Abstract Landscape and land-use are potential factors influencing the presence of insect pests and fungal pathogens, which can drive the onset of decline and mortality events. However, the impact of different types of landscapes on the community of insect-associated fungal pathogens still remains to be thoroughly understood. This study aimed to investigate the effect of landscape on plant-pathogenic fungi occurring in cork oak trees infested by Coraebus florentinus. Field surveys were conducted in 14 cork oak stands in Sardinia (Italy), classified as forest or woodland on the basis of the tree cover density. Fungi were isolated from wood materials sampled across various compartments of the gallery systems excavated by mature larvae of C. florentinus and identified based on morphological characteristics and DNA sequence analyses. Differences in fungal diversity between landscapes, as well as between gallery compartments and wood material types, were evaluated using ecological diversity indices and both non-parametric and ordination statistical methods. A total of 172 fungal isolates belonging to fourteen families and 26 species were obtained. Fungi in the Botryosphaeriaceae (41.28%), Nectriaceae (15.12%) and Cryphonectriaceae (12.79%) were the fungal families most frequently isolated from the infested branches. Diplodia corticola was the most frequently isolated species, representing 24.5 and 40.6% of total isolations in the forest and woodland areas, respectively. Multivariate analyses indicated that the presence and frequency of plant-pathogenic fungi were significantly associated with the predominant landscape. Results from this study emphasizes the importance of considering landscape types to facilitate risk assessment of the presence and spread of pathogenic fungi such as D. corticola and other members of the Botryosphaeriaceae family mainly involved in oak decline.
Abstract Woody biomass is a renewable carbon resource option for bioeconomy development and energy expansion. Understanding the spatial and temporal accessibility, quantity, and associated costs of woody biomass is critical for informed policy making and strategic planning. The Forest Sustainable and Economic Analysis Model (ForSEAM) is a dynamic linear optimization model developed to identify sources of conventional timber products and woody biomass feedstock from the United States (US) timberland. The model integrates demand, economic feasibility, and environmental sustainability with respect to current and future sources, land ownership, tree ages and species, harvesting systems, and costs for 305 regions in the conterminous US. Each region consists of a set of timber resources that can potentially be harvested for conventional industrial use and woody biomass for alternative use, such as bioenergy. Woody biomass sources include logging residues and the removal of small-diameter whole trees. Sustainability constraints ensure that harvests do not exceed annual growth, maintain proximity to roads, and account for changes in forest attributes over time. Three hypothetical pathways for woody biomass supply from 2021 to 2050 were simulated, and optimal solutions were presented. Results indicate that the United States can supply approximately 40 million dry tons forest woody biomass annually under a conservative supply pathway, 50 million dry tons under a moderate pathway, and up to 75 million dry tons under a high supply pathway. The estimated shadow value for additional woody biomass reaches approximately $95 per dry ton by 2050 under the high supply pathway, indicating increasing reliance on higher cost whole tree harvesting. The model framework can be used for policy analysis related to bioeconomy development and may be adapted for other regional uses.
Abstract Bark, characterized by high lignocellulose content, low ash variability, and a favorable calorific value, represents a promising yet underutilized feedstock for low-carbon bioenergy production. Short-rotation woody crops (SRWC’s) provide an ideal source for bioenergy production due to their rapid biomass accumulation. While logging residues from these crops are increasingly recovered, the bark fraction remains largely overlooked despite its localized abundance and low marginal cost. This study aimed to: (i) quantify absolute and relative bark thickness and biomass; (ii) develop predictive allometric models linking bark traits to tree-level variables (diameter at breast height (DBH) and total height); and (iii) evaluate the thermochemical fuel properties of bark. A systematic grid sampling design was used to establish 64 plots across 10 SRWC species (six conifers and four broadleaves) in northern Iran. Measurements of DBH, total height, and merchantable height were obtained from 1877 trees, while bark samples were analyzed for calorific value, ash content, fuel value index, and energy content. Bark content accounted for 11%–17% of total stem biomass in broadleaves (4.9–13.5 Mg ha−1) and 11%–25% in coniferous (2.8–6.7 Mg ha−1). Although coniferous exhibited a 24% greater average bark thickness, their total bark biomass yield was 48% lower than that of broadleaves. Bark moisture content peaked in Quercus castaneifolia and Taxodium distichum (>25%) and was lowest in Alnus subcordata and Pinus taeda (<15%). Fuel quality evaluation via ash content revealed that Acer platanoides and Populus deltoides exceeded 4%, whereas T. distichum remained below 2%. Broadleaves yielded 55% more potential energy per ha than coniferous, with P. deltoides and Alnus subcordata exceeding 11 GJ ha−1. Based on the integrated fuel value index, A. subcordata and T. distichum emerged as the most viable species for bioenergy deployment. This study establishes a practical, non-destructive empirical framework for quantifying and modeling bark biomass and thickness, offering critical data to guide species selection for decentralized biomass valorization.
Abstract Old-growth forests play a crucial role as carbon sinks due to their high biomass (basal area) and their high basal area increment. Therefore, understanding the factors that shape the relative basal area (BArel) and the relative increase in basal area (BAfrac_inc) of individual tree species in old-growth forests is essential for forest management. We investigated how and to what extent maximum diameter at breast height (DBHmax) and three ecological traits (i.e. mycorrhizal type, seed mass, and successional status) affect BArel and BAfrac inc of 61 tree species in an old-growth deciduous hardwood forest in Japan. Our analysis was based on 11 years of DBH records (≥5 cm). BArel was greater in tree species with large DBHmax, particularly those associated with ectomycorrhizal (ECM) fungi. In ECM species, conspecific adults distributed in clumps in the forest studied; therefore, in tree species with a high DBHmax, the number of large individuals increased, leading to a higher BArel. BArel was lower for small DBHmax tree species, especially those associated with arbuscular mycorrhizal (AM) fungi because conspecific adults were distributed far from each other, i.e. there were only a few large individuals. Structural equation modeling (SEM) revealed that seed mass also had a significant positive effect on both BArel and BAfrac_inc. However, this effect was much stronger indirectly via DBHmax because of the close relationship between seed mass and DBHmax. Successional status had little effect on BArel or BAfrac_inc, since there were little differences between successional statuses among the dominant species in the study forest. This study showed that the type of mycorrhizal fungi exerts a particularly strong influence on BArel and BAfrac_inc, primarily mediated through DBHmax. These findings suggest that DBHmax and mycorrhizal associations are key indicators for managing old-growth forests to maximize carbon sequestration and uptake.
Abstract The introduction of Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] provenances in Europe has been very successful across many countries and ecological environments and is currently considered a valuable option for future European forestry. However, many plantations have been established regardless of the origin of seeds or seedlings used and growth trends have rarely been linked to genetic data, particularly in old-growth stands. Nonetheless, Douglas-firplantations in Europe have sometimes been used as seed sources, disregarding any information on their genetic structure or geographic origin. In this work, we examined nine Douglas-fir plantations in italy of unknown origin and already included in the Italian National Register of Forest Basic Materials in the source-identified and selected categories. The sampled trees were genotyped by 13 well-known nuclear microsatellites and traced back to their proximal origin using a reference database compiled for the native range, including 38 natural populations. A predominance of coastal provenances was found across Italian seed stands, with seven out of the nine stands being assigned to the coastal area from Washington State and the Oregon Coast (Genetic Cluster I) of the native range. The remaining two stands were assigned to the Rocky Mountain variety from British Columbia and Idaho (Genetic Clusters X and VII–VIII). Italian stands were, on average, characterised by high levels of genetic richness and observed heterozygosity. The comparison of ecological conditions between Italian stands and the species’ native range highlighted that Douglas-fir in Italy was mainly established in warmer and drier conditions, further improving our understanding of its ecological plasticity. This supports its potential relevance to Italian and European forestry in a changing and uncertain future climate.
