We present a first comprehensive treatment of the foliicolous lichen biota of Brunei (Brunei Darussalam), a country c. 5765 km2 in size located on the northern coast of the island of Borneo. Based on a study of numerous leaves collected from 18 sites, resulting in 1745 individual collections, we identified 193 species in the material, including 21 new to science, raising the number of foliicolous lichens known from Brunei from 27 to 199 taxa. This is one of the highest numbers reported for single countries, after Brazil (455 species), Costa Rica (435), Ecuador (365), Mexico (340), Guyana (296), Australia (238), Bolivia and Colombia (228 each), and Papua New Guinea (213). However, relative to log-transformed area size, Brunei is one of the countries with the highest known foliicolous lichen diversity, having almost half the number of species as Costa Rica within an area little more than 10% of the size of the latter. The foliicolous lichen biota of Brunei has a dominant paleotropical element, clustering with that of Indonesia, Malaysia, the Philippines, Papua New Guinea and Australia. The newly described species are: Arthonia concentrica sp. nov., differing from A. trilocularis in the circular thallus with concentrically arranged, thinly pruinose ascomata; Arthonia flavirugosa sp. nov., differing from A. flavoverrucosa in the delicate, light yellowish ridges and the smaller ascospores; Arthonia tenuilobata sp. nov., differing from A. lobulicarpa in the more delicate lobes, pruinose ascomata and the brown ascospores; Byssolecania fumosocaerulea sp. nov., differing from B. fumosonigricans in the greyish blue outer fringe of the apothecia; Byssoloma inconspicuum sp. nov., differing from B. microcarpum in the dark brown apothecial disc and the excipulum lacking crystals; Byssoloma incrustatimurinum sp. nov., differing from B. murinum in the shorter, non-tapering ascospores and the crystals in the excipulum; Byssoloma subaeruginosum sp. nov., differing from B. usambarense in the dark aeruginous hypothecium and the (olive-)brown thallus; Chroodiscus lirellicarpus sp. nov., differing from C. argillaceus in the lirellate apothecia; Chroodiscus minutus sp. nov., differing from C. argillaceus in the very small apothecia; Echinoplaca septemseptata sp. nov., differing from E. tetrapla in the 7-septate ascospores; Eremothecella rugosa sp. nov., differing from E. calamicola in the ridged thallus and the longer conidia; Eremothecella verrucispora sp. nov., differing from E. calamicola in the brown, ornamented ascospores with more numerous septa; Fellhanera tutongensis sp. nov., differing from F. microdiscus in the 3-7-septate, more elongate, narrower ascospores; Mazosia bambusiradiata sp. nov., differing from M. bambusae in the radiately arranged thallus verrucae; Mazosia rugosa sp. nov., differing from M. pseudobambusae in the rugose instead of verrucose thallus surface; Ocellularia andulauensis sp. nov., differing from O. daniana in the more delicate, foliicolous thallus and the much smaller ascospores; Opegrapha albomarginata sp. nov., differing from all other species of Opegrapha with goniocystangia, in the white margin of the goniocystangia; Phylloporis verrucosula sp. nov., differing from P. palmae in the small perithecia and comparatively narrow ascospores; Porina riparia sp. nov., differing from P. pseudoapplanata [= Phyllophiale viridis] in the finely laciniate thallus with non-radiating photobiont; Spinomyces rubrotrichoides sp. nov. , differing from other species in the genus in the multiseptate, worm-like ascospores and from Rubrotricha helminthospora, with which it agrees in ascospore type, in the entirely whitish, more delicate sterile thallus setae; Trichothelium subrobinsonii sp. nov., differing from T. robinsonii in the consistently 7-septate ascospores. The following three species are new continental records: Bapalmuia pallescens (Paleotropics), Lyromma palmae (Paleotropics), and Tapellaria major (Paleotropics). We also include two keys: one to foliicolous species of Arthonia with 2-septate, pigmented ascospores and one to foliicolous species of Porina with Phyllophiale-type isidia.

Abstract. Global forest assessments assist climate policy development, ecosystem science, and conservation planning, yet they rely on biomass and canopy data that do not explicitly represent the stand structural attributes derived from tree diameter measurements. This limits the ability to compare size-related structure and within-stand heterogeneity at large spatial scales. Here we present a global, spatially explicit dataset of stand-level tree diameter structure for forest cover in 2020 at 0.027° (~3 km) resolution, based on 1,203,524 georeferenced forest inventory plots comprising 54.6 million trees (≥10 cm DBH) integrated with more than 50 environmental and satellite-derived covariates into machine learning models. The dataset provides the first globally consistent maps of three complementary diameter-based metrics: arithmetic mean diameter (Dmean), quadratic mean diameter (Dqm), and the coefficient of variation of diameter (Dcv), representing average tree size, large-tree dominance, and within-stand size variability, respectively. Model performance of the ecozone-specific Random Forest framework ranged from R² = 0.41–0.82 (RMSE = 3.91–4.63 cm) for Dmean, R² = 0.43–0.83 (RMSE = 4.38–5.27 cm) for Dqm, and R² = 0.47–0.62 with (RMSE = 0.10–0.13) for Dcv across different forest ecozones. By jointly quantifying central tendency and variability in tree size, the dataset revealed spatial patterns of forest structural organization not captured by existing biomass or canopy-height products. It provides a consistent baseline for cross-biome comparison of forest structure, supporting parameterization and evaluation of vegetation and Earth system models, while offering an independent benchmark for remotely sensed structural proxies. Furthermore, it enables spatial assessment of stand structural attributes, including large-tree dominance and structural complexity, facilitating integration of diameter-based structure into global analyses of carbon dynamics and ecosystem functioning.

The main hurdle in validating global maps of forest above-ground biomass (AGB) is the lack of reference data, particularly for validating maps that represent different epochs and spatial resolutions. Here we introduce AGBref the first global AGB reference dataset derived from a collection of National Forest Inventories (NFI), permanent research plots and local AGB maps from airborne LiDAR. This dataset provides biomass estimates for multiple epochs (2005, 2010, 2015, 2020) at various spatial resolutions or supports (500 m, 1 km, 10 km, 25 km). More importantly, the dataset comes with uncertainty estimates stemming from plot measurement errors and the biomass variability at different supports (within-pixel variability). AGBref also comes with a series of quality flags that inform users about the characteristics of grid cells according on the attributes of the plots within them. We further examine how filtering based on quality flags influences the representativeness of AGBref globally and across major biomes.

PREMISE:Asia's wet tropical forests face a severe biodiversity crisis, but few fossils record their evolutionary history. We recently discovered in situ cuticles on fossil leaves, attributed to the giant rainforest tree Dryobalanops of the iconic Dipterocarpaceae family, from the Plio-Pleistocene of Brunei Darussalam (northern Borneo). Studying these specimens allowed us to validate the generic identification and delineate affinities to living dipterocarp species. METHODS:We compared the leaf cuticles and architecture of these fossil leaves with the seven living Dryobalanops species. RESULTS:The cuticular features shared between the fossils and extant Dryobalanops, including the presence of giant stomata on veins, confirm their generic placement. The leaf characters are identical to those of D. rappa, an IUCN red-listed Endangered, northern Borneo endemic. The D. rappa monodominance at the fossil site, along with Dipterocarpus spp. leaf fossils, indicates a dipterocarp-dominated forest near the mangrove-swamp depocenter, most likely in an adjacent peatland. CONCLUSIONS:The Dryobalanops rappa fossils are the first fossil evidence of a living endangered tropical tree species and show how analysis of in situ cuticles can help illuminate the poorly known floristic history of the Asian tropics. This discovery highlights new potential for fossils to inform heritage values and paleoconservation in Southeast Asia.

Different regions of the tropics vary in overall tree species diversity, with the tropical Americas exhibiting strikingly higher regional tree species richness than Africa and Southeast Asia. We investigated whether these differences also occur at the local scale and whether the environmental conditions associated with tree species richness are consistent across tropical regions despite highly dissimilar species pools. A spatial random forest model was trained by using a network of 429 1-hectare plots across the tropics, together with 24 environmental variables, to predict plot-level tree α diversity. A combination of climatic, soil and topographical variables explained ∼86% of the variation in richness. Despite differences in regional species pools and the potentially disruptive effects of different geological, climatic and evolutionary histories, the relationship between environmental variables and local-scale tree species richness is closely similar across different continents. Our findings imply a pervasive role of niche-based mechanisms in structuring local tree species richness, regardless of the regional species assemblages. This pantropical convergence in the richness-environment relationship poses a challenge for ecology to explain.

Species' traits and environmental conditions determine the abundance of tree species across the globe. The extent to which traits of dominant and rare tree species differ remains untested across a broad environmental range, limiting our understanding of how species traits and the environment shape forest functional composition. We use a global dataset of tree composition of >22,000 forest plots and 11 traits of 1663 tree species to ask how locally dominant and rare species differ in their trait values, and how these differences are driven by climatic gradients in temperature and water availability in forest biomes across the globe. We find three consistent trait differences between locally dominant and rare species across all biomes; dominant species are taller, have softer wood and higher loading on the multivariate stem strategy axis (related to narrow tracheids and thick bark). The difference between traits of dominant and rare species is more strongly driven by temperature compared to water availability, as temperature might affect a larger number of traits. Therefore, climate change driven global temperature rise may have a strong effect on trait differences between dominant and rare tree species and may lead to changes in species abundances and therefore strong community reassembly.

Woody canopies regulate exchanges of energy, water and carbon, and their three-dimensional (3D) structure supports much of terrestrial biodiversity. Remote sensing technologies such as airborne laser scanning (ALS) now enable the 3D mapping of entire landscapes. However, we lack the large, harmonized and geographically representative ALS collections needed to build a global picture of woody ecosystem structure. To address this challenge, we developed the Global Canopy Atlas (GCA): 3,458 ALS acquisitions transformed into standardized and analysis-ready maps of canopy height and elevation at 1 m2 resolution. The GCA covers 56,554 km2 across all major biomes. 19% of this area has been scanned multiple times, and 87% of all GCA products are openly available, covering 95% of the total area. To showcase its wide range of applications, we applied the GCA in three case studies. First, we validated three global satellite-derived canopy height maps, finding poor performance at native resolution (1-30 m, R2 < 0.38) and moderate performance at 250 m resolution (R2 < 0.65). Second, analyzing global patterns in canopy gap size frequency we discovered an unexpectedly large variation of power law exponents from branch to stand level (α = 1.52 to 2.38), pointing to a fundamental scale-dependence of forest structure. Third, we developed a framework to standardize forest turnover quantification from multi-source, multi-temporal ALS. In a temperate forest in North America it revealed that 21% of canopy gaps closed within 12 years of opening and would thus be missed by infrequent monitoring. As demonstrated by these case studies, the GCA provides a novel data source for ecologists, foresters, remote sensing scientists and the ecosystem modelling community that substantially advances our ability to understand the structure and dynamics of woody ecosystems at global scales. ### Competing Interest Statement A Burt and M Demol are employees and/or shareowners of Sylvera Ltd. No other competing interests declared. Leverhulme Trust, https://ror.org/012mzw131, RPG-2020-341, RPG-2024-342 European Research Council, 101001905, 757526, 101059548 Natural Environment Research Council, https://ror.org/02b5d8509, NE/S01537X/1, NE/T011084/1, NE/Z504191/1 UK Research and Innovation, EP/Y003810/1 European Space Agency, FRM4BIOMASS Agence Nationale de la Recherche, ANR-10-LABX-25-01, ANR-19-CE32-0005-01 Oak Ridge National Laboratory United States Department of Energy, https://ror.org/01bj3aw27, DE-AC05-00OR22725 Project LIFE+ ForBioSensing, LIFE13ENV/PL/000048 National Fund for Environmental Protection and Water Management (Poland), 485/2014/WN10/OPNMLF/D Forest Research Institute, 261509 Royal Society, https://ror.org/03wnrjx87, RG/R1/251370 World Bank Government of Mozambique Innovate UK, 10004871 Czech Republic–Bavaria Free State ETC goal 2014–2020, Interreg V project No. 99 Deutsche Forschungsgemeinschaft, 411263134/2019-2022 NASA Land Cover Land Use Change and Carbon Monitoring System Program. Conselho Nacional de Desenvolvimento Científico e Tecnológico, 403297/2016-8, 401053/2019-9, 306386-2022-4 Amazon Fund, 14.2.0929.1 USAID, AID-OAA-A-11–00012 DELTA Lidar National Natural Science Foundation of China, 32401574 Australian Agency for International Development Dutch government Norwegian Agency for Development Cooperation, https://ror.org/04zbn7k04 United Kingdom Climate Change Unit European Cooperation in Science and Technology, https://ror.org/01bstzn19, LUC23023 JSPS KAKENHI, #21H05314, #21H02564 Universiti Brunei Darussalam, UBD/RSCH/1.18/FICBF(b)/2023/006 The Nature Conservancy ForestGEO FAPESP, 2017/22269-2 French Ministry of Higher Education and Scientific Research, One Forest Vision initiative French Ministry of Europe and Foreign Affairs, One Forest Vision initiative Western Australian government, State NRM program, Ngadju Conservation Aboriginal Corporation, Landgate program Western Australian Department of Biodiversity, Conservation and Attractions Australia's Terrestrial Ecosystems Research Network Government of Finland Government of Nepal German Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety, International Climate Initiative (IKI) German Development Bank KfW, International Climate Initiative (IKI) Natural Science Foundation of Shanghai, 23ZR1419200 National Key R&D Program of China, 2024YFF1308100 USAID/Wake Forest University, Cooperative Agreement No. 7205-2721-CA-00005 NASA, NISAR CAL/VAL French Government Ministry of Higher Education of Malaysia, FRGS/1/2020/WAB03/UKM/02/1 Canadian Forest Service, https://ror.org/0430zw506 Ontario Ministry of Natural Resources National Key Research and Development Program of China, 2024YFF1306501, 2024YFF0810500

Unraveling the mechanisms underlying the maintenance of species diversity is a central pursuit in ecology. It has been hypothesized that ectomycorrhizal (EcM) in contrast to arbuscular mycorrhizal fungi can reduce tree species diversity in local communities, which remains to be tested at the global scale. To address this gap, we analyzed global forest inventory data and revealed that the relationship between tree species richness and EcM tree proportion varied along environmental gradients. Specifically, the relationship is more negative at low latitudes and in moist conditions but is unimodal at high latitudes and in arid conditions. The negative association of EcM tree proportion on species diversity at low latitudes and in humid conditions is likely due to more negative plant-soil microbial interactions in these regions. These findings extend our knowledge on the mechanisms shaping global patterns in plant species diversity from a belowground view.

AimTo determine the relationships between the functional trait composition of forest communities and environmental gradients across scales and biomes and the role of species relative abundances in these relationships.LocationGlobal.Time periodRecent.Major taxa studiedTrees.MethodsWe integrated species abundance records from worldwide forest inventories and associated functional traits (wood density, specific leaf area and seed mass) to obtain a data set of 99,953 to 149,285 plots (depending on the trait) spanning all forested continents. We computed community-weighted and unweighted means of trait values for each plot and related them to three broad environmental gradients and their interactions (energy availability, precipitation and soil properties) at two scales (global and biomes).ResultsOur models explained up to 60% of the variance in trait distribution. At global scale, the energy gradient had the strongest influence on traits. However, within-biome models revealed different relationships among biomes. Notably, the functional composition of tropical forests was more influenced by precipitation and soil properties than energy availability, whereas temperate forests showed the opposite pattern. Depending on the trait studied, response to gradients was more variable and proportionally weaker in boreal forests. Community unweighted means were better predicted than weighted means for almost all models.Main conclusionsWorldwide, trees require a large amount of energy (following latitude) to produce dense wood and seeds, while leaves with large surface to weight ratios are concentrated in temperate forests. However, patterns of functional composition within-biome differ from global patterns due to biome specificities such as the presence of conifers or unique combinations of climatic and soil properties. We recommend assessing the sensitivity of tree functional traits to environmental changes in their geographic context. Furthermore, at a given site, the distribution of tree functional traits appears to be driven more by species presence than species abundance.

AimEcological and anthropogenic factors shift the abundances of dominant and rare tree species within local forest communities, thus affecting species composition and ecosystem functioning. To inform forest and conservation management it is important to understand the drivers of dominance and rarity in local tree communities. We answer the following research questions: (1) What are the patterns of dominance and rarity in tree communities? (2) Which ecological and anthropogenic factors predict these patterns? And (3) what is the extinction risk of locally dominant and rare tree species?LocationGlobal.Time period1990-2017.Major taxa studiedTrees.MethodsWe used 1.2 million forest plots and quantified local tree dominance as the relative plot basal area of the single most dominant species and local rarity as the percentage of species that contribute together to the least 10% of plot basal area. We mapped global community dominance and rarity using machine learning models and evaluated the ecological and anthropogenic predictors with linear models. Extinction risk, for example threatened status, of geographically widespread dominant and rare species was evaluated.ResultsCommunity dominance and rarity show contrasting latitudinal trends, with boreal forests having high levels of dominance and tropical forests having high levels of rarity. Increasing annual precipitation reduces community dominance, probably because precipitation is related to an increase in tree density and richness. Additionally, stand age is positively related to community dominance, due to stem diameter increase of the most dominant species. Surprisingly, we find that locally dominant and rare species, which are geographically widespread in our data, have an equally high rate of elevated extinction due to declining populations through large-scale land degradation.Main conclusionsBy linking patterns and predictors of community dominance and rarity to extinction risk, our results suggest that also widespread species should be considered in large-scale management and conservation practices.

Aim: We test the hypothesis that wind dispersal is more common among emergent tree species given that being tall increases the likelihood of effective seed dispersal. Location: Americas, Africa and the Asia-Pacific. Time period: 1970-2020. Major taxa studied: Gymnosperms and Angiosperms. Methods: We used a dataset consisting of tree inventories from 2821 plots across three biogeographic regions (Americas, Africa and Asia- Pacific), including dry and wet forests, to determine the maximum height and dispersal strategy of 5314 tree species. A web search was used to determine whether species were wind-dispersed. We compared differences in tree species maximum height between biogeographic regions and examined the relationship between species maximum height and wind dispersal using logistic regression. We also tested whether emergent tree species, that is species with at least one individual taller than the 95% height percentile in one or more plots, were disproportionally wind dispersed in dry and wet forests within each biogeographic region. Results: Our dataset provides maximum height values for 5314 tree species, of which more than half (2914) had no record of this trait in existing global databases. We found that, on average, tree species in the Americas have lower maximum heights compared to those in Africa and the Asia Pacific. The probability of wind dispersal increased significantly with tree species maximum height and was significantly higher among emergent than non-emergent tree species in both dry and wet forests in all three biogeographic regions. Main conclusion: Wind dispersal is more prevalent in tall, emergent tree species than in non-emergent species and may thus be an important factor in the evolution of tree species maximum height. By providing the most comprehensive dataset so far of tree species maximum height and wind dispersal strategies, this study paves the way for advancing our understanding of the eco-evolutionary drivers of tree size.

The forests of Southeast Asia harbour high levels of species diversity, providing a plethora of ecosystem services. However, this biodiversity is threatened by both climate and land-use change, the impacts of which are poorly understood. We modelled 1,498 tree species distributions under four shared socioeconomic pathways (SSPs) with varying global change intensities, and classified species into 11 spatially associated groups. We found both global changes to cause severe losses in tree distributions. Only under SSP1-2.6, the sustainable pathway with low intensities in both global changes, were distribution losses mitigated. Unexpectedly, losses were overall greatest under intermediate climate change pathways SSP2-4.5 and SSP3-7.0 rather than under the most extreme pathway, SSP5-8.5. This was because, although climate-driven losses were greatest under SSP5-8.5, land-use-driven losses were much more extensive under SSP2-4.5 and SSP3-7.0 than under SSP5-8.5. Crucially, other than SSP1-2.6, each SSP led to worst-case scenarios for several species groups. Our findings highlight that to most effectively conserve Southeast Asian tree distributions, policymakers need to prioritize a sustainable pathway that mitigates both global changes. Global change drivers such as climate and land-use change can impact biodiverse regions and damage the ecosystem services they provide. This study assessed the impact of such global change drivers on tree species distributions across Southeast Asian forests.

Trees structure the Earth's most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1-6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth's 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world's most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees.

The density of wood is a key indicator of the carbon investment strategies of trees, impacting productivity and carbon storage. Despite its importance, the global variation in wood density and its environmental controls remain poorly understood, preventing accurate predictions of global forest carbon stocks. Here we analyse information from 1.1million forest inventory plots alongside wood density data from 10,703 tree species to create a spatially explicit understanding of the global wood density distribution and its drivers. Our findings reveal a pronounced latitudinal gradient, with wood in tropical forests being up to 30% denser than that in boreal forests. In both angiosperms and gymnosperms, hydrothermal conditions represented by annual mean temperature and soil moisture emerged as the primary factors influencing the variation in wood density globally. This indicates similar environmental filters and evolutionary adaptations among distinct plant groups, underscoring the essential role of abiotic factors in determining wood density in forest ecosystems. Additionally, our study highlights the prominent role of disturbance, such as human modification and fire risk, in influencing wood density at more local scales. Factoring in the spatial variation of wood density notably changes the estimates of forest carbon stocks, leading to differences of up to 21% within biomes. Therefore, our research contributes to a deeper understanding of terrestrial biomass distribution and how environmental changes and disturbances impact forest ecosystems.

The density of wood is a key indicator of trees’ carbon investment strategies, impacting productivity and carbon storage. Despite its importance, the global variation in wood density and its environmental controls remain poorly understood, preventing accurate predictions of global forest carbon stocks. Here, we analyze information from 1.1 million forest inventory plots alongside wood density data from 10,703 tree species to create a spatially-explicit understanding of the global wood density distribution and its drivers. Our findings reveal a pronounced latitudinal gradient, with wood in tropical dry forests being up to twice as dense as that in boreal forests. In both angiosperms and gymnosperms, temperature and water availability emerged as the primary factors influencing the variation in wood density globally. This indicates similar environmental filters and evolutionary adaptations among distinct plant groups, underscoring the essential role of abiotic factors in determining wood density in forest ecosystems. Additionally, our study highlights the prominent role of disturbance, such as human modification and fire risk, in influencing wood density at more local scales. Factoring in the spatial variation of wood density notably changes the estimates of forest carbon stocks, leading to differences of up to 21% within biomes. Therefore, our research contributes to a deeper understanding of terrestrial biomass distribution and how environmental changes and disturbances impact forest ecosystems.

Tropical forests occupy small coral atolls to the vast Amazon basin. They occur across bioregions with different geological and climatic history. Differences in area and bioregional history shape species immigration, extinction and diversification. How this effects local diversity is unclear. The Indonesian archipelago hosts thousands of tree species whose coexistence should depend upon these factors. Using a novel dataset of 215 Indonesian forest plots, across fifteen islands ranging in area from 120 to 785 000 km 2 , we apply Gaussian mixed effects models to examine the simultaneous effects of environment, earthquake proximity, island area and bioregion upon tree diversity for trees ≥ 10 cm diameter at breast height. We find that tree diversity declines with precipitation seasonality and increases with island area. Accounting for the effects of environment and island area we show that the westernmost bioregion Sunda has greater local diversity than Wallacea, which in turn has greater local diversity than easternmost Sahul. However, when the model includes geological activity (here proximity to major earthquakes), bioregion differences are reduced. Overall, results indicate that multi‐scale, current and historic effects dictate tree diversity. These multi‐scale drivers should not be ignored when studying biodiversity gradients and their impacts upon ecosystem function.

1. Biodiversity is an important component of natural ecosystems, with higher species richness often correlating with an increase in ecosystem productivity. Yet, this relationship varies substantially across environments, typically becoming less pronounced at high levels of species richness. However, species richness alone cannot reflect all important properties of a community, including community evenness, which may mediate the relationship between biodiversity and productivity. If the evenness of a community correlates negatively with richness across forests globally, then a greater number of species may not always increase overall diversity and productivity of the system. Theoretical work and local empirical studies have shown that the effect of evenness on ecosystem functioning may be especially strong at high richness levels, yet the consistency of this remains untested at a global scale.2. Here, we used a dataset of forests from across the globe, which includes composition, biomass accumulation and net primary productivity, to explore whether productivity correlates with community evenness and richness in a way that evenness appears to buffer the effect of richness. Specifically, we evaluated whether low levels of evenness in speciose communities correlate with the attenuation of the richness-productivity relationship.3. We found that tree species richness and evenness are negatively correlated across forests globally, with highly speciose forests typically comprising a few dominant and many rare species. Furthermore, we found that the correlation between diversity and productivity changes with evenness: at low richness, uneven communities are more productive, while at high richness, even communities are more productive.4. Synthesis. Collectively, these results demonstrate that evenness is an integral component of the relationship between biodiversity and productivity, and that the attenuating effect of richness on forest productivity might be partly explained by low evenness in speciose communities. Productivity generally increases with species richness, until reduced evenness limits the overall increases in community diversity. Our research suggests that evenness is a fundamental component of biodiversity-ecosystem function relationships, and is of critical importance for guiding conservation and sustainable ecosystem management decisions.

During citizen-science expeditions to the Ulu Temburong National Park, Brunei, several individuals were collected of a semi-slug species of the genus Microparmarion that, based on morphology and in-the-field DNA-barcoding, was found to be an undescribed species. In this paper, we describe Microparmarion sallehi Wu, Ezzwan & Hamdani, n. sp., after field centre supervisor Md Salleh Abdullah Bat. We provide details on the external and internal reproductive morphology, the shell and the ecology of the type locality, as well as a diagnosis comparing it with related species. DNA barcodes were generated for five individuals and used for a phylogenetic reconstruction. Microparmarion sallehi sp. n. and M. exquadratus Schilthuizen et al., 2019 so far are the only Bornean species of the genus that live in lowland forest; other species are found in montane forests.

Understanding what controls global leaf type variation in trees is crucial for comprehending their role in terrestrial ecosystems, including carbon, water and nutrient dynamics. Yet our understanding of the factors influencing forest leaf types remains incomplete, leaving us uncertain about the global proportions of needle-leaved, broadleaved, evergreen and deciduous trees. To address these gaps, we conducted a global, ground-sourced assessment of forest leaf-type variation by integrating forest inventory data with comprehensive leaf form (broadleaf vs needle-leaf) and habit (evergreen vs deciduous) records. We found that global variation in leaf habit is primarily driven by isothermality and soil characteristics, while leaf form is predominantly driven by temperature. Given these relationships, we estimate that 38% of global tree individuals are needle-leaved evergreen, 29% are broadleaved evergreen, 27% are broadleaved deciduous and 5% are needle-leaved deciduous. The aboveground biomass distribution among these tree types is approximately 21% (126.4 Gt), 54% (335.7 Gt), 22% (136.2 Gt) and 3% (18.7 Gt), respectively. We further project that, depending on future emissions pathways, 17–34% of forested areas will experience climate conditions by the end of the century that currently support a different forest type, highlighting the intensification of climatic stress on existing forests. By quantifying the distribution of tree leaf types and their corresponding biomass, and identifying regions where climate change will exert greatest pressure on current leaf types, our results can help improve predictions of future terrestrial ecosystem functioning and carbon cycling.