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AimThe climate variability hypothesis proposes that species subjected to wide variation in climatic conditions will evolve wider niches, resulting in larger distributions. We test this hypothesis in tropical plants across a broad elevational gradient; specifically, we use a species-level approach to evaluate whether elevational range sizes are explained by the levels of thermal variability experienced by species.LocationCentral AndesTime periodPresent dayMajor taxa studiedWoody plantsMethodsCombining data from 479 forest plots, we determined the elevational distributions of nearly 2300 species along an elevational gradient (∼209 – 3800 m). For each species, we calculated the maximum annual variation in temperature experienced across its elevational distribution. We used phylogenetic generalized least square models to evaluate the effect of thermal variability on range size. Our models included additional covariates that might affect range size: body size, local abundance, mean temperature and total precipitation. We also considered interactions between thermal variability and mean temperature or precipitation. To account for geometric constraints, we repeated our analyses with a standardized measure of range size, calculated by comparing observed range sizes with values obtained from a null model.ResultsOur results supported the main prediction of the climate variability hypothesis. Thermal variability had a strong positive effect on the range size, with species exposed to higher thermal variability having broader elevational distributions. Body size and local abundance also had positive, yet weak effects, on elevational range size. Furthermore, there was a strong positive interaction between thermal variability and mean annual temperature.Main conclusionsThermal variability had an overriding importance in driving elevational range sizes of woody plants in the Central Andes. Moreover, the relationship between thermal variability and range size might be even stronger in warmer regions, underlining the potential vulnerability of tropical montane floras to the effects of global warming.

The relative importance of tree mortality risk factors remains unknown, especially in diverse tropical forests where species may vary widely in their responses to particular conditions. We present a new framework for quantifying the importance of mortality risk factors and apply it to compare 19 risks on 31 203 trees (1977 species) in 14 one-year periods in six tropical forests. We defined a condition as a risk factor for a species if it was associated with at least a doubling of mortality rate in univariate analyses. For each risk, we estimated prevalence (frequency), lethality (difference in mortality between trees with and without the risk) and impact ('excess mortality' associated with the risk, relative to stand-level mortality). The most impactful risk factors were light limitation and crown/trunk loss; the most prevalent were light limitation and small size; the most lethal were leaf damage and wounds. Modes of death (standing, broken and uprooted) had limited links with previous conditions and mortality risk factors. We provide the first ranking of importance of tree-level mortality risk factors in tropical forests. Future research should focus on the links between these risks, their climatic drivers and the physiological processes to enable mechanistic predictions of future tree mortality.

Recent studies have demonstrated that ecological processes that shape community structure and dynamics change along environmental gradients. However, much less is known about how the emergence of the gradients themselves shape the evolution of species that underlie community assembly. In this study, we address how the creation of novel environments leads to community assembly via two nonmutually exclusive processes: immigration and ecological sorting of pre-adapted clades (ISPC), and recent adaptive diversification (RAD). We study these processes in the context of the elevational gradient created by the uplift of the Central Andes. We develop a novel approach and method based on the decomposition of species turnover into within- and among-clade components, where clades correspond to lineages that originated before mountain uplift. Effects of ISPC and RAD can be inferred from how components of turnover change with elevation. We test our approach using data from over 500 Andean forest plots. We found that species turnover between communities at different elevations is dominated by the replacement of clades that originated before the uplift of the Central Andes. Our results suggest that immigration and sorting of clades pre-adapted to montane habitats is the primary mechanism shaping tree communities across elevations.

Crown damage can account for over 23% of canopy biomass turnover in tropical forests and is a strong predictor of tree mortality; yet, it is not typically represented in vegetation models. We incorporate crown damage into the Functionally Assembled Terrestrial Ecosystem Simulator (FATES), to evaluate how lags between damage and tree recovery or death alter demographic rates and patterns of carbon turnover. We represent crown damage as a reduction in a tree's crown area and leaf and branch biomass, and allow associated variation in the ratio of aboveground to belowground plant tissue. We compare simulations with crown damage to simulations with equivalent instant increases in mortality and benchmark results against data from Barro Colorado Island (BCI), Panama. In FATES, crown damage causes decreases in growth rates that match observations from BCI. Crown damage leads to increases in carbon starvation mortality in FATES, but only in configurations with high root respiration and decreases in carbon storage following damage. Crown damage also alters competitive dynamics, as plant functional types that can recover from crown damage outcompete those that cannot. This is a first exploration of the trade-off between the additional complexity of the novel crown damage module and improved predictive capabilities. At BCI, a tropical forest that does not experience high levels of disturbance, both the crown damage simulations and simulations with equivalent increases in mortality does a reasonable job of capturing observations. The crown damage module provides functionality for exploring dynamics in forests with more extreme disturbances such as cyclones and for capturing the synergistic effects of disturbances that overlap in space and time.

The high mortality and low recruitment of the myrmecophytic Acacia drepanolobium are not consistent with the demographic rates of monodominant species. The positive conspecific density dependence observed from the spatial analysis is consistent with the defensive benefits conferred by symbiotic ants to trees when they grow close to each other. Patches of savanna dominated by Acacia drepanolobium occur throughout East Africa on nutrient-rich vertisols, also known as black cotton soils. We assessed the survival and recruitment for all freestanding trees with diameter at knee height (dkh) ≥ 10 mm in one of such mono-dominated patches (47 ha) at the Mpala Research Centre, Kenya, with the aim of identifying demographic traits that might explain the dominance of this species. Over a mean 6-year interval, mortality and recruitment rates in the habitat were 4.55%/year and 1.42%/year respectively, resulting in a net loss of 17.8% of the initial individuals. Of the 30 species recorded from the first census, 11 decreased in abundance, nine increased, and the remainder 10 did not change in abundance. The monodominant A. drepanolobium had a high mortality (4.69%/year), a low recruitment (1.31%/year), and a 19% population decline. There was no evidence of conspecific negative density dependence for this species. Rather, we found a statistically significant positive correlation between the number of conspecific neighbors and individual-level probability of survival, consistent with the “shared defense” benefits that symbiotic ant colonies occupying multiple trees can confer to these latter in a small neighborhood. Thus, mortality of A. drepanolobium was higher in areas where it occurred in lower densities, which resulted in an increase in the spatial aggregation of conspecifics. Mortality increased with dkh size classes and was mostly caused by elephants and stem-boring beetles. The demographic rates during the study period in theory are inconsistent with those of monodominant species. The protection against herbivory conferred by mutualistic ants associated with this species remains the most probable explanation of its dominance in this habitat.

The study of community spatial structure is central to understanding diversity patterns over space and species co-occurrence at local scales. Although most analytical approaches consider horizontal and vertical dimensions separately, in this study we introduce a three-dimensional spatial analysis that simultaneously includes horizontal and vertical species associations. Using tree census data (2000–2016) and allometries from the Luquillo forest plot in Puerto Rico, we show that spatial organization becomes less random over time as the forest recovered from land-use legacy effects and hurricane disturbance. Tree species vertical segregation is predominant in the forest with almost all species that co-occur in the horizontal plane avoiding each other in the vertical dimension. Horizontal segregation is less common than vertical, whereas three-dimensional aggregation (a proxy for direct tree competition) is the least frequent type of spatial association. Furthermore, dominant species are involved in more non-random spatial associations, implying that species co-occurrence is facilitated by species segregation in space. This novel three-dimensional analysis allowed us to identify and quantify tree species spatial distributions, how interspecific competition was reduced through forest structure, and how it changed over time after disturbance, in ways not detectable from two-dimensional analyses alone.

QUESTION: Dispersal limitation (neutral hypothesis) and deterministic factors (niche hypothesis) shape floristic gradients including between‐site patterns of species’ dominance (co‐dominance). Because their relative importance remains poorly known, we ask how their comparative contribution to co‐dominance changes with elevation and geographical extent. LOCATION: Madidi region, NW Bolivia. METHODS: We analysed floristic composition and environmental factors of 90 plots spanning the gradient from Amazonian (

Made available in DSpace on 2021-06-25T10:27:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) The forests of Amazonia are among the most biodiverse plant communities on Earth. Given the immediate threats posed by climate and land-use change, an improved understanding of how this extraordinary biodiversity is spatially organized is urgently required to develop effective conservation strategies. Most Amazonian tree species are extremely rare but a few are common across the region. Indeed, just 227 ‘hyperdominant’ species account for >50% of all individuals >10 cm diameter at 1.3 m in height. Yet, the degree to which the phenomenon of hyperdominance is sensitive to tree size, the extent to which the composition of dominant species changes with size class and how evolutionary history constrains tree hyperdominance, all remain unknown. Here, we use a large floristic dataset to show that, while hyperdominance is a universal phenomenon across forest strata, different species dominate the forest understory, midstory and canopy. We further find that, although species belonging to a range of phylogenetically dispersed lineages have become hyperdominant in small size classes, hyperdominants in large size classes are restricted to a few lineages. Our results demonstrate that it is essential to consider all forest strata to understand regional patterns of dominance and composition in Amazonia. More generally, through the lens of 654 hyperdominant species, we outline a tractable pathway for understanding the functioning of half of Amazonian forests across vertical strata and geographical locations. Institute of Environment Department of Biological Sciences Florida International University School of Geography University of Leeds Center for Global Discovery and Conservation Science Arizona State University Instituto Nacional de Pesquisas da Amazônia (INPA) Ecology and Evolutionary Biology University of Michigan Departamento de Ciencias Forestales Universidad Nacional de Colombia Departamento de Biología Universidad Autónoma de Madrid Centro de Investigación en Biodiversidad y Cambio Global (CIBC-UAM) Universidad Autónoma de Madrid Naturalis Biodiversity Center Systems Ecology Vrije Universiteit Lancaster Environment Centre Lancaster University Environmental Change Institute University of Oxford Faculty of Environmental Sciences and Natural Resource Management Norwegian University of Life Sciences School of Geosciences University of Edinburgh Missouri Botanical Garden Brazilian Agricultural Research Corporation (Embrapa) Universidad Nacional de San Antonio Abad del Cusco Department of Intergrative Biology University of California Berkeley Department of Biology University of Turku Instituto de Investigaciones de la Amazonía Peruana UNELLEZ-Guanare Programa de Ciencias del Agro y el Mar Herbario Universitario (PORT) Compensation International Progress S. A.—Ciprogress Greenlife AMAP Université de Montpellier CIRAD CNRS INRAE IRD Environmental and Rural Science University of New England INRA UMR EcoFoG AgroParisTech CNRS CIRAD Université des Antilles Université de Guyane CIRAD UMR EcoFoG BIOMAS Universidad de Las Américas Instituto de Ecología Herbario Nacional de Bolivia Departamento de Biologia Universidade Federal de Rondônia Laboratoire Evolution et Diversité Biologique (EDB) CNRS/UPS School of Geography Earth and Environmental Sciences University of Plymouth Department of Ecology and Evolutionary Biology Cornell University Department of Geography University of Exeter Facultad de Ciencias Biológicas Universidad Nacional de la Amazonía Peruana Estación Biológica del Jardín Botánico de Missouri Institut de Ciència i Tecnologia Ambientals Universitat Autònoma de Barcelona School of Geography & Sustainable Development University of St Andrews Department of Environment and Development Federal University of Amapá Centre for Tropical Environmental and Sustainability Science (TESS) and College of Marine and Environmental Sciences James Cook University Department of Environmental Science and Policy George Mason University Inventory and Monitoring Program National Park Service Smithsonian Institution Department of Plant Sciences University of Cambridge Living with Lakes Centre Laurentian University DRGB Instituto Nacional de Innovación Agraria (INIA) Herbarium Amazonense (AMAZ) Universidad Nacional de la Amazonia Peruana Department of Ecology Universidade de São Paulo Institute for Biodiversity and Ecosystem Dynamics University of Amsterdam Centro de Estudos da Biodiversidade Universidade Federal de Roraima Museo de Historia Natural Noel Kempff Mercado Universidad Autónoma Gabriel Rene Moreno Faculdade de Ciências Agrárias Biológicas e Sociais Aplicadas Universidad do Estado de Mato Grosso Centro de Biociências Universidade Federal do Rio Grande do Norte Department of Ecology Evolution and Behaviour University of Minnesota Department of Geography University College London Departamento de Ciencias Biológicas Universidad de Los Andes (Colombia) Centro de Ciências Biológicas e da Natureza Universidade Federal do Acre Nicholas School of the Environment Duke University Iwokrama International Centre for Rainforest Conservation and Development Smithsonian’s National Zoo & Conservation Biology Institute Instituto de Ciencias Naturales Universidad Nacional de Colombia Universidade Federal Rural da Amazônia—UFRA/CAPES Museu Paraense Emílio Goeldi Laboratorio de Ecología de Bosques Tropicales y Primatología Fundación Natura Colombia Universidad de Los Andes Facultad de Forestales Universidad Nacional de la Amazonía Peruana Institute of Research for Forestry Development Universidad de los Andes School of Environmental and Forest Sciences (SEFS) University of Washington Universidad Regional Amazónica Ikiam Agteca-Amazonica Universidad Autónoma del Beni Instituto Amazónico de Investigaciones (IMANI) Universidad Nacional de Colombia Broward County Parks and Recreation Biological Sciences Florida Atlantic University-Davie Museu Universitário Universidade Federal do Acre Facultad de Ingeniería Ambiental Universidad Estatal Amazónica Department of Biology Washington University in St Louis National Institute for Space Research (INPE) Geoinformática & Sistemas (GeoIS) School of Earth Sciences and Environmental Sustainability Northern Arizona University Department of Geography and the Environment University of Texas at Austin Instituto de Ciência e Tecnologia São Paulo State University (UNESP) School of Anthropology and Conservation University of Kent Universidade Federal do Amazonas Herbario Alfredo Paredes (QAP) Universidad Central del Ecuador School of Geography Earth and Environmental Sciences University of Birmingham Department of Life Sciences Imperial College London Science and Education The Field Museum Universidad Tecnica del Norte Herbario Nacional del Ecuador Research Institute Alexander von Humboldt Instituto de Ciência e Tecnologia São Paulo State University (UNESP)

Background Neuromyelitis Optica (NMO) is an autoimmune disease of the Central Nervous System (CNS) mediated by Th17 cells and antibody response to the water channel protein Aquaporin 4 (AQP4), leading to chronic damage of the optic nerves and spinal cord. NMO animal models are substandard inducing disease inconsistently and weakly. Objectives Characterize a new NMO mouse model, which best represents the human disease in terms of incidence and chronicity of the disease, severity of symptoms and underlying molecular mechanisms. Methods C57BL/6 (WT) and IFN-γ receptor knockout (R-KO) mice were immunized subcutaneously with the AQP4201–220 peptide in Complete Freund Adjuvant and treated with pertussis toxin at day 0 and +2. WT were treated weakly with neutralizing anti-IFN-γ antibodies. mRNA expression and flow cytometry analysis of infiltrating CNS cells were performed. CNS histopathology was determined by immunofluorescence. In vivo B-cell depletion was made using anti-CD20 antibodies. Results WT mice treated with anti-IFN-γ and RKO mice showed ascendant paralysis starting from the tail to complete hind limb paralysis. Mice showed increased disease incidence and symptoms were more severe and chronic. CNS IL-17 expressing T cells and Th17 associated genes were upregulated in the absence of IFN-γ. CSN histological analysis showed an increased presence of T and B cells in lesion sites, associated with astrocytes and myelin loss. B-cell depletion in AQP4 primed RKO mice, diminished the incidence and severity of the disease confirming B cell pathogenicity. Conclusions AQP4 mouse model is strictly regulated by IFN-γ and its signaling, which control the disease progression and severity, by restraining pathogenic Th17 and B cells. Supported by grant from NIH (R21 Grant 12878760)

At local scales, it has been suggested that high levels of resources lead to increased tree growth via trait optimization (highly peaked trait distribution). However, this contrasts with (1) theories that suggest that trait optimization and high growth occur in the most common resource level and (2) empirical evidence showing that high trait optimization can be also found at low resource levels. This raises the question of how are traits and growth optimized in highly diverse plant communities. Here, we propose a series of hypotheses about how traits and growth are expected to be maximized under different resource levels (low, the most common, and high) in tree seedling communities from a subtropical forest in Puerto Rico, USA. We studied the variation in the distribution of biomass allocation and leaf traits and seedlings growth rate along four resource gradients: light availability (canopy openness) and soil K, Mg, and N content. Our analyses consisted of comparing trait kurtosis (a measurement of trait optimization), community trait means, and relative growth rates at three resource levels (low, common, and high). Trait optimization varied across the three resource levels depending on the type of resource and trait, with leaf traits being optimized under high N and in the most common K and Mg conditions, but not at any of the light levels. Also, seedling growth increased at high-light conditions and high N and K but was not related to trait kurtosis. Our results indicate that local-scale variability of soil fertility and understory light conditions result in shifts in species ecological strategies that increase growth despite a weak trait optimization, suggesting the existence of alternative phenotypes that achieve similar high performance. Uncovering the links between abiotic factors, functional trait diversity and performance is necessary to better predict tree responses to future changes in abiotic conditions.

Tree mortality drives changes in forest structure and dynamics, community composition, and carbon and nutrient cycles. Since tropical forests store a large fraction of terrestrial biomass and tree diversity, improved understanding of changing tree mortality and biomass loss rates is critical. Tropical tree mortality rates have been challenging to estimate due to low background rates of tree death, and high spatial and temporal heterogeneity. Furthermore, the causes of mortality remain unclear because many factors may be involved in individual tree death, and the rapid decomposition of wood in the tropics obscures evidence of possible causes of tree mortality. We present a field protocol to assess tree mortality in tropical forests. The protocol focuses on the rapid, repeatable and inexpensive assessment of individual tree death and damage. The protocol has been successfully tested with annual assessments of >62,000 stems in total in several ForestGEO plots in Asia and the Neotropics. Standardized methods for the assessment of tree death and biomass loss will advance understanding of the underlying causes and consequences of tree mortality.Tree mortality drives forest dynamics, community composition, and carbon and nutrient cycles. We present a field protocol to assess tree mortality in tropical forests. The protocol focuses on the rapid, repeatable and inexpensive assessment of individual tree death and damage. Standardized methods for the assessment of tree death and biomass loss will advance understanding of tree mortality.

International audience

ForestGEO is a network of scientists and long-term forest dynamics plots (FDPs) spanning the Earth's major forest types. ForestGEO's mission is to advance understanding of the diversity and dynamics of forests and to strengthen global capacity for forest science research. ForestGEO is unique among forest plot networks in its large-scale plot dimensions, censusing of all stems ≥1 cm in diameter, inclusion of tropical, temperate and boreal forests, and investigation of additional biotic (e.g., arthropods) and abiotic (e.g., soils) drivers, which together provide a holistic view of forest functioning. The 71 FDPs in 27 countries include approximately 7.33 million living trees and about 12,000 species, representing 20% of the world's known tree diversity. With >1300 published papers, ForestGEO researchers have made significant contributions in two fundamental areas: species coexistence and diversity, and ecosystem functioning. Specifically, defining the major biotic and abiotic controls on the distribution and coexistence of species and functional types and on variation in species' demography has led to improved understanding of how the multiple dimensions of forest diversity are structured across space and time and how this diversity relates to the processes controlling the role of forests in the Earth system. Nevertheless, knowledge gaps remain that impede our ability to predict how forest diversity and function will respond to climate change and other stressors. Meeting these global research challenges requires major advances in standardizing taxonomy of tropical species, resolving the main drivers of forest dynamics, and integrating plot-based ground and remote sensing observations to scale up estimates of forest diversity and function, coupled with improved predictive models. However, they cannot be met without greater financial commitment to sustain the long-term research of ForestGEO and other forest plot networks, greatly expanded scientific capacity across the world's forested nations, and increased collaboration and integration among research networks and disciplines addressing forest science.

SummaryBiogeographic events occurring in the deep past can contribute to the structure of modern ecological communities. However, little is known about how the emergence of environmental gradients shape the evolution of species that underlie community assembly. In this study, we address how the creation of novel environments lead to community assembly via two non-mutually exclusive processes: 1) the immigration and ecological sorting of pre-adapted clades (ISPC), and 2) recent adaptive diversification (RAD). We study these processes in the context of the elevational gradient created by the uplift of the Central Andes.We develop a novel approach and method based on the decomposition of species turnover into within- and among-clade components, where clades correspond to lineages that originated before mountain uplift. Effects of ISPC and RAD can be inferred from how components of turnover change with elevation. We test our approach using data from over 500 Andean forest plots.We found that species turnover between communities at different elevations is dominated by the replacement of clades that originated before the uplift of the Central Andes.Our results suggest that immigration and sorting of clades pre-adapted to montane habitats is the primary mechanism shaping communities across elevations.

Projected increases in cyclonic storm intensity under a warming climate will have profound effects on forests, potentially changing these ecosystems from carbon sinks to sources. Forecasting storm impacts on these ecosystems requires consideration of risk factors associated with storm meteorology, landscape structure, and forest attributes. Here we evaluate risk factors associated with damage severity caused by Hurricanes María and Irma across Puerto Rican forests. Using field and remote sensing data, total forest aboveground biomass (AGB) lost to the storms was estimated at 10.44 (±2.33) Tg, ca. 23% of island-wide pre-hurricane forest AGB. Storm-related rainfall was a stronger predictor of forest damage than maximum wind speeds. Soil water storage capacity was also an important risk factor, corroborating the influence of rainfall on forest damage. Expected increases of 20% in hurricane-associated rainfall in the North Atlantic highlight the need to consider how such shifts, together with high speed winds, will affect terrestrial ecosystems.

Aim Rarity, which is believed to influence extinction risk, can be defined in terms of local abundance, geographical range size and habitat breadth. Phylogenetic patterns in these attributes provide insight into the extent to which rarity and extinction risk are conserved during evolution and the potential for species-level heritability. We evaluated phylogenetic signal (i.e., related species resembling each other more than species drawn at random) and evolutionary conservatism (similarity among related species exceeding that expected from a Brownian model of evolution) in three axes of rarity (local abundance, geographical range size and habitat breadth) among species in a regional pool of tropical woody plants. Location The Madidi region in Bolivia. Time period 2001–2010. Major taxa studied Lignophyta clade. Methods We used a network of 48 1-ha forest plots and 442 0.1-ha forest plots to measure local abundance and habitat breadth of 1,700+ woody plant species (from 100+ plant families). We estimated geographical range size from occurrence records of individual species across the Neotropics. We characterized overall phylogenetic patterns of rarity using Blomberg's K and applied variance partitioning among taxonomic levels, as well as disparity analysis, to describe patterns of trait distribution at different depths in the phylogeny. Results We found phylogenetic signal, but not evolutionary conservatism, in the three axes of rarity. The variance in rarity among supra-specific taxa, particularly families and genera, exceeded that calculated from random draws of species from the Madidi region. Phylogenetic signal, estimated by the proportion of variance among supra-specific taxonomic levels, varied between 23 and 36% for local abundance and geographical range size, and between 9 and 10% for habitat breadth. Main conclusions The regional pool of woody plant species in Madidi exhibits phylogenetic signal in rarity that is consistent with biologically significant species-level heritability.

El texto analiza las politicas inclusivas que se desarrollan en tres universidades privadas de la ciudad de Cordoba con relacion al estudiante con discapacidad. Este trabajo propone como objetivo general caracterizar las politicas educativas inclusivas existentes en tres universidades privadas de la ciudad de Cordoba: la Universidad Catolica de Cordoba, la Universidad Blas Pascal y la Universidad Siglo 21 a partir de la Ley Superior de Educacion. Aqui se asume que la discapacidad es resultado de la interaccion entre la persona y el ambiente, en la que las instituciones tienen la responsabilidad de proveer bienes y servicios sociales, en igualdad de oportunidades, que den garantias para el ingreso, la permanencia y la vinculacion a la vida laboral, y con ello se logre la autonomia y la vida independiente de la persona con discapacidad.

Local factors can play an important role in defining tree species distributions in species rich tropical forests. To what extent the same applies to relatively small, species poor West African montane forests is unknown. Here, forests survive in a grassland matrix and fire has played a key role in their spatial and temporal dynamics since the Miocene. To what extent these dynamics influence local species distributions, as compared with other environmental variables such as altitude and moisture remain unknown. Here, we use data from the 20.28 ha montane forest plot in Ngel Nyaki Forest Reserve, South-East Nigeria to explore these questions. The plot features a gradient from grassland to core forest, with significant edges. Within the plot, we determined tree stand structure and species diversity and identified all trees &ge, 1 cm in diameter. We recorded species guild (pioneer vs. shade tolerant), seed size, and dispersal mode. We analyzed and identified to what extent species showed a preference for forest edges/grasslands or core forest. Similarly, we looked for associations with elevation, distance to streams and forest versus grassland. We recorded 41,031 individuals belonging to 105 morphospecies in 87 genera and 47 families. Around 40% of all tree species, and 50% of the abundant species, showed a clear preference for either the edge/grassland habitat or the forest core. However, we found no obvious association between species guild, seed size or dispersal mode, and distance to edge, so what leads to this sorting remains unclear. Few species distributions were influenced by distance to streams or altitude.

Forest community composition is the outcome of multiple forces, including those that increase taxonomic and functional divergence and those that promote convergence in traits. The mechanisms underlying these forces may not operate homogenously within communities; individuals of different species are never perfectly mixed, and thus, species tend to be surrounded and interact with different subsets of species. In fact, taxonomic and functional composition of neighborhoods of different focal species can be highly variable. Here, we examine whether mechanisms driving species‐level neighborhoods relate to intrinsic characteristics of focal species such as differences in life‐history and resource‐uptake strategies and in turn relate to species survival. We focus on two key characteristics: (1) seed mass, which defines a dominant axis of life‐history strategies related to stress tolerance, and (2) understory light preferences that sort species from light‐demanding pioneers to shade‐tolerant. We monitored seedling communities over 10 yr in Puerto Rico and calculated neighborhood trait dispersion in species‐level neighborhoods using seven functional traits. We examined whether species‐level characteristics, seed mass and preferred light conditions, influence patterns of functional dispersion in seedling neighborhoods using linear models. Then, we examined how species‐level functional neighborhoods impact seedling survival. We found that small‐ and large‐seeded species diverge in the type of functional neighborhoods they associate with. Large‐seeded species associate with neighbors that are more similar than expected in leaf economic traits, but more different than expected in seed mass and leaf area traits, while the opposite was found for small‐seeded species. This variation in species functional neighborhood was important in determining seedling survival. In sum, our results suggest that divergent and convergent forces do not operate homogenously over entire communities. Their relative role changes in space, and on a species‐by‐species basis, probably with a deterministic foundation linked to traits such as seed mass.

Questions What are the relative roles of (1) environmental niche partitioning (especially along soil chemistry gradients), (2) effective dispersal, and (3) landscape characteristics in structuring species assemblies of bryophyte and seed plant metacommunities? Location Ebro river basin, NE Spain. Methods We sampled biological soil crust (BSC) bryophytes and perennial seed plants from 54 plots in ten fragments of native vegetation from two contiguous landscapes with contrasting agricultural matrix types. Each plot was characterized with respect to soil electrical conductivity (EC, a proxy for presence of gypsum and halite), pH, vegetation cover and aspect. We used unconstrained ordinations to find the main floristic gradients and evaluated their relationship with environmental variables using Kendall correlations. We studied the spatial structure of floristic dissimilarities for bryophyte and seed plant communities by using multiple regression models on distance matrices (MRM), and individual species' responses by estimating species' densities along environmental gradients. We estimated effective isolation between plots within landscapes by means of partial MRM. Results We found 60 bryophyte and 57 seed plant species. Compositional dissimilarities were spatially structured. DCA showed clear floristic segregation of the two landscapes. The soil EC gradient was the main variable explaining compositional variation in both plant metacommunities, followed by soil pH. The effect of geographic distance between plots differed significantly between landscapes and matrix types, and was larger for seed plants than for bryophytes. Conclusions Only a handful of BSC bryophyte species can be regarded as either true gypsofuges or true gypsophiles, Gypsophilous bryophytes are fewer and less strongly associated with gypsum-rich sites than co-existing perennial seed plants. Overall, BSC bryophyte communities vary less over similar distances than corresponding seed plant communities, most likely due to higher dispersal ability. We argue that the topographically complex landscape of a less modified agricultural matrix imposes more ‘friction’ to bryophyte dispersal than a smoother landscape with a more intensely human-modified matrix. Effective conservation of fragmented arid agricultural landscapes must take into account the sensitivity of the biota to fragment intrinsic conditions, the properties and the management practices that shaped the landscape.

SUMMARY Inappropriate CD4+ T helper (Th) differentiation can compromise host immunity or promote autoimmune disease. To identify disease-relevant regulators of T cell fate, we examined mutations that modify risk for multiple sclerosis (MS), a canonical organ-specific autoimmune disease. This analysis identified a role for Zinc finger E-box-binding homeobox (ZEB1). Deletion of ZEB1 protects against experimental autoimmune encephalitis (EAE), a mouse model of multiple sclerosis (MS). Mechanistically, ZEB1 in CD4+ T cells is required for pathogenic Th1 and Th17 differentiation. Genomic analyses of paired human and mouse expression data elucidated an unexpected role for ZEB1 in JAK-STAT signaling. ZEB1 inhibits miR-101-3p that represses JAK2 expression, STAT3/STAT4 phosphorylation, and subsequent expression of interleukin-17 (IL-17) and interferon gamma (IFN-γ). Underscoring its clinical relevance, ZEB1 and JAK2 downregulation decreases pathogenic cytokines expression in T cells from MS patients. Moreover, a Food and Drug Administration (FDA)-approved JAK2 inhibitor is effective in EAE. Collectively, these findings identify a conserved, potentially targetable mechanism regulating disease-relevant inflammation., Graphical Abstract, In brief Qian et al. show that ZEB1 is required for the development of the autoimmune disease multiple sclerosis (MS). ZEB1, a transcription factor, promotes JAK-STAT signaling during Th1/Th17 differentiation by repressing expression of a JAK2-targeting miRNA. ZEB1 and JAK2 are potentially clinically relevant therapeutic targets for MS.

Aims To determine whether species that contribute most to a plot’s biomass are the most abundant (high local abundance at plot scale) or the most frequent (occur the most across plots at landscape scale), or both. In the tropical Andes, these patterns may change with elevation. This study assesses the contribution to plot’s above-ground biomass (AGB) of the plant community abundance pattern –the prevalence of within-plot dominant species– and the over-occurrence of regionally frequent species, in an elevation gradient. Methods We considered all trees ≥2.5 cm DBH from 446 0.1 ha plots in an Amazonia-Andes 260–4350 m elevation cline in N Bolivia. Plot AGB was calculated as the sum of AGBs for all stems contained. We grouped plots into four bins segregated by elevation and ran a bootstrap analysis over subsets of 58 random plots per bin with 100 iterations. Simpson evenness index (ED) for all species in each plot was used as a measure for its species abundance. Values for each plot’s species frequency was calculated as the mean of all species’ in the plot mean frequencies across the bin (i.e. the fraction of plots where each species occurs). We used linear models to correlate plot AGB with (1) elevation and mean annual precipitation (MAP), and (2) ED, plot species frequency and elevation. We performed all analyses at the species, genus and family levels. Results Plot AGB was related negatively with elevation, and thus positively with MAP, and also negatively with plot ED and plot species frequency, all significant. Plot species abundance therefore contributes positively to explain the relationship with AGB along elevational gradients, while plot species frequency does so negatively (i.e. less frequent species contribute more to a plot’s AGB across elevation). AGB, for both generic and familial levels was also significantly and negatively correlated with ED, but not related with plot species frequency biomass at these taxonomic levels. Conclusions Plot AGB was mainly associated with elevation and floristic composition where species, genera and families tended to be abundant at the local (plot) scale. Species that were less frequent at the regional scale contributed with more AGB regionally, while frequency at generic and familial scales did little to explain AGB patterns. This association seems stronger at lower elevations for all taxonomic levels while decreases toward higher elevation. Our study reveals a relationship between plot structural features like C stocks –influenced by species local abundances– and the distribution of taxa across the landscape.

What causes individual tree death in tropical forests remains a major gap in our understanding of the biology of tropical trees and leads to significant uncertainty in predicting global carbon cycle dynamics. We measured individual characteristics (diameter at breast height, wood density, growth rate, crown illumination and crown form) and environmental conditions (soil fertility and habitat suitability) for 26 425 trees ≥ 10 cm diameter at breast height belonging to 416 species in a 52-ha plot in Lambir Hills National Park, Malaysia. We used structural equation models to investigate the relationships among the different factors and tree mortality. Crown form (a proxy for mechanical damage and other stresses) and prior growth were the two most important factors related to mortality. The effect of all variables on mortality (except habitat suitability) was substantially greater than expected by chance. Tree death is the result of interactions between factors, including direct and indirect effects. Crown form/damage and prior growth mediated most of the effect of tree size, wood density, fertility and habitat suitability on mortality. Large-scale assessment of crown form or status may result in improved prediction of individual tree death at the landscape scale.

Understanding patterns and mechanisms of variation in the compositional structure of communities across spatial scales is one of the fundamental challenges in ecology and biogeography. In this study, we evaluated the effects of spatial extent (i.e. size of study region) on: 1) whether community composition can be better explained by environmental (i.e. niche-based) or spatial (e.g. dispersal-based) processes ; and 2) how climate and soils contribute to the influence of environment on plant community composition. We surveyed community composition across a network of 398 forest plots spanning a ∼4000 m elevational gradient in the Madidi region in northwestern Bolivia. Using redundancy analyses and hierarchical variation partitioning, we disentangled the effects of environmental and spatial predictors on species composition, further decomposing the environmental effect between its climatic and soil components. We repeated analyses for 200 sub-regions ranging in spatial extent from ∼250 to ∼17 500 km2. Our analyses show a high degree of idiosyncrasy in results that come from different sub-regions. Despite this variability, we were able to identify various important patterns in the structure of tropical plant communities in our study system. First, even though sub-regions varied in size by nearly two orders of magnitude, the total amount of explained variation in community composition was scale independent; at all spatial scales, environment and space accounted for about 25% of the differences in community composition among plots. Second, the measured environmental effect was higher than the spatial effect on average and in the vast majority of sub-regions. This was true regardless of the spatial extent of analysis. Finally, we found that both climatic and soil variables accounted for significant fractions of variation, but climate was always more important than soils.

Pragmatic methods to assess the status of biodiversity at multiple scales are required to support conservation decision-making. At the intersection of several major biogeographic zones, Bolivia has extraordinary potential to develop a monitoring strategy aligned with the objectives of the Group on Earth Observations Biodiversity Observation Network (GEO BON). Bolivia, a GEO Observer since 2005, is already working on the adequacy of national earth observations towards the objectives of the Global Earth Observation System of Systems (GEOSS). However, biodiversity is still an underrepresented component in this initiative. The integration of biodiversity into Bolivia’s GEO framework would confirm the need for a country level biodiversity monitoring strategy, fundamental to assess the progress towards the 2020 Aichi targets. Here we analyse and discuss two aspects of the process of developing such a strategy: (1) identification of taxonomic, temporal and spatial coverage of biodiversity data to detect both ava...

The aim of this work is to examine whether there exists a link between local and landscape patterns of species commonness, and if these are related to morphological traits in tropical plant communities. The Madidi region (Bolivian tropical Andes) is selected as study location. We estimated local and landscape commonness, rarity classes, height, diameter, number of stems, and habit for >2,300 species. We employed correlations to evaluate the relationship between local scale commonness and landscape scale commonness. We performed ANCOVA and multinomial logistic regressions to predict commonness and rarity variables from the morphological traits. We repeated the analyses for six different forest types, including dry forests and wet forests along a 3,477 m elevation gradient. We found a positive relationship between local and landscape commonness in all forest types. Additionally, we found that, plant height influences the local and landscape commonness, and that the apportioning of species into rarity classes depends greatly on the species habit and, at lesser degree, on the number of stems. Our main conclusions are: (1) Approaches to commonness and rarity based on abundance only or occurrence only could summarize most of the relevant information to characterize commonness and rarity patterns: both approaches, in practice, do not supply independent information. (2) The species traits determine which species are rare and which ones are common, which indicates that commonness and rarity patterns are the result of non-neutral trait-based community assembly processes.

Aim To test the niche breadth hypothesis (NBH), which states that dominant species have broader environmental tolerances than rare species, focusing on oligarchic species distributions (1) along the gradients of edaphic and climatic individual variables, and (2) within the n-dimensional environmental frame defined by all edaphic and climatic variability. Location Amazonian and Andean tropical rain forests along a ca. 3000 m elevation gradient, covering an area of 200 × 200 km in northwestern Bolivia. Methods All woody plants with a DBH ≥2.5 cm were measured in 98 0.1-ha plots. We analysed 18 chemical properties of the soils in each plot. Climatic and topographic variables were obtained from available open-access databases. Three measures were calculated for each of the species found at each forest type: (1) regional-scale dominance based on frequency and local abundance, (2) niche breadth along each of the environmental variables, and (3) total niche size within the whole environment. Results Oligarchic species showed broader niche breadths than the other species that constituted the community assembly in both Amazonian and Andean rain forests. The niche breadth of any species tended to be positively correlated with its degree of dominance. The Amazonian forest showed a stronger oligarchic pattern than the Andean forest, and the Amazonian common species showed larger niches overall. However, this pattern differed for some particular variables: Amazonian oligarchies had narrower niches along the variables related to organic matter and most climatic variables, whereas Andean oligarchies had narrower niches along several micronutrient factors and temperature variables. Conclusions The results provide strong empirical support for the NBH in tropical rain forests. However, different patterns of dominance were found in the two habitats: oligarchic species ranged from narrow-niched species to very broad generalist species. Broad-niched oligarchic species have also been reported in other regions, suggesting an important role of niche size linking commonness at different scales. Oligarchic species exhibit relatively narrow niches with respect to soil factors if measured along wide gradients, regardless of the forest type studied. In contrast, the opposite pattern was found for many climatic variables, indicating higher sensitivity to climate in Amazonia compared to the Andes. Despite these differences, Amazonia has much larger total niche sizes for its common species than the Andes overall.

The goal of this study was a quantitative assessment of two-dimensional commonness in the lowland, dry, and montane tropical forests of the Madidi region (Bolivia). This region spans a large elevational and environmental gradient, with great diversity differences among sites. We aimed to correlate commonness patterns at different scales with elevation and with the size of the species pool. We also developed 1) a measure of ecological commonness and 2) a criterion to separate common from uncommon species; both based on the h index of academic productivity. With this approach, we calculated the 1) mean commonness of all species of the community; 2) proportion of common species of the community; and 3) mean commonness of the common species. The results showed that the commonness patterns in the Madidi region are strongly linked to the size of the species pool, independently of the environmental heterogeneity involved and the type of forest and spatial scale considered. Although these factors do not affect the general quality of the community, they do influence differences in commonness among species. Overall, we identified strong support for the oligarchy hypothesis, regardless of the strength of the pattern, and conclude that a quantitative approach to commonness could lead to great insights into community structure.