The homogenization of temperate forests due to intensive management has led to biodiversity loss at local and landscape scales, threatening species persistence and ecosystem functions. However, experimental evidence on how structural heterogeneity among forest patches influences diversity at the landscape scale is lacking. Here, we test whether enhancing structural heterogeneity, via diverse deadwood enrichment and canopy gap creation treatments (Enhancement of Structural Beta Complexity, ESBC), can increase hoverfly diversity within landscapes and elucidate the contributions of local (α) diversity enrichment and turnover (β‐diversity) to this effect. We conducted a large‐scale forest experiment in 11 regions across Germany. Each region included two districts, representing small forest landscapes. In one district, we implemented patches with ESBC treatments, while in the other, serving as the control, we established patches without ESBC. Hoverflies were sampled in three seasonal intervals and across, in total, 234 forest patches (50 × 50 m; ESBC: 117, Control: 117) using pan traps. We applied a new integrative meta‐analytic framework that incorporates sample completeness to quantify taxonomic, functional, and phylogenetic diversity (TD, FD, PD) using Hill numbers at α, β, and γ scales. All three γ‐diversity dimensions—TD, FD and PD—were significantly higher in structurally heterogeneous forest landscapes than in homogeneous ones. The strongest effects were observed for TD, indicating functional and phylogenetic redundancy among species. Effect sizes declined with increasing order of Hill numbers, suggesting that rare species benefit most from structural heterogeneity. In most regions, γ‐diversity gains were driven by increases in α‐diversity rather than β‐diversity, highlighting the importance of interventions to increase local structural complexity. However, several regions also showed elevated β‐diversity, indicating context‐dependent effects of spatial heterogeneity. Synthesis and applications . Our results provide the first experimental evidence that enhancing structural heterogeneity at the landscape scale can restore multidimensional hoverfly diversity in temperate forests. They underscore the management value of ESBC as a scalable tool to restore biodiversity, increase ecological resilience and counteract biotic homogenization in production forests.

The diversity of resources, such as plants or dung of different mammal species, is an essential basis for the diversity of consumers at higher trophic levels. Here, animal carcasses provide an ephemeral and unpredictable resource of high nutrient content used by microbes, insects and vertebrates. While succession stage or season have already been identified as important for the composition and diversity of scavengers, the role of the carrion species is, compared to other necromass resources such as deadwood, not well understood. In this study, we investigated the role of ten mammal carrion species for the diversity of fungi, bacteria, Dipterans, Coleoptera and vertebrates. To do so, we exposed 100 carcasses of ten vertebrate species with varying body sizes in a low-mountain range area (Bavarian Forest National Park, Bavaria, Germany). To quantify the role of carrion species identity on the carcass necrobiome groups, we used sample coverage standardized diversity estimates of α-, β- and γ-diversity and uniqueness in composition. Despite a range in carcass size from 0.04 kg (single stoat carcass) to >100 kg (single red deer carcass), we found no significant differences in α- and β-diversity, except for bacteria. Thus, the highest γ-diversity was found in small-sized carrion species for vertebrate scavengers (stoat) and fungi (marten), and in medium-sized species for Coleoptera (beaver), bacteria (red fox) and Diptera (red fox). However, carcass size alone did not explain diversity. The uniqueness of Coleoptera was highest for beaver carcasses, while all other groups showed the highest uniqueness for stoat. Our findings suggest that particular small and medium-sized carcasses can make an important contribution to necrobiome diversity at the landscape scale, although the mechanisms underlying these patterns and their management implications require further studies.

Climate change influences the average global temperature and seasonality of our planet, therefore affecting animals' phenology. Insects have been found to show longer development times and increased growth rates at higher temperatures, with their developmental stages also being influenced by light availability. To disentangle the effects of temperature and light on their development and growth, we reared larvae of the two moth species Orthosia gothica (Linnaeus, 1758) and Orthosia cerasi (Fabricius, 1775) under four conditions, consisting of two ambient temperatures, namely 15 and 20 degrees C, and two different light cycles, namely 24 h of darkness and 12 h of light followed by 12 h of darkness. During the growth of the larvae, their biomass and size were measured repeatedly, and the pupation date of the larvae was recorded. We predicted that both higher temperature and light availability would have a positive effect on both the larvae's growth and development time. Our experiment showed that larvae of both species developed significantly faster at 20 degrees C. However, light availability had opposing effects on larval growth: it promoted final biomass and pupation date in O. gothica, but had negative effects on O. cerasi. These results support the idea that increasing temperatures will generally promote larval development and growth in moths. However, our findings also show that even closely related species can exhibit contrasting responses to light availability, suggesting that the influence of photoperiod on larval development is species-specific and may be linked to ecological or behavioural traits.

Understanding how landscape composition influences biodiversity is a central objective of landscape ecology. Because species respond to environmental conditions across different spatial scales, landscape effects are inherently scale-dependent, making the identification of ecologically relevant spatial scales essential for robust analyses of patterns in insect communities. We investigated the spatial scale at which landscape variables across habitats best explain insect biomass and diversity of (I) whole insect communities, (II) different taxonomic and functional groups and (III) tested whether empirically identified optimum scales of effect support common assumptions regarding the mobility and the trophic level of taxonomic groups. We quantified insect communities in gradients of land-use intensity and climate using data from 1293 Malaise trap samples from 179 plots in southern Germany to analyze the variance explained by environmental factors at different radii around sampling sites. We estimate the respective scale of effect for total insect biomass and diversity, as well as for different taxa and functional groups, using sample coverage standardized measures for diversity and a novel approach to estimate biomass for subgroups via sequencing reads. We find that the scale of effect of landscape variables differed between insect biomass and diversity. Overall diversity, as well as the diversity of most subgroups, was best explained by local habitat conditions (100—500 m). In contrast, although local conditions also contributed to explaining variation in overall biomass, larger scales (1500—2000 m) provided the strongest explanatory power. However, patterns differed between rare and dominant species. In addition, we could not confirm common assumptions with respect to species mobility or trophic level. Our findings highlight the importance of a thorough selection of the landscape scale when assessing diversity and biomass variables or taxon-specific groups and provide suggestions for the most suitable scale to be selected depending on the target variable under study in insect community research.

Effective conservation and restoration rely on understanding how biodiversity responds to environmental change. Centuries of wood production have simplified forest structure and reduced biodiversity. In a large-scale, replicated landscape experiment, we tested how restoring structural complexity through canopy gaps and deadwood increases the diversity of bats and birds, both flying insectivorous vertebrates, across spatial scales. We compared diversity between structurally heterogeneous and homogeneous temperate beech forests across 11 experimental landscapes in Germany. Both taxa were recorded using autonomous acoustic monitoring and automatic species identification. We quantified taxonomic, functional, and phylogenetic diversity within forest patches (α-diversity), among patches (β-diversity), and across the landscape (γ-diversity). Our experimental enhancement of structural complexity increased γ-diversity for both taxa but through distinct mechanisms. In bats, increases in γ-diversity were primarily driven by β-diversity, indicating greater dissimilarity in assemblages among patches, while γ-diversity in birds only increased through local gains in α-diversity. Bat diversity increases were mainly taxonomic, suggesting functional similarity to control assemblages, whereas birds showed the highest gains in functional diversity, indicating greater trait dissimilarity in heterogeneous forests. These differences likely reflect variation in spatial ecology, with bats responding more to spatially distributed heterogeneity within landscapes, while birds benefit from increasing local habitat complexity. Our results provide evidence that γ-diversity can be shaped by different mechanisms, indicating that forest restoration must be taxon specific and scale dependent to effectively enhance biodiversity.

Volatile organic compounds (VOCs) create invisible chemical landscapes that influence ecosystem processes. Yet whether VOC β-diversity (i.e., variability in VOC composition between patches) responds to structural heterogeneity and reflects silvicultural habitat management remains unclear. In a large field experiment, we quantified how enhanced structural beta complexity (ESBC) affects VOC β-diversity patterns and investigated potential drivers and ecological effects in temperate production forests. We sampled VOCs in ambient forest air using Tenax/Carboxen adsorbent traps at forest floor and 1 m heights across 234 treatment and control forest patches in six German regions. We analyzed VOCs via thermal desorption-gas chromatography mass-spectrometry (TD-GCMS) and examined environmental drivers including deadwood characteristics, canopy cover, tree species dissimilarity, and herb layer dissimilarity. We tested potential ecological relevance by analyzing saproxylic beetle community responses. VOC β-diversity increased significantly at 1 m height in heterogeneous forests compared to homogeneous forests, but we found no significant change at the forest floor. Deadwood volume and deadwood structural diversity, rather than canopy openness, were identified as the main drivers of increasing VOC β-diversity. Dissimilarity in beetle community composition was associated with VOC β-diversity, but only for forest floor VOCs, suggesting these chemical patterns may correlate with variables beetles respond to. Our findings suggest that volatile β-diversity represents an overlooked dimension of habitat heterogeneity, one that creates invisible chemical heterogeneity influencing inter- and intra-species interactions and ecosystem processes. We demonstrate that enhancing forest heterogeneity through deadwood retention increases both structural heterogeneity and volatile β-diversity.

Although habitat heterogeneity is known to enhance local species diversity, the effects of management-driven structural heterogeneity on understorey plant communities across spatial scales remain poorly understood, despite their crucial role for forest biodiversity and ecosystem functioning. To analyse how forest understorey plant communities respond to an enhancement of structural heterogeneity in managed forests, we established 11 experimental sites consisting of two paired forest landscapes, an untreated homogenous control and a treatment district (ESBC, Enhancement of Structural Beta-Complexity). In treatment districts, structural heterogeneity was enhanced through different combinations of local patch-scale manipulations of light and deadwood features, leading to greater between-patch heterogeneity at the landscape scale. We performed a meta-analysis across these 11 sites using a Hill-Chao number and sample coverage standardisation framework. Gamma diversity increased across taxonomic, functional and phylogenetic facets in structurally heterogeneous forests (ESBC districts) via higher alpha diversity. This effect was positively associated with heterogeneity in light availability between forest patches, but not with their mean light availability. In contrast, we found no evidence supporting that species turnover among patches (i.e. beta diversity) significantly contributes on average to the observed increase in gamma diversity. However, both the direction and magnitude of beta diversity responses varied substantially among study sites. On average, structurally heterogeneous forests supported higher species richness for both open and closed forest habitat species. Synthesis and applications. Our findings highlight the benefits of enhancing structural heterogeneity for understorey plant diversity in managed forest landscapes. Specifically, management strategies that create a spatial mosaic of interventions, such as combining single-tree removal with gap felling, can increase the variety of light niches among forest patches, thereby supporting the conservation of a wide range of understorey plant species, including forest specialists.

Most production forests are managed primarily for timber production, leading to homogenous forests at landscape scale and reduced biodiversity. To explore whether silviculturally enhanced forest structural heterogeneity can promote biodiversity at landscape scale, we conducted a large-scale experiment in eight German forests. We manipulated structural beta complexity, i.e., the heterogeneity of structural elements between forest patches, by experimentally introducing variation in canopy cover and different types of deadwood across 156 patches of 50 x 50 m each, to investigate its effects on biodiversity. Here we analyzed the response of soil nematode communities to heterogenization by assessing taxonomic and functional diversity across patch (alpha-diversity), site (gamma-diversity), and between-patch (beta-diversity) scales using Hill-Chao numbers as diversity indices. Additionally, we tested whether environmental variables correlate with nematode diversity responses. Our results show that functional diversity is more responsive than taxonomic diversity. Increases in beta-diversity of common and dominant functional groups occurred simultaneously with declines in alpha- and gamma-diversity. This pattern indicates that local community dissimilarity can rise without an increase in overall landscape-level richness and suggests a shift toward more specialized nematode communities in response to the interventions. Moreover, we found that certain site-specific conditions, such as soil texture and understory plant biomass, correlated with these effects. Overall, our findings reveal complex, scale-dependent responses of nematode diversity to changes in aboveground forest structure and highlight the need to further investigate the context dependence of forest biodiversity management to provide informed recommendations. This study represents an important first step toward understanding how to increase soil beta-diversity through enhanced forest structural heterogeneity at management-relevant (i.e., landscape level) spatial scales.

Above-ground and below-ground interactions are essential for the assembly of forest communities and the maintenance of multiple ecosystem functions. However, there is limited understanding of how above-ground plant and below-ground soil microbial communities are associated across different climatic zones and along environmental gradients. Using comprehensive inventory data from 186 permanent plots along elevation gradients across three climate zones (subtropical, temperate-subtropical and temperate mountain forests), we examined the diversity associations between different groups of plants (woody and herbaceous) and soil microbes (fungi and bacteria). Associations between soil fungi and plants were stronger than those between soil bacteria and plants, particularly at the beta diversity level. Moreover, we observed that associations between soil microbes and plants were more pronounced in forests at low latitudes and intermediate elevations, and were sensitive to local abiotic conditions, including climatic and edaphic variables. Synthesis: These findings suggest that variation in climatic and edaphic conditions along environmental gradients is associated with differences in the strength of above-ground-below-ground associations. In addition to direct effects of climate change, plant and soil microbial communities could thus be indirectly affected via their biotic interactions under changing environmental conditions. This could have far-reaching consequences for community assembly and ecosystem functioning.

Climate warming threatens the persistence of insect populations by forcing them to adjust their phenology-responses that may be constrained by local adaptation and involve physiological trade-offs. We investigated how hymenopterans with contrasting seasonal phenology and from different climates adjust their emergence timing under current and projected future climates. We also examined the consequences of these adjustments on body mass at emergence as a key fitness trait. We analysed the emergence timing of 14,921 individuals from five cavity-nesting bee and wasp species exposed to cold, warm and hot post-winter temperature treatments in a common garden experiment to identify potential genotype-environment interactions. Insects had developed at 161 sites of origin across southern Germany covering multi-annual mean temperatures (MAT) of 5.9 to 10 degrees C and differing in the temperature deviation (Delta T) that insects experienced during development in the pre-emergence year relative to MAT. Emergence timing was highly plastic to post-winter temperatures, with insects emerging earlier in warmer treatments. However, emergence was modulated by MAT and Delta T, suggesting genetic adaptation to long-term climatic conditions and adjustments to short-term temperature deviations. For spring-emerging species, individuals from sites with higher MAT and warmer treatments emerged the earliest (cogradient variation). In contrast, the latest summer-emerging species exhibited countergradient variation: in the cold treatment, individuals from higher MAT emerged later than those from lower MAT. In spring species, mass loss was higher in warmer post-winter treatments, with the strongest reductions observed in cool-adapted individuals. Mass loss was particularly rapid for summer females in warmer treatments, with individuals emerging later losing up to 34% of their mass. However, body mass of summer insects was independent of MAT and Delta T. Our results demonstrate high plasticity of cavity-nesting Hymenoptera to post-winter temperatures but also suggest that local adaptation and responses to early-life temperature can compromise fitness under rapid climate changes. This large-scale experimental study highlights the complex drivers of insect emergence phenology and fitness and suggests that cool-adapted, spring-emerging species may be most vulnerable to ongoing climate warming.Read the free for this article on the Journal blog.

Insects make up the majority of all animal species, with 70% occurring in the tropics1, yet the impacts of warming on tropical insects remain highly uncertain2. This stems from sparse, taxonomically biased data on thermal tolerance of tropical insects and an incomplete understanding of the underlying physiological mechanisms3. Here we compared environmental temperatures with field-measured upper and lower thermal tolerance limits of around 2,300 insect species along Afrotropical and Neotropical elevational gradients and identified genomic signatures of thermal tolerance across the insect tree of life. We show that thermal tolerances do not proportionally track environmental temperatures but approach an asymptote in tropical lowlands. Insects at high elevations utilize plasticity to cope with rising temperatures, whereas lowland species have limited plastic abilities. Heat tolerance showed strong differences among insect orders and families, reflected in the thermal stability of proteins, suggesting that variation in thermal tolerance is founded in the fundamental protein architecture. Up to 52% of future surface temperatures and 38% of air temperatures in the Amazonian lowlands can cause heat mortality in half of the studied community. Our data suggest a limited capacity of insects in the Earth's most biodiverse regions to buffer future warming.

Metacommunity theory has expanded our understanding of how spatial dynamics and local interactions influence species communities. Different assembly archetypes, reflecting different roles of species differences, habitat differences, and dispersal have been described, but we lack empirical studies specifically in terrestrial habitats testing which archetype is most important. In a replicated design, we experimentally enhanced structural between-patch heterogeneity in homogeneous production forests and developed a statistical framework controlling for sample incompleteness to detect different metacommunity processes. Meta-analyses on > 100 K individuals of > 1.3 K beetle species showed an increase of ~60 species in heterogenized forests at γ-level promoted by increasing α-diversity consistent with the mass-effect and an increase of β-diversity by ~10% supporting species-sorting. Additionally, we tested β-deviations from random assembly as a proxy of neutral processes. Findings indicate that enhancing structural heterogeneity can shift forests from patch-dynamics dominance towards mass-effect and species-sorting, offering a promising pathway to restore biodiversity in managed landscapes.

Centuries of timber production have homogenized many forests by reducing variation in canopy density and deadwood availability, with far-reaching consequences for biodiversity and trophic interactions. Recent studies indicate that increasing structural heterogeneity through canopy gap creation and deadwood enrichment can promote biodiversity and support tree regeneration. These management practices may also influence tree performance, among others assessed by folivory and leaf fluctuating asymmetry, which indicate how well trees resist leaf damage and maintain developmental stability under environmental stress. However, it remains unknown whether such management enables trees to mitigate folivory and developmental instability, especially across macroclimatic gradients such as elevation. We conducted a large-scale experiment in Germany across 11 pairs of forests: one structurally homogeneous control forest and one experimentally heterogenized forest, where canopy gaps and deadwood were created to increase between-patch structural heterogeneity. The forests spanned an elevation gradient from 38 to 1143 m. Across all forest pairs, we sampled 19,656 leaves from 1404 European beech (Fagus sylvatica L.) trees. We quantified folivory, leaf fluctuating asymmetry, microclimatic conditions (temperature, vapour pressure deficit) and biotic pressures (predation, parasitism, competition). Experimental enhancement of structural heterogeneity reduced folivory overall but increased leaf fluctuating asymmetry. Folivory increased with elevation, while leaf fluctuating asymmetry declined, producing an inverse relationship: At low elevations, structural enhancement reduced folivory but increased asymmetry, whereas at high elevations it increased folivory but reduced asymmetry. Microclimatic variables explained variation in both folivory and leaf asymmetry more consistently than biotic pressures. These findings extend the stress-gradient framework by showing that identical management interventions can yield opposite outcomes depending on the macroclimatic gradient associated with elevation. Thus, integrating elevation and climate context into forest management seems to be crucial for maintaining the resilience of temperate forests under global change.Read the free for this article on the Journal blog.

ABSTRACT Ecophysiological rules such as the Heat Conservation and Thermal Melanism Hypotheses, the Heat Transfer Theory or Bogert's Rule predict different relationships between insect body size, colour lightness and thermal environments. Forests provide scale‐dependent thermal conditions – strong macroclimatic gradients across regions and microclimatic buffering depending on canopy density, with dense canopies producing cooler, more stable conditions and open canopies allowing higher light and heat input. Consequently, trait–environment relationships may vary accordingly. Here we test across both macro‐ and microclimatic scales whether temperature and solar radiation shape insect communities across different taxa with distinct activity periods. Location: Five forest regions across Germany. Time period: 2007–2018, non‐continuous sampling. Major taxa studied: Predominantly diurnal Coleoptera and Heteroptera and nocturnal Lepidoptera. We used linear mixed effect models to test the response of mean community values to macro‐ and micro‐climatic variables. We found smaller Coleoptera and smaller and lighter‐coloured Lepidoptera with increasing seasonal mean temperature, in line with the Heat Conservation and Thermal Melanism Hypotheses. However, increasing solar radiation became increasingly important at microclimatic scales, with consistently smaller and darker‐coloured Coleoptera and darker‐coloured Lepidoptera in forests with open canopies, in line with the Heat Transfer Theory and Bogert's Rule. Heteroptera showed only a response in body size at the macroclimatic scale. Our findings suggest that cross‐taxon community responses to macroclimate follow different mechanisms than those to microclimate and might be determined by the life history traits of the selected taxa. Further studies on arthropods with different activity periods in forests along microclimate gradients will help to further disentangle these mechanisms. Changes in macroclimate caused by climate change, along with changes in canopy cover at the microclimatic level, make understanding the mechanism how this leads to scale‐dependent environmental trait filtering and consequently affects insect communities increasingly important.

Spiders are important arthropod predators in temperate forests. Their diversity depends on structurally heterogeneous habitats offering diverse microhabitats. Yet, modern silviculture has homogenized temperate forest structure at local and landscape scales. The consequences of this homogenization for landscape-level spider diversity, however, remain largely unknown. We sampled spiders using pitfall traps across 234 patches in a large-scale, replicated field experiment at 11 forest sites across Germany. At each site, one treatment district was experimentally heterogenized through canopy gap creation, thinning and deadwood enrichment, and a second homogeneous district remained untreated as a control. We applied a novel meta-analytic framework to compare α-, β- and γ-diversity of spiders between treatment and control districts, standardized for sample coverage along Hill numbers giving increasing weight to abundance and included taxonomic, functional and phylogenetic diversity facets. We also investigated spider community assembly in response to deadwood enrichment, canopy openness and heterogeneous forest structure. Based on 18,540 spider individuals from 206 species, treatment districts exhibited significantly lower γ- and α-diversity across all diversity facets and Hill numbers, particularly when focusing on rare species (q = 0). In contrast, β-diversity increased in treatment districts for phylogenetic and functional diversity across Hill numbers (q = 0, 1, 2). The simultaneous decrease in α- and γ-diversity despite higher β-diversity renders the increase in compositional turnover insufficient to compensate for local diversity losses. Although spiders were more abundant in treatment patches, habitat filtering, rather than niche competition, shaped the community. Our findings corroborate previous results of high spider abundances but lower taxonomic and functional diversity in canopy gaps due to strong habitat filtering effects. However, we demonstrate for the first time that this lower α-diversity is linked to a lower γ-diversity despite increases in β-diversity. Homogenous forests support higher γ-diversity through greater three-dimensional canopy habitat availability. Yet, failure to account for species frequencies using Hill numbers and coverage standardization may result in a substantial underestimation of arboreal spider diversity in pitfall traps. Nonetheless, higher abundances in heterogeneous forests point towards increased prey availability and predator pressure.

In forest ecosystems, soundscape recordings are increasingly used to measure loss or shifts in biodiversity. In particular, acoustic indices can quantify the response of biodiversity to human interventions. However, most soundscape studies only use observational data, which precludes causal conclusions. To improve the use of acoustic indices as tools for conservation, experimental validation is essential. In a before-after experiment, we manipulated the canopy structural complexity of 59 broadleaf forest patches (50 m x 50 m) in Germany through silvicultural interventions, recorded their before-after soundscapes and calculated four well-established acoustic indices. The manipulation entailed a variation in logging intensity (0-33.3 % of basal area), different spatial arrangements (aggregated as gaps vs. distributed as thinnings), and the creation of standing deadwood. Linear mixed models controlling for pre-treatment levels showed increasing Soundscape Saturation and Acoustic Complexity with logging intensity particularly during the day, probably as a response of increased bird vocalization. During the night, these indices were lower in gaps, probably as a response of lower canopy insect activity in the absence of trees. We found more Events per Second, a measure of acoustic activity, in open canopy forests. None of the small-scale interventions altered the before-after synchrony of the circadian soundscape pattern, indicating no drastic shifts in the vocalizing community. Our results demonstrate that enhancing forest complexity by interventions can increase soundscape diversity in commercial forests and highlight the importance of recording the whole diurnal cycle for comprehensive insights into temperate forest soundscapes.

Tropical old-growth forests continue to decline worldwide, resulting in a huge loss of biodiversity. The extent to which the expansion of second-growth forests can counteract biodiversity loss is context-dependent and controversial. To test the recovery of bird communities along a gradient from active pastures and cacao plantations, through regenerating forest on land last used for agriculture between 1 and 38 years ago, to old-growth forest, we sampled simultaneous audio recordings from 66 plots, from which an expert identified all bird species detected at fixed time points throughout the day. The study area is characterized by typical small-scale agriculture with remnant trees in the Ecuadorian Choc & oacute; Forest. To quantify different aspects of biodiversity, we used incidence-based Hill numbers focusing on infrequent, frequent and highly frequent species in taxonomic, functional and phylogenetic diversity, considering sample coverage (an objective measure of sample completeness). Bird community composition changed with the regrowth gradient represented on the first axis of the ordination. Differences in bird communities were also very robust to changes in sample coverage. The sample coverage decreased significantly along the recovery gradient and affected the different measures of alpha diversity. Although the results controlled by sample coverage showed no change in taxonomic and phylogenetic diversity, the functional diversity of infrequent, frequent and highly frequent species decreased along the recovery gradient. Cacao plantations exhibited particularly high diversity values, highlighting the potential of these patches to support woodland and shrubland species in agriculture. Furthermore, several forest species regularly used the agricultural areas, attracted by remnant trees characteristic of the small-scale agricultural landscape in our study region. Synthesis and applications. Our results highlight the importance of standardizing biodiversity measures and incorporating beta diversity in biodiversity monitoring. We demonstrate that taxonomic, phylogenetic and functional bird diversity can be high in secondary forests within smallholder agricultural landscapes. This underscores the potential for natural forest recovery, particularly when recovery patches are embedded within a forest matrix that includes old-growth stands. Los bosques tropicales antiguos siguen disminuyendo en todo el mundo, lo que provoca una enorme p & eacute;rdida de biodiversidad. La capacidad de la expansi & oacute;n de los bosques de segundo crecimiento para contrarrestar la p & eacute;rdida de biodiversidad depende del contexto y es controvertida. Para comprobar la recuperaci & oacute;n de las comunidades de aves a lo largo de un gradiente que abarca pastos activos, plantaciones de cacao, bosques en regeneraci & oacute;n en tierras utilizadas por & uacute;ltima vez para la agricultura entre 1 y 38 a & ntilde;os atr & aacute;s, y bosques primarios, realizamos grabaciones de audio simult & aacute;neas en 66 parcelas. A partir de dichas grabaciones, un experto identific & oacute; todas las especies de aves detectadas en momentos estandarizados a lo largo del d & iacute;a. El & aacute;rea de estudio se caracteriza por la t & iacute;pica agricultura a peque & ntilde;a escala con & aacute;rboles remanentes en el bosque del Choc & oacute; ecuatoriano. Para cuantificar diferentes aspectos de la biodiversidad, utilizamos n & uacute;meros de Hill basados en la incidencia, centr & aacute;ndonos en especies poco frecuentes, frecuentes y altamente frecuentes en diversidad taxon & oacute;mica, funcional y filogen & eacute;tica, teniendo en cuenta la cobertura de la muestra (una medida objetiva de la completitud de la muestra). La composici & oacute;n de la comunidad de aves sigui & oacute; el gradiente de rebrote representado en el primer eje de la ordenaci & oacute;n. Las diferencias en las comunidades de aves tambi & eacute;n fueron robustas a los cambios en la cobertura de la muestra. La cobertura de las muestras disminuy & oacute; significativamente a lo largo del gradiente de recuperaci & oacute;n y afect & oacute; a las distintas medidas de diversidad alfa. Aunque los resultados controlados por la cobertura muestral no mostraron cambios en la diversidad taxon & oacute;mica y filogen & eacute;tica, la diversidad funcional de especies poco frecuentes, frecuentes y muy frecuentes disminuy & oacute; a lo largo del gradiente de recuperaci & oacute;n. Las plantaciones de cacao mostraron valores de diversidad particularmente elevados, lo que pone de relieve el potencial de estos parches para sustentar especies forestales y arbustivas en la agricultura. Adem & aacute;s, varias especies forestales utilizaron regularmente las & aacute;reas agr & iacute;colas, inducidas por & aacute;rboles remanentes caracter & iacute;sticos del paisaje agr & iacute;cola a peque & ntilde;a escala de nuestra regi & oacute;n de estudio. S & iacute;ntesis y aplicaciones. Nuestros resultados ponen de manifiesto la importancia de estandarizar las medidas de biodiversidad e incorporar la diversidad beta en el seguimiento de la biodiversidad. Hemos demostrado que la diversidad taxon & oacute;mica, filogen & eacute;tica y funcional de las aves puede ser alta en bosques secundarios dentro de paisajes agr & iacute;colas de peque & ntilde;a escala. Esto pone de manifiesto el potencial de recuperaci & oacute;n de los bosques naturales, en particular cuando las parcelas de recuperaci & oacute;n est & aacute;n integradas en una matriz forestal que incluye bosques antiguos.

Woody species diversity is crucial for the resilience of forests under climate change. The early stages of regeneration, particularly after canopy disturbance, shape the composition of future forest. Light availability, browsing pressure and their interactions should be key drivers of woody species diversity, biomass and density, but are not well understood due to limited experimental setups. We used exclosures in a mixed broadleaf forest with high woody diversity to protect seedlings from browsing by roe deer ( Capreolus capreolus ), the predominant ungulate in Central Europe. In a full‐factorial design, we paired 75 exclosure (fenced) and control (unfenced) plots in both closed canopy stands and experimental gaps. We measured woody regeneration 1 and 4 years after the start of the treatments. Rarefaction‐extrapolation curves revealed that diversity of common (Shannon diversity) woody species was highest in sunny and shaded exclosures (7), compared to sunny (4.5) and shaded (3.5) controls, for species that had outgrown the 130 cm browsing‐susceptible height of roe deer. Stage‐structured matrix models showed that saplings ≤20 cm had the highest probability of reaching >130 cm within 3 years in sunny exclosures (1.51%), followed by sunny controls (0.32%), shaded exclosures (0.27%) and shaded controls (0.07%). Browsing resulted in homogenized woody regeneration, particularly in forest gaps. Increasing light availability did not compensate for diversity loss by browsing. Given the densities of roe deer in the study area—typical for many Central European forests—effective population control or fencing appears essential to maintain high diversity of future forest shaping and forestry relevant woody species, especially in open forests. Synthesis and applications . Our results provide strong evidence that in the current context of increasing tree mortality and subsequent light availability, roe deer act as a keystone species. It is crucial to implement browsing protection measures and control roe deer population before or immediately after canopy disturbance. Otherwise, the rapid growth of a few dominant, browsing‐resistant woody species will significantly reduce the woody plant diversity of future forests.

Production forests are often managed primarily for timber production, leading to biotic homogenization and reduced biodiversity. To explore strategies that promote biodiversity while maintaining timber yields, we conducted a large-scale experiment in eight German forests. We manipulated structural β-complexity, i.e., the heterogeneity of structural elements across forest patches, by experimentally introducing variation in canopy gaps and different types of deadwood across 156 plots of 50 × 50 m each, to investigate its effects on forest biodiversity. We analyzed soil nematode communities, which are important bioindicators and contributors to ecosystem processes, by assessing taxonomic and functional diversity across patch (α), site (γ), and between-patch (β) scales using Hill–Chao numbers. Additionally, we tested whether environmental variables explain nematode diversity responses. Our results show that functional diversity is more responsive than taxonomic diversity, with increased β-diversity of common and frequent taxa alongside simultaneous declines in α– and γ-diversity. This pattern suggests a shift toward more specialized nematode communities in response to the intervention. Moreover, we found that site-specific conditions, such as sand content and understory biomass, modulated these effects. Overall, our findings reveal complex, scale-dependent responses of nematode diversity to aboveground forest structural changes, emphasizing the need to consider environmental context in forest biodiversity management. This study represents an important first step toward understanding and enhancing soil biodiversity at management-relevant spatial scales. ### Competing Interest Statement The authors have declared no competing interest. DFG, DFG–FZT 118, 202548816, 459717468

Based on the concept of the extended phenotype, bird nest characteristics can serve as indicators for adaptations to changing environmental conditions. We examined how the nest mass of three cavity‐nesting tit species Paridae varied across 22 mixed forests in Germany in response to elevation, canopy openness, and species body mass. We predicted that nest mass should increase with elevation and canopy openness, due to thermoregulation being more demanding in colder or warmer climatic conditions, and decrease with body mass, as larger species have greater thermoregulatory capabilities. To test these predictions and to assess the consequences of nest mass variation for reproductive success, we recorded nest mass, clutch size, and pre‐fledging brood size in 576 standardized nest boxes. Nest boxes were installed along an elevational gradient of approximately 1000 m a.s.l., either in forest gaps with fluctuating microclimatic conditions or in closed forests with buffered microclimates. We found that nest mass increased by ~ 60% along the elevational gradient, but the effect of canopy openness on nest mass was not significant, while nest mass decreased along the ranked species from the smallest Periparus ater to the medium‐sized Cyanistes caeruleus and the largest Parus major . Structural equation modeling revealed that heavier nests were associated with larger clutch sizes, which in turn resulted in larger pre‐fledging brood sizes. Altogether, our results suggest that forest tits adjust nest construction in response to macroclimatic conditions, thereby compensating for the thermoregulatory challenges posed at higher elevations and their small body size. This strategy may be critical for maintaining reproductive success in changing environments.