Search

Biotic interactions are crucial for determining the structure and dynamics of communities; however, direct measurement of these interactions can be challenging in terms of time and resources, especially when numerous species are involved. Inferring species interactions from species co‐occurrence patterns is increasingly being used; however, recent studies have highlighted some limitations. To our knowledge, no attempt has been made to test the accuracy of the existing methods for detecting mutualistic interactions in terrestrial ecosystems. In this study, we compiled two literature‐based, long‐term datasets of interactions between butterflies and herbaceous plant species in two regions of Germany and compared them with observational abundance and presence/absence data collected within a year in the same regions. We tested how well the species associations generated by three different co‐occurrence analysis methods matched those of empirically measured mutualistic associations using sensitivity and specificity analyses and compared the strength of associations. We also checked whether flower abundance data (instead of plant abundance data) increased the accuracy of the co‐occurrence models and validated our results using empirical flower visitation data. The results revealed that, although all methods exhibited low sensitivity, our implementation of the Relative Interaction Intensity index with pairwise null models performed the best, followed by the probabilistic method and Spearman's rank correlation method. However, empirical data showed a significant number of interactions that were not detected using co‐occurrence methods. Incorporating flower abundance data did not improve sensitivity but enhanced specificity in one region. Further analysis demonstrated incongruence between the predicted co‐occurrence associations and actual interaction strengths, with many pairs exhibiting high interaction strength but low co‐occurrence or vice versa. These findings underscore the complexity of ecological dynamics and highlight the limitations of current co‐occurrence methods for accurately capturing species interactions. [ABSTRACT FROM AUTHOR]

Background Large research consortia can generate tremendous amounts of biological information, including high-resolution soil, vegetation, and climate data. While this knowledge stock holds invaluable potential for answering evolutionary and ecological questions, making these data exploitable for modelling remains a daunting task due to the many processing steps required for synthesis. This might result in many researchers to fall back to a handful of ready-to-use data sets, potentially at the expense of statistical power and scientific rigour. In a push for a more stringent approach, we introduce BEpipeR, an R pipeline that allows for the streamlined synthesis of plot-based Biodiversity Exploratories data. Methods BEpipeR was designed with flexibility and ease of use in mind. For instance, users simply choose between aggregating forest or grassland data, or a combination thereof, effectively allowing them to process any experimental plot data of this research consortium. Additionally, instead of coding, they parse most processing information in a user-friendly way through parameter sheets. Processing includes, among others, the creation of a spatially explicit plot-ID template, data wrangling, quality control, plot-wise aggregations, the calculation of derived metrics, data joining to a large composite data set, and metadata compilation. Results With BEpipeR, we provide a feature-rich pipeline that allows users to process Biodiversity Exploratories data in a flexible and reproducible way. This pipeline might serve as a starting point for aggregating the numerous data sets of this and potentially similar research consortia. In this way, it might be a primer for the construction of consortia-wide composite data sets that take full advantage of the consortia’s rich information stocks, ultimately boosting the visibility and participation of individual research projects. Conclusions The BEpipeR pipeline permits the user-friendly processing and plot-wise aggregation of Biodiversity Exploratories data. With modifications, this framework may be easily adopted by other research consortia.

ABSTRACT Biotic interactions are crucial for determining the structure and dynamics of communities; however, direct measurement of these interactions can be challenging in terms of time and resources, especially when numerous species are involved. Inferring species interactions from species co‐occurrence patterns is increasingly being used; however, recent studies have highlighted some limitations. To our knowledge, no attempt has been made to test the accuracy of the existing methods for detecting mutualistic interactions in terrestrial ecosystems. In this study, we compiled two literature‐based, long‐term datasets of interactions between butterflies and herbaceous plant species in two regions of Germany and compared them with observational abundance and presence/absence data collected within a year in the same regions. We tested how well the species associations generated by three different co‐occurrence analysis methods matched those of empirically measured mutualistic associations using sensitivity and specificity analyses and compared the strength of associations. We also checked whether flower abundance data (instead of plant abundance data) increased the accuracy of the co‐occurrence models and validated our results using empirical flower visitation data. The results revealed that, although all methods exhibited low sensitivity, our implementation of the Relative Interaction Intensity index with pairwise null models performed the best, followed by the probabilistic method and Spearman's rank correlation method. However, empirical data showed a significant number of interactions that were not detected using co‐occurrence methods. Incorporating flower abundance data did not improve sensitivity but enhanced specificity in one region. Further analysis demonstrated incongruence between the predicted co‐occurrence associations and actual interaction strengths, with many pairs exhibiting high interaction strength but low co‐occurrence or vice versa. These findings underscore the complexity of ecological dynamics and highlight the limitations of current co‐occurrence methods for accurately capturing species interactions.

Context: Forest microclimate influences biodiversity and plays a crucial role in regulating forest ecosystem functions. It is modified by forest management as a result of changes in forest structure due to tree harvesting and thinning. Objectives: Here, we investigate the impacts of even-aged and uneven-aged forest management on stand- and landscape-level heterogeneity of forest microclimates, in comparison with unmanaged, old-growth European beech forest. Methods: We combined stand structural and topographical indices derived from airborne laser scanning with climate observations from 23 meteorological stations at permanent forest plots within the Hainich region, Germany. Based on a multiple linear regression model, we spatially interpolated the diurnal temperature range (DTR) as an indicator of forest microclimate across a 4338 ha section of the forest with 50 m spatial resolution. Microclimate heterogeneity was measured as α-, β-, and γ-diversity of thermal niches (i.e. DTR classes). Results: Even-aged forests showed a higher γ-diversity of microclimates than uneven-aged and unmanaged forests. This was mainly due to a higher β-diversity resulting from the spatial coexistence of different forest developmental stages within the landscape. The greater structural complexity at the stand-level in uneven-aged stands did not increase α-diversity of microclimates. Predicted DTR was significantly lower and spatially more homogenous in unmanaged forest compared to both types of managed forest. Conclusion: If forest management aims at creating a wide range of habitats with different microclimates within a landscape, spatially co-existing types of differently managed and unmanaged forests should be considered, instead of focusing on a specific type of management, or setting aside forest reserves only. [ABSTRACT FROM AUTHOR]

Most forests in Central Europe are subject to human management, especially timber harvesting, which alters soil conditions by creating gaps in the forest canopy and reduces the availability of deadwood. However, consequences of these management practices, in particular the combined effect of gap formation and deadwood removal, have been largely neglected. Here, we investigated the abundance, diversity and community composition of oribatid mites (Acari: Oribatida) in forests where deadwood availability and gap formation were manipulated in a full factorial design (Control, Gap, Deadwood, Gap + Deadwood). Forest gaps of about 30 m in diameter were established by felling trees, which were subsequently removed (Gap) or left on site as deadwood (Gap + Deadwood). Nearby forest sites without gaps were enriched with the equal amount of felled trees (Deadwood) or left untreated (Control). Experimental treatments were established at 29 forest sites including deciduous and coniferous stands in three regions of Germany, i.e. the Swabian Alb, Hanich-Dün and Schorfheide-Chorin in the south, center and north, respectively. One year after establishment of the treatments, we sampled 10,777 individuals and 104 species of oribatid mites. Deadwood addition significantly increased the density of oribatid mites in the Hainich-Dün from 24,036 to 46,658 ind. m-². Specifically, species of Oppiidae with relatively short life cycles and high reproductive output benefited from the additional deadwood supply, resulting in shifts in community compositions between treatments with and without deadwood. By contrast, mean oribatid mite density decreased from an average of 64,083 in controls to 36,621 ind. m-² in forest gaps of the Schorfheide-Chorin and the Swabian Alb. Presumably, adverse abiotic conditions, mainly amplified drought, induced higher mortality rates in these regions. Overall, deadwood addition and forest gap formation had strong effects on oribatid mite communities, although the magnitude of each effect was similar between forest types and largely determined by regional context. This emphasizes that the effects of forest management practices on oribatid mite communities cannot be generalized across regional scales, suggesting that management plans should carefully consider regional differences. • Large logs of deadwood increase the density of oribatid mites in forest soil. • Forest gaps reduce the density and species number of oribatid mites. • Effects of deadwood addition and forest gap formation differ between regions. • Deadwood addition to forest gaps does not mitigate detrimental effects of gaps. [ABSTRACT FROM AUTHOR]

Biodiversity loss, as often found in intensively managed agricultural landscapes, correlates with reduced ecosystem functioning, for example, pollination by insects, and with altered plant composition, diversity, and abundance. But how does this change in floral resource diversity and composition relate to occurrence and resource use patterns of trap‐nesting solitary bees? To better understand the impact of land‐use intensification on communities of trap‐nesting solitary bees in managed grasslands, we investigated their pollen foraging, reproductive fitness, and the nutritional quality of larval food along a land‐use intensity gradient in Germany. We found bee species diversity to decrease with increasing land‐use intensity irrespective of region‐specific community compositions and interaction networks. Land use also strongly affected the diversity and composition of pollen collected by bees. Lack of suitable pollen sources likely explains the absence of several bee species at sites of high land‐use intensity. The only species present throughout, Osmia bicornis (red mason bee), foraged on largely different pollen sources across sites. In doing so, it maintained a relatively stable, albeit variable nutritional quality of larval diets (i.e., protein to lipid (P:L) ratio). The observed changes in bee–plant pollen interaction patterns indicate that only the flexible generalists, such as O. bicornis, may be able to compensate the strong alterations in floral resource landscapes and to obtain food of sufficient quality through readily shifting to alternative plant sources. In contrast, other, less flexible, bee species disappear. [ABSTRACT FROM AUTHOR]

Abstract Background How land use shapes biodiversity and functional trait composition of animal communities is an important question and frequently addressed. Land-use intensification is associated with changes in abiotic and biotic conditions including environmental homogenization and may act as an environmental filter to shape the composition of species communities. Here, we investigated the responses of land snail assemblages to land-use intensity and abiotic soil conditions (pH, soil moisture), and analyzed their trait composition (shell size, number of offspring, light preference, humidity preference, inundation tolerance, and drought resistance). We characterized the species’ responses to land use to identify ‘winners’ (species that were more common on sites with high land-use intensity than expected) or ‘losers’ of land-use intensity (more common on plots with low land-use intensity) and their niche breadth. As a proxy for the environmental ‘niche breadth’ of each snail species, based on the conditions of the sites in which it occurred, we defined a 5-dimensional niche hypervolume. We then tested whether land-use responses and niches contribute to the species’ potential vulnerability suggested by the Red List status. Results Our results confirmed that the trait composition of snail communities was significantly altered by land-use intensity and abiotic conditions in both forests and grasslands. While only 4% of the species that occurred in forests were significant losers of intensive forest management, the proportion of losers in grasslands was much higher (21%). However, the species’ response to land-use intensity and soil conditions was largely independent of specific traits and the species’ Red List status (vulnerability). Instead, vulnerability was only mirrored in the species’ rarity and its niche hypervolume: threatened species were characterized by low occurrence in forests and low occurrence and abundance in grasslands and by a narrow niche quantified by land-use components and abiotic factors. Conclusion Land use and environmental responses of land snails were poorly predicted by specific traits or the species’ vulnerability, suggesting that it is important to consider complementary risks and multiple niche dimensions.

Abstract Biodiversity loss, as often found in intensively managed agricultural landscapes, correlates with reduced ecosystem functioning, for example, pollination by insects, and with altered plant composition, diversity, and abundance. But how does this change in floral resource diversity and composition relate to occurrence and resource use patterns of trap‐nesting solitary bees? To better understand the impact of land‐use intensification on communities of trap‐nesting solitary bees in managed grasslands, we investigated their pollen foraging, reproductive fitness, and the nutritional quality of larval food along a land‐use intensity gradient in Germany. We found bee species diversity to decrease with increasing land‐use intensity irrespective of region‐specific community compositions and interaction networks. Land use also strongly affected the diversity and composition of pollen collected by bees. Lack of suitable pollen sources likely explains the absence of several bee species at sites of high land‐use intensity. The only species present throughout, Osmia bicornis (red mason bee), foraged on largely different pollen sources across sites. In doing so, it maintained a relatively stable, albeit variable nutritional quality of larval diets (i.e., protein to lipid (P:L) ratio). The observed changes in bee–plant pollen interaction patterns indicate that only the flexible generalists, such as O. bicornis, may be able to compensate the strong alterations in floral resource landscapes and to obtain food of sufficient quality through readily shifting to alternative plant sources. In contrast, other, less flexible, bee species disappear.

Effects of forest management on forest biodiversity have received increasing attention in both research and forestry practice. Despite advances in technology, monitoring of biodiversity remains time and cost-intensive and requires specific taxonomic expertise. In forest management, however, there is increasing interest and need to integrate biodiversity monitoring into forest inventories efficiently to estimate the potential effects of forest management on biodiversity. Forest management systems can differ greatly depending on management goals and the intensity and frequency of the applied silvicultural interventions. To identify management effects on biodiversity, an estimation of biodiversity using forest structural attributes may be a reasonable approach. Forest structure can – compared to conventional species-based monitoring - easily be captured during forest inventories and does not require specific taxonomic expertise. The IBP (Index of Biodiversity Potential) is a composite index aiming to provide practitioners with an efficient tool for estimating biodiversity at the local level. We recorded the IBP on 147 plots in three regions of Germany, where detailed biodiversity monitoring had been conducted. This study quantified the relationship between changes in the IBP scores and changes in species richness for 13 taxonomic groups. To determine this, we analyzed estimated relationships between the IBP and species richness using a count regression model. We found positive estimated relationships with species richness of birds, fungi, true bugs, lichens, and moths in at least 3 of 5 examined forest types. However, for spiders, bats, carabids, necrophagous and saproxylic beetles, either no relationship with the IBP or estimated relationships with only one forest type were found. Changes in scores for the IBP’s factors number of vertical layers, large living trees, tree-related microhabitats, and proportion of gaps correlated with changes in the measured species richness in many cases. Even though the IBP is generally not adequate to predict actual presence or precise number of species, it can be utilized to depict a forest stand’s potential in terms of species richness. Due to its easy and time-efficient application, it could be a useful proxy used in combination with species-based monitoring approaches.

Evidence from experimental and established grasslands indicates that plant biodiversity can modify the water cycle. One suspected mechanism behind this is a higher infiltration capacity (νB) and hydraulic conductivity (K) of the soil on species‐rich grasslands. However, in established and agriculturally managed grasslands, biodiversity effects cannot be studied independent of land‐use effects. Therefore, we investigated in established grassland systems how land‐use intensity and associated biodiversity of plants and soil animals affect νB and K at and close to saturation. On 50 grassland plots along a land‐use intensity gradient in the Biodiversity Exploratory Schwäbische Alb, Germany, we measured νB with a hood infiltrometer at several matrix potentials and calculated the saturated and unsaturated K. We statistically analysed the relationship between νB or K and land‐use information (e.g., fertilising intensity), abiotic (e.g., soil texture) and biotic data (e.g., plant species richness, earthworm abundance). Land‐use intensity decreased and plant species richness increased νB and K, while the direction of the effects of soil animals was inconsistent. The effect of land‐use intensity on νB and K was mainly attributable to its negative effect on plant species richness. Our results demonstrate that plant species richness was a better predictor of νB and K at and close to saturation than land‐use intensity or soil physical properties in the established grassland systems of the Schwäbische Alb. [ABSTRACT FROM AUTHOR]

Deadwood may alter the chemical and microbial properties of forest soils. However, it is unclear how downed deadwood (logs) of different tree species affect nutrients, microbial activity and biomass in different forest soils and regions. We investigated the effect of logs on underlying soils after 8 years of decomposition in an experiment consisting of 13 log tree species replicated at 30 forest sites across three German regions with distinct climate and geology. Soils beneath logs were compared to soils without recognizable influence of deadwood (control) 8 m away. Carbon, nitrogen, phosphorous and calcium concentrations increased by 5–18% in the soils under logs, whereas soil potassium, magnesium, iron, manganese and aluminum were not or slightly negatively affected by logs. Soils beneath logs exhibited 33%, 18% and 54% higher carbon mineralization, microbial biomass and ergosterol (component of fungal cell membranes) contents, respectively. Despite major differences in decay rates, the effect on soil properties hardly differed among the 13 log tree species. The effect of logs on microbial and chemical soil parameters increased with decreasing concentration of carbon, nitrogen, phosphorous and pH in the prevailing forest soils. Consequently, the strongest effects of logs on soil parameters occurred in plots with low soil nutrient contents and low soil pH. Our results suggest that logs of all tree species primarily increase the microbial activity and nutrient contents of acidic and nutrient-poor soils. [ABSTRACT FROM AUTHOR]

Intensive land use has been shown to alter the composition and functioning of soil communities. Due to their low dispersal ability, oribatid mites are particularly vulnerable to land-use intensification and species which are not adjusted to management-related disturbances become less abundant. We investigated how different land-use parameters in forests and grasslands affect oribatid mite diversity and abundance, with a focus on: (1) species-level impacts, by classifying species as increasing ('winners') or decreasing ('losers') in abundance with higher land-use intensity, and (2) reproductive impact, by investigating whether sexual and parthenogenetic species react differently. We collected 32,542 adult oribatid mites in 60 forests and grasslands of known land-use intensity in two regions of Germany. Diversity and total abundance as well as the proportion of sexual species were higher in forests than in grasslands. Diversity declined with higher land-use intensity in forests, but increased with higher mowing and fertilization in grasslands. Depending on land-use parameter and region, abundance either declined or remained unaffected by increasing intensity. Gravidity was higher in sexual than in parthenogenetic species and sexuals had 1.6× more eggs per gravid female. Proportions of sexual species and gravid females decreased with land-use intensity in forests, but increased with mowing in grasslands. At the species level, 75% of sexuals and 87.5% of parthenogens were 'losers' of higher percentages of dead wood originating from management-related disturbances. Across land-use parameters and habitats, a similar proportion of sexual and parthenogenetic oribatid mite species were 'losers' of high land-use intensity. However, 'winner' species were more common among sexuals. [ABSTRACT FROM AUTHOR]

Soil P pools are strongly driven by microbial activities, and vice versa, P pools shape bacterial communities and their functional potential. Biological soil crusts (biocrusts) represent a microbial hotspot for nutrient turnover. We compared biocrusts and bulk soil samples from different temperate beech (Fagus sylvatica L.) forests representing a gradient in soil texture, nutrient concentrations, and pH values at biocrust peak biomass. We measured the total and plant-available P and N concentrations and assessed the bacterial potential to mineralize (phoD, phnX), solubilize (gcd), and take up P (pstS and pitA) and mineralize (chiA, apr) and fix N (nifH) by quantifying the respective marker genes (qPCR). We found an increase of absolute and relative bacterial abundance involved in P turnover in biocrusts, but the strategy to acquire P differed between the regions as bacteria harboring the starvation-induced pstS gene were most abundant where labile P was lowest. In contrast, the region with lowest total P concentrations has a higher potential to utilize more stable phosphonates. N mineralization was strongly correlated to P turnover at regions with increased labile N and P concentrations. Interestingly, the potential to fix N was highest in the bulk soil where total P concentrations were highest. Even though the correlation of N and P turnover is strongest if their ratio is low, the acquisition strategy strongly depends on soil properties. [ABSTRACT FROM AUTHOR]

Background: How land use shapes biodiversity and functional trait composition of animal communities is an important question and frequently addressed. Land-use intensification is associated with changes in abiotic and biotic conditions including environmental homogenization and may act as an environmental filter to shape the composition of species communities. Here, we investigated the responses of land snail assemblages to land-use intensity and abiotic soil conditions (pH, soil moisture), and analyzed their trait composition (shell size, number of offspring, light preference, humidity preference, inundation tolerance, and drought resistance). We characterized the species' responses to land use to identify 'winners' (species that were more common on sites with high land-use intensity than expected) or 'losers' of land-use intensity (more common on plots with low land-use intensity) and their niche breadth. As a proxy for the environmental 'niche breadth' of each snail species, based on the conditions of the sites in which it occurred, we defined a 5-dimensional niche hypervolume. We then tested whether land-use responses and niches contribute to the species' potential vulnerability suggested by the Red List status. Results: Our results confirmed that the trait composition of snail communities was significantly altered by land-use intensity and abiotic conditions in both forests and grasslands. While only 4% of the species that occurred in forests were significant losers of intensive forest management, the proportion of losers in grasslands was much higher (21%). However, the species' response to land-use intensity and soil conditions was largely independent of specific traits and the species' Red List status (vulnerability). Instead, vulnerability was only mirrored in the species' rarity and its niche hypervolume: threatened species were characterized by low occurrence in forests and low occurrence and abundance in grasslands and by a narrow niche quantified by land-use components and abiotic factors. Conclusion: Land use and environmental responses of land snails were poorly predicted by specific traits or the species' vulnerability, suggesting that it is important to consider complementary risks and multiple niche dimensions. [ABSTRACT FROM AUTHOR]

Abstract Plant functional traits reflect individual and community ecological strategies. They allow the detection of directional changes in community dynamics and ecosystemic processes, being an additional tool to assess biodiversity than species richness. Analysis of functional patterns in plant communities provides mechanistic insight into biodiversity alterations due to anthropogenic activity. Although studies have consi‐dered of either anthropogenic management or nutrient availability on functional traits in temperate grasslands, studies combining effects of both drivers are scarce. Here, we assessed the impacts of management intensity (fertilization, mowing, grazing), nutrient stoichiometry (C, N, P, K), and vegetation composition on community‐weighted means (CWMs) and functional diversity (Rao's Q) from seven plant traits in 150 grasslands in three regions in Germany, using data of 6 years. Land use and nutrient stoichiometry accounted for larger proportions of model variance of CWM and Rao's Q than species richness and productivity. Grazing affected all analyzed trait groups; fertilization and mowing only impacted generative traits. Grazing was clearly associated with nutrient retention strategies, that is, investing in durable structures and production of fewer, less variable seed. Phenological variability was increased. Fertilization and mowing decreased seed number/mass variability, indicating competition‐related effects. Impacts of nutrient stoichiometry on trait syndromes varied. Nutrient limitation (large N:P, C:N ratios) promoted species with conservative strategies, that is, investment in durable plant structures rather than fast growth, fewer seed, and delayed flowering onset. In contrast to seed mass, leaf‐economics variability was reduced under P shortage. Species diversity was positively associated with the variability of generative traits. Synthesis. Here, land use, nutrient availability, species richness, and plant functional strategies have been shown to interact complexly, driving community composition, and vegetation responses to management intensity. We suggest that deeper understanding of underlying mechanisms shaping community assembly and biodiversity will require analyzing all these parameters.

Land-use intensification can increase provisioning ecosystem services, such as food and timber production, but it also drives changes in ecosystem functioning and biodiversity loss, which may ultimately compromise human wellbeing. To understand how changes in landuse intensity affect the relationships between biodiversity, ecosystem functions, and services, we built networks from correlations between the species richness of 16 trophic groups, 10 ecosystem functions, and 15 ecosystem services. We evaluated how the properties of these networks varied across land-use intensity gradients for 150 forests and 150 grasslands. Land-use intensity significantly affected network structure in both habitats. Changes in connectance were larger in forests, while changes in modularity and evenness were more evident in grasslands. Our results show that increasing land-use intensity leads to more homogeneous networks with less integration within modules in both habitats, driven by the belowground compartment in grasslands, while forest responses to land management were more complex. Land-use intensity strongly altered hub identity and module composition in both habitats, showing that the positive correlations of provisioning services with biodiversity and ecosystem functions found at low land-use intensity levels, decline at higher intensity levels. Our approach provides a comprehensive view of the relationships between multiple components of biodiversity, ecosystem functions, and ecosystem services and how they respond to land use. This can be used to identify overall changes in the ecosystem, to derive mechanistic hypotheses, and it can be readily applied to further global change drivers. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A large-scale study combining pheromone trapping and experimental logs. • Management decreases abundance and attack probability of native ambrosia beetles. • The abundance of invasive X. germanus may be increased by management. • Pest control of native T. domesticum is less effective at high management intensities. • Substrate availability, microclimate and antagonists drive ambrosia beetle abundance. Abstract Land-use intensification has been shown to negatively affect biodiversity and ecosystem functioning. Because higher trophic levels are expected to suffer most strongly from intensification, negative consequences for ecosystem services, such as biological pest control by natural enemies, are likely. In European beech forests ambrosia beetles are common secondary pests of freshly cut wood and stored timber, but they may also infest living trees that are highly stressed. We examined whether forest management intensity, ranging from unmanaged beech forests to non-natural conifer plantations, affects the abundance, attack rate, and breeding success of ambrosia beetles across three regions of Germany. We applied pheromone trapping to estimate the abundance of ambrosia beetles and exposed experimental beech logs to measure infestation rates and breeding success. In general, we found decreasing abundance and attack probability by ambrosia beetles with increasing management intensity, which is most likely related to the availability of suitable breeding substrate. However, the abundance of the invasive species Xylosandrus germanus increased with increasing management intensity in one region, where high management intensity was represented by pine forests; the drier and warmer conditions in this forest type most likely increased population densities. Breeding success of Trypodendron domesticum increased with increasing management intensity, suggesting less effective pest control by natural antagonists, in particular by specialised parasitoids, at high management intensities. We conclude that the availability of breeding substrate, in combination with microclimate and antagonist effectiveness, shape ambrosia beetle populations in Central European forests. Forest management strategies should thus reduce the availability of breeding substrate in production forests, in particular where microclimatic conditions are favourable for beetle reproduction (i.e. warm, moist). Moreover, unmanaged forest patches should be maintained to promote parasitoid abundance and thus to mitigate negative effects of climate change, such as increasing drought stress of trees. [ABSTRACT FROM AUTHOR]

While forest management strongly influences biodiversity, it remains unclear how the structural and compositional changes caused by management affect different community dimensions (e.g. richness, specialisation, abundance or completeness) and how this differs between taxa. We assessed the effects of nine forest features (representing stand structure, heterogeneity and tree composition) on thirteen above‐ and belowground trophic groups of plants, animals, fungi and bacteria in 150 temperate forest plots differing in their management type. Canopy cover decreased light resources, which increased community specialisation but reduced overall diversity and abundance. Features increasing resource types and diversifying microhabitats (admixing of oaks and conifers) were important and mostly affected richness. Belowground groups responded differently to those aboveground and had weaker responses to most forest features. Our results show that we need to consider forest features rather than broad management types and highlight the importance of considering several groups and community dimensions to better inform conservation. [ABSTRACT FROM AUTHOR]

The relationship between trees and root-associated fungal communities is complex. By specific root deposits and other signal cues, different tree species are able to attract divergent sets of fungal species. Plant intraspecific differences can lead to variable fungal patterns in the root’s proximity. Therefore, within the Beech Transplant Experiment, we analyzed the impact of three different European beech ecotypes on the fungal communities in roots and the surrounding rhizosphere soil at two time points. Beech nuts were collected in three German sites in 2011. After one year, seedlings of the different progenies were out-planted on one site and eventually re-sampled in 2014 and 2017. We applied high-throughput sequencing of the fungal ITS2 to determine the correlation between tree progeny, a possible home-field advantage, plant development and root-associated fungal guilds under field conditions. Our result showed no effect of beech progeny on either fungal OTU richness or fungal community structure. However, over time the fungal OTU richness in roots increased and the fungal communities changed significantly, also in rhizosphere. In both plant compartments, the fungal communities displayed a high temporal turnover, indicating a permanent development and functional adaption of the root mycobiome of young beeches.

Abstract In the past 30 years, many stand structural attributes (SSAs) have been suggested and structural indices have been developed to describe the complex structure of forests. Most studies, however, have explored the potential and limits of structural measures to quantify forest structures by applying multiple measures to one stand or few measures to several stands. However, the interdependencies of multiple structural attributes across many stands of different forest management types and developmental stages have not yet been explored. Using 20 structural attributes and 124 completely inventoried 1 ha sized stands we tested to what extent structural characteristics reflect different stand types and management intensities, and how these characteristics change over time. We found that single SSAs do not show the clear gradients that they were intended to reflect, suggesting that stand structure should be described by multiple structural attributes, and that these should represent different structural aspects (including vertical, and horizontal heterogeneity, density, and diversity). A principal component analysis showed that combining several SSAs, allowed us to distinguish between stand types. The structure of mature stands remained rather constant over the observed period of about 6 years, while that of young stands changed more rapidly due to ingrowth and mortality. The older the stands, the less the large trees contributed to stand growth relative to their size. We conclude that multiple stand structural attributes are needed to characterise stand types, management effects and to explain stand productivity. [ABSTRACT FROM AUTHOR]

Abstract: Evidence from experimental grasslands indicated that plant biodiversity modifies the water cycle, but it is unclear if this is also true for established land‐use systems. Therefore, we investigated how actual evapotranspiration (ETa), downward flux (DF), and upward flux (UF) in soil are related with land use and plant diversity in agriculturally managed grassland. In three Central European regions (“Biodiversity Exploratories”), we studied 29 grassland plots (50 × 50 m; 9–11 plots per region) covering the land‐use classes pasture, mown pasture, and meadow, in at least triplicate per region. From 2010 to 2015, we measured soil moisture, meteorological conditions, plant species richness, cover, and number of species in the functional groups of grasses, herbs, and legumes, aboveground biomass and root biomass on each plot. Annual ETa, DF, and UF were calculated for two soil layers with a soil water balance model and statistically analysed for land‐use and biodiversity effects with analysis of variance. Water fluxes were not significantly affected by land‐use class. UF did not vary between plots with different species richness and plant functional group composition. DF from topsoil increased with increasing number of grass species. ETa from topsoil decreased with increasing species richness and with the number of herb or legume species, whereas ETa from subsoil increased. Our results demonstrate that plant diversity influences the soil depth partitioning of water use, but the complex drivers of this relationship in agriculturally managed grassland still need to be disentangled. [ABSTRACT FROM AUTHOR]

The current biodiversity decline through anthropogenic land-use not only involves local species losses, but also homogenization of communities, with a few generalist species benefitting most from human activities. Most studies assessed community heterogeneity (β-diversity) on larger scales by comparing different sites, but little is known about impacts on β-diversity within each site, which is relevant for understanding variation in the level of α-diversity, the small-scale distribution of species and associated habitat heterogeneity. To obtain our dataset with 36,899 individuals out of 117 different plant- and leafhopper (Auchenorrhyncha) species, we sampled communities of 140 managed grassland sites across Germany by quantitative vacuum suction of five 1 m2 plots on each site. Sites differed in land-use intensity as characterized by intensity of fertilization, mowing and grazing. Our results demonstrate a significant within-site homogenization of plant- and leafhopper communities with increasing land-use intensity. Correspondingly, density (− 78%) and γ-diversity (− 35%) declined, particularly with fertilization and mowing intensity. More than 34% of plant- and leafhopper species were significant losers and only 6% were winners of high land-use intensity, with abundant and widespread species being less affected. Increasing land-use intensity adversely affected dietary specialists and promoted generalist species. Our study emphasizes considerable, multifaceted effects of land-use intensification on species loss, with a few dominant generalists winning, and an emerging trend towards more homogenized assemblages. By demonstrating homogenization for the first time within sites, our study highlights that anthropogenic influences on biodiversity even occur on small scales. [ABSTRACT FROM AUTHOR]

Plant functional traits reflect individual and community ecological strategies. They allow the detection of directional changes in community dynamics and ecosystemic processes, being an additional tool to assess biodiversity than species richness. Analysis of functional patterns in plant communities provides mechanistic insight into biodiversity alterations due to anthropogenic activity. Although studies have consi-dered of either anthropogenic management or nutrient availability on functional traits in temperate grasslands, studies combining effects of both drivers are scarce. Here, we assessed the impacts of management intensity (fertilization, mowing, grazing), nutrient stoichiometry (C, N, P, K), and vegetation composition on community-weighted means ( CWMs) and functional diversity (Rao's Q) from seven plant traits in 150 grasslands in three regions in Germany, using data of 6 years. Land use and nutrient stoichiometry accounted for larger proportions of model variance of CWM and Rao's Q than species richness and productivity. Grazing affected all analyzed trait groups; fertilization and mowing only impacted generative traits. Grazing was clearly associated with nutrient retention strategies, that is, investing in durable structures and production of fewer, less variable seed. Phenological variability was increased. Fertilization and mowing decreased seed number/mass variability, indicating competition-related effects. Impacts of nutrient stoichiometry on trait syndromes varied. Nutrient limitation (large N:P, C:N ratios) promoted species with conservative strategies, that is, investment in durable plant structures rather than fast growth, fewer seed, and delayed flowering onset. In contrast to seed mass, leaf-economics variability was reduced under P shortage. Species diversity was positively associated with the variability of generative traits. Synthesis. Here, land use, nutrient availability, species richness, and plant functional strategies have been shown to interact complexly, driving community composition, and vegetation responses to management intensity. We suggest that deeper understanding of underlying mechanisms shaping community assembly and biodiversity will require analyzing all these parameters. [ABSTRACT FROM AUTHOR]

Grasslands belong to the ecologically most relevant habitats in cultural landscapes, but also provide high economic value when used as meadows or pastures. Land-use intensification in grasslands negatively affects plant diversity as well as arthropod communities that depend on plants as food source and habitat, with important consequences for the provision and resilience of ecosystem functioning. In this study, we sampled grassland moth species and investigated whether species composition, diversity and life-history trait characteristics of moth communities respond to the type and intensity of land use, comparing 26 sites in three different regions of Germany. Consistent across the three regions, we found that pastures grazed by cattle, horses or sheep harbour fundamentally different moth communities than meadows (mown and fertilized grasslands). Overall land-use intensity (LUI)-i.e., grazing intensity, amount of fertilizer applied and mowing frequency taken together-significantly reduced abundance and species richness as well as diversity. Some 27.6% of the species showed significant negative responses to LUI. A shift towards generalist life-history traits was observed: in frequently mown and fertilized meadows, rare specialist species were replaced by ubiquist species, i.e., highly reproductive habitat generalists. These results show the sensitivity of moths, an important group of arthropod herbivores and pollinators, to land use change in grassland ecosystems. The functional homogenization of life-history traits in plants along land-use gradients is mirrored by their herbivore consumers, leaving high-intensity grasslands less diverse and potentially less resilient to environmental disturbances. [ABSTRACT FROM AUTHOR]

Plant functional traits are widely used to predict community productivity. However, they are rarely used to predict individual plant performance in grasslands. To assess the relative importance of traits compared to environment, we planted seedlings of 20 common grassland species as phytometers into existing grassland communities varying in land-use intensity. After 1 year, we dug out the plants and assessed root, leaf, and aboveground biomass, to measure plant performance. Furthermore, we determined the functional traits of the phytometers and of all plants growing in their local neighborhood. Neighborhood impacts were analyzed by calculating community-weighted means ( CWM) and functional diversity ( FD) of every measured trait. We used model selection to identify the most important predictors of individual plant performance, which included phytometer traits, environmental conditions (climate, soil conditions, and land-use intensity), as well as CWM and FD of the local neighborhood. Using variance partitioning, we found that most variation in individual plant performance was explained by the traits of the individual phytometer plant, ranging between 19.30% and 44.73% for leaf and aboveground dry mass, respectively. Similarly, in a linear mixed effects model across all species, performance was best predicted by phytometer traits. Among all environmental variables, only including land-use intensity improved model quality. The models were also improved by functional characteristics of the local neighborhood, such as CWM of leaf dry matter content, root calcium concentration, and root mass per volume as well as FD of leaf potassium and root magnesium concentration and shoot dry matter content. However, their relative effect sizes were much lower than those of the phytometer traits. Our study clearly showed that under realistic field conditions, the performance of an individual plant can be predicted satisfyingly by its functional traits, presumably because traits also capture most of environmental and neighborhood conditions. [ABSTRACT FROM AUTHOR]

The nearly universal positive relationship between the distribution and abundance of species has been explained by several hypotheses but hitherto no consensus has been reached. Here, we used monitoring data of 105 phytophagous true bug species (Heteroptera) from 150 grassland sites over six years to test how (1) range position, (2) resource use, (3) resource availability, (4) density-dependent habitat selection, (5) metapopulation dynamics, and (6) habitat dispersal affect the distribution-abundance relationship. For the use in a confirmatory path analysis, we constructed causal pathways representing the hypothesized relationships and tested them separately and in a combined analysis. Our results show that the distribution-abundance relationship in phytophagous true bugs is driven by habitat-availability. An increasing local density of the host-plants increases the distribution of the species in the landscape, which in turn increases their local abundance. Thereby habitat availability facilitates dispersal success. We conclude that local abundance of herbivores facing habitat destruction could decline owing to a decrease in population dynamics between sites at the landscape scale. Finally, our results underline the potential of confirmatory path analysis for testing competing hypotheses. [ABSTRACT FROM AUTHOR]

Questions: To what extent is trait variation in grasses and forbs driven by land-use intensity, climate, soil conditions and plant diversity of the local neighbourhood? Do grass and forb species differ in the degree of intraspecific trait variation? Location: Managed grasslands in three regions of Germany. Methods: Using a phytometer approach,we raised 20 common European grassland species (ten forbs and ten grasses) and planted them into 54 plots of different land-use types (pasture, meadow, mown pasture). After 1 yr in the field, we measured above- and below-ground plant functional traits. Linear mixed effects models (LMEM) were used to identify the most powerful predictors for every trait. Variation partitioning was applied to assess the amount of inter- and intraspecific trait variation in grasses and forbs explained by environmental conditions (land-use intensity, climate and soil conditions) and plant species diversity of the local neighbourhood. Results: For 12 out of the 14 traits studied, either land-use intensity or local neighbourhood diversity were predictors in the best LMEM. Land-use intensity had considerably stronger effects than neighbourhood diversity. Root dry matter content and root phosphorus concentration of forbs were more affected by land-use intensity than those of grasses. For almost all traits, intraspecific trait variation of grasses was much higher than that of forbs, while traits of forbs varied more among species. Overall, inter- and intraspecific variation was of the same magnitude. Conclusion: The similar magnitude of intra- and interspecific trait variation suggests that both sources should be considered in grassland studies at a scale similar to that of our study. The high amount of intraspecific trait variation that was explained by environmental factors and local neighbourhood diversity clearly demonstrates the high potential of species to adjust to local conditions, which would be ignored when only considering species mean trait values. [ABSTRACT FROM AUTHOR]

Dung beetles (Scarabaeidae) are common detritivores, and especially the tunnelling genera Geotrupes , Anoplotrupes and Onthophagus enhance the soil quality and support nutrient cycles by rapid burial of mammalian dung. These functionally important beetles are faced with a wide range of anthropogenic disturbances and changes in environmental conditions due to land use. We thus conducted quantitative surveys of the abundance (converted to total biomass) of dung beetles and their dung removal rates (g per two days) in 150 forest and 150 grassland sites with varying land-use intensity, located in north-east, central and south-west Germany. We used dung from livestock (cow, sheep, horse) and game animals (wild boar, red deer and fox) to provide a characteristic spectrum of dung resources on each site. Most dung beetle species showed habitat preferences: Anoplotrupes , Typhaeus and several Aphodius species almost exclusively occurred in forests, while most Onthophagus individuals were found in grasslands. In total we collected 18780 individuals from 33 species. The average dung beetle biomass was 36 times higher in forests than in grasslands, and their effective dung removal rate was 3 times increased. The beetles’ total biomass was strongly correlated to their removal rates. In forests, the amount of wood harvesting significantly reduced dung removal rates by 20%, and mowing frequency (−7%) and fertilisation (−4%) had a significant negative effect in grasslands. Dung removal by beetles increased with grazing intensity (+6%), however, and was higher in non-native coniferous forests (+22%). Overall, our study demonstrates negative effects of habitat conversion from forest to grassland, and negative effects of land-use intensity within forests and grasslands on dung beetle activities. [ABSTRACT FROM AUTHOR]

The green algal genus Klebsormidium (Klebsormidiophyceae, Streptophyta) is a typical member of biological soil crusts (BSCs) worldwide. Ecophysiological studies focused so far on individual strains and thus gave only limited insight on the plasticity of this genus. In the present study, 21 Klebsormidium strains ( K. dissectum, K. flaccidum, K. nitens, K. subtile) from temperate BSCs in Central European grassland and forest sites were investigated. Photosynthetic performance under desiccation and temperature stress was measured under identical controlled conditions. Photosynthesis decreased during desiccation within 335-505 min. After controlled rehydration, most isolates recovered, but with large variances between single strains and species. However, all K. dissectum strains had high recovery rates (>69%). All 21 Klebsormidium isolates exhibited the capability to grow under a wide temperature range. Except one strain, all others grew at 8.5 °C and four strains were even able to grow at 6.2 °C. Twenty out of 21 Klebsormidium isolates revealed an optimum growth temperature >17 °C, indicating psychrotrophic features. Growth rates at optimal temperatures varied between strains from 0.26 to 0.77 μ day. Integrating phylogeny and ecophysiological traits, we found no phylogenetic signal in the traits investigated. However, multivariate statistical analysis indicated an influence of the recovery rate and growth rate. The results demonstrate a high infraspecific and interspecific physiological plasticity, and thus wide ecophysiological ability to cope with strong environmental gradients. This might be the reason why members of the genus Klebsormidium successfully colonize terrestrial habitats worldwide. [ABSTRACT FROM AUTHOR]

Along with the global decline of species richness goes a loss of ecological traits. Associated biotic homogenization of animal communities and narrowing of trait diversity threaten ecosystem functioning and human well-being. High management intensity is regarded as an important ecological filter, eliminating species that lack suitable adaptations. Below-ground arthropods are assumed to be less sensitive to such effects than above-ground arthropods., Here, we compared the impact of management intensity between (grassland vs. forest) and within land-use types (local management intensity) on the trait diversity and composition in below- and above-ground arthropod communities., We used data on 722 arthropod species living above-ground (Auchenorrhyncha and Heteroptera), primarily in soil (Chilopoda and Oribatida) or at the interface (Araneae and Carabidae)., Our results show that trait diversity of arthropod communities is not primarily reduced by intense local land use, but is rather affected by differences between land-use types. Communities of Auchenorrhyncha and Chilopoda had significantly lower trait diversity in grassland habitats as compared to forests. Carabidae showed the opposite pattern with higher trait diversity in grasslands. Grasslands had a lower proportion of large Auchenorrhyncha and Carabidae individuals, whereas Chilopoda and Heteroptera individuals were larger in grasslands. Body size decreased with land-use intensity across taxa, but only in grasslands. The proportion of individuals with low mobility declined with land-use intensity in Araneae and Auchenorrhyncha, but increased in Chilopoda and grassland Heteroptera. The proportion of carnivorous individuals increased with land-use intensity in Heteroptera in forests and in Oribatida and Carabidae in grasslands., Our results suggest that gradients in management intensity across land-use types will not generally reduce trait diversity in multiple taxa, but will exert strong trait filtering within individual taxa. The observed patterns for trait filtering in individual taxa are not related to major classifications into above- and below-ground species. Instead, ecologically different taxa resembled each other in their trait diversity and compositional responses to land-use differences. These previously undescribed patterns offer an opportunity to develop management strategies for the conservation of trait diversity across taxonomic groups in permanent grassland and forest habitats. [ABSTRACT FROM AUTHOR]

Terrestrial filamentous green algae of the widely distributed, cosmopolitan genusKlebsormidium(Klebsormidiophyceae, Streptophyta) are typical components of biological soil crusts (BSCs). These communities occur in all climatic zones and on all continents, where soil moisture is limited or where there has been disturbance. BSCs form water-stable aggregates that have important ecological roles in primary production, nitrogen fixation, nutrient cycling, water retention and stabilization of soils. Although available data onKlebsormidiumare limited, its functional importance in BSCs is regarded as high. Therefore, in the present studyKlebsormidiumstrains were isolated from BSCs sampled from various grassland and forest plots of different land use intensities in Central Europe, as provided by the Biodiversity Exploratories, and its intraspecific genetic diversity was evaluated. Previous phylogenetic analyses revealed a relationship between sequence similarity and habitat preference with a higher genetic diversity than expected from a morphological classification. We isolated and sequenced 75Klebsormidiumstrains. The molecular phylogeny based on the ITS regions showed that all strains belong to either the previously described clade B/C or clade E. This classification was supported by morphological characteristics: strains assigned to clade B/C were identified asKlebsormidiumcf.flaccidumorKlebsormidiumcf.dissectum, and strains from clade E asK. nitensorKlebsormidiumcf.subtile. Within one clade the strains showed low sequence divergences. These minor differences were independent of the sampling region and land use intensity. Interestingly, most of the strains assigned to clade E were isolated from forest sites, whereas strains from clade B/C occurred equally in grassland and forest sites. Therefore, it is reasonable to assume that habitat with its microenvironmental conditions, and not biogeography, controls genetic diversity inKlebsormidium. [ABSTRACT FROM PUBLISHER]

Plant diversity and land-use intensity have been shown to affect invertebrate herbivory. Several hypotheses predict positive (e.g. associational susceptibility) or negative (e.g. associational resistance) relationships of herbivory with plant species richness. Also, the strength and direction of reported relationships vary greatly between studies leading to the conclusion that relationships either depend on the specific system studied or that other unconsidered factors are more important. Here, we hypothesized that plant phylogenetic diversity is a stronger predictor of invertebrate herbivory than plant species richness because it integrates additional information about the phenotypical and functional composition of communities. We assessed the community-wide invertebrate herbivory, plant species richness and phylogenetic diversity across a range of land-use intensities including a total of 145 managed grasslands in three regions in Germany. Increasing land-use intensity decreased plant species richness and phylogenetic diversity. Plant species richness did not predict invertebrate herbivory. By contrast herbivory moderately increased with increasing plant phylogenetic diversity even after accounting for the effects of region and land use. The strength of direct effects of land-use intensity and indirect effects via altered phylogenetic diversity on herbivory, however, varied among regions. Our results suggest that increasing phylogenetic diversity of plant communities increases invertebrate herbivory probably by providing higher resource diversity. Differences between regions underline the need to account for regional peculiarities when attempting to generalize land-use effects on invertebrate herbivory. [ABSTRACT FROM AUTHOR]

Deadwood decay is an important ecosystem process in forest ecosystems, but the relative contribution of specific wood properties of tree species, activities of wood-degrading enzymes, and decomposer communities such as fungi and insects is unclear. We ask whether wood properties, in particular differences between angiosperms and gymnosperms, and organismic diversity of colonizers contribute to wood decomposition. To test this, we exposed deadwood logs of 13 tree species, covering four gymnosperms and nine angiosperm species, in 30 plots under different forest management in three regions in Germany. After a decomposition time of 6.5 years Carpinus betulus and Fagus sylvatica showed the highest decay rates. We found a positive correlation of decay rate with enzyme activities, chemical wood properties (S, K concentration) and organismic diversity, while, heartwood character, lignin content, extractive concentration and phenol content were negatively correlated with decay rate across all 13 tree species. By applying a multi-model inference approach we found that the activity of the wood-degrading enzymes laccase and endocellulase, beetle diversity, heartwood presence, wood ray height and fungal diversity were the most important predictor variables for wood decay. Although we were not able to identify direct cause and effect relations by our approach, we conclude that enzyme activity and organismic diversity are the main drivers of wood decay rate, which greatly differed among tree species. Maintaining high tree species diversity will therefore result in high structural deadwood diversity in terms of decay rate and decay stage. [ABSTRACT FROM AUTHOR]

Abstract Land use and corresponding habitat loss are major drivers of local species extinctions. Orthoptera as important grassland herbivores showed different responses to land‐use intensity in different studies, and the susceptibility of this group remains unclear. We sampled annually for seven years 150 temperate grassland sites across three regions in Germany, for which land‐use gradients were quantified as mowing, grazing, and fertilization intensity. We analyzed the effects of land‐use intensity on orthopteran diversity and community abundance. To describe species‐specific responses to environmental gradients, we employed a new approach termed “niche model,” coupled with a randomization procedure, which is sensitive even for rare species for which trends may otherwise be difficult to detect. Based on abundance‐weighted means for each species, we quantified the species' occurrence along land‐use gradients and identified potential losers and winners of intensive land use. Overall, high land‐use intensity negatively affected orthopteran diversity across years and regions, corresponding to decreases with high fertilization, mowing, and grazing intensity. Intensive mowing and grazing negatively affected abundance. Diversity and abundance increased with the time after the last cut. The niche model detected 15 of 29 Orthoptera species as losers of land use, showing significantly higher abundance in grasslands with low‐intensity land use. Two species were winners of high land‐use intensity, whereas the remaining 12 were assigned as opportunists. Most species were losers of high fertilization intensity, followed by frequent mowing. Grazing intensity was least detrimental at the species level. Omnivorous, herbivorous, and graminivorous species did not differ in their response to land‐use intensity, whereas bryovorous/lichenivorous Tetrix species showed consistently negative responses to intensive land use. Our highly replicated, long‐term and large‐scale survey suggests that further land‐use intensification threatens many Orthoptera and causes a consistent diversity loss. Low intensity of fertilization, infrequent mowing, and variable grazing will help to maintain a high diversity of orthopterans. The generality of our niche model approach advances studies on species' susceptibility in various study systems.

Context: Abundance and diversity of bumblebees have been declining over the past decades. To successfully conserve bumblebee populations, we need to understand how landscape characteristics affect the quantity and quality of floral resources collected by colonies and subsequently colony performance. Objectives: We therefore investigated how amount and composition of pollen collected by buff-tailed bumblebee Bombus terrestris colonies was affected by the surrounding landscape (i.e. the proportion of forest, urban, semi-natural habitats) and how they were related to colony growth. Methods: Thirty B. terrestris colonies were placed at grassland sites differing in surrounding landscape. Colonies were established in spring when availability of flowering plants was highest, and their weight gain was monitored for 1 month. We additionally recorded the quantity and compared plant taxonomic composition and nutritional quality (i.e. amino acid composition) of pollen stored. Results: Bumblebee colonies varied little in the pollen spectra collected despite differences in surrounding landscape composition. They collected on average 80 % of pollen from woody plants, with 34 % belonging to the genus Acer. Early colony growth positively correlated with total amount of woody pollen and protein collected and decreased with increasing proportions of semi-natural habitats and total amino acid concentrations. Conclusions: Our results suggest that woody plant species represent highly important pollen sources for the generalist forager B. terrestris early in the season. We further show that colony growth of B. terrestris is predominantly affected by the quantity, not quality, of forage, indicating that several abundant plant species flowering throughout the bumblebees' foraging season may cover the colonies' nutritional needs. [ABSTRACT FROM AUTHOR]

Land use and corresponding habitat loss are major drivers of local species extinctions. Orthoptera as important grassland herbivores showed different responses to land-use intensity in different studies, and the susceptibility of this group remains unclear. We sampled annually for seven years 150 temperate grassland sites across three regions in Germany, for which land-use gradients were quantified as mowing, grazing, and fertilization intensity. We analyzed the effects of land-use intensity on orthopteran diversity and community abundance. To describe species-specific responses to environmental gradients, we employed a new approach termed "niche model," coupled with a randomization procedure, which is sensitive even for rare species for which trends may otherwise be difficult to detect. Based on abundance-weighted means for each species, we quantified the species' occurrence along land-use gradients and identified potential losers and winners of intensive land use. Overall, high land-use intensity negatively affected orthopteran diversity across years and regions, corresponding to decreases with high fertilization, mowing, and grazing intensity. Intensive mowing and grazing negatively affected abundance. Diversity and abundance increased with the time after the last cut. The niche model detected 15 of 29 Orthoptera species as losers of land use, showing significantly higher abundance in grasslands with low-intensity land use. Two species were winners of high land-use intensity, whereas the remaining 12 were assigned as opportunists. Most species were losers of high fertilization intensity, followed by frequent mowing. Grazing intensity was least detrimental at the species level. Omnivorous, herbivorous, and graminivorous species did not differ in their response to land-use intensity, whereas bryovorous/lichenivorous Tetrix species showed consistently negative responses to intensive land use. Our highly replicated, long-term and large-scale survey suggests that further land-use intensification threatens many Orthoptera and causes a consistent diversity loss. Low intensity of fertilization, infrequent mowing, and variable grazing will help to maintain a high diversity of orthopterans. The generality of our niche model approach advances studies on species' susceptibility in various study systems. [ABSTRACT FROM AUTHOR]

The article presents a study aimed to evaluate the imports and exports of dissolved nitrogen from mull-type organic layers to identify control techniques of nitrogen (N) leaching among beech forests in Central Europe. The study is conducted through the continuous measurement of dissolved N fluxes with throughfall and through mull-type organic layers. The results of the study indicate that dissolved N exports from organic layers contain significan amount of throughfall-derived N.

Lichens are very sensitive to habitat changes and their species richness is likely to decline under intensive land use. Currently, a comprehensive study analyzing lichen species richness in relation to land-use types, extending over different regions and including information on habitat variables, is missing for temperate grasslands. In three German regions we studied lichen species richness in 490 plots of 16 m representing different land-use types, livestock types, and habitat variables. Due to the absence of low-intensity pastures and substrates such as woody plants, deadwood and stones, there were no lichens in the 78 plots in Schorfheide-Chorin. In the two other regions, the richness of lichen species was 45 % higher in pastures than in meadows, and 77 % higher than in mown pastures, respectively. Among the pastures, the richness of all lichen species was on average 10 times higher in sheep-grazed pastures than in the ones grazed by cattle or horses. On average, the richness of all lichen species increased by 3.3 species per additional microhabitat. Furthermore, the richness of corticolous lichens increased by 1.2 species with 10 % higher cover of woody plants, lignicolous lichen species richness increased by 4.8 species with 1 % higher cover of deadwood, and saxicolous lichen species richness increased by 1.0 species with 1 % higher cover of stones. Our findings highlight the importance of low-intensity land use for lichen conservation. In particular, the degradation of grasslands rich in microhabitats and the destruction of lichen substrates by intensification, and conversion of unfertilized pastures formerly grazed at low intensity to meadows should be avoided to maintain lichen diversity. [ABSTRACT FROM AUTHOR]

1. Arthropod communities in water-filled tree holes may be sensitive to impacts of forest management, for example via changes in environmental conditions such as resource input. 2. We hypothesized that increasing forest management intensity (ForMI) negatively affects arthropod abundance and richness and shifts community composition and trophic structure of tree hole communities. We predicted that this shift is caused by reduced habitat and resource availability at the forest stand scale as well as reduced tree hole size, detritus amount and changed water chemistry at the tree holes scale. 3. We mapped 910 water-filled tree holes in two regions in Germany and studied 199 tree hole inhabiting arthropod communities. 4. We found that increasing ForMI indeed significantly reduced arthropod abundance and richness in water-filled tree holes. The most important indirect effects of management intensity on tree hole community structure were the reduced amounts of detritus for the tree hole inhabiting organisms and changed water chemistry at the tree hole scale, both of which seem to act as a habitat filter. Although habitat availability at the forest stand scale decreased with increasing management intensity, this unexpectedly increased local arthropod abundance in individual tree holes. However, regional species richness in tree holes significantly decreased with increasing management intensity, most likely due to decreased habitat diversity. We did not find that the management-driven increase in plant diversity at the forest stand scale affected communities of individual tree holes, for example via resource availability for adults. 5. Our results suggest that management of temperate forests has to target a number of factors at different scales to conserve diverse arthropod communities in water-filled tree holes. [ABSTRACT FROM AUTHOR]

A gap still exists in published data on variation of morphological and ecological traits for common bird species over a large area. To diminish this knowledge gap, we report here average values of 99 bird species from three sites in Germany from the Biodiversity Exploratories on 24 ecological and functional traits. We present our own data on morphological and ecological traits of 28 common bird species and provide additional measurements for further species from published studies. This is a unique data set from live birds, which has not been published and is available neither from museum nor from any other collection in the presented coverage. Dataset: available as the supplementary file. Dataset license: CC-BY

Aims The biochemical defense of lichens against herbivores and its relationship to lichen frequency are poorly understood. Therefore, we tested whether chemical compounds in lichens act as feeding defense or rather as stimulus for snail herbivory among lichens and whether experimental feeding by snails is related to lichen frequency in the field. Methods In a no-choice feeding experiment, we fed 24 lichen species to snails of two taxa from the Clausilidae and Enidae families and compared untreated lichens and lichens with compounds removed by acetone rinsing. Then, we related experimental lichen consumption with the frequency of lichen species among 158 forest plots in the field (schwäbische alb, germany), where we had also sampled snail and lichen species. Important findings In five lichen species, snails preferred treated samples over untreated controls, indicating chemical feeding defense, and vice versa in two species, indicating chemical feeding stimulus. Interestingly, compared with less frequent lichen species, snails consumed more of untreated and less of treated samples of more frequent lichen species. removing one outlier species resulted in the loss of a signifi- cant positive relationship when untreated samples were analyzed separately. However, the interaction between treatment and lichen frequency remained significant when excluding single species or including snail genus instead of taxa, indicating that our results were robust and that lumping the species to two taxa was justified. our results imply lichen-feeding snails to prefer frequent lichens and avoid less frequent ones because of secondary compound recognition. This supports the idea that consumers adapt to the most abundant food source. [ABSTRACT FROM AUTHOR]

Increased warming in spring and prolonged summer drought may alter soil microbial denitrification. We measured potential denitrification activity and denitrifier marker gene abundances (nirK, nirS, nosZ) in grasslands soils in three geographic regions characterized by site-specific land-use indices (LUI) after warming in spring, at an intermediate sampling and after summer drought. Potential denitrification was significantly increased by warming, but did not persist over the intermediate sampling. At the intermediate sampling, the relevance of grassland land-use intensity was reflected by increased potential N2O production at sites with higher LUI. Abundances of total bacteria did not respond to experimental warming or drought treatments, displaying resilience to minor and short-term effects of climate change. In contrast, nirS- and nirK-type denitrifiers were more influenced by drought in combination with LUI and pH, while the nosZ abundance responded to the summer drought manipulation. Land-use was a strong driver for potential denitrification as grasslands with higher LUI also had greater potentials for N2O emissions. We conclude that both warming and drought affected the denitrifying communities and the potential denitrification in grassland soils. However, these effects are overruled by regional and site-specific differences in soil chemical and physical properties which are also related to grassland land-use intensity. [ABSTRACT FROM AUTHOR]

Large dead wood is an important structural component of forest ecosystems and a main component of forest carbon cycles. CO2 emissions from dead wood can be used as a proxy for actual decomposition rates. The main drivers of CO2 emission rates for dead wood of temperate European tree species are largely unknown. We applied a novel, closed chamber measurement technique to 360 dead wood logs of 13 important tree species in three regions in Germany. We found that tree species identity was with 71% independent contribution to the model (R² = 0.62) the most important driver of volume-based CO2 emission rates, with angiosperms having on average higher rates than conifers. Wood temperature and fungal species richness had a positive effect on CO2 emission rates, whereas wood density had a negative effect. This is the first time that positive fungal species richness-wood decomposition relationship in temperate forests was shown. Certain fungal species were associated with high or low CO2 emission rates. In addition, as indicated by separate models for each tree species, forest management intensity, study region, and the water content as well as C and N concentration of dead wood influenced CO2 emission rates. [ABSTRACT FROM AUTHOR]

Among saproxylic beetles, many early colonizers prefer particular host species. Ranking of preferred hosts of local saproxylic beetle communities is critical for effective dead-wood management in forests, but is rarely done because experiments with numerous tree species are labour and cost intensive., We analysed the host preference of local saproxylic beetle communities on logs of 13 tree species in relation to management (unmanaged and managed beech stands, conifer plantations on natural beech sites) in three regions of Germany during the most critical period for host specificity, that is the first two years after harvesting. Hosts were ranked quantitatively based on the ordinal ranking of hosts by single beetle species, which in turn was based on the variation in beetle abundance. First, we employed a Bradley-Terry model in which ranking was derived from paired comparisons of host trees. Then, a model-based recursive partitioning of the Bradley-Terry model tested whether host preference of beetle communities is affected by stand management, region and decay progress of dead wood., Our results indicated that beetle communities overall avoided logs of Fraxinus, Pseudotsuga, Larix and Tilia, and Carpinus ranked highest in preference . Carpinus also ranked highest for communities of broadleaf specialists; Picea abies ranked highest for communities of conifer specialists. Model-based recursive partitioning revealed that ranking of local hosts in conifer stands differed from that of broadleaf stands, and that ranking of hosts in broadleaf stands differed between regions, but only in the first year for both., Synthesis and applications. Early-colonizing saproxylic beetle communities vary locally in their choice of host trees. Therefore, forest managers should focus on the enrichment of dead wood of regional tree species and tree species of the local stand to successfully promote early-colonizing beetle. [ABSTRACT FROM AUTHOR]

The effects of management on insect communities have been studied in several forest ecosystems, although the consequences for single potential pests are only known for a few species. The present study investigated whether forest management affects the infestation of European beech trees by the beech scale Cryptococcus fagisuga., We assessed the densities of C. fagisuga on a total of 520 trees ( Fagus sylvatica) at 104 forest sites, representing three main types of beech forest management intensity across three regions in Germany., The infestation rates on beech trees were 16% in the South- West, 20% in the Centre and 35% in the North- East of Germany, although the rates per plot did not differ significantly among regions. No significant differences between unmanaged beech, managed even-aged beech and managed uneven-aged beech forests were found because of high variability in beech scale infestation observed among forest sites and within forest management types. Highest infestation rates occurred on widely dispersed mature trees within thickets with shelterwood stage and lowest infestation rates occurred on young beech trees in the thicket stage., The results of the present study suggest that the infestation rates of C. fagisuga on beech depend on tree age and canopy openness rather than on management intensity. [ABSTRACT FROM AUTHOR]