Francesco de Bello’s research while affiliated with Desertification Research Centre and other places

Anthropogenic biodiversity decline threatens the functioning of ecosystems and the many benefits they provide to humanity¹. As well as causing species losses in directly affected locations, human influence might also reduce biodiversity in relatively unmodified vegetation if far-reaching anthropogenic effects trigger local extinctions and hinder recolonization. Here we show that local plant diversity is globally negatively related to the level of anthropogenic activity in the surrounding region. Impoverishment of natural vegetation was evident only when we considered community completeness: the proportion of all suitable species in the region that are present at a site. To estimate community completeness, we compared the number of recorded species with the dark diversity—ecologically suitable species that are absent from a site but present in the surrounding region². In the sampled regions with a minimal human footprint index, an average of 35% of suitable plant species were present locally, compared with less than 20% in highly affected regions. Besides having the potential to uncover overlooked threats to biodiversity, dark diversity also provides guidance for nature conservation. Species in the dark diversity remain regionally present, and their local populations might be restored through measures that improve connectivity between natural vegetation fragments and reduce threats to population persistence.

Floral traits describe organs or structures directly related to plant reproduction, and they are essential to understanding plant–pollinator interactions, notably for conservation purposes. The growth of plant trait‐based approaches lies in the availability of data shared by the international research community on dedicated platforms, as well as in protocols compiled in handbooks on how to measure these traits in a standardized way. Floral traits are important pieces that are missing from these handbooks, likely due to the complexity of flower morphology. Here, we present a handbook of standardized protocols dedicated to floral traits that can be applied to a wide set of temperate plant species to quantify these traits at the scale of plant communities. The 24 floral traits are grouped into three categories: visual and olfactory cues, accessibility and resources. We also provide four additional features related to flower abundance and phenology that we recommend measuring to scale up individual species' trait values to overall plant communities. By collecting these floral traits in a standardized way, we promote applications in the context of community ecology to predict the diversity of pollinator communities, identify the effects of environmental changes and study plant–pollinator networks.

Understanding how land use affects temporal stability is crucial to preserve biodiversity and ecosystem functions. Yet, the mechanistic links between land-use intensity and stability-driving mechanisms remain unclear, with functional traits likely playing a key role. Using 13 years of data from 300 sites in Germany, we tested whether and how trait-based community features mediate the effect of land-use intensity on acknowledged stability drivers (compensatory dynamics, portfolio effect, and dominant species variability), within and across plant and arthropod communities. Trait-based plant features, especially the prevalence of acquisitive strategies along the leaf-economics spectrum, were the main land-use intensity mediators within and across taxonomic and trophic levels, consistently influencing dominant species variability. Functional diversity also mediated land-use intensity effects but played a lesser role. Our analysis discloses trait-based community features as key mediators of land-use effects on stability drivers, emphasizing the need to consider multi-trophic functional interactions to better understand complex ecosystem dynamics.

A popular approach assessing trait–environment relationships is the Community Weighted Means (CWMs) method, which evaluates changes in communities' average trait values along gradients. Recently, the use of CWM as response in general linear models have been criticized for inflated Type I errors. In some scenarios of compositional turnover along a gradient, CWM tests can provide significant results even for randomly generated traits. Null models have been proposed to correct for such effects. However, the results of analyses relating traits to the environment must be interpreted within the framework of the accepted dichotomy between species-level (observations are species) vs. community-level (observations are community parameters) analyses, like with CWM. Within this framework, Type I error rate with CWM tests should not be a priori considered inflated when community-level analysis is used to identify changes in community trait structure. On the other hand, identifying specific traits that cause species turnover, and species adaptation, is more appropriate with methods approaching the species-level analyses. Between these families of analyses, a great variety of methods exist that test different trait–environment relationships, each with different null hypotheses and ecological questions. There is no single trait–environment relationship. Using a spectrum of methods provides a comprehensive picture of the diversity of trait–environment relationships.

Questions To comprehensively understand ecological dynamics within a forest ecosystem, it is vital to explore how surrounding trees influence the growth of individual trees in a community. This study investigates the importance of biotic interactions on tree growth by examining several metrics of competitive interactions and community structure and considering three classes of intrinsic growth rates among the focal individuals: slower, intermediate, and faster‐growing trees. We also separated the focal trees based on their canopy position. Location Brazilian subtropical forests. Methods We assessed various factors related to the focal trees and their neighbors, including differences in traits, neighborhood crowding, phylogenetic distance, and overall trait composition within the community. We then ran linear mixed‐effects models to test how these different metrics influenced the growth rates of the focal trees. Results Our results indicate that phylogenetic distance is linked to higher growth. Specific leaf area (SLA), leaf area (LA), and wood density (WD) are significantly related to tree growth. Trees surrounded by neighbors with higher SLA than themselves grow better, particularly smaller trees. Similarly, taller trees with smaller LA than their neighbors grow better. Trees in the intermediary growth class grow better when they have higher WD than their neighbors. Conversely, smaller trees benefit from greater WD difference between the focal trees and their neighbors, while height difference negatively impacts faster‐growing trees. Moreover, communities with higher SLA and WD positively impact the growth of faster‐growing trees. Conclusions We conclude that the interactions between trees are mediated by their ecological differences, but the performance and responses to surrounding competitors vary along with their grow class and position within a community. This study has revealed that the tree's intrinsic growth rate mediates the effect of traits and phylogeny of surrounding trees on individual tree growth.

Aims: We introduce ReSurveyEurope — a new data source of resurveyed vegetation plots in Europe, compiled by a collaborative network of vegetation scientists. We describe the scope of this initiative, provide an overview of currently available data, governance, data contribution rules, and accessibility. In addition, we outline further steps, including potential research questions. Results: ReSurveyEurope includes resurveyed vegetation plots from all habitats. Version 1.0 of ReSurveyEurope contains 283,135 observations (i.e., individual surveys of each plot) from 79,190 plots sampled in 449 independent resurvey projects. Of these, 62,139 (78%) are permanent plots, that is, marked in situ, or located with GPS, which allow for high spatial accuracy in resurvey. The remaining 17,051 (22%) plots are from studies in which plots from the initial survey could not be exactly relocated. Four data sets, which together account for 28,470 (36%) plots, provide only presence/absence information on plant species, while the remaining 50,720 (64%) plots contain abundance information (e.g., percentage cover or cover–abundance classes such as variants of the Braun-Blanquet scale). The oldest plots were sampled in 1911 in the Swiss Alps, while most plots were sampled between 1950 and 2020. Conclusions: ReSurveyEurope is a new resource to address a wide range of research questions on fine-scale changes in European vegetation. The initiative is devoted to an inclusive and transparent governance and data usage approach, based on slightly adapted rules of the well-established European Vegetation Archive (EVA). ReSurveyEurope data are ready for use, and proposals for analyses of the data set can be submitted at any time to the coordinators. Still, further data contributions are highly welcome.

1. How biodiversity underpins ecosystem resistance (i.e. ability to withstand environmental perturbations) and recovery (i.e. ability to return to a pre-perturbation state), and thus, stability under extreme climatic events is a timely question in ecology. To date, most studies have focussed on the role of taxonomic diversity, neglecting how community functional composition and diversity beget stability under exceptional climatic conditions. In addition, land use potentially modulates how biodiversity and ecosystem functions respond to extreme climatic conditions. 2. Using an 11-year time-series of plant biomass from 150 permanent grassland plots spanning a gradient of land-use intensity, we examined how taxonomic and functional components of biodiversity affected resistance and recovery of biomass under extreme drought. 3. The association between biodiversity, land use and biomass varied across years, especially in the driest years. Species-rich or functionally diverse communities (associated with low land-use intensity) buffered extreme droughts better, while species-poor communities or those dominated by fast-growing species (associated with high land-use intensity) had higher recovery capabilities after a moderate-to-extreme drought. 4. Synthesis. Our results show that plant community functional and taxonomic components determine grasslands resistance and recovery under moderate-to-extreme drought. In turn, this points to the importance of designing landscapes with both extensively and intensively managed grasslands. Functionally or taxonomically rich communities (favoured under low land-use intensity) would preserve biomass under extreme droughts, whereas species-poor or fast-growing communities (favoured by high land-use intensity) would restore biomass after extreme droughts.

Aim Identifying the drivers of ecological stability is critical for ensuring the maintenance of ecosystem functioning and services, particularly in a changing world. Different ecological mechanisms by which biological communities stabilize ecosystem functions (i.e. “stabilizing effects”) have been proposed, yet with various theoretical expectations and debated conclusions. Here we propose a unified framework that aims at reconciling, and combining, different approaches to reliably test the strength of three stabilizing effects on the temporal constancy of ecosystem functions: the effects of (a) dominant species, (b) species asynchrony, and (c) diversity. Innovation Compared to existing developments the approach allows, for the first time, disentangling these three stabilizing effects at the level of individual communities. So far this was not possible, and conclusions depended on indirect tests and comparative analyses across communities. We also propose a graphical representation of the relative contributions of the three stabilizing effects on a ternary plot, allowing us to easily compare communities sampled in various ecological contexts in a standardized space. Main conclusions Our study answers the current need for a unified framework to link theoretical concepts on the temporal stability of ecological communities to data analysis. The present development promises flexible tests for a deeper understanding of the ecological stabilization of biodiversity and the relative importance of its components.