified a functional AtLHT1 homolog in hybrid aspen, which harbors the potential to enhance overall plant N levels and hence increase biomass production. This finding provides a valuable tool for N nutrition studies in trees and opens new avenues to optimizing tree N-use efficiency.

Beschreibung: For the first time, an economic analysis of a fully simulated forest transformation process from even-aged to uneven-aged stand structure using natural regeneration was performed using an individual tree growth simulator. A comparison to a ‘business as usual’ management approach (i.e. age-class scenario) was also made. Norway spruce (Picea abies (L.) Karst.)-dominated forests of different ages were selected for the simulation: forest at thinning stage (52 years; hereafter, ‘younger stand’) and a mature stand (95 years) to explore different starting points for the transformation. The harvested and remaining stand volume showed only little fluctuation over the course of the simulation period in the case of the transformation (uneven-aged) scenario. The age-class scenario, on the other hand, showed peaks and drops in the timber volume. The land expectation values at the end of transformation were higher (i = 1 or 2 per cent) or equal (i = 3 per cent) to those of the age-class scenario for the younger stand. The transformation of younger forests appears to be economically interesting (under interest rates above 2 per cent) as the early revenues of more intensive thinnings achieve an equilibrium growing stock well below the potential maximum growing stock of an even-aged stand. This suggests transformation management to be economically efficient under the given silvicultural and economic conditions. The transformation of mature stands was found to be less economically viable due to the lower holding values for the transformation (uneven-aged) scenario compared with the age-class scenario. However, the holding values of the younger stand were higher for all interest rates compared with the age-class scenario. This study concludes that transformation (uneven-aged) scenario yielded more economically viable silvicultural approach (in the case of younger forests) and a steadier trend in harvested and remaining timber volume showing no major fluctuations. Transformation approach also forms a better foundation where other ecosystem services can be built.

Beschreibung: Bush encroachment affects ~45 million ha of Namibia and, without appropriate restoration measures, it negatively affects rangeland productivity and biodiversity. Thinning is a common method to counteract bush encroachment. The thinning strategy applied in north-central Namibia was assessed to examine how effective it has been in reducing bush encroachment. Trees/shrubs were selectively thinned manually, targeting all height classes, except individuals with stem diameters ≥18 cm. We investigated the effects on the vegetation and soil properties using surveys on three freehold farms (in 2016 and 2017) in bush-encroached and previously thinned habitats. Our results revealed significant differences in the mean total nitrogen (TN) content between the treatments; thinned areas had higher TN content which would be beneficial for fast-growing grasses. In the thinned plots, the occurrence probability of red umbrella thorn (Vachellia reficiens Warwa) was significantly reduced, indicating that it was the most harvested species; and umbrella thorn (Vachellia tortilis (Burch.) Brenan spp. heteracantha) was increased, indicating that it favoured reduced densities of dominant species. Natural regeneration was rapid; the tree/shrub abundance in the 0–1-m height class in the thinned area surpassed those in the non-thinned by 34 per cent, ~7.2 years since thinning. Thinning significantly reduced tree/shrub abundances of the 1–3- and 〉3-m height classes, which was still evident 7.2 years since thinning. Based upon the generalized linear mixed-effects model, tree/shrub counts between treatments may equalize in ~14 and 15 years for the 1–3- and 〉3-m height classes, respectively. Thinning was effective in reducing tree/shrub abundances and can be used to restore wildlife habitat on the Namibian farmland: however, post-thinning management is required to maintain an open savannah vegetation structure as the 0–1-m height class cohort will eventually grow into mature trees/shrubs.

Beschreibung: Norway spruce (Picea abies Karst. (L.)) in the boreal zone can be managed as even-aged or uneven-aged stands, or be grown with no management at all. Here, we investigated how these management options affect carbon dynamics, particularly the carbon stocks in the forest ecosystem (trees and soil), and albedo, and their combined effect on radiative forcing compared to a reference case, clear-cut site before planting seedlings. This allowed us to assess the potential of different management regimes to mitigate global warming. We ran long-term simulations under the current climate on a sub-mesic site in central Finland (62oN) using an eco-physiological forest-ecosystem model. Compared to even-aged management, no management (old-growth forest) increased ecosystem carbon stocks by 47 per cent and decreased albedo by 15 per cent, whereas uneven-aged management reduced ecosystem carbon stocks by 16 per cent and increased albedo by 10 per cent. Only the no management option resulted in a significant net cooling effect whereas for even-aged and uneven-aged management, the opposing effects of changes in albedo and carbon stocks largely cancelled each other with little remaining net effect. On the other hand, the latter one even made a small net warming contribution. Overall, maintaining higher ecosystem carbon stocks implied the larger cooling benefits. This was evident even though lower albedo enhanced radiation absorption, and thus warming. Increasing use of the no management option by forest owners may require proper incentives such as compensation for lost harvest incomes.

Beschreibung: Synergistic regulation in leaf architecture and photosynthesis is essential for salt tolerance. However, how plant sex and inorganic nitrogen sources alter salt stress-dependent photosynthesis remains unknown. Leaf anatomical characteristics and photosynthesis of Populus cathayana Rehder females and males were investigated under salt stress conditions combined with nitrate NO3− and ammonium NH4+ supplies to clarify the underlying mechanisms. In salt-stressed females, we observed an increased mesophyll spongy cell density, a reduced chloroplast density, a decreased surface area of chloroplasts adjacent to the intercellular air space (Sc/S) and an increased mesophyll cell area per transverse section width (S/W), consequently causing mesophyll conductance (gm) and photosynthesis inhibition, especially under NH4+ supply. Conversely, males with a greater mesophyll palisade tissue thickness and chloroplast density, but a lower spongy cell density had lower S/W and higher Sc/S, and higher gm and photosynthesis. NH4+-fed females had a lower CO2 conductance through cell wall and stromal conductance perpendicular to the cell wall, but a higher chloroplast conductance from the cell wall (gcyt1) than females supplied with NO3−, whereas males had a higher chloroplast conductance and lower CO2 conductance through cell wall when supplied with NO3− instead of NH4+ under salt stress. These findings indicate sex-specific strategies in coping with salt stress related to leaf anatomy and gm under both types of nitrogen supplies, which may contribute to sex-specific CO2 capture and niche segregation.

Beschreibung: DORMANCY-ASSOCIATED MADS-box (DAM) and SHORT VEGETATIVE PHASE (SVP) genes have been implicated in the regulation of winter dormancy in perennials. Ectopic expression of apple (Malus × domestica Borkh. ‘Royal Gala’) DAM and SVP genes delays budbreak and constrains lateral shoot outgrowth. In this study, we used RNA interference (RNAi) to simultaneously target all apple DAM and SVP genes in order to study their role and mode of action in the regulation of bud dormancy, budbreak and flowering. A synthetic construct carrying a hairpin fragment assembled from sequences specific to coding regions of three DAM and two SVP genes was used to generate transgenic lines. Reduced expression of DAM/SVP genes resulted in delayed leaf senescence and abscission in autumn, failure to enter bud dormancy in winter and continual growth of new leaves regardless of the season for over 3 years. Precocious flowering but normal flower morphology, fertility and fruit development were observed. The non-dormant phenotype was associated with modified phytohormone composition. The content of gibberellins (GAs) and jasmonates (JAs) was significantly increased in terminal buds of RNAi lines compared with wildtype plants, accompanied by elevated expression of the key GA biosynthesis pathway gene GIBBERELLIN 20 OXIDASE-2 (MdGA20ox-2) along with the FLOWERING LOCUS T gene MdFT2. The key mediator of plasmodesmatal closure, MdCALLOSE SYNTHASE 1 (MdCALS1), was repressed in RNAi lines. This study provides functional evidence for the role of DAM/SVP genes in vegetative phenology of apple and paves the way for production of low-chill varieties suitable for growth in warming climates.

Beschreibung: Species interactions mediate tree responses to water limitation because competition and/or facilitation alter plant physiology and growth. However, because it is difficult to isolate the effects of plant–plant interactions and water limitation from other environmental factors, the mechanisms underlying tree physiology and growth in coexisting plants under drought are poorly understood. We investigated how species interactions and water limitation impact the physiology and growth of trembling aspen (Populus tremuloides), narrowleaf cottonwood (Populus angustifolia) and ponderosa pine (Pinus ponderosa) seedlings in a controlled environment growth chamber, using aspen as a focal species. Seedlings were grown in pots alone or with a con- or hetero-specific seedling, and were subjected to a water limitation treatment. Growth, water status and physiological traits were measured before, during and after the treatment. Under well-watered conditions, the presence of another seedling affected growth or biomass allocation in all species, but did not impact the physiological traits we measured. Under water limitation, the presence of a competing seedling had a marginal impact on seedling growth and physiological traits in all species. Throughout the study, the magnitude and direction of seedling responses were complex and often species-specific. Our study serves as an important step toward testing how species’ interactions modify physiological responses and growth in well-watered and water-limited periods.

Beschreibung: Climate change is projected to have a major influence on forest tree populations and composition. Translocation of species outside their historic range has been suggested to maintain healthy forests and tree species. The introduction of exotic species into botanical gardens and arboretums worldwide demonstrates the ability of many trees to grow outside their natural habitat and may play an important part in avoiding climate driven extinction if grown in a matching climate. However, it remains to be determined which climatic factors are the most important predictors of climatic match. In this study we use information from the arboretum in Hørsholm, Denmark, to analyse differences in performance of translocated Oak (Quercus) and show how data from tree collections can be used to predict success of assisted migration. Our data included archive lists of georeferenced Northern hemisphere introductions of Quercus, and assessments of their survival and growth rates in nursery and the Hørsholm arboretum. Using logistic and linear regression we modelled the importance of different bioclimatic predictor variables for survival and growth rate. Several correlations were identified across the Quercus genus. Survival of Quercus species depended primarily on the temperatures at the origin, whereas growth on the other hand was more dependent on a match in precipitation. The negative correlations indicated that introductions were less successful from sites with higher temperatures and wetter conditions. The study demonstrates an approach to use historical data collected from arboreta and botanical gardens in climate change research. This new approach can provide useful information in relation to assisted migration for an array of poorly investigated species where this may be the only source of information.

Beschreibung: In this study we investigated the behaviour of aggregate prediction errors in a forest inventory augmented with multispectral Airborne Laser Scanning and airborne imagery. We compared an Area-Based Approach (ABA), Edge-tree corrected ABA (EABA) and Individual Tree Detection (ITD). The study used 109 large 30 × 30 m sample plots, which were divided into four 15 × 15 m subplots. Four different levels of aggregation were examined: all four subplots (quartet), two diagonal subplots (diagonal), two edge-adjacent subplots (adjacent) and subplots without aggregation. We noted that the errors at aggregated levels depend on the selected predictor variables, and therefore, this effect was studied by repeating the variable selection 200 times. At the subplot level, EABA provided the lowest mean of root mean square error ($overline{mathrm{RMSE}}$) values of 200 repetitions for total stem volume (EABA 21.1 percent, ABA 23.5 percent, ITD 26.2 percent). EABA also fared the best for diagonal and adjacent aggregation ($overline{mathrm{RMSE}}$: 17.6 percent, 17.4 percent), followed by ABA ($overline{mathrm{RMSE}}$: 19.3 percent, 18.2 percent) and ITD ($overline{mathrm{RMSE}}$: 21.8, 21.9 percent). Adjacent subplot errors of ABA were less correlated than errors of diagonal subplots, which resulted also in clearly lower RMSEs for adjacent subplots. This appears to result from edge tree effects, where omission and commission errors cancel for trees leaning from one subplot into the other. The best aggregate performance was achieved at the quartet level, as expected from fundamental properties of variance. ABA and EABA had similar RMSEs at the quartet level ($overline{mathrm{RMSE}}$ 15.5 and 15.3 percent), with poorer ITD performance ($overline{mathrm{RMSE}}$ 19.4 percent).

Beschreibung: Deciduous trees mostly rely on non-structural carbohydrates (NSC—soluble carbohydrates and starch) stored prior to dormancy to sustain both spring bloom and the initial phase of spring growth prior to the transition of leaves from sink to source. Winter management of NSC, their loss due to respiration, reallocation patterns and remobilization during spring, seems to be key to a timely and synchronous bloom. To assess tree dependence on NSC during dormancy, we tested whether the interruption of local branch NSC accumulation prior to dormancy by defoliation and the interruption of NSC translocation by phloem girdling influence spring phenology in three major deciduous Mediterranean nut crop species: Prunus dulcis (Mill.) D.A Webb, a hybrid between Pistacia integerrima (J. L. Stewart ex Brandis) and P. atlantica Desf. (referred to as P. integerrima), and Juglans regia L. Defoliation treatments had different effects on NSC concentration in different species depending on the time of application. However, despite the significant initial impact (increase or decrease of NSC concentration), with time this impact diminished resulting in overall similar concentrations between control and defoliated branches suggesting the presence of NSC reallocation during dormancy. Phloem girdling in P. dulcis and P. integerrima resulted in reduced export activity and greater NSC concentrations, while in J. regia girdling resulted in lower NSC concentrations, indicating that this species requires a net import of NSC during dormancy. Bud break was distinctly delayed by both defoliation and phloem girdling in all the three species, providing evidence of the significant roles that fall NSC accumulation and winter NSC management play in priming trees for spring growth resumption.

Beschreibung: Improving the efficiency of fertilizer application is paramount to both the sustainability and profitability of forest plantations. Therefore, developing reliable, cost-effective tools to assess tree nutritional status is of great interest. This investigation sought to assess the use of phloem sap-derived metabolites as an indicator of nutritional status on a background of seasonal water availability of Eucalyptus globulus (Labill) trees grown under field conditions. Phloem is a central conduit for long-distance transport and signaling in plants and offers great promise in reflecting plant-scale resource limitations. Changes in the abundance of solutes and isotopes in phloem sap are sensitive to environmental cues. With a focus on both water and nutrient availability, we characterize patterns in phloem sugars, amino acids and the abundance of carbon isotopes in phloem sap obtained from E. globulus among different seasons and fertilizer treatments. Phloem-derived total amino acid concentration was found to increase with an increasing nitrogen (N) supply; however, this response was lost with the concurrent addition of phosphorus and at the highest level of N supply. Significant seasonal variation in all measured parameters was also detected, highlighting the need for caution in making quantitative relationships with growth. Broader implications of the interactive effects of both water supply and multi-nutrient additions and relationships with growth are discussed.