The Black Woodpecker (Dryocopus martius L.) is both an ecosystem engineer and an umbrella species: it has the capacity to modify its environment through cavity excavation, which in turn favors a ...large range of species that depend on cavities but are unable to dig them themselves (secondary cavity nesters). However, the factors driving cavity excavation by the Black woodpecker at the tree scale remain poorly known. We analyzed the characteristics of trees bearing Black Woodpecker cavities to assess the bird's local habitat requirements and their conservation potential as habitat trees. We compared the traits and characteristics of trees bearing Black Woodpecker cavities (n = 60) and control trees (n = 56) in two managed lowland broadleave-dominated forests in France. We hypothesized that:(i)Cavity-trees would have lower wood density and display more conks of fungi than control-trees;(ii)The local environment of cavity-trees would be less crowded than those of the control trees. In particular, the first branch would be higher up, and their first neighboring tree would be further away from cavity-trees compared to control-trees;(iii)Cavity-trees would display a higher number of other woodpecker cavities and more saproxylic microhabitats than the control-trees.
We validated most of our hypotheses and showed that cavity trees differed significantly from their control counterparts. Black Woodpeckers excavate trees with softer wood and higher first branches in a less crowded environment, thus minimizing both the energy dedicated to cavity excavation and predation risk. Second, cavity-trees bear more microhabitats and play a complementary umbrella role than what was documented before. They also appear a good candidate for habitat-tree conservation.
In terms of biodiversity-friendly management measures, it would be beneficial to favor large isolated standing trees devoid of low branches (notably beech), especially in stands dominated by other tree species.
•We analyzed the characteristics of trees bearing Black Woodpecker cavities.•We assess the bird's requirements and conservation potential as habitat trees.•We showed that cavity-trees significantly differed from their equivalent counterparts.•Black woodpecker cavity trees appear a good candidate for habitat-tree conservation.
•We compared Tree-related microhabitats (TreMs) in the Dinarides and Carpathians.•Density and diversity of TreMs were very high in beech dominated primary forests.•Geographical region was not a ...primary driver of TreM profile.•Tree species richness, DBH, and snags were the main drivers of TreM profile.•These findings may provide a benchmark for forest management practices.
Tree-related microhabitats (TreMs) are important features for the conservation of biodiversity in forest ecosystems. Although other structural indicators of forest biodiversity have been extensively studied in recent decades, TreMs have often been overlooked, either due to the absence of a consensual definition or a lack of knowledge. Despite the increased number of TreM studies in the last decade, the role of drivers of TreM profile in primary forests and across different geographical regions is still unknown. To evaluate the main drivers of TreM density and diversity, we conducted the first large-scale study of TreMs across European primary forests. We established 146 plots in eight primary forests dominated by European beech (Fagus sylvatica L.) in the Carpathian and Dinaric mountain ranges. Generalized linear mixed effect models were used to test the effect of local plot characteristics and spatial variability on the density and diversity (alpha, beta, and gamma) of TreMs. Total TreM density and diversity were significantly positively related with tree species richness and the proportion of snags. Root mean square tree diameters were significantly related to alpha and gamma diversity of TreMs. Both regions reached similarly high values of total TreM densities and total TreM densities and diversity were not significantly different between the two regions; however, we observed between the two regions significant differences in the densities of two TreM groups, conks of fungi and epiphytes. The density and diversity of TreMs were very high in beech-dominated mountain primary forests, but their occurrence and diversity was highly variable within the landscapes over relatively short spatial gradients (plot and stand levels). Understanding these profile provides a benchmark for further comparisons, such as with young forest reserves, or for improving forest management practices that promote biodiversity.
Retention forestry implies that biological legacies like dead and living trees are deliberately selected and retained beyond harvesting cycles to benefit biodiversity and ecosystem functioning. This ...model has been applied for several decades in even-aged, clearcutting (CC) systems but less so in uneven-aged, continuous-cover forestry (CCF). We provide an overview of retention in CCF in temperate regions of Europe, currently largely focused on habitat trees and dead wood. The relevance of current meta-analyses and many other studies on retention in CC is limited since they emphasize larger patches in open surroundings. Therefore, we reflect here on the ecological foundations and socio-economic frameworks of retention approaches in CCF, and highlight several areas with development potential for the future. Conclusions from this perspective paper, based on both research and current practice on several continents, although highlighting Europe, are also relevant to other temperate regions of the world using continuous-cover forest management approaches.
•Large trees are more prone to bear TreMs and hence considered habitat trees.•The richness of TreMs does not increase in tall trees.•Tree species composition impacts on TreMs occurrence and ...richness.•Combined-objective forestry ensures high level of TreMs occurrence in mature forests.•Close-to-nature forestry enhances TreMs richness.
Mediterranean forests are important sources of income for society and represent biodiversity hotspots, characterized by a mosaic of forest structures, from short-rotation even-aged stands to old-growth forests. However, such increased complexity requires forest management to balance timber production with biodiversity conservation at various spatial scales. This study investigated the impacts of forest structures and management alternatives on the occurrence and richness of Tree-related Microhabitats (TreMs) – as proxies for forest biodiversity – in three Mediterranean forests in Italy. The generalized linear mixed model was applied to assess the relationship between a large set of forest structural parameters and the occurrence and richness of TreMs at the tree level, and resulted in an overall model accuracy higher than 80%. The same model was then implemented in hypothetical forest structures, resulting from no management, close-to-nature forestry and combined management system. Results show that at early developmental stages of the stand, no management slightly anticipates the occurrence of TreMs, while in mature forests, the combined forest management system effectively balances forest productivity with biodiversity conservation. The close-to-nature management system is recommended for promoting TreMs richness. Such findings might be used to support sustainable forest management and valorise the multifunctional role of Mediterranean forests.
Retention forestry, which retains a portion of the original stand at the time of harvesting to maintain continuity of structural and compositional diversity, has been originally developed to mitigate ...the impacts of clear‐cutting. Retention of habitat trees and deadwood has since become common practice also in continuous‐cover forests of Central Europe. While the use of retention in these forests is plausible, the evidence base for its application is lacking, trade‐offs have not been quantified, it is not clear what support it receives from forest owners and other stakeholders and how it is best integrated into forest management practices. The Research Training Group ConFoBi (Conservation of Forest Biodiversity in Multiple‐use Landscapes of Central Europe) focusses on the effectiveness of retention forestry, combining ecological studies on forest biodiversity with social and economic studies of biodiversity conservation across multiple spatial scales. The aim of ConFoBi is to assess whether and how structural retention measures are appropriate for the conservation of forest biodiversity in uneven‐aged and selectively harvested continuous‐cover forests of temperate Europe. The study design is based on a pool of 135 plots (1 ha) distributed along gradients of forest connectivity and structure. The main objectives are (a) to investigate the effects of structural elements and landscape context on multiple taxa, including different trophic and functional groups, to evaluate the effectiveness of retention practices for biodiversity conservation; (b) to analyze how forest biodiversity conservation is perceived and practiced, and what costs and benefits it creates; and (c) to identify how biodiversity conservation can be effectively integrated in multi‐functional forest management. ConFoBi will quantify retention levels required across the landscape, as well as the socio‐economic prerequisites for their implementation by forest owners and managers. ConFoBi's research results will provide an evidence base for integrating biodiversity conservation into forest management in temperate forests.
This paper describes the background, research questions and design of the Research Training Group “ConFoBi” (Conservation of Forest Biodiversity in Multiple‐use Landscapes of Central Europe). ConFoBi focusses on the effectiveness of retention forestry, that is, retaining structural elements of old forests within a production forest matrix, and combines ecological studies on forest biodiversity with social and economic studies of biodiversity conservation across multiple spatial scales. The aim of ConFoBi is to assess whether and how structural retention measures are appropriate for the conservation of forest biodiversity in multiple‐use landscapes of temperate Europe.
Protecting structural features, such as tree‐related microhabitats (TreMs), is a cost‐effective tool crucial for biodiversity conservation applicable to large forested landscapes. Although the ...development of TreMs is influenced by tree diameter, species, and vitality, the relationships between tree age and TreM profile remain poorly understood. Using a tree‐ring‐based approach and a large data set of 8038 trees, we modeled the effects of tree age, diameter, and site characteristics on TreM richness and occurrence across some of the most intact primary temperate forests in Europe, including mixed beech and spruce forests. We observed an overall increase in TreM richness on old and large trees in both forest types. The occurrence of specific TreM groups was variably related to tree age and diameter, but some TreM groups (e.g., epiphytes) had a stronger positive relationship with tree species and elevation. Although many TreM groups were positively associated with tree age and diameter, only two TreM groups in spruce stands reacted exclusively to tree age (insect galleries and exposed sapwood) without responding to diameter. Thus, the retention of trees for conservation purposes based on tree diameter appears to be a generally feasible approach with a rather low risk of underrepresentation of TreMs. Because greater tree age and diameter positively affected TreM development, placing a greater emphasis on conserving large trees and allowing them to reach older ages, for example, through the establishment of conservation reserves, would better maintain the continuity of TreM resource and associated biodiversity. However, this approach may be difficult due to the widespread intensification of forest management and global climate change.
Importancia de conservar los árboles viejos y grandes para la continuidad de los microhábitats relacionados
Resumen
La protección de las características estructurales, como los microhábitats relacionados a los árboles (MhAr), es una herramienta económica importante para la conservación de la biodiversidad que puede aplicarse en los paisajes boscosos extensos. Aunque el diámetro, especie y vitalidad del árbol influyen sobre el desarrollo de los MhAr, todavía se sabe poco sobre las relaciones entre la edad del árbol y el perfil. Modelamos los efectos de la edad y diámetro del árbol y las características del sitio sobre la riqueza y presencia de los MhAr en algunos de los bosques primarios más preservados de Europa, incluyendo los bosques mixtos de hayas y abetos, con una estrategia basada en los anillos de crecimiento y un conjunto con datos de 8038 árboles. Observamos un incremento generalizado en la riqueza de MhAr en los árboles viejos y grandes en ambos tipos de bosques. La presencia de grupos específicos de MhAr tuvo una relación variada con el diámetro y la edad del árbol, aunque algunos grupos de MhAr (p. ej.: epífitas) tuvieron una relación positiva más fuerte con la elevación y la especie del árbol. Mientras que muchos grupos de MhAr estuvieron asociados positivamente con la edad y diámetro del árbol, sólo dos grupos de MhAr en los abetos reaccionaron exclusivamente a la edad del árbol (galerías de insectos y savia expuesta) sin responder al diámetro. Por lo tanto, la retención de los árboles con fines de conservación basada en los diámetros parece ser una estrategia plausible con un riesgo bajo de subrepresentación de los MhAr. Ya que a mayor edad y diámetro del árbol hubo efectos positivos en el desarrollo de los MhAr, poner un mayor énfasis sobre la conservación de los árboles grandes y permitirles alcanzar una edad mayor, por ejemplo, a través del establecimiento de reservas de conservación, mantendría de mejor manera la continuidad del MhAr y de la biodiversidad asociada. Sin embargo, esta estrategia puede ser complicada debido a la intensificación generalizada de la gestión forestal y el cambio climático mundial.
【摘要】
保护结构特征, 如与树有关的微生境 (TreM), 是适用于大型森林景观生物多样性保护且具有成本效益的重要工具。虽然 TreM 的发展受到树木直径、物种和生存力的影响, 但人们对树龄和 TreM 基本特征之间的关系仍知之甚少。本研究利用基于树木年轮的方法和包含8038棵树的大型数据集, 模拟了树龄、直径和位点特征对欧洲一些最完整的温带原始森林 (包括山毛榉和云杉混交林) TreM 丰富度和出现率的影响。我们发现在这两种森林类型中, 古树和大树的 TreM 丰富度总体上有所增加。特定 TreM 类型的出现率与树龄和直径有不一致的关系, 但一些 TreM 类型 (如附生植物) 与树种和海拔有较强的正相关关系。虽然许多 TreM 类型与树龄和直径呈正相关关系, 但云杉林中只有2种 TreM 类型只与树龄有相关性 (昆虫孔道和裸露的白木质), 而与直径没有相关性。因此, 为了保护目的而根据树木直径保留树木似乎是一种普遍可行的方法, 这种方法对 TreMs 代表性不足的风险相当低。 由于更大的树龄和直径对 TreMs 的发展有积极作用, 因此更应强调对大树的保护, 使其生长到更大树龄, 来更好地保持 TreM 资源和相关生物多样性的连续性 (如通过建立保护区) 。然而, 由于森林管理和全球气候变化问题的普遍加剧, 这种方法可能也面临困难。【翻译: 胡怡思; 审校: 聂永刚】
Key message
Drivers of the abundance and richness of tree-related microhabitats are similar in mountain forests of Europe and North America and their occurrence may be explained by tree functional ...groups.
A common approach to support forest-dwelling species in managed forests is to preserve valuable habitat trees. To assess the quality of habitat trees, a hierarchical typology of tree-related microhabitats (TreMs) is applied in the European context for inventory standardization. The first aim of this study was to evaluate whether it is possible to use this hierarchical typology as a standard protocol regardless of location, which is important for potentially standardizing future studies of TreMs, by testing whether the typology could be applied to the western North American mountain forests of Idaho. The second aim of the study was to analyse drivers that influence TreMs in forests of the region. Thirdly, we assessed whether the occurrence of TreMs could be explained by functional groups of trees across the western mountain forests of Idaho and Central European mountain forests, using TreM inventory data previously collected in the Black Forest, Germany. Abundance and richness of TreMs per tree were analyzed as a function of tree species, live status (dead vs. live trees), diameter at breast height (DBH), and site factors (latitude and altitude). Our results show that the TreM typology could be applied with slight modifications in the forests of Idaho. The abundance and richness of TreMs per tree increased with DBH. Snags offered more TreMs per tree than live trees. We were able to group tree species from the two continents in functional groups that were related to the occurrence of certain TreMs. Tree functional groups offer an opportunity to predict the role of certain tree species for habitat provision through TreMs. Combinations of trees from different functional groups could be used to optimize provisioning of TreMs within forest stands.
Water-filled tree holes (WHs), commonly referred to as dendrotelmata, develop when water accumulates in cavities related to tree architecture or in rotten parts of the tree. These structures can ...occur in forest ecosystems and may represent essential microhabitats in the life cycle of various animal species. WHs form temporary microhabitats during wet periods and sometimes sustain water throughout dry seasons. Research on the use of WHs by organisms mainly focuses on invertebrates developing in these while vertebrates are rarely mentioned. A literature search on the use of WHs by vertebrates revealed that attention has been given only to vertebrates in tropical and subtropical systems, mostly to groups with aquatic stages, such as amphibians. To fill the knowledge gap on the use of WHs by vertebrates in temperate forests, we conducted a camera study in three sites across Germany. We identified a total of 28 vertebrate species including 11 mammal, 17 bird and one amphibian species using the WHs. The recorded videos showed that vertebrates use the WHs mainly for nutrition and hydration. With an expected future increase in frequency and intensity of dry spells in central Europe, these microhabitats may sustain healthy forest ecosystems by providing resources for wildlife. Reliable, updated data about the importance of WHs for vertebrates is required to urge forest managers and stakeholders to enforce the preservation of these microhabitats.
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