Biodiversity and ecosystem functions are highly interdependent: systems richer in species often exhibit more intense ecological processes and greater resilience to disturbances. Although a positive relationship between biodiversity and ecosystem functions (BEF) has been demonstrated across all major ecosystem types and in both controlled and natural environments, the underlying mechanisms remain incompletely understood.In terrestrial ecosystems, BEF research has primarily focused on productivity and its resilience to disturbances, while other key functions—such as mortality, water use, light use efficiency, and soil respiration—have received less attention, and some processes, like soil CH₄ uptake, are still largely unexplored.To better understand how BEF interconnections vary across pedoclimatic gradients and vegetation compositions, we established the BioFUN Network, sampling more than 230 sites across Italy using a standardized protocol. The implementation of BioFUNet was made possible through the contribution of over 60 participants involved in field sampling and laboratory analyses. While the network is designed to expand and enrich its database over time, the initial campaign targeted forests (175 sites), silvopastoral systems (32), and grasslands (30).Here we present the results of the core network that focused on the main Italian forest communities, found either as pure or mixed stands: Fagus sylvatica, Quercus ilex, Quercus suber, Quercus pubescens, Picea abies, Abies alba, and Larix decidua. These were surveyed across their full pedoclimatic ranges.The survey encompassed aboveground tree structure, microhabitats, soil physicochemical properties, root traits, soil gas fluxes (CO₂, CH₄, N₂O), together with environmental DNA (eDNA) analyses from soil and litter samples. eDNA was used to characterize microbial, invertebrate, and vertebrate communities.The BioFUN design enables the quantification of how tree species mixing influences both ecosystem functioning (soil processes) and the composition of associated biodiversity. All data are stored in BioFUNBase, which also integrates complementary datasets from external sources, allowing the testing of multiple ecological hypotheses. The poster will present the first results of the campaign with a focus on the effects of tree diversity on soil gas fluxes.

Functional traits can vary in response to tree species mixing, which in turn might influence biomass production and, consequently, carbon (C) sequestration in diverse forests. However, evidence for consistent broad-scale patterns in tree trait responses, particularly regarding trait identity and their contribution to above-ground biomass outcomes, remains limited. Using data from even-aged forest stands in 11 tree diversity experiments in Europe and Brazil, encompassing 40 tree species, we estimated the influence of species mixing on above-ground biomass components (woody, litterfall and understory biomass), as well as effects of mixing on plasticity-driven changes in species- and community-level functional traits. At the community level, specific leaf area (SLA) and leaf area index (LAI) were higher in mixtures than expected values based on monocultures, while leaf nitrogen per area decreased, and leaf nitrogen per mass remained stable. SLA increases were primarily due to the response of less dominant tree species. Woody and litterfall biomass increased in mixtures, whereas understory biomass remained unchanged. At the species level, diversity-driven plastic changes were observed in multiple traits, but only SLA showed a consistent shift across species. Tree diversity effects on above-ground biomass were influenced by both functional diversity and diversity-driven trait shifts, where increased SLA and LAI enhanced woody biomass accumulation, while higher LAI in diverse stands reduced understory biomass. Together, these results show that tree species mixing alters canopy structure and light-related traits, with shifts in SLA and LAI constituting key pathways through which mixed forests accumulate more woody biomass.Read the free for this article on the Journal blog.

The NBFC Digital Platform represents the core digital infrastructure of the National Biodiversity Future Center, designed to enable data-driven governance of biodiversity and ecosystem services in Italy. It integrates heterogeneous biodiversity monitoring data, ranging from in situ ecological networks and Earth observation products to genomic, functional, and experimental datasets.Through advanced modelling frameworks, artificial intelligence, and high-performance computing (HPC) capabilities, the Platform provides a modular environment for simulating ecosystem dynamics, forecasting the impacts of climate and land-use change, and supporting restoration and conservation strategies.Its architecture connects national observatories, research infrastructures, and Living Labs, offering interactive tools for data visualisation, model coupling, and decision support. By bridging science, technology and policy, the NBFC Platform aims to establish a new paradigm of digital governance for biodiversity and ecosystem services, fostering transparent access to knowledge, reproducible research and informed decision-making across multiple spatial and temporal scales.

Efficient water management is critical in modern agriculture due to unsustainable depletion of water resources, intensified by climate change. Digital technologies such as IoT offer opportunities to optimize water use through precise, real-time assessment of water requirements. This study presents ACQUAOUNT-Farm, a real-time platform designed to assist farmers in irrigation planning across Mediterranean environments. The tool integrates on-site IoT sensors (soil moisture, water flow, weather) with a physically based model following the FAO-56 dual crop coefficient approach, embedded within a user-friendly interface. The platform requires minimal input data, providing soil moisture monitoring and scheduling capabilities suitable for non-expert users. ACQUAOUNT-Farm updates daily, reconstructing hourly soil moisture and irrigation needs up to one week ahead and generating an irrigation calendar based on crop-specific water stress thresholds. ACQUAOUNT-Farm was tested on four farms in southern Tunisia for citrus and potato crops (2024-2025). Simulated and observed soil moisture showed good agreement for three out of four farms (R² ≈ 0.65, RMSE ≈ 0.022 m³ m⁻³, MAE ≈ 0.016 m³ m⁻³), with errors below sensor accuracy (0.03 m³ m⁻³) up to two days in all farms, confirming the model's forecasting ability. Compared to farmers' practices, ACQUAOUNT-Farm indicated water savings of 63–65% for one citrus field and 80–84% for autumn potato, while spring potato showed 17–33% savings. In one citrus field, the model confirmed the farmer's deficit irrigation strategy. These results suggest that ACQUAOUNT-Farm has the potential to support farmers in Mediterranean regions in reducing water withdrawals.

Biodiversity–ecosystem function (BEF) relationships are generally positive and have been documented across nearly all ecosystem types, including marine, freshwater, grassland, and forest systems. Understanding the mechanisms that regulate these relationships offers great potential to guide ecosystem restoration and design productive, resilient ecosystems.Although agroforestry systems are inherently based on species mixtures and are widely recognized for their capacity to meet growing global food demands while providing multiple ecosystem services - such as carbon sequestration, soil protection, and biodiversity conservation - the study of BEF relationships within agroforestry remains largely underexplored. Only a limited number of biodiversity-manipulation experiments have been established globally in this sector.To address this gap, a large-scale agroforestry BEF experiment has been established at the experimental farm of the University of Sassari, managed by the Centro Biodiversità Vegetale and Innovative Agriculture units (Surigheddu, Sardinia) and funded by the National BIodiversity Future Center (NextGenerationEU). The experimental site covers approximately 10 hectares and is organized into three blocks, each consisting of 30 plots (35 m × 35 m). One of the main objectives of the experiment is to identify successful species mixtures for restoring productivity and ecosystem functioning in Mediterranean marginal lands.Nine species representing three life forms—trees, shrubs, and annuals—typical of Mediterranean drought-resistant vegetation were selected: Prunus amygdalus, Ceratonia siliqua, Olea europaea, Ficus carica, Quercus ilex (inoculated with Tuber aestivum), Punica granatum, Pistacia lentiscus, Myrtus communis, and one annual species that changes each year.All nine species are planted both as monocultures and in two-, three-, and four-species mixtures. The mixtures were designed based on either traditional associations (e.g., olive and fig) or hypothesized positive functional interactions, such as pairing deep- and shallow-rooted species to enhance resource complementarity and system resilience.This experimental device constitutes a unique Living Lab within the NBFC framework and a core node of the BEF-Italy network, providing an open platform to investigate biodiversity–functioning linkages, promote nature-based solutions, and co-design climate-resilient agroforestry systems for Mediterranean landscapes.

This presentation provides an overview of a recent initiative and large investment in biodiversity undertaken in Italy. It focuses on establishing the Italian National Biodiversity Future Center (NBFC), the first National Research and Innovation Center dedicated to biodiversity, funded through European Union funds—NextGenerationEU. The NBFC includes key actions to monitor biodiversity, enhance conservation efforts, restore ecosystems, and value terrestrial, marine, and urban biodiversity. To deal with such a complex roadmap, the NBFC is designed following the Hub&Spoke model. It comprises 6 thematic Spokes dedicated to the sea, land and wetlands, and cities, with two crosscutting spokes dedicated respectively to training, communication, knowledge sharing, innovation, and policies through international connections. A primary objective is to encourage data sharing among various institutions, organizations, and countries to foster international collaboration in biodiversity protection. The NBFC is working to create a national digital platform for data analysis and biodiversity informatics, as well as collecting biodiversity data and acting as a digital twin for monitoring and conservation. This digital platform will connect biodiversity to ecosystem functions and services. This multilevel digital platform is a vital resource for the national and international scientific community, policymakers, and organizations responsible for protecting biological diversity in various environmental contexts. All actions undertaken by the NBFC are based on the Nature-based Solutions approach, providing a wide range of options for biodiversity restoration and management. Additionally, Citizen Science initiatives contribute to the NBFC's objectives by raising public awareness about the need to understand, monitor, conserve, and restore biodiversity. The NBFC's activities also aim to promote human health and well-being. In line with the One Health approach, healthy ecosystems are essential for resilience to diseases, food security, and improved quality of life. Through this initiative, Italy aims to strengthen its commitment to safeguarding biodiversity while promoting sustainable development and ecological resilience.

Tree diversity often increases stand-level growth, but whether neighbourhood diversity effects on individual tree growth change with climatic conditions remains unclear. Here, using 852,170 records of 113,701 individuals from 129 species in 15 tree diversity experiments across four biomes, we address this knowledge gap with a synthesis of tree growth data spanning a broad climate gradient. We examine how neighbourhood-scale (defined as a focal tree and the adjacent trees) taxonomic and functional diversity effects on tree growth vary with climate, both spatially (across sites) and temporally (within sites). Increasing species richness and trait dissimilarity from monospecific to high-diversity neighbourhoods enhanced individual tree growth by 7-13% on average. The positive diversity effect increased from dry to wet climates, contrasting with most prior studies, but was unaffected by interannual climatic variation within sites. Given that tree-tree interactions are ubiquitous and likely to interact with climate in both young and old forests, our findings suggest incorporating neighbourhood diversity as a management tool to enhance forest productivity, while considering underlying mechanisms and interactions with climate, thereby facilitating targeted and site-specific climate and biodiversity benefits.

Biodiversity monitoring represents a pressing global priority, and assessing forest community composition plays a crucial role due to its influence on ecosystem functions. The spatial distribution of forest species becomes essential for understanding biodiversity dynamics, territorial planning, aiding nature conservation and enhancing ecosystem resilience amid global change. Association Rule Mining, commonly applied to other scientific contexts, is now innovatively adopted in the ecological field to explore the relationships among co-occurring plant species and extract hidden interpretable patterns, also with abiotic and biotic conditions. Multiple heterogeneous data sources were integrated through data preprocessing into a unique dataset, including georeferenced information about 151 plant species monitored within 6,784 plots across Italy and several bioclimatic indices, soil-related factors, and variables from earth observations. The Frequent Pattern Growth algorithm, used for association rule mining, provided interesting and encouraging findings, suggesting ecological rules among plant species and environmental conditions. Indeed, temperature seasonality between 650–700 and precipitation seasonality between 45–50 resulted very correlated with Picea abies (confidence = 90.9%, lift = 7.13). Patterns detected for Picea abies highlighted its ecological specificity, indicating a strong association with cold, highly seasonal environments, and particular plant communities. Some species appeared acting as community ”hubs”, frequently co-occurring with other species, suggesting ties to specific environmental or biotic conditions. These findings represent a valuable resource for future research, especially in regions with similar environmental settings and when prior ecological knowledge exists, also underlining the importance of publicly accessible, high-quality ecological data.

Mixed-species forestry is a promising approach to enhance productivity, increase carbon sequestration, and mitigate climate change. Diverse forests, composed of species with varying structures and functional trait profiles, may have higher functional and structural diversity, which are attributes relevant to a number of mechanisms that can influence productivity. However, it remains unclear whether the context-dependent roles of functional identity, functional diversity, and structural diversity can lead to a generalized understanding of tree diversity effects on stand productivity. To address these gaps, we analyzed growth data from 83,600 trees from 89 species across 21 young tree diversity experiments spanning five continents and three biomes. Results revealed a positive saturating relationship between tree species richness and stand productivity, with reduced variability in growth rates among more diverse stands. Structural equation modeling demonstrated that functional diversity mediated the positive effects of species richness on productivity. We additionally report a negative relationship between structural diversity and productivity, which decreased with increasing species richness. When partitioning net diversity effects, we found that selection effects played a dominant role in driving the overall increase in productivity in these predominantly young stands, contributing 77% of the net diversity effect. Selection effects increased with diversity in wood density. Furthermore, acquisitive species with lower wood density and higher leaf nitrogen content had higher productivity in more diverse stands, while conservative species showed neutral to slightly negative responses to species mixing. Together, these results suggest that combining acquisitive with conservative species allows acquisitive species to drive positive selection effects while conservative species tolerate competition. Thus, contrasting resource-use strategies can enhance productivity to optimize mixed-species forestry, with potential for both ecological and economic benefits.

Ensuring the sustainability of forest ecosystems requires understanding the mechanisms underlying tree growth and predicting their relative influence across taxa and environments. Functional ecology posits that variation in tree growth is related to individual differences in functional traits, which serve as proxies for resource acquisition and investment strategies. However, studies of trait-growth relationships have produced inconsistent results, likely due to unaccounted factors like interspecific interactions, ontogeny, differing leaf habit strategies, and variation in resource acquisition and allocation. We investigated the utility of key functional traits as predictors of tree height growth rates in common garden experiments in the absence of interspecific interactions. We posit that trait-growth relationships vary with age and between two groups relating to leaf habit: deciduous and evergreen species. Using data from 38 tree species planted in monoculture plots across seven sites of the International Diversity Experiment Network with Trees (IDENT) in North America and Europe, we compiled height growth rates over 9 years post-germination. We modelled growth using a Bayesian hierarchical generalized linear model incorporating four above-ground functional traits related to resource acquisition and investment: specific leaf area (SLA), wood density (WD), leaf dry matter content (LDMC) and seed mass (SM). Improvements in predictive power due to the variation of trait effects with age and leaf habit were evaluated via alternative hypothesis-driven models, using the Expected Log Pointwise Predictive Density (ELPD) as a performance measure. Trait effects on growth varied with age and leaf habit, shifting between positive and negative effects, reflecting changes in resource acquisition and investment strategies. The relationships between traits and growth were strongest during the first three growing seasons for deciduous species and during the seventh to the ninth for evergreen species. Accounting for age and leaf habit substantially improved predictive power. Synthesis. Traits are not consistently associated with tree growth rates but instead reflect dynamic resource acquisition and investment strategies over time and between deciduous and evergreen species. Despite this variability, our findings confirm the utility of functional traits to predict tree growth rates, especially when trait effects are considered to vary with age and leaf habit.

Soil respiration (SR) is a key component of terrestrial carbon-climate feedbacks, yet its seasonal dynamics in drylands remain poorly understood. In mesic ecosystems, SR is primarily temperature driven, whereas in dry-lands it shifts seasonally from temperature to moisture control as autotrophic and heterotrophic respiration become water limited during dry periods. Identifying the soil temperature at which SR transitions from temperature to moisture limitation is therefore essential for predicting SR under climate change. We examined temperature and moisture response functions of SR across forests, shrublands, and grasslands in arid and semiarid regions to determine the soil temperature threshold of SR (STTSR) and its drivers. Across sites, SR was positively correlated with mean annual precipitation, soil moisture, and soil organic carbon, while negatively correlated with soil temperature. The significant variability in the temperature thresholds of SR (STTSR) that was observed between sites (17.9 degrees C f 5.3 degrees C; mean f SD) was best explained by the mean annual temperature (MAT) at the site. Sites with higher air temperatures exhibited higher STTSR, suggesting that the compartments and metabolic processes involved in SR are adapted to local temperatures. This observed SR adaptation occurred at two different scales. Besides STTSR were positively correlated with MAT within each vegetation type, STTSR were systematically higher under short-stature vegetation types (grasslands and shrublands) compared to high-stature vegetation types (forests), suggesting that grasses and shrubs have developed the evolutionary capacity to push the STTSR to warmer temperatures and hence withstand better drought stress than trees. Our findings suggest that: (1) process-based models assuming simple linear or exponential SR-temperature relationships overestimate SR in water-limited ecosystems; and (2) projected warming and increasing water scarcity, together with shifts in vegetation dominance, may strongly modify the temperature sensitivity of SR.

Fire disturbance is a global eco-evolutionary force affecting plant species persistence and distribution. Pyrogeographic studies so far have identified pyroregions based on their similarity in climate and fire regime parameters. However, which fire-related traits tend to promote or hinder plant species persistence and distribution in different pyroregions remains underexplored. We implement a trait-based approach focusing on 38 tree species in the Mediterranean Basin (Italy), testing whether 1) species distribution across different pyroregions is associated with fire regime, 2) species in different pyroregions exhibit distinct fire-related trait values and, if so, 3) trait differences suggest better abilities to cope with fire and aridity in species distributed in more fire-prone and arid regions (e.g. thicker bark). We ran multivariate analyses (Correspondence Analysis) and linear models (Standardized Major Axis, Ordinary Least Squares) to address our goals. Findings tend to positively answer our questions, emphasizing the importance of including fire-related traits in pyroregionalization studies. Noticeably, the most fire-prone pyroregions collapse into one region from a functional perspective, with species characterized by trait values indicative of adaptations to fire and aridity. A trait-based approach may contribute to refine pyroregionalization exercises while proving useful for management purposes, such as identifying species or life histories whose traits may facilitate their persistence in the face of future, likely exacerbating, fire regimes.

Mixed-species forests are proposed to enhance tree resistance and resilience to drought. However, growing evidence shows that tree species richness does not consistently improve tree growth responses to drought. The underlying mechanisms remain uncertain, especially under unprecedented multiyear droughts. We used a network of planted tree diversity experiments to investigate how neighborhood tree diversity and species' functional traits influence individual tree responses to drought. We analyzed tree cores (948 trees across 16 species) from nine young experiments across Europe featuring tree species richness gradients (1-6 species), which experienced recent severe droughts. Radial growth response to drought was quantified as tree-ring biomass increment using X-ray computed tomography. We applied hydraulic trait-based growth models to analyze single-year drought responses across all sites and site-specific responses during consecutive drought years. Growth responses to a single-year drought were partially explained by the focal species' hydraulic safety margin (representing species' drought tolerance) and drought intensity, but were independent of neighborhood species richness. The effects of neighborhood functional diversity on growth responses shifted from positive to negative with increasing drought duration during a single growing season. Tree diversity effects on growth responses strengthened during consecutive drought years and were site-specific with contrasting directions (both positive and negative). This indicates opposing diversity effects pathways under consecutive drought events, possibly resulting from competitive release or greater water consumption in diverse mixtures. We conclude that tree diversity effects on growth under single-year droughts may differ considerably from responses to consecutive drought years. Our study highlights the need to consider trait-based approaches (specifically, hydraulic traits) and neighborhood scale processes to understand the multifaceted responses of tree mixtures under prolonged drought stress. This experimental approach provides a robust framework to test biodiversity-ecosystem functioning (BEF) relationships relevant for young, planted forests under increased drought stress.

Tree diversity influences litter decomposition both directly, through changes in litter quality and composition, and indirectly, by altering the local decomposition environment (LDE). However, the role of the LDE in shaping litter decomposition rates remains less explored than the direct effects. A standardized decomposition experiment using cellulose and wood substrates was conducted over the course of a year across seven tree diversity experiments in Europe and North America to explore how tree diversity, through its influence on the LDE, impacts decomposition rates. Tree functional diversity enhanced the decomposition rate of high‐quality substrate (cellulose) but had no effect on the decomposition rate of low‐quality substrate (wood). The impact of LDE was context‐dependent, with decomposition rates being highest under favourable climatic conditions, such as moderate temperatures and high precipitation. Contrary to the common assumption that litter decomposes faster in broadleaved and arbuscular (AM)‐dominated stands, our findings show that decomposition was faster in mixtures containing coniferous species and ectomycorrhizal (EM)‐associated trees, suggesting that LDE plays a larger role than initially thought. Synthesis . This study highlights the crucial role of LDE in shaping decomposition rates. While tree functional diversity generally enhances decomposition under favourable climatic conditions, LDE played a more significant role than previously recognized in EM stands, suggesting that faster decomposition rates in AM stands are primarily due to litter quality. These findings emphasize the context‐dependent nature of decomposition and the importance of considering LDE in understanding how tree diversity influences decomposition processes.

Rainfall data is probably one of the longest-recorded climatic parameters in Lebanon. On the central coast of Lebanon, the Beirut weather station started collecting rainfall data in 1876. However, the recorded data is not available at one data provider source. Published data is found in historical documents but it reaches the early 1970s and then appears a data gap till 1990. Still the data is available, but it might be found to be saved privately. This study investigated the SPI variability on annual time scale between the years 1876 and 2021. The SPI was computed using R-Stat software to compare every year between 1876 and 2021. The majority (about 70% of the years) of the years are near normal in the precipitation rate. The Standardized Precipitation Index (SPI) demonstrated a normal distribution of years. Dry and wet years constitute about 15% of the total 146 years (1876-2021). Extremely dry years might appear in two consecutive years between 50 to 60 years count. After 1991, there were no wet years it was only near normal and few dry years. The last 30 years showed a trend of increasing drought years without any occurrence of wet years. This study demonstrated the importance of keeping records of at least rainfall data and it must be recorded on a daily basis or intensity on time. It is highly important on a managerial basis and for water security reasons to understand the drought event occurrence and investigate the changes in rainfall rates. Climate change scenarios always forecast a decrease in rainfall rates which will not appear without such studies.

Increasing tree diversity is considered a key management option to adapt forests to climate change. However, the effect of species diversity on a forest's ability to cope with extreme drought remains elusive. In this study, we assessed drought tolerance (xylem vulnerability to cavitation) and water stress (water potential), and combined them into a metric of drought-mortality risk (hydraulic safety margin) during extreme 2021 or 2022 summer droughts in five European tree diversity experiments encompassing different biomes. Overall, we found that drought-mortality risk was primarily driven by species identity (56.7% of the total variability), while tree diversity had a much lower effect (8% of the total variability). This result remained valid at the local scale (i.e within experiment) and across the studied European biomes. Tree diversity effect on drought-mortality risk was mediated by changes in water stress intensity, not by changes in xylem vulnerability to cavitation. Significant diversity effects were observed in all experiments, but those effects often varied from positive to negative across mixtures for a given species. Indeed, we found that the composition of the mixtures (i.e., the identities of the species mixed), but not the species richness of the mixture per se, is a driver of tree drought-mortality risk. This calls for a better understanding of the underlying mechanisms before tree diversity can be considered an operational adaption tool to extreme drought. Forest diversification should be considered jointly with management strategies focussed on favouring drought-tolerant species.

Plant diversity effects on community productivity often increase over time. Whether the strengthening of diversity effects is caused by temporal shifts in species-level overyielding (i.e., higher species-level productivity in diverse communities compared with monocultures) remains unclear. Here, using data from 65 grassland and forest biodiversity experiments, we show that the temporal strength of diversity effects at the community scale is underpinned by temporal changes in the species that yield. These temporal trends of species-level overyielding are shaped by plant ecological strategies, which can be quantitatively delimited by functional traits. In grasslands, the temporal strengthening of biodiversity effects on community productivity was associated with increasing biomass overyielding of resource-conservative species increasing over time, and with overyielding of species characterized by fast resource acquisition either decreasing or increasing. In forests, temporal trends in species overyielding differ when considering above- versus belowground resource acquisition strategies. Overyielding in stem growth decreased for species with high light capture capacity but increased for those with high soil resource acquisition capacity. Our results imply that a diversity of species with different, and potentially complementary, ecological strategies is beneficial for maintaining community productivity over time in both grassland and forest ecosystems.

Enhancing tree diversity may be important to fostering resilience to drought-related climate extremes. So far, little attention has been given to whether tree diversity can increase the survival of trees and reduce its variability in young forest plantations. We conducted an analysis of seedling and sapling survival from 34 globally distributed tree diversity experiments (363,167 trees, 168 species, 3744 plots, 7 biomes) to answer two questions: (1) Do drought and tree diversity alter the mean and variability in plot-level tree survival, with higher and less variable survival as diversity increases? and (2) Do species that survive poorly in monocultures survive better in mixtures and do specific functional traits explain monoculture survival? Tree species richness reduced variability in plot-level survival, while functional diversity (Rao's Q entropy) increased survival and also reduced its variability. Importantly, the reduction in survival variability became stronger as drought severity increased. We found that species with low survival in monocultures survived comparatively better in mixtures when under drought. Species survival in monoculture was positively associated with drought resistance (indicated by hydraulic traits such as turgor loss point), plant height and conservative resource-acquisition traits (e.g. low leaf nitrogen concentration and small leaf size). Synthesis. The findings highlight: (1) The effectiveness of tree diversity for decreasing the variability in seedling and sapling survival under drought; and (2) the importance of drought resistance and associated traits to explain altered tree species survival in response to tree diversity and drought. From an ecological perspective, we recommend mixing be considered to stabilize tree survival, particularly when functionally diverse forests with drought-resistant species also promote high survival of drought-sensitive species. Rising climate extremes, such as drought, can cause major uncertainty in the survival of young trees. Tree diversity can reduce survival variability and stabilize tree survival. Functionally diverse communities with drought-tolerant species can promote the survival of drought-sensitive species.image

Tree diversity can promote both predator abundance and diversity. However, whether this translates into increased predation and top-down control of herbivores across predator taxonomic groups and contrasting environmental conditions remains unresolved. We used a global network of tree diversity experiments (TreeDivNet) spread across three continents and three biomes to test the effects of tree species richness on predation across varying climatic conditions of temperature and precipitation. We recorded bird and arthropod predation attempts on plasticine caterpillars in monocultures and tree species mixtures. Both tree species richness and temperature increased predation by birds but not by arthropods. Furthermore, the effects of tree species richness on predation were consistent across the studied climatic gradient. Our findings provide evidence that tree diversity strengthens top-down control of insect herbivores by birds, underscoring the need to implement conservation strategies that safeguard tree diversity to sustain ecosystem services provided by natural enemies in forests.