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Tree related microhabitats in temperate and Mediterranean European forests: A hierarchical typology for inventory standardization
Abstract
Tree related Microhabitats (hereafter TreMs) have been widely recognized as important substrates and structures for biodiversity in both commercial and protected forests and are receiving increasing attention in management , conservation and research. How to record TreMs in forest inventories is a question of recent interest since TreMs represent potential indirect indicators for the specialized species that use them as substrates or habitat at least for a part of their life-cycle. However, there is a wide range of differing interpretations as to what exactly constitutes a TreM and what specific features should be surveyed in the field. In an attempt to harmonize future TreM inventories, we propose a definition and a typology of TreM types borne by living and dead standing trees in temperate and Mediterranean forests in Europe. Our aim is to provide users with definitions which make unequivocal TreM determination possible. Our typology is structured around seven basic forms according to morphological characteristics and biodiversity relevance: i) cavities lato sensu, ii) tree injuries and exposed wood, iii) crown deadwood, iv) excrescences, v) fruiting bodies of saproxylic fungi and fungi-like organisms, vi) epiphytic and epixylic structures, and vii) exudates. The typology is then further detailed into 15 groups and 47 types with a hierarchical structure allowing the typology to be used for different purposes. The typology, along with guidelines for standardized recording we propose, is an unprecedented reference tool to make data on TreMs comparable across different regions, forest types and tree species, and should greatly improve the reliability of TreM monitoring. It provides the basis for compiling these data and may help to improve the reliability of reporting and evaluation of the conservation value of forests. Finally, our work emphasizes the need for further research on TreMs to better understand their dynamics and their link with biodiversity in order to more fully integrate TreM monitoring into forest management.
... Tree-related microhabitats (TreMs) are heterogeneous substrates located on living or dead trees that are suitable for specialized species to develop and breed [13][14][15]. They promote heterogeneity of the forest stands and can be used as indicators since they may capture a large proportion of stand biodiversity [13,16] for a broad spectrum of taxonomic groups [13]. ...
... Tree-related microhabitats (TreMs) are heterogeneous substrates located on living or dead trees that are suitable for specialized species to develop and breed [13][14][15]. They promote heterogeneity of the forest stands and can be used as indicators since they may capture a large proportion of stand biodiversity [13,16] for a broad spectrum of taxonomic groups [13]. Retaining different-dimension trees can increase diversity, as they offer various types of TreMs [17]. ...
... Tree-related microhabitats (TreMs) are heterogeneous substrates located on living or dead trees that are suitable for specialized species to develop and breed [13][14][15]. They promote heterogeneity of the forest stands and can be used as indicators since they may capture a large proportion of stand biodiversity [13,16] for a broad spectrum of taxonomic groups [13]. Retaining different-dimension trees can increase diversity, as they offer various types of TreMs [17]. ...
This study examines microhabitat abundance and composition on retention trees in 20 young stands in Latvia that were clear-cut between 2002 and 2004. Retention trees play a vital role in sustaining biological diversity after clear-cutting, but their mortality rate is often high due to post-harvest environmental changes. This study compares tree-related microhabitat (TreM) abundance and composition on retention trees of different dimensions, species, and vitality. The tree height and diameter were measured, and the living status and position of each tree were determined. The research questions of the study were to assess the relationships between TreMs, tree dimensions, and species, as well as to compare the occurrence of TreMs on living and dead wood. The comprehensive analysis revealed that larger tree diameters and specific tree species (Populus tremula, Fraxinus excelsior, and Salix caprea) lead to a higher abundance of TreMs. The results also highlighted the importance of preserving deadwood within forest stands as it enhances the observed abundance of TreMs. This study provides the missing information on TreMs in Latvia, thus providing data for comparison in a wider region.
... TreMs are identified as a specific substrate or site of occurrence of a single species or a group of organisms for at least part of their life cycle, offering a place for development, foraging or shelter (Larrieu et al., 2018b). The >60 types of TreMs hitherto described (Kraus et al., 2016) are utilized by a wide range of taxa, including rare and endangered stenotopic species of invertebrates or vertebrates Winter and Möller, 2008). ...
... BF is inhabited by an exceptional number of species of saproxylic insects and fungi (Gutowski et al., 2022;Jaroszewicz et al., 2019). Insect activity leads to the formation of galleries and bore holes (Larrieu et al., 2018b), and the enormous diversity of fungi ultimately leads to the appearance of different fruiting bodies. Moreover, interactions between fungi and insects that lead to wood decomposition influence the formation of other abundant TreM groups such as mould cavities, branch holes and canopy deadwood (Kõrkjas et al., 2021). ...
... Furthermore, some studies merged inventoried TreM types into TreM groups to make the results comparable with previous research (Paillet Kozák et al., 2018). Using typologies which distinguish different numbers of TreM types based on different criteria could be troublesome when comparing the quantitative and qualitative characteristics of TreMs in different studies (Larrieu et al., 2018b). The use of a limited typology in previous research to distinguish TreM types could have led to an underestimation of the TreM indices of a given forest, and the different criteria used for TreM censusing makes comparison of the densities/frequency of different TreMs between studies less reliable. ...
Tree-related Microhabitats (TreMs) are a key structural element having a significant impact on the biodiversity and functioning of forest ecosystems. Although forests enjoying long-term protection host richer and more abundant TreMs compared to managed stands, the quantity and quality of such microstructures in primeval temperate forests are unknown. This study investigates for the first time the assemblage of TreMs in the Białowieża Forest (BF), which is regarded as the last surviving fragment of pristine lowland forests in the temperate zone of Europe. Relatively undisturbed by human activity since the last glacial period, the BF ecosystem has remained remarkably intact, which may have given rise to its unique TreM assemblage. Here, we show that a primeval forest is characterized by an exceptionally high richness and density of TreMs compared to previously studied natural forests, and that the richness, density and diversity of TreMs are spatially heterogeneous at the micro-scale but homogeneous at the macro-scale. This indicates that adjacent small fragments of habitat (0.05 ha) may have different TreM profiles, but large patches of forest (several ha) host similar assemblages of TreMs. Our profile of TreMs depends on the basal area and density of living trees, the basal area of dead standing trees and the dominance of specific TreM-hosting tree species in a stand. Our study suggests that both the ecological continuity and complexity of a forest supporting many different tree species and the diversity of TreM-forming biota that typically occurs in primeval temperate forests are factors that appear to contribute to the observed profile of TreMs. The results of our study set a benchmark for the quantity and quality of TreMs in broadleaved temperate forests and indicate that the long-term spontaneous natural processes occurring in primeval forests lead to the emergence of ultra-rich, complex assemblages of TreMs.
... Since the direct assessment of forest biodiversity is highly challenging due to the large number of species involved (Larsson et al., 2001) and the low levels of congruence between taxa (e.g., Larrieu et al., 2018), emphasis has been put on habitat structural complexity (Lindenmayer et al., 2000). Deadwood is a key component of structural complexity and a key resource for roughly 30 % of forest-dwelling taxa (Stokland et al., 2012). ...
... Its spatial distribution in riparian forests is strongly influenced by flood dynamics and forest management (e.g., Oettel et al., 2022). Tree-related microhabitats (hereafter referred to as TreMs) have also been identified as key features for forest-dwelling taxa (Larrieu et al., 2018) associated with a part of biodiversity that is not usually associated with deadwood (Stokland et al., 2012). In addition, since about 60 % of TreMs are saproxylic (i.e., they contain decaying wood), recording TreMs is an efficient way of assessing saproxylic taxa. ...
... The decay stage of the standing and lying dead trees was recorded (see Bütler et al., 2020 for the description of the five wood decay stages). The survey of TreMs was based on the hierarchical typology established by Larrieu et al. (2018), to which the two forms "snag base coarse woody debris" and "rootplate" were added. In total, the used typology consisted of 9 forms (cavities, tree injuries and exposed wood, crown deadwood, excrescences, fruiting bodies of saproxylic fungi and slime moulds, epiphytic and epixylic structures, fresh exudates, snag base coarse woody debris, and rootplates), 17 groups and 50 types (see Appendix for the description of each type). ...
Riparian forests are considered as complex and biologically rich habitats. They play a crucial role for biodiversity conservation, in particular in landscapes under strong management pressure. Tree-related microhabitats (TreMs) support a wide array of biodiversity and some authors have suggested using them as indirect biodiversity indicators in forest ecosystems. This study investigates TreM profiles of a temperate riparian forest as last natural forest ecosystem in a context of intensively managed landscape along the Ciron river and of surrounding pine plantations of the Landes de Gascogne forest (France) and explores their drivers at tree and plot scales. A total of 28 transects perpendicular to the river, representing 84 0.1 ha-plots, were selected along the Ciron river and three of its tributaries. At tree scale, diameter at breast height (dbh), tree species and tree status (living, standing or lying dead) were significant predictors of TreM diversity. At plot scale, Alnus glutinosa was found to significantly contribute to riparian forest TreM profiles by hosting specific TreMs. The same role was highlighted for broadleaved species in pine plantations. At plot scale, the drivers of TreM diversity varied depending on plot location in the transect (riparian forest, plantation forest, intermediate area). We found that the presence of lying dead trees is an important driver of TreM diversity at plot scale, particularly in plantation stand and we thus suggest lying dead trees be included in future studies focusing on TreMs. The rich TreM profile of riparian forests highlights their crucial role in biodiversity conservation.
... Conservation strategies are applied in both production and oldgrowth forests as well as in forests with an enrichment of deadwood and the retention of veteran trees and tree-related microhabitats (hereafter TreMs, as used in Larrieu et al., 2018) (Brunet et al., 2010;Bütler et al., 2013;Winter and Möller, 2008). The importance of the oldgrowth attributes of beech forests for biodiversity has been shown for a number of the taxonomic and functional groups (Bauhus et al., 2009) that develop in TreMs. ...
... In recent years, TreMs, including those in beech forests, have been recognized as an indicator of habitat heterogeneity (Asbeck et al., 2021;Basile et al., 2020;Khanalizadeh et al., 2020;Kozák et al., 2018;Larrieu et al., 2018). The cavity type and the presence of epiphytes, the fruiting bodies of fungi, and various types of perched deadwood are among the features that distinguish different TreMs and contribute to their role as pivotal habitats, often for very small and difficult-to-record animal and fungal species (Möller, 2009). ...
... The cavity type and the presence of epiphytes, the fruiting bodies of fungi, and various types of perched deadwood are among the features that distinguish different TreMs and contribute to their role as pivotal habitats, often for very small and difficult-to-record animal and fungal species (Möller, 2009). Accordingly, a higher diversity of TreMs provides a higher diversity of niches for a higher diversity of organisms, such that TreMs can serve as an indicator in biodiversity assessments and as a focus of efforts to promote integrative forest management (Asbeck et al., 2021;Larrieu et al., 2018;Martin et al., 2022;Paillet et al., 2018;Regnery et al., 2013;Winter and Möller, 2008). ...
Tree-related microhabitats (TreMs) provide a quantitative indicator of habitat heterogeneity in forests, including beech (Fagus) forests. However, systematic analyses of the factors driving TreM diversity and composition in Fagus sylvatica and F. orientalis forests are lacking. In this study, the TreMs of beech forests on 203 plots of 22 forest sites (production and old-growth forest) across the full longitudinal range of both species were assessed following a standardized TreM protocol. A unified diversity and ordination framework based on Hill numbers was applied to account for unobserved TreM types and to extend the sensitivity of our findings focusing from rare to dominant TreMs. The composition of TreM assemblages was mostly determined by Fagus species and elevation, a surrogate for climate, and with focus on dominant TreMs by DBH, whereas old-growth versus production forest had no effect. The coverage of detected TreMs per plot increased with the number of trees assessed and DBH, but was lower in old-growth than in production forests. When standardized for sampling * Corresponding author at: Field Station Fabrikschleichach, 2 coverage, the diversity of rare and dominant TreM types was higher in old-growth than in production forests, but increased with elevation only focusing on dominant TreMs. These findings corroborate regional studies showing a higher TreM diversity in old-growth forests. Moreover, they demonstrate the importance of focusing conservation efforts on forests of both Fagus species and at different elevations, covering the full range of TreM assemblages. Future studies comparing TreM diversity in different forests should standardize diversity by sample coverage, as currently done in many biodiversity studies.
... Tree-related microhabitats (TreMs) are distinct structure present on trees that act as habitat for one or more species during at least a part of their life cycle to develop, feed, shelter or breed. Tree microhabitats are not born by all trees (Larrieu et al., 2018). The TreMs formation rate and number depends upon the size of the tree . ...
... The TreMs formation rate and number depends upon the size of the tree . Generally, invertebrates or vertebrates make habitat on trees (Larrieu et al., 2018). Number and types of microhabitats per tree vary depending upon the tree species and the maturity of the tree because this increase markedly with increased tree diameter. ...
... It was due to enumeration of six selected trees species with only > 20 cm DBH in 94 plots covering 42.30 ha area. Out of 7 forms, 15 groups and 47 types of TreMs (Larrieu et al., 2018), 4 forms, 5 groups and 14 types were found in the present study (Table 2). Vuidot et al. (2011) found the presence of more microhabitat types as ivy, non-woodpecker cavities, conks, woodpecker cavities, canker, dead crown, cracks, bark pockets, bark losses and bryophytes in five French forests. ...
Trees Outside Forests (TOF) are found in all strata as urban, suburban and rural. Some TOF serve as Tree Related Micro Habitats (TreMs). We conducted the assessment of TreMs on TOF in Kathmandu valley of central Nepal. Inventory was performed in 209 randomly selected points by Excel using circular plots with 20 m radius. Out of 6210 individuals of 150 tree species recorded from the study area, 1038 TOF of 64 species were found to serve as TreMs. 4 forms, 5 groups and 14 types of TreMs were recorded. Habitat types per tree varied from 1 to 6. 1, 2, 3, 4 and 5 habitat types were found in 665 (64.07 %), 293 (28.23 %), 67 (6.45 %), 8 (0.77 %) and 4 (0.38 %) trees respectively. 6 habitat types were found in one Cinnamomum camphora tree (0.10 %) with 8.60 m height and 75 cm DBH. Out of all the forms, groups and types, all were found in Urban TOF, one type (mistletoe) in suburban TOF and one form (fruiting bodies of saproxylic fungi and slime moulds) along with three types (mistletoe, invertebrate nest and sap run) were absent in rural TOF. The study explored the TreMs on TOF in Kathmandu valley. It provides the baseline data useful for micro habitats as well as biodiversity conservation.
... TreMs are defined as 'distinct, well-delineated structures occurring on living or standing dead trees that constitute a particular and essential substrate or life site for species or species communities during at least a part of their life cycle to develop, feed, shelter or breed' (Larrieu et al. 2018). They represent the potential habitat of a variety of species of different taxonomic Downloaded from https://academic.oup.com/forestry/advance-article/doi/10.1093/forestry/cpad034/7223810 by Lib4RI -Library of Eawag, Empa, PSI, WSL user on 17 July 2023 groups (e.g. ...
... They represent the potential habitat of a variety of species of different taxonomic Downloaded from https://academic.oup.com/forestry/advance-article/doi/10.1093/forestry/cpad034/7223810 by Lib4RI -Library of Eawag, Empa, PSI, WSL user on 17 July 2023 groups (e.g. Larrieu et al. 2014;Ouin et al. 2015;Kraus et al. 2018;Larrieu et al. 2018), and are becoming increasingly important as ecological indicators to assess the value of forest habitats, particularly in managed forests (Santopuoli et al. 2019;Asbeck et al. 2021). ...
... Recognizing the role of TreMs in habitat management, many authors focused on the development of classification systems (Winter and Möller 2008;Vuidot et al. 2011;Kraus et al. 2016). Although some studies (Larrieu et al. 2018;Paillet et al. 2018) highlighted TreMs as important ecological niches for several living organisms, in particular beetle communities, little is known about the relationship between the abundance and richness (i.e. diversity) of TreMs and beetle communities. ...
Integrating the conservation of biodiversity into silvicultural practices is one of the main challenges facing forest owners in the promotion of an emergent approach to sustainable forest management across European forests. The Mediterranean forests are among the richest biodiverse forest ecosystems due to their environmental heterogeneity, but climate change is threatening their integrity, with critical implications for the availability of ecosystem services. Forests managed for commercial purposes are under increasing pressure to provide timber while supporting biodiversity. This study aims to analyse the relationship between tree-related microhabitats (TreMs), which are structures occurring on living or standing dead trees that constitute an essential substrate for several living species, and beetles, an important indicator species group for forest biodiversity monitoring. Four generalized linear models were fitted to assess the influence of environmental factors, forest structure, and biodiversity-related parameters on the abundance and richness of beetles, mainly on saproxylic beetles. The study highlights significant associations between the abundance and richness of individual groups and types of TreMs and the Italian Red List of saproxylic species. Therefore, TreMs can serve as a tool to map, monitor, and enhance forest biodiversity in managed forests.
... We also surveyed Tree-related Microhabitats on living trees, carefully examining the trunk from the ground to the crown and following the hierarchical classification proposed by Kraus et al. (2016), integrated with the one proposed by Larrieu et al. (2018), and recording microhabitat abundance of every veteran tree. These are primarily cavities, injuries, crown deadwood, excrescences, fruiting bodies of fungi, mould, epiphytic and epixylic structures, and exudates (Larrieu et al., 2018). ...
... We also surveyed Tree-related Microhabitats on living trees, carefully examining the trunk from the ground to the crown and following the hierarchical classification proposed by Kraus et al. (2016), integrated with the one proposed by Larrieu et al. (2018), and recording microhabitat abundance of every veteran tree. These are primarily cavities, injuries, crown deadwood, excrescences, fruiting bodies of fungi, mould, epiphytic and epixylic structures, and exudates (Larrieu et al., 2018). ...
... As the trunk diameter increases, trees can offer a more diverse mosaic of microhabitats, such as large cavities or various stages of wood decomposition (e.g., Asbeck et al., 2021, Grossmann et al., 2018, Parisi et al., 2022b, Table 3 -Abundances of each type of microhabitat censused (description and illustrations from Kraus et al., 2016 andLarrieu et al., 2018 Winter and Möller, 2008). Indeed, we found that larger trees hosted a great abundance of microhabitats (e.g., Tree ID 12, 16, 13, 11, see Fig. IV). ...
Osmoderma eremita and Cerambyx cerdo are saproxylic beetle species, included in the IUCN Red List and in the EU/92 Habitats Directive. Their occurrence has been recorded, through appropriate traps, in several localities in Italy, including urban and peri-urban parks, mostly associated with veteran trees. In this study, traps were tested over 17 veteran oak trees in the Castelporziano Presidential Estate (Latium, Rome province, central Italy) and the abundance of sampled saproxylic beetles was related to the growing stock volume (GSV) and the abundance of microhabitats. Moreover, we compared three different trapping methods: a trap designed to monitor C. cerdo (CC), and two traps designed for monitoring O. eremita, i.e., the Black Cross Window Trap (BCWT) and the Black Bottle Traps (BBT). We found that larger trees hosted a great variety of microhabitats, in particular cavities, which abundance was correlated with the number of specimens sampled, especially O. eremita species. Both classic traps (i.e., CC traps and BCWT) and the herein-introduced BBT variants were effective for capturing large saproxylic beetles.
In this work, we underline the importance of the preservation of veteran trees to the occurrence of threatened saproxylic beetles, and we contributed to (i) extending general knowledge of the habitat preferences of saproxylic beetles and (ii) improving new cost-effective trapping system variants.
... Humid and shaded hollows are also colonized by some lichens, especially calicioids (Tibell, 1999) Broken or irregular treetops Broken or irregular tops of large trees provide nesting places for large birds of prey, e.g., Golden Eagle (Aquila chrysaetos) and Osprey (Pandion haliaetus) (Kuuluvainen, 2002) Dead branches and treetops Dead branches of living trees are an abundant microhabitat: they can constitute half of the total deadwood surface area in managed conifer-dominated boreal forests (Svensson et al., 2014). They serve as a substrate for saproxylic insects, fungi, and lichens (Larrieu et al., 2018), including rare species, e.g., the lichen Erioderma pedicellatum on dead branches of old spruces in the Russian Far East, Alaska, and eastern North America ( Bark pockets Partially loose pieces of bark form a pocket between the bark and the tree trunk. These pockets are essential for many invertebrates and, if sufficiently large, can also be used as nesting places by some birds (e.g., treecreepers, Certhidae) or as day roosts by bats (Winter & Möller, 2008) Cracks, scars, and bark loss Cracks on the trunk provide nesting and hiding places for invertebrates, e.g., spiders and flat bugs; larger ones can also serve for birds and bats (Michel & Winter, 2009). ...
... Cracks and scars also host some crustose lichens and various fungi and microorganisms (Roll-Hansen and Roll-Hansen, 1980). Exposed wood is used by saproxylic invertebrates, fungi, and lichens (Larrieu et al., 2018) Fire scars Charred, exposed wood resulting from earlier forest fires occurs on fire-resistant conifers (e.g., Pinus sylvestris) and usually on larger trees, which are more likely to survive a fire. The fire scars serve as a substrate for species specialized on charred wood, e.g., the lichens Carbonicola anthracophila, C. myrmecina, and Hertelidea botryosa (Fig. 5.3d;Andersson et al., 2009;Lõhmus & Kruustük, 2010) Resin and sap flows Resinoses can host specialized fungi, such as Chaenothecopsis spp. ...
... Occurrence and examples of species utilizing the microhabitat Cankers and burls Cankers and burls provide substrates for epiphytic bryophytes and lichens. They are also used by certain Lepidoptera (Larrieu et al., 2018) Witch brooms Brooms are dense branch growths caused by pathogenic fungi, e.g., Chrysomyxa arctostaphyli on white and black spruce (Paragi, 2010). They provide nest sites and food sources for arthropods, birds, and small mammals, such as red squirrels (Tamiasciurus hudsonicus) (Tinnin et al., 1982) Fungal fruiting bodies Fungal fruiting bodies are used as habitat or food sources by various insects, such as beetles (Jonsell et al., 2001). ...
Living trees are fundamental for boreal forest biodiversity. They contribute to stand structural diversity, which determines the range of habitat niches available for forest-dwelling species. Specific characteristics of living trees, such as species, age, and presence of microhabitats, determine how species utilize trees for food, as nesting places, or as growing substrates. This chapter explores the associations between living trees and aboveground biodiversity, reviews the factors such as soil productivity, hydrological regime, stand successional stage, and forestry activities that influence the characteristics of living trees and stand structural diversity, and presents the consequences of current and future climate change on boreal biodiversity.
... To quantify the potential of individual trees to host biodiversity, the concept of tree-related microhabitats (TreMs) was developed. This concept includes standardized typologies for TreM assessment to ensure compatibility between different studies (Kraus et al., 2016;Larrieu et al., 2018). We refer to TreMs as "distinct, well-delineated structures occurring on living or standing dead trees, that constitute a particular and essential substrate or life site for species or species communities during at least a part of their life cycle to develop, feed, shelter or breed" . ...
... We identified occurrences of 47 distinct TreM types (Appendix S6) on all cored trees based on the typology by Larrieu et al. (2018), and these types were pooled into 15 TreM groups described by the same typology based on the similarities in their morphological characteristics and biodiversity relevance. We defined TreMs richness as the number of different TreM types per tree, and the occurrence of TreM groups was set to 1 if at least one TreM type from the respective TreM group was present on a tree and was set to 0 if none of the TreM types from the respective TreM group were present. ...
... However, the magnitude of the effect was lower for tree age than for diameter. This pattern may result from the thresholds for rot hole opening (diameter of opening >10 or >30 cm based on the type of rot hole [Appendix S6]) applied when surveying TreMs based on Larrieu et al. (2018) typology; large trees are more likely to form large rot hole openings. Previously, the occurrence of rot holes on beech trees was related to low tree growth and not explicitly to the age or size of the tree (Fritz & Heilmann-Clausen, 2010). ...
Protecting structural features, such as tree-related microhabitats (TreMs), is a cost-effective tool crucial for biodiversity conservation applicable to large forested landscapes. While 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. While many TreM groups were positively associated with tree age and diameter, only 2 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 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 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. Article Impact Statement: Conservation of habitat trees based on size, without considering tree age, may impair landscape-level biodiversity potential. This article is protected by copyright. All rights reserved.
... One key aspect to keep in mind during the creation of structurally more complex forests is the provisioning of TreMs. These structures provide important habitats for forest-dwelling species and are defined as "distinct, well delineated structures occurring on living or standing dead trees, that constitute a particular and essential substrate or life site for species or species communities during at least a part of their life cycle to develop, feed, shelter or breed" (Larrieu et al., 2018). ...
... These structures occurred frequently on standing decaying Norway spruce trees that slowly lose their bark. If TreMs are considered a multi-taxon forest biodiversity indicator, their increase in abundance and richness suggests that the treated plots will host an increased species pool in the near future (Asbeck, Großmann, et al., 2021;Basile et al., 2020;Larrieu et al., 2018;Paillet et al., 2018). ...
... There are almost no time series data of TreM development available based on empirical data (Puverel et al., 2019), just a single study reported the cross-sectional development of TreMs (Courbaud et al., 2017), probably grounded in the differences existing (observer bias) in TreM inventories. Even when using a standardized and easy-to-follow inventory protocol (Kraus et al., 2016;Larrieu et al., 2018), the results showed relatively large differences in the recording of TreMs for individual trees in control plots. This may be partially explained by the significant mortality, which changes tree attributes and also the visibility of TreMs in defoliated crowns. ...
We report on a structural complexity enhancement (SCE) experiment that was designed to test ecological restoration measures in the Black Forest National Park, Germany. The main goal was to understand as to whether the creation of standing and downed deadwood within previously managed, single-layered Norway spruce (Picea abies L.) forests accelerates the development of forest structure, richness, and diversity of a range of taxonomic groups. Here we introduce the experimental design and describe the development of stand structure including abundance and richness of tree-related microhabitats (TreMs) within 5 years after initiation of the experiment in October 2016. To enhance structural complexity in treatment plots, 10 trees per plot were toppled using a skidder winch, and another 10 trees were ring barked at a height of around 60 cm above ground level with a chainsaw. To monitor stand structure, we collected data on common forest attributes such as diameter at breast height (DBH), tree height, and TreMs of all trees in the six experimental and six control plots measuring 0.25 ha in size before the treatments were carried out in 2016 and again in 2020/21. We analyzed the abundance and richness of TreMs using generalized linear mixed models with DBH and treatment vs. control as predictors. The SCE treatment resulted in a significant increase in deadwood volumes (4.2 vs. 439.5 m3) as well as in TreM abundance and richness (increase of 0.74 TreMs per tree). This indicates that the SCE treatment was effective to increase biodiversity-relevant structures such as deadwood and TreMs, in previously managed Norway spruce-dominated stands. The ongoing monitoring of a range of taxonomic groups (birds, bats, small mammals, coleoptera, fungi, mosses, and vascular plants) in this experiment will demonstrate to what extent the enhancement in structural complexity will lead to an enrichment in species richness and diversity.
... Dead trees were also recorded. Visual assessment of beech stem quality features-the presence of ramicorn branches, forking, cracks, and epicormic shoots [10,30]-was carried out. The presence of epicormic branches was recorded at the lowest three meters of the stem. ...
... Dead trees were also recorded. Visual assessment of beech stem quality features-the presence of ramicorn branches, forking, cracks, and epicormic shoots [10,30]was carried out. The presence of epicormic branches was recorded at the lowest three meters of the stem. ...
The expansion of European beech to northeastern regions due to climate change is anticipated , especially if assisted migration techniques are employed. Marginal populations of European beech are exposed to unfavorable growing conditions that are challenging for their survival and multifunctionality. Under such conditions, the structural complexity of stands is a critical factor that supports the sustainability of these populations. In this study, five stands of European beech in Latvia, which are currently the most northeastern stands in Europe, were investigated. In each of the stands, two sample plots (area 500 m 2) were randomly established. The dimensions of trees, stem quality features, and spatial structure of the stands were assessed. The stands varied in density but were found to be productive as indicated by comparable tree dimensions to those in core populations. The studied beech stands displayed low species mingling and tended towards monospecies composition, with some structural diversification likely due to small-scale disturbances and varying stand densities, suggesting that spatial diversity was influenced by species composition and competition among trees. The analyzed European beech stands were in the maturing phase, but displayed diverse diameter and height structures, indicating that natural ecological processes were occurring, akin to those found in non-marginal regions. The stem quality of the trees was intermediate, with frequent occurrences of ramicorn, epicormic branches, and forking (41.8%, 53.5%, and 26.3%, respectively), while stem cracks were rare (4.6%). However, these features can provide crucial microhabitats for biodiversity. Therefore, European beech has the potential for diversification in forestry and ensuring sustainability at the edge of its range expansion. The main implications of this study highlight the diverse structural characteristics of the European beech stands, indicating the influence of species competition and small-scale disturbances, providing valuable insights for forest management and conservation strategies. Although, this study has a few potential limitations that should be considered, including the relatively small sample size and the absence of long-term data.
... The recording of tree microhabitats was conducted during the leafless period (January to February 2020) by checking visually for TreMs over the whole plot. Following microhabitats according to Larrieu et al. (2018) were recorded: a) cavities (woodpecker breeding cavities, rot holes and dendrotelms), b) tree injuries (exposed sapwood and heartwood, bark pockets), c) crown deadwood, d) Fruiting bodies of saproxylic fungi and slime moulds (perennial polypores). Additionally, coarse bark was recorded. ...
... With the introduction of a deciduous tree species into pure coniferous stands it is highly likely that the number of tree related micro habitats is increasing, as deciduous tree species tend to have higher number of microhabitats (Vuidot et al. 2011). Tree microhabitats, a large range of structures grouped together, are keystone structures for a high biodiversity in forest (Bütler et al. 2013;Larrieu et al., 2018). Many species are dependent on tree microhabitats as breeding sites, shelter or for foraging (Larrieu et al. 2012;Michel and Winter, 2009;Winter and Möller, 2008). ...
The conversion from pure coniferous stands to mixed forests is a major goal of forest management strategies in the light of climate change. However, the effects of forest conversion on the associated species diversity and the factors driving diversity changes remain poorly understood. To investigate these effects, we established 54 plots in a managed forest in southern Germany, where large areas have been converted from pure spruce to mixed spruce-beech stands since the middle of the 20th century. Our sampling plots consisted of three different age classes and increasing proportions of beech, measured by the number of stems. We sampled fungi, plants, invertebrates, and birds and combined classical methods (identification by specialists) and metabarcoding for species identification. Furthermore, important forest structure and site parameters were recorded to test their influence on species alpha and beta diversity. Alpha diversity of embryophytes, and therein tracheophytes, increased with increasing availability of light, whereas fungi decreased. With increasing humus thickness alpha diversity of insects, especially dipterans and hymenopterans increased, whereas embryophytes, tracheophytes and fungi decreased. Increasing numbers of habitat trees increased the alpha diversity overall, especially in tracheophytes and hymenopterans. The proportion of beech determined the alpha diversity of one out of 12 taxa and influenced the beta diversity of 10 from 12 taxa. However, factors influencing the diversity are taxa dependent. Our study indicates that the proportion of beech had less impact on alpha diversity but impacts beta diversity. Changes in forest structures and environmental conditions occurring during forest conversion are as important as the introduction of beech for alpha and beta diversity.
... The presence, abundance and richness of TreMs, which are crucial for the life cycles of many forest-dwelling species in terms of breeding, foraging, nesting, or hiding spaces, have been used to guide selection of valuable habitat trees during silvicultural operations in European forests (Asbeck et al., 2021;Larrieu et al., 2018). ...
... These surveys were carried out by the same person to avoid observer bias (Paillet, Coutadeur, et al., 2015;Paillet, Pernot, et al., 2015). TreMs were recorded following the standardized typology of Larrieu et al. (2018), with 15 hierarchical groups and 47 types, relevant to forest-dwelling species (Appendix S2). The summary of the main characteristics of surveyed trees are presented in Tables 1 and 2. Data analysis was performed using R 1.4.1717 ...
Retention of structural elements such as deadwood and habitat trees at the level of forest stands has been promoted to integrate biodiversity conservation into multiple-use forest management. The conservation value of habitat trees is largely determined by the presence, richness, and abundance of tree-related microhabitats (TreMs). Since TreMs are often lacking in intensively managed forests, an important question of forest conservation is how the abundance and richness of TreMs may be effectively restored. Here, we investigated whether the strict protection of forest through cessation of timber harvesting influenced TreM occurrence at tree and stand levels. For that purpose, we compared four managed and four set-aside stands (0.25 ha each) in the Białowieża Forest, with identical origin following clear-cuts approximately 100 years ago. We found that the abundance and richness of TreMs on living trees were not significantly different between stands that were either conventionally managed or where active forest management ceased 52 years ago. Yet, our analysis of TreMs on tree species with contrasting life-history traits revealed that short-lived, fast-growing species (pioneers) developed TreMs quicker than longer-lived, slower-growing species. Hence, tree species such as Populus or Betula, which supply abundant and diverse TreMs, can play an important role in accelerating habitat restoration.
... TreMs are frequently used multi-taxon biodiversity indicators (Asbeck et al., 2021;Larrieu et al., 2018). Previous studies have shown that older trees are more likely to have TreMs (Paillet et al., 2017). ...
... Thus, we highlight the importance of large and old trees, as described by Gossner et al. (2014). The monitoring methodology of TreMs, despite their importance, has not yet been generally harmonised (Kovac et al., 2020), however proposals have been made for harmonised typology and guidelines for their standardised recording (Larrieu et al., 2018). Based on our results, TreMs can be detected indirectly in several ways, so monitoring programs don't necessarily need to be supplemented with this group of indicators. ...
As the multi-scale study of biodiversity is extremely resource-intensive, proxy indicators taken from various databases are often used to answer questions on a larger spatial scale. Considering differences in the scale and methods, the application of such indicators (especially from different monitoring systems) requires careful consideration and standard methods of validation. In order to demonstrate this, we validated the results of the MAES-HU (National Ecosystem Assessment of Hungary) forest condition assessment (based on the Hungarian NFD-National Forestry Database) with thematically richer, finer-scale field data. We also examined the relationships of some MAES-HU indicators with other variables significant for nature conservation, not currently included in the NFD. We found the MAES-HU scoring was similar to the fine-scale score results in the case of tree species composition indicators, however, less so for structural indicators. The MAES-HU assessment uses the values of the NFD, averaged for forest management units, and thus tends to underestimate structural variety. This highlights a potential loss of important conservation-related information. During the examination of relationships with other indicators that are not included in the large-scale MAES-HU assessment, we found that the presence of large-diameter and old trees correlates with tree-related microhabitats and large standing deadwood, but no relationship was found for other investigated indicators (game pressure, further deadwood indicators). This highlights the need for integrating some key conservation indicators (presence of old and large trees, quantity and quality of standing and lying deadwood) into existing forest monitoring systems in order to optimise the resources dedicated to multipurpose data collection. Our study also highlights that applying indicators as proxies requires the full knowledge of monitoring methods and validated indicator-indicanda relationships.
... Similarly, as trees grow and age, the number and diversity of tree-related microhabitats increases, but this varies considerably between habitats even within tree species. As many species are dependent on the tree-related microhabitats and not tree age, experts have developed a hierarchical typology for the classification of the diversity of tree-related microhabitats to facilitate cross ecosystem comparisons and to quantitatively inventory and measure their contributions to biodiversity [14]. ...
... In addition, practice should promote mixed stands with species that tend to develop tree-related microhabitats at an earlier age [4]. The impact of interventions on treerelated microhabitats should be assessed, and candidate trees that are likely to support a diversity of tree-related microhabitats in young forest stands should be identified, selected, and preserved [14]. Without a better understanding of the relationship between forest age structure, small-habitat features, and species requirements throughout the forest life cycle, we risk ineffective management practices that fail to meet societal demands. ...
Loss of insect biodiversity is widespread, and in forests habitat loss is one of the major drivers responsible. Integrative forest management must consider the preservation and promotion of key habitat features that provide essential microhabitats and resources to conserve biodiversity alongside ecosystem functions and services.
... Stump diameter was measured at a height of 0.3 m. For all living and dead trees, TreMs were inventoried following the classification of Larrieu et al. (2018) comprising 47 TreMs in 15 TreM-groups and 7 TreM-categories (Table 3). For countable microhabitats (e.g. ...
... Catalog of tree-related microhabitats (afterLarrieu et al. 2018) ...
The individual or grouped retention of habitat trees in managed multiple-use forests has become an approach used to protect biodiversity-related structural attributes typically found in old close-to-nature forests. This study focuses on the effect of one such retention approach in the managed forests of Baden-Württemberg, Germany, ten years after its introduction. Specifically, we asked: (1) How effective are habitat tree groups (HTGs) at providing large living trees (LLTs > 80 cm DBH), tree-related microhabitats (TreMs), and dead wood?, and (2) which tree and stand variables have the greatest influence on the occurrence of TreMs? For this purpose, we inventoried 326 HTGs and 94 reference plots in forests dominated by the most widely occurring native conifer and broadleaf tree species, silver fir (Abies alba) and European beech (Fagus sylvatica). In accordance with our hypotheses, LLTs and TreMs were significantly more abundant in HTGs than in reference plots in both forest types. More importantly, when retaining 5% of the forest area as HTGs (a common retention level), old forest attributes such as woodpecker cavities, rot-holes or exposed heartwood increased significantly at the stand level while the volume of LLTs almost tripled, and volume of snags increased by 25%. However, quantities of these two attributes remain below minimum thresholds recommended in the scientific literature. A conversion of 15–25% of the stand area into HTGs is needed to increase the stand level abundance of TreMs such as concavities, exposed sapwood, or crown dead wood significantly in the short term. At the single-tree level, tree diameter (DBH), tree species, vitality and neighborhood competition had a significant influence on modeled TreM abundance. At the stand level, TreM occurrence increased with stand age and amount of snags, whereas TreM richness declined with stand density. Ten years after introducing the retention approach, forest stands with HTGs comprised significantly more important structural attributes than those without. Selecting HTGs with high stand volume or low tree density that also include snags, a mix of tree species, LLTs, and some low-vitality habitat trees could further improve this practice.
... Trees of at least 50 cm dbh were recorded and assessed for TreMs following the field key Table 2 Response variables: Forest structure and nature conservation values. To describe forest management intensity on the parcels, we use the index ForMI (Kahl and Bauhus 2014), consisting of three components (iHarv = proportion of harvested volume to total volume; iNonat = proportion of volume of non-natural species to total volume; iDwcut = proportion of sawn deadwood to total deadwood volume) Larrieu et al. (2018) to calculate TreM density (per ha), the abundance of trees with TreMs (per ha), and the abundance of trees with a dbh ≥ 50 cm (per ha). For each forest parcel, the prevailing stand age was classified into 25-year classes (0-25 yrs, 26-50 yrs, and so on) by expert estimation in the field. ...
... Rights reserved. 2: Which of the following activities are carried out in your forest (both by you and by third parties)?A3: Tree-related microhabitatsTreM categories were used as defined inLarrieu et al. (2018). ...
Small-scale private forests cover large areas in Europe and often contain structures and habitats of high nature conservation value that are increasingly put under pressure due to a rising interest in fuelwood and wood products. We investigate the distribution of variables like living tree and deadwood volumes, management intensity, diversity and density of tree-related microhabitats recorded in 81 small-scale private forest parcels in the Lower Saxon Hills (northwest Germany). We provide an assessment of the influence of predictors like the individual forest owners’ goals and activities, as stated by them in a quantitative survey, as well as landscape parameters like parcel size, slope, landscape fragmentation and forest continuity. Our results indicate that there are two types of structures of conservation value in small-scale private forests: slowly evolving structures (type A) like large-diameter living trees and tree-related microhabitats which mostly depend on landscape parameters that act on longer time scales, and fast evolving structures (type B) like deadwood that are influenced by both owner attitudes and landscape parameters. The resulting implications for integrative forest and conservation management are discussed. When considering the conservation of the slowly evolving type A structures, long-term commitments to conservation legislation, financial incentives and generation-spanning education of forest owners are necessary. Efforts to promote the faster evolving type B structures might prove particularly advantageous in small-scale private forests given the structural diversity of the stands, but also the often strong identification of owners with their land.
Graphical abstract
... Compared to the INFC15, our survey method was simplified, and the number of variables to collect was reduced to those required for the COST Action Bottoms-UP database and for potential modelling studies (statistical and dynamic) in the context of other projects by Eurac Research. In addition, we collected tree-related microhabitats (Kraus et al. 2016, Larrieu et al. 2018, which were required by the COST Action database but were not included as surveyed variable in the INFC15. ...
... As an aiding tool in the field, it is recommended to use the smartphone app reporting codes, descriptions and illustrations of the different microhabitat types. Furthermore, the surveyor should be trained regarding the protocol guideline for standardised TreM survey by Larrieu et al. (2018). If possible, it is recommended to take multiple pictures of the different microhabitats, indicating the related tree ID so that structures can be compared between forest plots in case of issues in the identification. ...
On initiative of the government of the Autonomous Province of Bolzano-Südtirol (Province Bolzano-Südtirol, Region Trentino-Alto Adige, Italy) a biodiversity monitoring program was established, starting with sampling on terrestrial sites in 2019 and on running water sites in 2021. The Biodiversity Monitoring South Tyrol (BMS in short) is a long-term project with repetitions on a regular basis. The BMS was launched and is conducted by the Institute for Alpine Environment of Eurac Research in collaboration with the Museum for Nature South Tyrol and the province of South Tyrol’s Nature Conservation Department, as well as the Department for Agriculture. BMS surveys biodiversity throughout the area of South Tyrol and within the most important habitat types, including near-natural, agricultural, and urban habitats. BMS spans sites from the planar zone up to the high alpine zone. At the center of the monitoring are specified monitoring sites; all surveys are conducted in or directly around these sites. In total, we investigate 320 terrestrial survey sites over a period of five years, which is 64 single sites per year. For the monitoring of running waters (in short aquatic BMS) we investigate 120 sites in total over a period of four years.
... The list of TreMs was compilated by extending the lists of other authors (e.g. Bütler et al., (2013); Kraus et al., (2016); Paillet et al., (2018)) and then grouping the individual TreMs found into 13 basic classes according to Larrieu et al., (2018) . To include forest age as a factor, we used the age of the oldest forest stand group [Age_-MAX] within a 1 ha sampling plot extracted from forest management plans, which is a good reflection of actual age of the stands, as all the stands surveyed had been managed in the past (including currently unmanaged reserves). ...
Many of native forests in Europe have been transformed into even-aged production forests of commercially attractive conifers. In recent decades, a moderate shift back to a more native tree species composition accompanied by the maturation of some close natural stands has been evident in the Czech Republic. We aimed to investigate the effects of increasing age and contribution of native tree species on bird species and to identify the potential critical thresholds of these factors in central European forests. For this purpose, bird monitoring and forest structure measurements were carried out at 120 plots in production forests and 20 forest reserves located on 20 study sites throughout the Czech Republic. These plots covered gradients of native tree species contribution and stand age. Birds were counted during the 2018, 2019 and 2020 breeding seasons using passive acoustic monitoring, followed by subsequent computer analysis of the recordings. We assessed relationships between differences in bird species composition and structural and environmental factors. We also used generalised additive models (GAMs) to investigate the effects of individual structural and environmental factors on birds, taking into account their occurrence frequencies and habitat preferences. Our results convincingly documented, that dissimilarities in bird species composition, especially species turnover, strongly coincided with differences in the share of conifer basal area and stand age. The effect of tree species composition on the bird species turnover reflected the habitat preferences of individual species. In addition, we found that some cavity-nesting species were strictly associated with stands with a low contribution of conifers and high stand age. The presence of forest older than at least 125, but sometimes up to 280 years is a critical factor for rare and old-growth bird species. Conversely, the high contribution of conifers (more than app. 60 % of basal area) inhibited the occurrence of the species-rich communities, especially the birds associated with close natural stands. Therefore, increasing the area of mature close-natural stands would be beneficial for bird diversity, especially for rare species. In central Europe, however, the rotation length of forest stands is usually less than 120 years in order to maximise timber production. Forest management practices should therefore support the maturation of forest stands and the transformation of tree species composition towards more native broadleaved forest stands. These measures are essential for the protection of species-rich bird communities, especially old-growth-associated birds, in central Europe.
... In fact, these plantations, which play a significant role in wood production [29], are typically located in flat areas and with homogeneous conditions, particularly suitable for SPOT. Future research could also explore the feasibility of assessing forest-floor biodiversity attributes, such as fallen trees, coarse woody debris, and trunk-and root-related microhabitats [30,31], which can usually require significant time and manual effort during field inventories [32]. In this context, the wide range of movements of SPOT could overcome the problems related to static terrestrial laser scanning in detection of microhabitats [33,34]. ...
In the context of the potential future use of unmanned ground vehicles for forest inventories, we present the first experiences with SPOT, a legged robot equipped with a LiDAR instrument and several cameras that have been used with a teleoperation approach for single-tree detection and measurements. This first test was carried out using the default LiDAR system (the so-called enhanced autonomy payload - EAP, installed on the board of SPOT to guide autonomous movements) to understand advantages and limitations of this platform to support forest inventory activities. The test was carried out in the Vallombrosa forest (Italy) by assessing different data acquisition methods. The first results showed that EAP LiDAR generated noisy point clouds where only large trees (DBH ≥ 20 cm) could be identified. The results showed that the accuracy in tree identification and DBH measurements were strongly influenced by the path used for data acquisition, with average errors in tree positioning no less than 1.9 m. Despite this, the best methods allowed the correct identification of 97% of large trees.
... Furthermore, relict tree stands often contain very old trees (Fazan et al. 2012;Tang et al. 2013;Camarero et al. 2018), and old trees are known to provide numerous microhabitats (Lindenmayer & Laurance 2017;Nordén et al. 2018). These microhabitats (sometimes denominated in literature as 'tree related microhabitats'; Kraus et al. 2016;Larrieu et al. 2018;Bütler et al. 2020) can also be formed by tree-associated taxa such as bryophytes or lichens. Some in turn foster a wide variety of other living organisms (e.g. ...
Trees have a crucial importance in the functioning of ecosystems on Earth. They are among the largest and longest-living taxa and provide habitat and shelter to numerous species belonging to diverse groups of organisms. Relict trees are of particular interest through their history of survival and adaptation, and because they potentially shelter rare or threatened organisms today. We investigated for the first time the diversity and distribution of epiphytic lichens and bryophytes found on the Cretan (Greek) endemic and relict phorophyte Zelkova abelicea (Ulmaceae). Our results showed that Z. abelicea hosts a high number of epiphytes. The Levka Ori mountain range in western Crete seems to be a hot spot for epiphytic lichens on Z. abelicea. Bryophytes had the highest diversity on Mt Kedros in central Crete but were absent from several other sites. Moreover, 17% of the studied lichens were recorded for the first time for Crete and 5% have never been recorded for Greece. Geographical position and browsing intensity seem to be important factors influencing the epiphytic community encountered. Tree morphology (dwarfed or arborescent) was also significant in influencing community composition although it was not possible to dissociate this factor from the effect of topography. Dwarfed individuals were found to have as much epiphytic diversity as arborescent trees. Ecological indicator values showed that high epiphytic diversity was found in some sites despite signs of eutrophication and disturbance due to pastoral activities and suggest the co-occurrence of both disturbance tolerant and sensitive species. Our results show how little is known about the biodiversity of Cretan phorophytes and highlights the need for further research on the topic.
... While both barks generally maintain a smooth texture, a notable distinction arises in the occurrence of numerous small cracks that form as Carpinus matures (Johnson, 2004). These microhabitats host numerous species with low coverages and different life strategies and functional traits (Larrieu et al., 2018). Examples of such species include O. affine, O. pumilum, Ulota crispa, Orthodicranum montanum, and L. cavifolia. ...
Functional diversity is widely recognised as the key to understanding the role of ecological mechanisms in shaping the patterns of species coexistence across different environmental gradients. Despite research in this area, there is a considerable knowledge gap on the ecological mechanisms that shape the composition of bryophyte communities, especially those at risk. One of the most endangered group of species are usually woodland specialist bryophytes, therefore, understanding the factors determining their occurrence should be a priority. One of the model species belonging to this group is Dicranum viride, a target species of international conservation importance, and of particular interest for forest managers responsible for forest ecosystems protection. We examined the effect of the tree phorophyte species on the realised niche of D. viride in the temperate forest ecosystems. The specific tree species that D. viride inhabits greatly influences its realised niche. Both phorophyte species we examined, i.e. Fagus sylvatica and Carpinus betulus, can sustain the presence of D. viride, but the key determinant is the availability of suitable microhabitats, such as specific combinations of bryophyte species within bark irregularities. Our findings indicate that even in regions where the effects of forest management are noticeable, the preservation of trees with diverse microhabitats facilitate the existence of rare moss species with D. viride as an example. As a moss with a narrow ecological amplitude, D. viride occurrence patterns can be used as a tool in monitoring studies and for improving forest management strategies aimed at harmonising wood production with the conservation of biodiversity and ecosystem functioning. As a result, this information can be significant for conservation strategies, as it highlights the importance of identifying and preserving certain tree species to protect both particular epiphyte communities and individual target species.
... Veteran trees are usually old but can also be quite young with developed sap-runs caused by wounds or diseases. They provide numerous different TreMs (Larrieu et al., 2017) for hoverflies, including moist decaying wood, sap-runs, rot holes, cracks, rotting heartwood, etc. (van Steenis, 2023). ...
This document provides the basis for a Conservation Action Plan for threatened
European hoverfly species which are specialised on veteran trees or wet decaying
wood, including the Orange-horned Wasp Fly (Sphiximorpha petronillae Rondani, 1850), the Red-legged Leafwalker (Chalcosyrphus pannonicus Oldenberg, 1916), the Royal Wasp Fly (Primocerioides regale Violovitsch, 1985), the Golden Forest Fly (Brachypalpus chrysites Egger, 1859), Jacobson’s Leafwalker (Chalcosyrphus jacobsoni Stackelberg, 1921) and the Black-legged Leafwalker (Chalcosyrphus nigripes Zetterstedt, 1838), five of which are classified as Endangered on the European Red List and one as Vulnerable. Veteran trees are defined as “trees with habitat features such as wounds or decay” (Woodland Trust, 2008). Veteran trees are usually old but can also be quite young with developed sap-runs caused by wounds or diseases. They provide numerous different TreMs (Larrieu et al., 2017) for hoverflies, including moist decaying wood, sap-runs, rot holes, cracks, rotting heartwood, etc. (van Steenis, 2023).
... They provide living space for many species of insects, animals and birds in the form of structures on the tree stem called tree-related microhabitats (TreMs; e.g. Larrieu et al., 2018). TreMs act as important biodiversity indicators and are of great interest to European forest monitoring programs, research and forest practitioners (e.g. ...
Monitoring biodiversity in forests is crucial for their management and preservation, especially in light of increasing climatic disturbances. However, traditional methods of surveying forest biodiversity, such as the inventory of tree-related microhabitats (TreMs), are costly and time-consuming. For many years, terrestrial laser scanning (TLS) was the main method for producing highly accurate 3D models of forests. However, with recent advancements in 3D scanning technologies, there are now numerous alternatives available on the market. The aim of this study was to evaluate the performance of four different 3D data acquisition methods, i.e. close-range photogrammetry (CRP), fish-eye photogrammetry (FEP), mobile laser scanning (MLS), and mixed reality depth camera (MRDC), in terms of accuracy and ability to measure biodiversity (TreMs) at tree-stem level, in comparison to TLS. Analysis was performed based on geometric accuracy and point neighbourhood relevance. CRP was the most accurate alternative to TLS for TreM measurement with a median error of 1.5 cm, while FEP provided a good balance between accuracy (median error 1.4 cm) and speed of data collection. Although MLS showed promising results (median error 1.6 cm), noise in the point cloud limited its ability to identify TreMs. MRDC, on the other hand, had lower quality (median error 3.6 cm) and lower point density, making it unsuitable for TreM segmentation. Nevertheless, the study demonstrated the feasibility of augmenting the real world with virtual content at single-tree-stem level using mixed reality technology. Overall, the 3D scanning technologies presented hold great promise for recording the evolution of biodiversity at stem level.
... Furthermore, forest regeneration with subsequent changes and stabilisation of the microclimate [40,54] provides suitable conditions for species favouring more stable and specific microclimatic conditions, including several indicator species [55]. At our sites, the occurrence of more sensitive lichen species, e.g., Acrocordia gemmata, Arthonia vinosa and Lobaria pulmonaria had increased over time, and also the richness of indicators was positively related to higher total bryophyte species abundance and richness. ...
Retention of trees from the previous generation is one of the most widespread conservation practices in forests used for timber production. Despite the comparatively long history of this approach in Europe, there is a lack of long-term studies on the effectiveness of retention trees in preserving epiphyte communities. We compared the diversity of bryophyte and lichen species on retention trees in 20 young forest stands in Latvia in two assessments, 11 years and 18 years after clearfelling. Linear mixed-effects models showed that richness of both lichens and bryophytes remained stable during the assessment years, while bryophyte cover and diversity on retention trees increased over time. The main indicator of higher species richness, cover and diversity on retention trees in managed forests in hemi-boreal vegetation zone was the tree species, with deciduous trees playing the key role. They also provided essential habitat for rare species. Regarding bryophytes, ash, elm, and aspen can be suggested as more efficient retention trees, thus aiding the continuity of bryophyte succession in young forest stands. For lichens, lime could also be prioritised.
... The existing knowledge paves the way to directly test biodiversity indicators of SFM and their thresholds, and to overcome the current approach of assessing forest management sustainability through proxies that mostly showed weak correlation with the indicandum (Gao et al., 2015). For biodiversity sustainability, these proxies include tree composition, size and age distribution, gap structure, deadwood amount and tree-related microhabitats (Müller and Bütler, 2010;Larrieu et al., 2018). Their indirect indication is intrinsically limited (Barton et al., 2020;Zeller et al., 2022) and would need to be complemented with a direct analysis of several taxonomic groups (Burrascano et al., 2018). ...
The European biodiversity and forest strategies rely on forest sustainable management (SFM) to conserve forest biodiversity. However, current sustainability assessments hardly account for direct biodiversity indicators. We focused on forest multi-taxon biodiversity to: i) gather and map the existing information; ii) identify knowledge and research gaps; iii) discuss its research potential. We established a research network to fit data on species, standing trees, lying deadwood and sampling unit description from 34 local datasets across 3591 sampling units. A total of 8724 species were represented, with the share of common and rare species varying across taxonomic classes: some included many species with several rare ones (e.g., Insecta); others (e.g., Bryopsida) were represented by few common species. Tree-related structural attributes were sampled in a subset of sampling units (2889; 2356; 2309 and 1388 respectively for diameter, height, deadwood and microhabitats). Overall, multi-taxon studies are biased towards mature forests and may underrepresent the species related to other developmental phases. European forest compositional categories were all represented, but beech forests were over-represented as compared to thermophilous and boreal forests. Most sampling units (94%) were referred to a habitat type of conservation concern. Existing information may support European conservation and SFM strategies in: (i) methodological harmonization and coordinated monitoring; (ii) definition and testing of SFM indicators and thresholds; (iii) data-driven assessment of the effects of environmental and management drivers on multi-taxon forest biological and functional diversity, (iv) multi-scale forest monitoring integrating in-situ and remotely sensed information.
... The abundance of natural cavities is often related to a forest's age, the species composition of the trees and the management practices. Tree hollows and cavities are keystone microhabitats, used by a broad range of fauna for shelter and breeding (Larrieu et al. 2018). With the clearing of large, old trees or conversion of forest stands, the proportion of trees offering hollows decreases (Vesk et al. 2008). ...
The gradual conversion of forest stands to single-aged and single-species stands is resulting in the loss of natural roosts for many animal groups. The installation of bat boxes is one solution to compensate for the lack of natural roosting opportunities. The box models differ in their design and material, which to some extent can determine their suitability for bats. We investigated the occupancy of 187 boxes made of wood, ceramic and two sizes concrete with styrofoam; and the intra-seasonal (spring migration, breeding, mating/migration) thermal profile for each type of box. The environment of the boxes was defined by parameters that could directly affect the box’s thermal conditions (solar energy availability), or be related to sociality (distances, obstacles) or food availability (edge of forest, water). The box occupancy depended on the box type and the season: styrofoam-concrete boxes were preferred, with a higher occupancy during the mating and migration period (>75%), whereas the highest species richness occurred in ceramic boxes. Box types also differed significantly in their diurnal thermal profiles: the wooden boxes had inside temperatures similar to outside the box, whereas the styrofoam-concrete and with expanded clay aggregate (ceramic type) averaged 2°C higher. Overall, we found 6 bat species, although we concentrated our analysis on the most common species: Pipistrellus nathusii (88%). For this species, none of the parameters that could affect the box thermal condition had an impact on the occupancy, whereas the presence of obstacles and the distance to a water body, proved to be important. To ascertain that our results may be valid and be the result of differences in the box thermal properties, we tested the relationship of the box occupancy to the latitude, using data available in the literature. The occupancy of wooden boxes from the latter dataset significantly decreases with latitude, whereas for the concrete (with addition of sawdust or styrofoam) it increases, although this relationship is not significant and requires a larger sample.
... With raw data related to temperature and precipitation during the most extreme months, the bioclimatic indices have been measured to perform the patterns of bioclimatology along environmental gradients (Rivas-Martínez et al. 2011;Gopar-Merino et al. 2015). This approach has been mainly applied in Temperate, Mediterranean, and Boreal areas (Malhi et al. 1999;Bobbink et al. 2010;Larrieu et al. 2018), and has been studied with a limited number of examples in Tropical ecosystems (Pieretti et al. 2015;Barlow et al. 2018). Coupling with geographic information systems (GIS), the WBCS allows quick quantification of climatic variables from temperature and precipitation data (Ninyerola et al. 2000(Ninyerola et al. , 2006, which then analyzes bioclimatic patterns and trends as the representation of geo-ecological complexity (Gopar-Merino et al. 2015). ...
Bioclimatic classification is an effective approach to reflect and investigate the role of climate in determining the potential natural vegetation distribution at different temporal and spatial scales. Especially, the diversity of physical features in tropical mountainous regions causes the complexity of phytogeographical belts at large scales. A set of parameters and indices of the Worldwide Bioclimatic Classification System (WBCS) was used to generate a bioclimatic map at a scale of 1:100,000 of the territory of Van Chan district, Vietnam. In this study, due to the lack of observed data, GIS analysis of precipitation and temperature data was conducted by using a simple downscaling method for "WorldClim" resource (1 km spatial resolution) and statistical data of two meteorological stations in 1961-2013 was used for bioclimatic map validation. The resulting map presents 11 isobioclimatic units, which are advantageous for confirming the diagnosis of the bioclimatic features and describing the relationships between climatic variables and the corresponding distributions of natural vegetation. This approach is useful to explain the territorial diversity in environmental applications for the assessment of ecological adaptation, nature conservation, landscape regionalization, and planning.
... Another important role of TOFs is to reverse the effects of land use/land cover change (LULCC) to maintain ecosystem functionality and resilience in landscapes [24]. Microhabitats are an extensive biodiversity stock [25]; studies highlight the importance of these for biodiversity conservation [26] and their vulnerability to external pressures [27]. As aforementioned, TOFs could potentially show a high level of microhabitat presence and perform a function of protection for these elements, and so they should be studied. ...
Trees outside forests (TOFs) are important landscape features that provide numerous functions (ecosystem services) that are not valued due to a lack of knowledge about these resources. The aim of this study was to evaluate the changes induced by the anthropogenic land use change in relation to their effects on TOFs. The dynamics of TOFs were examined through detailed photointerpretation mapping and characterization by land use/land cover and other environmental variables. The landscape function of TOFs and relative dynamics were analyzed, revealing landscape simplification due to the loss of TOFs, both in number and area, and a relative loss of connectivity. In 2000, TOFs accounted for 2.6% more forest area than mapped in the regional forest map; in fifteen years, about 30% of the total area has been lost, one-third of which has been converted to forest and the remainder permanently lost. The causes of the loss of TOFs are partly due to the abandonment of agricultural land, but also to the actions of farmers who remove these elements for various reasons. In protected areas (Natura 2000 network), the loss is less due to the different characteristics of land use/cover and land management.
... Dabei stellen Altersund Zerfallsphasen mit grossen Mengen Totholz (Spies und Franklin 1991;Spies und Turner 1999) in verschiedenen Zersetzungsstadien (Commarmot und Brang 2011) und mit assoziierten Baum-Mikrohabitaten (z. B. Löchern, Spalten, lose Rinde und Epiphyten) essenziellen Lebensraum für eine grosse Anzahl typischer Waldarten dar (Larrieu et al. 2018;Paillet et al. 2017). ...
Die naturnahe Waldwirtschaft schafft zwar vertikal strukturierte Waldbestände, offene Störungsflächen und Strukturen der Alters- und Zerfallsphasen sind jedoch im Vergleich zu Naturwäldern selten. Waldarten, die an solche defizitären Strukturen gebunden sind, sind daher häufig gefährdet. Zur Struktur- und Biodiversitätsförderung im Wald kommen daher unterschiedliche Instrumente zum Einsatz, die gleichzeitig einen Gradienten der forstlichen Nutzungsintensität repräsentieren: von Nicht-Nutzung in grossen Naturwaldreservaten, über die Integration kleiner, unbewirtschafteter Alt- und Totholzinseln in eine bewirtschaftete Waldmatrix, bis hin zur Strukturförderung durch intensive forstliche Eingriffe. Doch welche Artengruppen profitieren wovon? Wie lange dauert es, bis sich die gewünschten Lebensraumstrukturen einstellen? Und kann durch einen kombinierten Einsatz verschiedener, komplementärer Instrumente die Biodiversität auf Landschaftsebene erhöht werden? Im Folgenden werden drei Forschungsprojekte aus Baden-Württemberg vorgestellt, die diese Zusammenhänge beleuchten sollen.
... Bouget et al. (2013) highlighted that the diversity of deadwood forms was a key factor for the diversity of saproxylic beetles (>2600 species in mainland France; Bouget et al., 2019). Larrieu et al. (2014) showed that a patch smaller than 10 ha of long-term unharvested beech-fir forest could not guarantee a diversity of TreMs, whereas each TreM type constitutes the living environment for distinct communities, sometimes strictly associated with a single TreM type (Larrieu et al., 2018). Moreover, several authors recommend (e.g. ...
... Table 2 provides the description and the measuring unit of all the attributes included in the dataset at plot level. It includes parameters used for assessing old-growth forests [6][7][8] , linking them to the main type forests management, in order to both select indicators useful for assessing the conservation degree of forest habitat types, and identify good practices for nature conservation in these ecosystems. Litter cover ( < 2 cm depth) % C_litter2 ...
Forests supply multiple ecosystem services and host a large proportion of the Earth's terrestrial biodiversity. In particular, they provide habitats for many taxonomic groups which can be threatened by forest unsustainable management practices. Type and intensity of forest management are widely recognized as the main drivers of structure and functions in forests ecosystems. However, to better understand the impacts and the benefits deriving from forest management, there is a big need to standardize procedures of field data collection and data analysis. Here, we provide a georeferenced dataset of vertical and horizontal structure of forest types belonging to 4 habitat types, sensu Council Directive 92/43/EEC. The dataset includes structural indicators commonly linked to old-growth forests in Europe, in particular the amount of standing and lying deadwood. We collected data on 32 plots (24 of 225 m2, and 8 of 100 m2, according to different forests type) during spring and summer of 2022, in Val d'Agri (Basilicata, Southern Italy). The dataset we provide follows the common national standard for field data collection in forest habitat types, published by ISPRA in 2016 with the aim to promote a greater homogeneity in assessment of habitat conservation status at Country and biogeographical level, as requested by the Habitats Directive.
... Another important challenge to selection management is to find the balance between improving stand quality and the conservation of biological diversity [12]. Indeed, the defects that are recognized by foresters for having the most impact on tree quality, such as fungal infections, cankers and advance decay [13,14], are also recognized as tree-related microhabitats that are key structural elements supporting forest biodiversity [15]. These distinctive structures are essential substrates for a diversity of species and communities to properly develop and spread [5,16]. ...
Northern hardwoods are susceptible to a wide range of defects that can reduce the amount of sound wood with desirable qualities, such as the clear sapwood of sugar maple trees. Yet, the rate at which trees decline in quality due to the development of such defects has never been quantified in northern hardwood forests due to a dearth of repeat inventories that record the appearance of defects over time. As a result, it remains uncertain whether, and how, selection management reduces the probability of decline in quality. In this study, we quantify the rate at which trees decline in quality due to the development of defects, and we test several hypotheses regarding the influence of selection management on quality. Our results show that (1) the probability of decline in quality increases as trees grow larger; (2) crown dieback also increases the probability of decline in quality; (3) the probability of decline in quality is slightly lower in managed stands than in unmanaged stands, and (4) the probability of decline in quality increases with the mean annual temperature of the site. Finally, we combined our estimates of the probability of decline in quality with previous estimates of the probability of mortality to assess the overall risk associated with retaining trees of different species, sizes, and vigour profiles. The resulting metric can inform efforts to improve the management of northern hardwood forests by providing an integrated estimate of the risk that the value of a tree will be reduced, or eliminated, due to mortality or decline in quality.
... However, the conservation of old forest tracks alone is not sufficient in the context of extensive forestry presently occurring in the Canadian boreal forest. There is also a critical need to adjust forestry practices in managed forest landscapes to increase at the landscape level the amount of old forests by combining the use of longer rotations, partial harvesting under continuous forest cover Gauthier et al., 2009) and in managed clearcut landscapes, enhanced retention through a mesofilter approach (sensu Hunter, 2005) of keystone tree species for a range of tree decay stages (structural heterogeneity generated by tree senescence) for key excavators (Martin et al., 2004;Drapeau et al., 2009b;Drever and Martin, 2010;Edworthy and Martin, 2013) and other dendromicrohabitats that are critical for biodiversity (Larrieu et al., 2018;Martin et al., 2022). ...
Structural complexity generated by forest development processes and tree species compositional changes provide key habitat features for vertebrate communities that rely upon tree size and decay processes for foraging, denning or nesting. Complexity of forest structure in old stands could not only be key for harboring increased taxonomic species diversity but also greater functional diversity through more complexity in networks of tree cavity dependent species. Using a nest web approach that hierarchically links cavity-bearing trees with cavity formation agents (natural decay processes and avian excavators) and cavity users (non-excavator species), we compared network characteristics of nest webs along a time since fire gradient in a naturally disturbed boreal mixedwood forest landscape in eastern North America. Since 2003, twelve 24 to 40 ha plots ranging from 61 to more than 245 years after fire were surveyed at the Lake Duparquet Research and Teaching Forest in Abitibi, Quebec, Canada to detect active nesting, and denning cavities. We found that network complexity both in terms of number of vertebrate species and number of interactions among species, increased along the age gradient and was significantly higher in the older stands than predicted by chance. Whereas cavity-nesting communities in old forests used a higher diversity of tree species over a wide range of decay stages, trembling aspen remained a key cavity-bearing tree throughout the age gradient. Woodpeckers were the main cavity formation agents whereas less than 1% of cavities originated from natural decay. The structural development of older forests is thus a driver for functional diversity in cavity-using vertebrate communities through higher interaction richness in nest webs, among cavity-bearing trees, excavators and non-excavating users. The pivotal contribution of the entire gradient of old forest cover types to the overall complexity of nest webs in the boreal mixedwood zone is also a key for the resilience of the cavity-using vertebrate community to natural disturbances. We discuss how such resilience may be compromised by even-aged industrial timber harvesting with short rotations that shifts the age structure of boreal landscapes toward regenerating and young pole forests whereas old forest cover types become below their historical range of variability.
... For quantifying biodiversity, tree species diversity (using the Shannon index, Shannon, and Weaver 1949) and structural diversity (using the Post Hoc index, Staudhammer and LeMay 2001) were considered in terms of alpha diversity (representing diversity within each stand) and gamma diversity (representing diversity within the forest enterprise, i.e., at the landscape scale). The amount of deadwood (accounting for deadwood accumulation by natural mortality and harvest residue, as well as decomposition) and the number of habitat trees (i.e., trees bearing microhabitats (Larrieu et al. 2018), here assumed as large, old trees with a diameter of > 70 cm) were furthermore considered, due to their importance for various taxonomic groups (Gossner et al. 2013). ...
Unlabelled:
Climate change severely affects mountain forests and their ecosystem services, e.g., by altering disturbance regimes. Increasing timber harvest (INC) via a close-to-nature forestry may offer a mitigation strategy to reduce disturbance predisposition. However, little is known about the efficiency of this strategy at the scale of forest enterprises and potential trade-offs with biodiversity and ecosystem services (BES). We applied a decision support system which accounts for disturbance predisposition and BES indicators to evaluate the effect of different harvest intensities and climate change scenarios on windthrow and bark beetle predisposition in a mountain forest enterprise in Switzerland. Simulations were carried out from 2010 to 2100 under historic climate and climate change scenarios (RCP4.5, RCP8.5). In terms of BES, biodiversity (structural and tree species diversity, deadwood amount) as well as timber production, recreation (visual attractiveness), carbon sequestration, and protection against gravitational hazards (rockfall, avalanche and landslides) were assessed. The INC strategy reduced disturbance predisposition to windthrow and bark beetles. However, the mitigation potential for bark beetle disturbance was relatively small (- 2.4%) compared to the opposite effect of climate change (+ 14% for RCP8.5). Besides, the INC strategy increased the share of broadleaved species and resulted in a synergy with recreation and timber production, and a trade-off with carbon sequestration and protection function. Our approach emphasized the disproportionally higher disturbance predisposition under the RCP8.5 climate change scenario, which may threaten currently unaffected mountain forests. Decision support systems accounting for climate change, disturbance predisposition, and BES can help coping with such complex planning situations.
Supplementary information:
The online version contains supplementary material available at 10.1007/s10113-022-02015-w.
... Vertically structured stands (positive correlations with DBHsd) provide suitable habitat characteristics for insectivorous bat species, which corresponds with results of Jung et al. (2012). Old trees with cavities or bark pockets can be used for resting purposes, which was described by Larrieu et al. (2018), Yoshikura et al. (2011) andMichel et al. (2011). Tree species richness, as well as different types of bark and flowering trees seem not to influence the diversity of bats. ...
Key message
Authors have analyzed the possible correlation between measurements/indicators of forest structure and species richness of many taxonomic or functional groups over three regions of Germany. Results show the potential to use structural attributes as a surrogate for species richness of most of the analyzed taxonomic and functional groups. This information can be transferred to large-scale forest inventories to support biodiversity monitoring.
Context
We are currently facing a dramatic loss in biodiversity worldwide and this initiated many monitoring programs aiming at documenting further trends. However, monitoring species diversity directly is very resource demanding, in particular in highly diverse forest ecosystems.
Aims
We investigated whether variables applied in an index of stand structural diversity, which was developed based on forest attributes assessed in the German National Forest Inventory, can be calibrated against richness of forest-dwelling species within a wide range of taxonomic and functional groups.
Methods
We used information on forest structure and species richness that has been comprehensively assessed on 150 forest plots of the German biodiversity exploratories project, comprising a large range of management intensities in three regions. We tested, whether the forest structure index calculated for these forest plots well correlate with the number of species across 29 taxonomic and functional groups, assuming that the structural attributes applied in the index represent their habitat requirements.
Results
The strength of correlations between the structural variables applied in the index and number of species within taxonomic or functional groups was highly variable. For some groups such as Aves, Formicidae or vascular plants, structural variables had a high explanatory power for species richness across forest types. Species richness in other taxonomic and functional groups (e.g., soil and root-associated fungi) was not explained by individual structural attributes of the index. Results indicate that some taxonomic and functional groups depend on a high structural diversity, whereas others seem to be insensitive to it or even prefer structurally poor stands.
Conclusion
Therefore, combinations of forest stands with different degrees of structural diversity most likely optimize taxonomic diversity at the landscape level. Our results can support biodiversity monitoring through quantification of
... Retention forestry has initially been introduced in clearcutting systems, but is now also applied in continuous cover forestry (Gustafsson et al., 2020). Many retention programs focus on the retention of 'habitat trees' (ForstBW, 2016), i.e. trees that are particularly large, dead or characterized by 'tree-related microhabitats' (Larrieu et al., 2018), or small forest patches which are retained beyond harvesting cycles. A regular distribution of retention elements across the forest matrix aims at providing structures in sufficient quantity and connectivity to support forest-dwelling species with specific structural requirements. ...
Retention forestry, which retains small set-asides within forests managed for timber production and other services , is an important conservation instrument for enhancing structural complexity and biodiversity in multi-functional forests. However, in contrast to local scale effects, its large-scale effectiveness is largely unknown, as this requires area-wide and sufficiently precise information on key structural elements and associated species' habitats. Bats are particularly sensitive to forest structural characteristics and are target organisms of most retention programs. To assess their response to existing retention efforts, we here compared key habitat structures and overall habitat suitability for bats across forest areas with and without retention, using forest type and structure variables derived from remote sensing along with topographic, climatic and land-cover variables in a multi-scale modelling approach. Based on acoustic data from 135 1-hectare plots across the Black Forest, Ger-many, we calibrated region-wide species distribution models for 9 bat species or bat species groups thereby identifying the best-performing scale (50-1000 m radius) for each predictor and species(-group). Among predictors and species(-groups), forest cover and structural variables explained most (44.0 % and 38.3 %) of bat habitat selection, with forest height heterogeneity (16.4 %) and the percentage area with standing dead trees (11.7 %) performing best, mostly at small scales (50-100 m). Forests with retention showed higher values of these key structural variables, resulting in higher predicted habitat suitability for all species(-groups), highlighting positive effects of retention on structural complexity in forests and on species that benefit thereof.
... To assess the diversity of ecological niches on trees, we counted the number of microhabitats on all the trees of the trial area. Tree microhabitats are various dead parts of a tree, abnormal growths of a living part of a tree, fruiting bodies of saproxylic fungi, etc. Tree microhabitats of saproxylobiont insect species were counted and evaluated according to the L. Larrieu's classification (Larrieu et al. 2018). In total, they are represented by 7 types: ...
The paper focuses on the results of the study of beetle communities (Insecta: Coleoptera) in beech forests at the foothills of the Volcanic Carpathians. 4438 specimens of beetles, belonging to 346 species of 58 families have been collected using interception traps (polytraps). The theoretically calculated number of expected species (Chao estimation) is 474. The families of rove beetles (Staphylinidae)-56 species (16.2%), weevils (Curculionidae)-31 species (9%) and minute tree-fungus beetles (Ciidae)-22 species (6.4%) predominate in terms of species richness. Among rove beetles in terms of quantity Mycetoporus longulus (38.7%), Lordithon exoletus (9.5%), Platarea brunea (7.5%), Lordithon lunulatus (5.2%) are eudominants. Among the representatives of the weevil guild Anisandrus dispar (41.9%), Xyleborinus saxesenii (22.5%) and Taphrorychus bicolor (15.2%) are eudominants. Dominants are presented by one species-Ernoporicus fagi (9,2%). Cis fagi (13.4%), C. festivus (10.8%) are eudoninantes among minute tree-fungus beetles. C. micans and Sulcacis nitidus (9.3% each), Ennearthron cornutum (8.1%) and Orthocis alni (7%) represent a group of dominants. The ecological characteristics of the beetle fauna have been in the focus of the author's attention: 6 trophic groups were identified according to the peculiarities of trophic. Sapro-phages predominate on the larval stage-129 species and on the imago stage with the total number of 103 species. Since the feeding of larvae and imago varies, the ratios of trophic groups for larvae and imago is different. However, both stages of development are characterized by the predominance of saprophagous and mycetophagous beetles. 26 categories were identified according to the types of microhabitats. Xylodetriticolous, fungicolous, phytodetriticolous and arboricolous constitute the group of predominant categories on the larval stage. Xylodetriticolous, fungicolous and phytodetriticolous are predominants on the imago stage. 2 groups have been indentified according to ecological valence. 3 groups each have been singled out according to landscape preferences and to the humidity criterion.
Averting climate change‐induced forest diebacks increasingly relies on tree species planted outside of their natural range and on the addition of non‐native tree species to mixed‐species forests. However, the consequences of such changes for associated biodiversity remain poorly understood, especially for the forest canopy as a largely understudied forest stratum. Here, we used flight interception traps and a metabarcoding approach to study the taxonomic and functional (trophic guilds) composition and taxon richness of canopy arthropods. We sampled 15 monospecific and mixed stands of native European beech, native Norway spruce—planted outside its natural range—and non‐native Douglas fir in North‐West Germany. We found that diversity of arthropods was lower in non‐native Douglas fir compared to native beech stands. Taxon richness of herbivores was reduced by both conifer species. Other functional guilds, however, were not affected by stand type. Arthropod composition differed strongly between native broadleaved beech and monospecific coniferous (native spruce or non‐native Douglas fir) stands, with less pronounced differences between the native and non‐native conifers. Beech‐conifer mixtures consistently hosted intermediate arthropod diversity and community composition compared to the respective monospecific stands. Moreover, arthropod diversity had a positive relationship with the number of canopy microhabitats. Our study shows that considering arthropod taxa of multiple functional groups reveals the multifaceted impact of non‐native tree species on forest canopy arthropod communities. Contrasting to previous studies that primarily focused on the forest floor, we found that native beech hosts a rich diversity of arthropods, compared to lower diversity and distinct communities in economically attractive, and especially in non‐native, conifers with few canopy microhabitats. Broadleaf‐conifer mixtures did not perform better than native beech stands, but mitigated negative effects of conifers—making such mixtures a compromise to foster both forest‐associated diversity and economic yield.
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As we contemplate the future of forest landscapes under changing climate conditions and land‐use demands, there is increasing value in studying historic forest conditions and how these landscapes have changed following past disturbances. Historic landscape paintings are a potential source of data on preindustrial forests with highly detailed, full‐color depictions of overstory and understory environments. They display key details about forest community composition, microhabitat features, and structural complexity from a time well before the advent of color photography. Despite these paintings' potential, their scientific applications have been impeded by questions of validity. How truly accurate are the images portrayed in these paintings? How much of an image is an artist's manipulation of a scene to best illustrate an allegory or romanticized view of nature? Following an established assessment model from historical ecology for evaluating resource validity, we demonstrate how scholarship on art history can be integrated with ecological understanding of forest landscapes to follow this model and address these questions of image veracity in 19th century American art. Further, to illustrate the potential use of these historic images in ecological studies, we present in a case study assessing microhabitat features of 10 different paintings. While this paper explores 19th century landscape art broadly, we focus our art historical review in particular on Asher Durand, a prolific and influential artist associated with the so‐called “Hudson River School” in the mid‐1800s. Durand left clear records about his perspectives on accurately depicting nature, and from a review of images and writings of Durand, we find support for the potential use of many of his paintings and sketches in historic forest ecology research. However, we also identify important caveats regarding potential ecological interpretations from these images. More broadly, because 19th century landscape paintings are not always directly transcriptive, and because regional art cultures differed in the 1800s, we cannot within this paper speak about landscape image veracity across all 19th century landscape art. However, in following established methods in historical ecology and integrating tools from art history research, we show that one can identify accurate historic landscape paintings for application in scientific studies.
Forest decline caused by climate change has been a growing challenge for European foresters for decades. The accumulation of tree-related microhabitats (TreMs) and deadwood during decline can enhance stand structural heterogeneity and provide crucial habitat features for many forest ecological guilds. We analysed changes in deadwood and TreM assemblages using a trait-based approach in three case studies: drought-induced decline in highland Pyrenean fir and lowland oak forests, and windstorm/pest-induced dieback in highland Bavarian spruce forests. Decline caused significant changes in deadwood and TreM characteristics and composition in three forest contexts. However, tree density with cavities, exudates, or crown deadwood was not linked to decline intensity. Declining conifer forests had more large deadwood and downed woody debris, and their TreM assemblages were more saproxylic, less epixylic, and included more cracks and exposed sapwood. TreM assemblages in drought-declining forests had higher diversity, functional richness, and more dead tops than healthy stands. In Bavarian spruce forests, there was more decayed downed deadwood, and the TreM assemblages were more associated with the base of the tree, snags, and logs. Overall, forest decline significantly boosts ecological niche resources, typically scarce in managed forests, which could benefit many forest biodiversity groups. Though post-disturbance management should respect tree species-dependent economic balance and avoid phytosanitary risks, it should also consider the ecological benefits of decline-induced heterogeneity.
Graphical Abstract
A diversity of microhabitats has been suggested to play a key role in mediating the co-occurrence of trees with specific tree-inhabiting biodiversity, which may further influence ecosystem functioning. However, this triple relationship between tree characteristics, tree-related microhabitats (TreMs), and biodiversity has not been described explicitly enough to set quantitative targets of ecosystem management. The two major approaches directly targeting TreMs in ecosystem management are tree-scale field assessment of TreMs and precautionary management, which both require insights into the predictability and magnitude of specific biodiversity-TreM relationships. To obtain such insights, we analysed tree-scale relationships between the diversity of TreM development processes (four classes: peculiarity; pathology; injury; emergent epiphyte cover) and selected biodiversity variables based on 241 live trees (age range 20-188 years) of two species (Picea abies, Populus tremula) in hemiboreal forests in Estonia. We addressed the diversity and abundance of epiphytes, arthropods, and gastropods; their specific response to TreMs was disentangled from tree age and tree size effects. We found that a relatively small improvement in the biodiversity responses studied was attributable solely to TreMs, and that such contribution was more frequently observed in young trees. Unexpectedly, several age- or size-independent effects of TreMs were negative, suggesting trade-offs with other factors of biodiversity relevance (such as tree foliage suppression due to injuries that created TreMs). We conclude that tree-scale microhabitat inventories have only limited potential to resolve the general problem of providing diverse habitats for biodiversity in managed forests. The basic sources of uncertainty are that microhabitat management is mostly indirect (managing TreM-bearing trees and stands rather than TreMs themselves) and that snapshot surveys cannot address various time perspectives. We outline a set of basic principles and constraints for spatially heterogeneous and precautionary forest management that includes TreM diversity considerations. These principles can be further elaborated through multi-scale research on functional biodiversity links of TreMs.
Intensifying forest management and a reduction in the rotation period necessitates the development of intensive biodiversity conservation strategies, such as the triad concept, which aims at ensuring habitat connectivity. Such an approach depends on the relationships between biodiversity components and manageable stand characteristics. Mostly, the biological value of stands has been associated with age, although stand structures, which are often intercorrelated with age, might be of primary importance. The relationships between ground cover vegetation, which is a principal component and indicator of the biological value of temperate conifer forests, and stand characteristics were assessed in pre-harvesting/harvesting age and old-growth coniferous stands in the eastern Baltic region (Latvia). The old-growth stands were nearly two times older than the pre-harvesting/harvesting age stands. Both stand groups showed generally similar ground cover flora, though ground cover vegetation showed higher variability in the old-growth stands. The principal gradients of ground cover vegetation were related to light, site fertility, and structural diversity, as well as the degree of deciduous (particularly Betula spp.) admixture in a tree stand. Considering the explicit contrasts, stand age did not affect ground cover vegetation, implying the principal effects of stand structure, which are manageable characteristics. This implies the potential for specific management to aid the ecological connectivity of stands in commercial forest landscapes.
Beetles are one of the most diverse and often highly specialized groups among saproxylic organisms and play a key role in forest dynamics. To develop conservation plans in forests threatened by human activities, such as construction sites, it is crucial to identify key parameters characterizing forest structure in turn influencing saproxylic beetle diversity and abundance. Here, we investigate the difference in forest structure parameters and their cascading effect on saproxylic beetle communities between a forest site affected by the construction site expansion of the Turin–Lyon High-Speed Railway Line and a nearby second forest site. Our study showed differences in forest structure parameters between the two sites, in particular in the overall volume and diameter of coarse woody debris and in standing dead tree abundance. Even saproxylic beetle community structure was different between the two sites and this difference was linked to the different abundance and species richness of standing dead trees. Our findings provide information for the development of a local conservation plan for the saproxylic beetle community within forest habitats. Increasing the volume of deadwood and enriching tree diversity can locally sustain abundant and diverse communities and, eventually, support those species that are threatened by the building site expansion.
Assessing the impacts of natural disturbance on the functioning of complex forest systems are imperative in the context of global change. The unprecedented rate of contemporary species extirpations, coupled with widely held expectations that future disturbance intensity will increase with warming, highlights a need to better understand how natural processes structure habitat availability in forest ecosystems. Standardised typologies of tree-related microhabitats (TreMs) have been developed to facilitate assessments of resource availability for multiple taxa. However, natural disturbance effects on TreM diversity have never been assessed. We amassed a comprehensive dataset of TreM occurrences and a concomitant 300-year disturbance history reconstruction that spanned large environmental gradients in temperate primary forests. We used nonlinear analyses to quantify relations between past disturbance parameters and contemporary patterns of TreM occurrence. Our results reveal that natural forest dynamics, characterised
The bee-mimicking hoverfly species Criorhina pachymera shows pronounced geographical variation in abdominal colour pattern. Based on 218 records from 22 European countries, we describe six abdomen forms divided over two main groups. Group A in western, northern and central parts of Europe contains abdomen forms A1–A3 with slender pollinose bands on the third and fourth tergite. Group B in south-eastern Europe contains forms B1–B3 with broad pollinose bands. These groups are separated by the Alps and the Carpathians, such as the separation of the original distributions of the two main postglacial recolonization lineages of honey bees in Europe. As these honey bee groups differ by the width of the pollinose bands on the third to fifth tergite, Batesian mimicry can explain the group distribution of C. pachymera with slender or broad pollinose bands. The different forms of C. pachymera in both groups are categorised by the extent of orange colouration on the second and third tergite. The darkest form A1, has a widespread distribution in Europe. Intermediate bright forms A2 and A3 occur predominantly in a belt along the southern margin of the group A distribution and in Sweden. Dark form B1 and intermediate bright form B2 occur on the Balkan peninsula and in neighbouring regions. The brightest form B3, is found in Italy, Switzerland (Ticino) and Greece. There is an average increase in the extent of orange colouration on the second and third tergite with decreasing geographical latitude, making temperature a likely additional cause for the described abdominal colour variation.
The global biodiversity crisis is, along with climate change, the greatest challenge facing mankind. To ensure the long-term protection of biodiversity, conservation objectives must be agreed upon by all stakeholders, defined in concepts, and appropriate actions taken. This involves considering the often contrasting needs of nature and people and examining ethical-moral issues about the value of nature as well as different approaches to nature conservation. In this thesis, conservation objectives and values in German forest conservation concepts, considering ecological, political and social aspects are analysed in an interdisciplinary approach. The present state of forest conservation in Germany is discussed and current and future challenges are described. Based on this assessment of needs new methods for the classification of conservation objectives and for the assessment of forest conservation objects are presented and possible changes in conservation responsibility in view of climate change are proposed. Forests support a significant proportion of global biodiversity and provide essential ecosystem services, and their long-term conservation and sustainable use is becoming more important than ever in the face of climate change. Due to the diverse demands for conservation and use, a consensus on the objectives is necessary in forest conservation. Only a transparent system based on consistent objectives and measures is likely to be sufficiently accepted and implemented. Therefore, a hierarchical framework for the classification of nature conservation objectives was developed in Chapter 2 of this thesis. Within higher-level target areas, desired target properties were assigned to conservation objects, which are to be achieved through certain measures. Using this framework, the contents of biodiversity and forest conservation concepts were examined for commonalities and differences. A broad consensus on conservation objectives was found in the concepts across different stakeholder groups and spatial scales, with the conservation of species, ecosystems and structures in forests rated as particularly important. Deficits were identified with regard to genetic diversity, abiotic resources and social-cultural objectives, as well as a mismatch in the transfer of knowledge. The reasons for these inconsistencies in forest conservation include conflicting objectives, lack of coordination across scales and inadequate implementation of objectives. In private forests, which make up half of the German forest area, the implementation of nature conservation measures is a particular challenge. Private forest owners often have reservations about sovereign nature conservation regulations and are less willing to participate due to the financial expenses involved. In order to ensure higher acceptance, forest conservation measures should be financially compensated. However, the contractual agreement of nature conservation services and financial remuneration (= contract-based nature conservation) has so far found limited application in private forests. Since the successful implementation of contract-based forest conservation requires a system of reasonable measures, the conservation objects identified in Chapter 2 (forest habitat types, structures and processes in forests) were assigned a conservation value in Chapter 3 on the basis of the need for, and the worthiness of, protection. Oak and mixed oak forests, dry-warm beech forests, historical forms of forest use (coppice forests or wood pastures) and natural structures such as deadwood (deciduous tree species, standing and lying) or habitat trees have a high nature conservation value. Based on the initial value and the expected value development, it was assessed whether conservation or restoration measures within the framework of contract-based forest conservation with varying durations are suitable. Contract-based forest conservation is particularly suitable for conservation objects with a high initial value if a loss of value can be avoided and if a high increase in value can be expected. It is not suitable for low initial values and a low restoration potential. With this framework, private forest owners can easily assess which nature conservation measures are suitable in their forest, increasing the likelihood that they will apply contract-based forest conservation in the future. Climate change and its predicted effects in terms of intensity and frequency of disturbances require an adaptation of silvicultural management. In Germany, silvicultural planning tools such as forest development types are often only related to the economic productivity function, while nature conservation demands are given little consideration. Therefore, the framework developed in Chapter 3 for the conservation value assessment of forest habitat types was adapted in Chapter 4 to the economically relevant tree species (beech, oak, pine, spruce, fir, Douglas-fir and larch) and further developed for application in forest stands according to the potential natural vegetation of the location. With the new framework, the nature conservation impacts of silvicultural planning and future tree species composition in forest stands can be spatially-explicitly assessed. Certain silvicultural combinations of tree species can lead to a reduction in the initial nature conservation value, which is determined by the forest habitat type naturally occurring there. The highest nature conservation value can be achieved if the planned tree species are both autochthonous and a natural component of the respective forest habitat type. The framework was trialled to assess planned forest development types using a Germany-wide transect. In most cases, the forest development type combinations led to a reduction of the initial nature conservation value, as the restricted tree species selection of the forest development types did not correspond to the diverse species composition of the natural forest habitat types. With this evaluation framework, forest planning can also be assessed in terms of nature conservation and be adapted to a tree species composition that is as close to nature and site-specific as possible. The uncertainties of climate change and the associated changes in environmental conditions also pose new challenges for nature conservation and may require an adaptation of the conservation objectives and justifications. Chapter 5 therefore investigated whether the favourable conservation status of forest habitat types of the Habitats Directive remains a well-founded objective when confronted with climate change. In this context, both the question of the conservation justification and an assessment of the future development trend of the conservation status of forest habitat types of the Habitats Directive were addressed. It was shown that current niche and species distribution models of habitat types and tree species indicate that a climate change-induced increase in drought can lead to losses in area of forest habitat types such as the subalpine sycamore-beech forest and the montane-alpine soil-acid spruce forest. In the case of bog woodland and alluvial forests, successful restoration should be the first priority before future development can be assessed. Forest habitat types on secondary sites, such as mixed oak forests, will probably continue to require active management measures to restore and secure a favourable conservation status in the long term. The distribution models for beech forest habitat types showed increasing uncertainty regarding future distribution, and for the most part no significant negative change could be identified, even under climate change. Flexibilisation and adaptation of conservation objectives should therefore only take place on the basis of evidence and within the framework of adaptive management. Overall, no clear indications is found to abandon the favourable conservation status of forest habitat types under climate change as a well-founded objective of nature conservation. This thesis discusses the importance of forest conservation concepts in today’s world and the difficulties that can arise in the classification and implementation of forest conservation objectives. Furthermore, the challenges that may arise in the conservation value assessment of conservation objects and tree species as well as in future implementation of forest conservation measures are identified. It was found that the systematic analysis of conservation objectives has gained importance in conservation research and that there is a broad consensus on the objectives of forest conservation in Germany. Nevertheless, there is a considerable need for more specification, especially with regard to the implementation of contract-based nature conservation in private forests. The frameworks presented for the derivation of nature conservation values can be helpful in turning abstract properties such as nature conservation values into a simplified and comprehensible system. Forestry and nature conservation stakeholders can thus be sensitised to the conservation value of forest biodiversity. In order to reduce existing prejudices between stakeholders, it is also necessary to further revise the funding system in Germany with regard to its financial scope and the effectiveness of conservation measures, and to provide practical recommendations for action based on scientific findings. This thesis underlines that a constant adaptation of forest management strategies is necessary for forest conservation and silviculture to cope with the challenges of climate change. For forests to maintain their diverse functions and ecosystem services in the future, semi-natural, species-rich resilient mixed forests composed of predominantly native tree species should be favoured and the existing objectives in nature conservation should not be abandoned without reason. Only in this way can forest conservation in Germany and also worldwide be successful in the long term.
This paper introduces the importance of veteran trees, tree related microhabitats (TreMs) and their associated hoverfly (Diptera, Syrphidae) fauna. A broader perspective of creating larval habitat is discussed, based on published and novel insights. It focuses on hoverflies that specialise on veteran trees and reflects upon protection and management regimes to conserve veteran trees, TreMs and associated woody habitats. The lack of veteran trees breeding sites can be resolved by tree veteranisation or by using artificial breeding boxes. Whilst protection of veteran trees is essential, enhancement of open areas with flower resources is also vitally important for the survival of saproxylic hoverflies. The larval and adult ecology of only three out of the 134 known European saproxylic species are properly understood. Thus several suggestions are offered for future research aimed at a thorough understanding of the natural history of this unknown and ecologically relevant group of species. The list includes faunistic surveys and investigations into population dynamics, dispersal capacity and habitat preferences. Alongside this research there is a need to investigate the creation of breeding sites including veteranisation techniques and the use of breeding boxes.
Weltweit wird ein Rückgang der Biodiversität beobachtet und es wird erwartet, dass dieser im Zuge der Klimaveränderung noch weiter fortschreitet. Grosse Waldschutzgebiete sind ein wichtiges Element für den Schutz der Biodiversität. Im Klimawandel ist mit einer Zunahme an Extremereignissen wie Stürmen, Insektenmassenvermehrungen und Trockenheit zu rechnen. Dieses überregionale Phänomen wird sowohl Schutzgebiete als auch bewirtschaftete Landschaften betreffen, möglicherweise aber nicht im gleichen Ausmass. Extremereignisse könnten sich negativ auf die Biodiversität auswirken oder aber auch Chancen für den Biodiversitätsschutz bieten. Dies erfordert eine neue Diskussion über die Wirksamkeit verschiedener Strategien zum Schutz von Biodiversität und damit verbundenen Ökosystemfunktionen. Hier diskutieren wir die Chancen und Grenzen grosser Waldschutzgebiete für den Biodiversitätsschutz in Mitteleuropa unter den vom globalen Wandel neu gesetzten Rahmenbedingungen im Lichte ökologischer Prinzipien und neuer Forschungsergebnisse.
Natural disturbances are an integral part of forest ecosystems. They ensure the creation of new habitats, maintain high spatial heterogeneity and disrupt the ecological succession processes. Forest ecosystems in a particular region are historically adapted to the disturbance complexes affecting that region (i.e. the disturbance regime). They are also largely affected by so-called anthropogenic disturbances (e.g. logging). The process of progressive tree death due to these different disturbances is called "forest dieback". Generally, these diebacks are followed by salvage or sanitation logging to harvest the commercial value of the trees before they deteriorate or to contain future pest outbreaks. This logging is considered to be additional disturbance. However, ongoing changes in climate and land use are leading to changes in the regime of these disturbances. In the extreme, if the change in these regimes is too great, it can lead to a shift towards a non-forest ecosystem. These regime shifts could then result in regional extinctions of forest species and alter the ecosystem services provided by forests to human societies. The study of these forest diebacks is therefore of central importance. In this thesis, we focus on the response of saproxylic beetles (i.e. beetles linked for part or all of their life cycle to dead wood), an ecological group threatened in temperate managed forests due to the scarcity of the dead wood resource. We also analyse habitat changes caused by these diebacks (i.e. disturbance legacies). For this purpose, we study three case studies of European dieback: (i) Pyrenean fir (Abies alba) and (ii) Loire Valley oak (Quercus spp.) caused by droughts, and (iii) Bavarian spruce (Picea abies) caused by storms and Ips typographus} outbreaks. On each of these sites, we inventoried the dead wood and tree-related microhabitats present on the plots as well as saproxylic beetles. These surveys revealed significant changes in habitats, resulting in increases in dead wood and changes in tree-related microhabitat composition. These changes appeared to be modulated by the severity of dieback. In cascade, these habitat changes induced modifications in the local composition of saproxylic beetles. For both coniferous forests, habitat changes induced positive effects of dieback on local beetle diversity, both taxonomic and functional. Furthermore, we observed homogenisations of saproxylic beetle communities in the landscape due to dieback. Furthermore, we highlighted the importance of dieback at the landscape scale on local taxonomic, functional and phylogenetic assemblages of saproxylic beetles. We also show that functional and phylogenetic diversity were mostly driven by landscape processes. Finally, we noted that sanitary and salvage logging did not affect local beetle diversity but strongly altered their ecological relationships. Our results highlight the value that can be gained from declining areas for the conservation of otherwise threatened species groups in managed forest areas, by maintaining the habitats created (i.e. dead wood and tree-related microhabitats). Finally, they highlight the need to consider the maintenance of these declining areas on a landscape scale.
Habitat trees are defined as standing live or dead trees providing ecological niches (microhabitats) such as cavities, bark pockets, large dead branches, cracks or trunk rot. They are of prime concern for forest biodiversity as they can harbor many threatened species of flora and fauna. Habitat trees are a legacy of the past and are of exceptional importance given the hundreds of years such a tree might need to reach this status. The retention of habitat trees with a suitable distribution in the landscape is a challenge for forest management, because these trees generally do not match with forestry economic schemes and are sometimes thought to represent a potential danger for forest workers and visitors. Furthermore, the future of many habitat trees (and their microhabitats) will be highly dependent on changing forest policies for forest bioenergy purposes in many parts of Europe. If no conservation strategies are established, energy wood harvesting will lead to a strong decrease of habitat trees in managed forests, as quite all trees, even dead, can be harvested for this goal. Consequently, setting up a strategy of deliberate retention of habitat trees requires a shift in management objectives and practices towards encouraging the development of old-growth structures. At the stand level, at least 5 to 10 habitat trees per hectare should be retained in harvested stands to mitigate the effects of harvesting. Therefore, it would be of prime concern to establish harmonized measures relating to habitat trees and their microhabitats which could be adopted as biodiversity indicators in European forests.
International conventions and resolutions on biological diversity, sustainable forest management and climate change have led in recent decades to an increasing interest in having reference values from forests undisturbed by man. An outstanding example of such an undisturbed forest is the primeval forest of Uholka-Shyrokyi Luh within the Carpathian Biosphere Reserve (Ukraine). It is approximately 9000 ha (90 km2) in area and is thought to be the largest primeval forest of almost pure European beech (Fagus sylvatica L.). In 2010, the Swiss Federal Institute for Forest, Snow and Landscape Research WSL, the Ukrainian National Forestry University UNFU and the Carpathian Biosphere Reserve CBR carried out a sampling inventory of the Uholka-Shyrokyi Luh forest (survey perimeter 10?282 ha) to obtain representative data for the main forest parameters. Given the remoteness of the area, long walking distances and difficult terrain, careful planning and organisation were required, as well as the logistic support of the local forest service. The field work was carried out by six mixed teams of Swiss and Ukrainian students and scientists, guided by three survey leaders from Switzerland and Ukraine. Two teams together shared a leader and a cook, and lived in decentralized camps, which were moved every week to minimize the walking needed to reach the sample plots. The collaboration between the Ukrainians and Swiss worked very well and was enriching for both sides. During the two-month sampling period, the teams assessed 314 sample plots laid out on a systematic grid. All living and standing dead trees = 6 cm DBH (diameter at 1.3 m above ground) within the 500 m2 circle plots were measured and assessed for features relevant for biodiversity. Lying deadwood was assessed with line-intersect sampling (3 lines each 15 m long per plot), and small trees (= 10 cm height and < 6 cm DBH) were surveyed on subplots consisting of three concentric circles 5, 10 and 20 m2 in area. The stand structure and any traces of anthropogenic use were assessed on a circular interpretation area of 2500 m2 around the sample plot centre. The primeval forest of Uholka-Shyrokyi Luh shows all the typical features of an old-growth forest shaped by small-scale disturbances. The structure was mainly three-layered, and most of the gaps encountered were not larger than the crown of a canopy tree. The growing stock per ha was 582 (± 14) m3 (mean ± standard error) and the deadwood volume 163 (± 8) m3. The ratio of standing to lying deadwood was 1:?5. The maximum DBH measured was 150 cm, and 10 trees per ha had a DBH of at least 80 cm. The density of habitat trees, i.e. living trees with features such as cracks, holes, bark damage or similar that provide microhabitats, was 150 (± 8) per ha (35?% of the living trees). Of all the trees recorded, 97?% were beech, although 14 other tree species were identified. All species found in the tree population = 6 cm DBH were also present in the regeneration. Traces of human presence were encountered on 19?% of the assessed plots (interpretation areas), mainly in the buffer and regulated protection zone of the protected massif. Most of these traces do not affect the integrity and pristine character of the forest. Nevertheless, they imply a certain pressure exerted from the nearby settlements and from the mountain pastures. The data obtained provide good reference values for old-growth beech forests and a valuable basis for more detailed analyses and comparisons with other old-growth and managed forests. The inventory was carried out and documented in a replicable way, and can thus be repeated if desired. The plots may also be used for other non-destructive studies, e.g. on fungi.
European forest managers are implementing set-aside measures in managed forests to restore key structures for forest biodiversity such as tree-related microhabitats (TreMs). However, the time required to regenerate these structures is little known. We assessed the patterns of thirteen TreM types on 282 plots in 24 lowland forests in southwestern France. We applied a synchronic sequence ranging from 1 to 80 years after the last harvest, a time frame which is considered long enough to observe significant changes in the TreM profile. We sampled lowland beech–oak coppice-with-standards stands representative of the different forest ownerships and management regimes occurring in France; our assessment included both public and private forests with or without formal management plans. We found that both TreM density and diversity just after harvesting were lower, though not significantly so, in private stands without any management plan than in the other management regimes. We observed both significantly higher TreM density and diversity in plots harvested 10–15 years ago than in plots harvested 1–5 years ago. The next marked difference did not occur until stands had been harvested 70–80 years ago. Globally, time since last harvest was the best explanatory variable for variations in both TreM density and diversity. We therefore recommend: (1) conserving more habitat trees in harvested areas, particularly cavity trees, since the densities we observed were much lower than the densities required by cavity-dwelling species, and (2) letting set-aside patches freely complete several full silvigenetic cycles. This latter practice would avoid the inefficacy (or possibly even negative effects) of a temporary conservation network, and would also simplify management of the network over time. Further research should assess TreM occurrences in a permanent reserve network. Diachronic observations would make it possible to highlight the drivers of TreM profile development.
We present an aerial robotic platform for remote tree cavity inspection, based on a hexacopter Micro-Aerial vehicle (MAV) equipped with a dexterous manipulator. The goal is to make the inspection process safer and more efficient and facilitate data collection about tree cavities, which are important for the conservation of biodiversity in forest ecosystems. This work focuses on two key enabling technologies, namely a vision-based cavity detection system and strategies for high level control of the MAV and manipulator. The results of both simulation and real-world experiments are discussed at the end of the paper and demonstrate the effectiveness of our approach.
Large quantities of deadwood and a high density of old microhabitat-bearing trees are characteristic elements of natural forests, especially of the old-growth phases. These are often absent or rare in managed forests, even in forests under close-to-nature management. Yet, an important share of forest biodiversity is strictly or primarily dependent on such elements for their survival, especially ‘saproxylic’ species, those are species depending on deadwood.
Tree related microhabitats are therefore recognised as important substrates and structures for biodiversity in forests. The retention of both existing and future tree microhabitats is thus one important aspect to take in to consideration in forest management. Giving tree microhabitats increased attention will help sustain and increase the habitat value for biodiversity also in managed forests .
This reference field list is developed to support training exercises conducted in Integrate+ Marteloscope sites. It aims at supporting forest managers, inventory personnel and other groups in identifying and describing tree microhabitats in the course of such exercises. It can also find use as illustrative material in forest education and as background documentation for other training events and field excursions.
Traditionally the purpose of National Forest Inventories (NFIs) has been to provide continuously updated information regarding the state of a given nation's forest resources, including their timber volumes, species composition and sustainable development. But with increased international reporting requirements - to the FAO, the ITTO, the UN's Framework Convention on Climate Change, the Ministerial Conference Protecting Forest in Europe and other international bodies - the potential role of how NFIs can accurately respond to these requirements has received some considerable attention. Addressing the issue of how well countries are able to respond to current international reporting requirements, this book discusses the importance of comparable reporting, and the possible approaches for achieving comparability across Europe and globally. It includes country status reports from 37 countries, worldwide, and it discusses methodologies and techniques for a common reporting system. With its collection of inventories and detailed discussions on the current status and future needs of NFIs, this book provides an invaluable resource for anyone involved in developing, managing, monitoring or contributing to forest inventories, as well as to those who are researching or practising forest resource management.
Context
Hoverflies are often used as bio-indicators for ecosystem conservation, but only few studies have actually investigated the key factors explaining their richness in woodlands.
Objectives
In a fragmented landscape in southwest France, we investigated the joint effects of woodland area, structural heterogeneity, connectivity and history on the species richness of forest-specialist hoverflies, and whether there was a time lag in the response of hoverflies to habitat changes, and tested the effect of spatiotemporal changes.
Methods
Current species richness was sampled in 48 woodlands using 99 Malaise traps. Structural variables were derived from a rapid habitat assessment protocol. Old maps and aerial photographs were used to extract past and present spatial patterns of the woodlands since 1850. Relationships between species richness and explanatory variables were explored using generalized linear models.
Results
We show that current habitat area, connectivity, historical continuity and the average density of tree-microhabitats explained 35 % of variation in species richness. Species richness was affected differently by changes in patch area between 1979 and 2010, depending on woodland connectivity. In isolated woodlands, extinction debt and colonization credit were revealed, showing that even several decades are not sufficient for hoverflies to adapt to landscape-scale habitat conditions.
Conclusions
These findings emphasise the importance of maintaining connectedness between woodlands, which facilitates the dispersion in a changing landscape. Our results also highlight the benefits of using a change-oriented approach to explain the current distribution patterns of species, especially when several spatial processes act jointly.
Beech forests previously covered substantial areas of the continental region of Europe, however, their current distribution is limited to a small percentage of their former yet still potential range. Many beech forests are now protected under the European Union-wide conservation approach of Natura 2000. We analyse the impact of Natura 2000 on the management of beech forests via social science data on management practices gathered from 73 interviews with local stakeholders within nine case study sites in Austria, France, and Germany, and via an ecological analysis of Natura 2000 management plans (MPs). Our data reveals that the Natura 2000 implementation has had little impact on forest management practices. We found that the Natura 2000 network is well known amongst stakeholders, yet the objectives and measures for beech forest protection are usually vaguely defined in the MPs. According to our interviewees, in many cases this vagueness results in a disregard for the MPs, which hence fail to guide the management of the forests protected under Natura 2000. In addition, when ecological thresholds are included in the MPs, they are often below recommendations based on conservation research. In the case of the structural bio-indicator deadwood, the thresholds given by MPs for a favourable site conservation status were significantly lower than those considered within conservation science to be necessary in order to conserve typical beech forest biodiversity. We conclude that while Natura 2000 has raised awareness of the importance of European beech forests for biodiversity conservation, it needs significant additional efforts to make it an effective policy for forest biodiversity conservation.
Hoverflies (Diptera: Syrphidae) provide crucial ecological services and are increasingly used as bioindicators in environmental assessment studies. Information is available for a wide range of life history traits at the species level for most Syrphidae but little is recorded about the environmental requirements of forest hoverflies at the stand scale. The aim of this study was to explore whether the structural heterogeneity of a stand influences species richness or abundance of hoverflies in a montane beech-fir forest. We used the
catches of Malaise traps set in 2004 and 2007 in three stands in the French Pyrenees, selected to represent a wide range of structural heterogeneity in terms of their vertical structure, tree diversity, deadwood and tree-microhabitats. We assessed hoverfly assemblages by recording species richness, abundance and functional diversity. Malaise traps caught 2,374 hoverflies belonging to 104 species. The catches of hoverflies fluctuated both in species richness and abundance between 2004 and 2007. Strictly forest species were only
caught in the most heterogeneous stand. Species strictly associated with fir were not recorded in the least heterogeneous stand although fir was present. Although most of the functional groups were recorded in the three stands, species richness, abundance and functional diversity decreased dramatically from the most heterogeneous to the least heterogeneous stand. However, the species assemblages in the less heterogeneous stands were not perfect subsets of that in the most heterogeneous stand, as some additional species not found in the most heterogeneous stand were also present.
The Violet Click Beetles - Limoniscus violaceus (Müller, 1821) – is a coleopteran species living within wood mould of hollow trees. Endangered in Europe, it is included in Annex II of the “Habitats” directive that aims to ensure the preservation of habitats and species of Community interest throug the Natura 2000 network. Managers of this kind of area must consequently guarantee the favorable conservation status of the species. However, difficulties for detecting the species have limited the accumulation of knowledge about its biology and its ecology. This weakness has motivated this doctoral thesis. First, all data relative to the species’ distribution are compiled. 184 localities in 17 countries are given. Several discordances with Natura 2000 data are highlighted. A survey method using emergence traps is developed and tested in 5 French Natura 2000 areas. A predictive model of the presence of Limoniscus violaceus based on two factors easy to handle (the degree of hollowing of the cavity and the circumference at 30 cm height) is identified. The study of
these factors’ thresholds and their confidence intervals leads to a decision rule for the assessment of habitats favorable to Limoniscus violaceus. Meanwhile, analysis of the composition of assemblages of species sampled result to the determination of 231 saproxylic beetles. Preservation of cavities favorable for Limoniscus violaceus appears beneficial for the majority of them, justifying it potentially being an umbrella species. For further prospection, a list of indicator species is identified. It helps to prioritize areas where
monitoring of hollow trees and Limoniscus violaceus should be considered. Study of the dispersal from results of emergence traps crossed with bibliographic knowledge suggests that average population size is around 10 adults with 3 individuals dispersing per cavity each year. Sex-Ratio analysis gives complementary information about the functioning of the species populations. Finally, a case study of conservation strategy in the Forest of Grésigne is presented. To ensure the recruitment of trees that will guarantee the long term persistence of the species, management guidelines are given, based on the current forest management plan and on the results of a study on the origin of cavities.
Process-orientated, unmanaged forest remnants are not sufficient for halting the loss of forest biodiversity. Thus, integrated biodiversity-promoting management for forest inhabitants is needed. Microhabitats, such as tree cavities or bark pockets, are essential for the preservation of saproxylic species and of critical importance for endangered ones. This study investigates (1) which factors trigger the formation of microhabitats at both the individual tree and aggregated plot level, and (2) whether the co-occurrence of microhabitats differs between managed (=logged) and unmanaged forests. Relationships between the occurrence of 17 microhabitat types and individual tree features (e.g. light availability, and tree vitality) and plot characteristics (e.g. stand density index and stand age) in 398 plots dominated by Fagus sylvatica or Pseudotsuga menziesii in Germany and the USA were studied using random-effects logistic and normal regression modelling. Separate analyses were performed for German beech forests, German Douglas-fir forests, and the US Douglas-fir forests. Our results show that (1) tree diameter in breast height (DBH), tree vitality and branchiness or epicormic branches are highly related with the occurrence of one or more microhabitats on individual trees in managed and unmanaged beech and US Douglas-fir forests. In managed German Douglas-fir forests, vitality is not a predictor for the occurrence of microhabitats on a tree, but tree density and the maximum age of trees in a stand in addition to DBH and branchiness have an effect. Time since last management is not a statistically significant predictor for the presence of microhabitats at the tree level, but it is for German beech at the plot level. In Douglas-fir-dominated forests both in Germany and in the USA, the stand density index was the only common predictor at the plot level. (2) Unmanaged German beech and Douglas-fir forests exhibit more statistically significant and positive correlations with microhabitat groups than managed stands, implying that the presence of one microhabitat group on a tree is associated with the presence of other microhabitat groups. We finally conclude that measures for supporting microhabitat inhabitants in managed forests are scale and species dependent (tree versus plot level; beech versus Douglas-fir-dominated forests). Trees that carry microhabitats seem to have similar features independently of forest management. At the plot level, density management may trigger the accumulation of microhabitats. Our results indicate that in forest management, it is possible to consider the factors influencing the formation of microhabitats and implement adequate forest practices to advance their formation.
Forests without harvesting: an opportunity for the saproxylic biodiversity Veteran trees and deadwood are key elements to maintain forest biodiversity. Setting aside protected forest ar-eas and old-growth patches is a recent concept intended to favor deadwood dependent species. We compared forest areas where no harvesting occurred for at least 30 years with regularly managed forests, in order to as-sess the efficiency of such conservation measures. We collected data from 24 sites in Switzerland, where we in-ventoried dead trees and habitat structures such as cavities, cracks, bark pockets, etc. In unmanaged forests we found deadwood amounts of 98–143 m 3 and 20 snags > 30 cm DBH per hectare, one and half time more large trees (> 60 cm DBH) und twice as many habitat structures as in managed forests. The latter had in average 15–19 m 3 of deadwood and 3 snags > 30 cm DBH per hectare. Deadwood amounts in un-managed forests were similar to the ones in natural forests of central Europe. However, we found 10–50 times less veteran trees (> 80 cm DBH) than in natural forests (1 vs. 0.2 trees per hectare in unmanaged vs. managed forests). For equal diameter classes, trees had more habitat structures in unmanaged than in managed forests. Forest managers plan to intensify wood harvesting in Swiss forests. Consequently, we recommend to urgently set aside protected forest areas and old-growth patches, to maintain and favor habitat trees in managed forests, and to introduce an efficient sustainable deadwood management in any forest. S owohl national als auch international gehört heutzutage die Förderung der Artenvielfalt zur nachhaltigen Waldbewirtschaftung. Aus der Wissenschaft ist bekannt, dass Totholz und alte Bäume Schlüsselelemente für die Biodiversität im Wald sind. Die Anzahl saproxylischer (alt-und tot-holzabhängiger) Arten steigt mit zunehmenden Alt-und Totholzmengen stark (z.B. Martikainen et al 2000). Damit solche Arten langfristig überleben, müssen geeignete Habitate sowohl zeitlich als auch räumlich kontinuierlich vorhanden sein (Grove 2002). Die Bewirtschaftungsintensität der Schweizer Wälder variierte im Laufe der Zeit stark. Über Jahr-hunderte war der Rohstoff Holz der wichtigste Ener-gieträger und Baustoff. Die Wälder wurden intensiv genutzt und tote Bäume kaum im Wald belassen. In den letzten Jahrzehnten konnte sich der Wald allmählich von der intensiven Holznutzung des 19. und zu Beginn des 20. Jahrhunderts erholen. Immer mehr Holz blieb ungenutzt in den Wäldern. Dadurch wurden diese vorratsreicher und dunkler (Brassel & Brändli 1999). Was für lichtbedürftige Arten nachteilig ist, wurde für zahlreiche saproxyli-sche Arten zum Vorteil. Gesamtschweizerisch stieg der durchschnittliche Totholzvorrat auf gemeinsa-men Probeflächen des zweiten und dritten Landes-forstinventars von 10.3 m 3 pro Hektar in den 90er-Jahren auf 18.5 m 3 pro Hektar elf Jahre später. 1 Wir können daher annehmen, dass sich die Situation für die saproxylischen Arten leicht entspannt hat. Das Problem der Habitatsknappheit für diese Arten ist aber trotzdem noch nicht gelöst. Die meisten Wälder der Schweiz und Europas bieten immer noch zu wenig Totholz für die davon abhängigen Arten. Im Vergleich zu den knapp 20 m 3 Totholz pro Hektar in den Schweizer Wäldern sind europäische Naturwälder mit ungefähr 20–200 m 3 1 Brändli UB, ABegg M, dUc P, ginzler c (2010) Biologi-sche Vielfalt. In: Brändli UB, editor. Schweizerisches Landes-forstinventar. Ergebnisse der dritten Aufnahme 2004–2006. Birmens dorf: Eidgenöss Forsch.anstalt Wald Schnee Land-schaft. In Vorbereitung.
Mycena juniperina Aronsen was collected in March 2013 in the Origano-Brachypodietum association from trunks of living Juniperus communis in the Pieniny Mts (S Poland). The species is described and illustrated based on Polish specimens, its ecology and general distribution are outlined, and it is compared with similar species: M. meliigena (Berk. & Cooke) Sacc., M. pseudocorticola Kühner, and others.