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The search for simple principles that underlie the spatial structure and dynamics of plant communities is a long-standing challenge in ecology. In particular, the relationship between species coexistence and the spatial distribution of plants is challenging to resolve in species-rich communities. Here we present a comprehensive analysis of the spatial patterns of 720 tree species in 21 large forest plots and their consequences for species coexistence. We show that species with low abundance tend to be more spatially aggregated than more abundant species. Moreover, there is a latitudinal gradient in the strength of this negative aggregation–abundance relationship that increases from tropical to temperate forests. We suggest, in line with recent work, that latitudinal gradients in animal seed dispersal and mycorrhizal associations may jointly generate this pattern. By integrating the observed spatial patterns into population models8, we derive the conditions under which species can invade from low abundance in terms of spatial patterns, demography, niche overlap and immigration. Evaluation of the spatial-invasion condition for the 720 tree species analysed suggests that temperate and tropical forests both meet the invasion criterion to a similar extent but through contrasting strategies conditioned by their spatial patterns. Our approach opens up new avenues for the integration of observed spatial patterns into ecological theory and underscores the need to understand the interaction among spatial patterns at the neighbourhood scale and multiple ecological processes in greater detail. 

Thanks to substantial support for biodiversity data mobilization in recent decades, billions of occurrence records are openly available, documenting life on Earth and enabling timely research, awareness raising, and policy-making. Initiatives across local to global scales have been separately funded to serve different, yet often overlapping audiences of data users, and have developed a variety of platforms and infrastructures to meet the needs of these audiences. The independent progress of biodiversity data providers has led to innovations as well as challenges for the community at large as we move towards connecting and linking a diversity of information from disparate sources as Digital Extended Specimens (DES). Recognizing a need for deeper and more frequent opportunities for communication and collaboration across the globe, an ad-hoc group of representatives of various international, national, and regional organizations have been meeting virtually since 2020 to provide a forum for updates, announcements, and shared progress. This group is provisionally named International Partners for the Digital Extended Specimen (IPDES), and is guided by these four concepts: Biodiversity, Connection, Knowledge and Agency. Participants in IPDES include representatives of the Global Biodiversity Information Facility (GBIF), Integrated Digitized Biocollections (iDigBio), American Institute of Biological Sciences (AIBS), Biodiversity Collections Network (BCoN), Natural Science Collections Alliance (NSCA), Distributed System of Scientific Collections (DiSSCo), Atlas of Living Australia (ALA), Biodiversity Information Standards (TDWG), Society for the Preservation of Natural History Collections (SPNHC), National Specimen Information Infrastructure of China (NSII), and South African National Biodiversity Institute (SANBI), as well as individuals involved with biodiversity informatics initiatives, natural science collections, museums, herbaria, and universities. Our global partners group strives to increase representation from around the globe as we aim to enable research that contributes to novel discoveries and addresses the societal challenges leading to the biodiversity crisis. Our overarching mission is to expand on the community-driven successes to connect biodiversity data and knowledge through coordination of a globally integrated network of stakeholders to enable an extensible technical and social infrastructure of data, tools, and working practices in support of our vision. The main work of our group thus far includes publishing a paper on the Digital Extended Specimen (Hardisty et al. 2022), organizing and hosting an array of activities at conferences, and asynchronous online work and forum-based exchanges. We aim to advance discussion on topics of broad interest to our community such as social and technical capacity building, broadening participation, expanding social and data networks, improving data models and building a backbone for the DES, and identifying international funding solutions. This presentation will highlight some of these activities and detail progress towards a roadmap for the development of the human network and technical infrastructure necessary to support the DES. It provides an opportunity for feedback from and engagement by stakeholder communities such as TDWG and other initiatives with a focus on data standards and biodiversity informatics, as we solidify our plans for the future in support of integrated and interconnected biodiversity data and credit for those doing the work. 

Abstract AimWhile the floras of eastern Asia (EA) and eastern North America (ENA) share numerous genera, they have drastically different species richness. Despite an overall similarity in the quality of their temperate climates, the climate of EA is more spatially heterogeneous than that of ENA. Spatial environmental heterogeneity has been found to play a key role in influencing species richness in some regions. Here, we tested the following hypotheses: (a) EA species will occupy larger climatic niches than their ENA congeners, (b) congeners of EA‐ENA disjunct genera will occupy statistically equivalent climatic niches, and (c) congeners of EA‐ENA disjunct genera will occupy more similar climatic niches than expected by their respective physiographic context. LocationNorth America and Asia. Time periodPresent. Major taxa studiedSeed plants. MethodsPredictions generated by ecological niche models (ENMs) were compared for 88 species across 31 EA‐ENA disjunct genera. ENM predictions were assessed for geographic and ecological breadth. Tests for niche equivalency and similarity were performed for congeneric species pairs to determine if species of disjunct genera have experienced niche conservatism or divergence. ResultsEA species tend to occupy greater amounts of climatic niche space than their close relatives in ENA. Over two‐thirds of the conducted niche comparisons show that EA‐ENA congeners either occupy equivalent climatic niche space within these broader climatic regimes or occupy non‐equivalent niches that are as similar as expected given their physiographic contexts. Main conclusionsEA species tend to occupy larger climatic niches, and congeners of EA‐ENA disjunct genera tend to occupy equivalent/similar niche space within their respective distributions, with differences in occupied niches possibly due to their respective physiographic contexts, highlighting how niche‐neutral processes and niche conservatism may affect the distributions of disjunct species. 

Abstract Plant microbiomes are known to influence host fitness and ecosystem functioning, but mechanisms regulating their structure are poorly understood.Here, we explored the assembly mechanisms of leaf epiphytic and endophytic bacterial communities using a subtropical forest biodiversity experiment.Both epiphytic and endophytic bacterial diversity increased as host tree diversity increased. However, the increased epiphytic diversity in more diverse forests was driven by greater epiphytic diversity (i.e. greaterα‐diversity) on individual trees, whereas the increased endophytic diversity in more diverse forests was driven by greater dissimilarity in endophytic composition (i.e. greaterβ‐diversity) among trees. Mechanistically, responses of epiphytes to changes in host diversity were consistent with mass effects, whereas responses of endophytes were consistent with species sorting.Synthesis. These results provided novel experimental evidence that biodiversity declines of plant species will lead to biodiversity declines of plant‐associated microbiomes, but the underlying mechanism may differ between habitats on the plant host. 

When Darwin visited the Galapagos archipelago, he observed that, in spite of the islands’ physical similarity, members of species that had dispersed to them recently were beginning to diverge from each other. He postulated that these divergences must have resulted primarily from interactions with sets of other species that had also diverged across these otherwise similar islands. By extrapolation, if Darwin is correct, such complex interactions must be driving species divergences across all ecosystems. However, many current general ecological theories that predict observed distributions of species in ecosystems do not take the details of between-species interactions into account. Here we quantify, in sixteen forest diversity plots (FDPs) worldwide, highly significant negative density-dependent (NDD) components of both conspecific and heterospecific between-tree interactions that affect the trees’ distributions, growth, recruitment, and mortality. These interactions decline smoothly in significance with increasing physical distance between trees. They also tend to decline in significance with increasing phylogenetic distance between the trees, but each FDP exhibits its own unique pattern of exceptions to this overall decline. Unique patterns of between-species interactions in ecosystems, of the general type that Darwin postulated, are likely to have contributed to the exceptions. We test the power of our null-model method by using a deliberately modified data set, and show that the method easily identifies the modifications. We examine how some of the exceptions, at the Wind River (USA) FDP, reveal new details of a known allelopathic effect of one of the Wind River gymnosperm species. Finally, we explore how similar analyses can be used to investigate details of many types of interactions in these complex ecosystems, and can provide clues to the evolution of these interactions. 

Abstract Arbuscular mycorrhizal (AM) and ectomycorrhizal (EcM) associations are critical for host-tree performance. However, how mycorrhizal associations correlate with the latitudinal tree beta-diversity remains untested. Using a global dataset of 45 forest plots representing 2,804,270 trees across 3840 species, we test how AM and EcM trees contribute to total beta-diversity and its components (turnover and nestedness) of all trees. We find AM rather than EcM trees predominantly contribute to decreasing total beta-diversity and turnover and increasing nestedness with increasing latitude, probably because wide distributions of EcM trees do not generate strong compositional differences among localities. Environmental variables, especially temperature and precipitation, are strongly correlated with beta-diversity patterns for both AM trees and all trees rather than EcM trees. Results support our hypotheses that latitudinal beta-diversity patterns and environmental effects on these patterns are highly dependent on mycorrhizal types. Our findings highlight the importance of AM-dominated forests for conserving global forest biodiversity.