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As Earth’s climate has varied strongly through geological time, studying the impacts of past climate change on biodiversity helps to understand the risks from future climate change. However, it remains unclear how paleoclimate shapes spatial variation in biodiversity. Here, we assessed the influence of Quaternary climate change on spatial dissimilarity in taxonomic, phylogenetic, and functional composition among neighboring 200-kilometer cells (beta-diversity) for angiosperm trees worldwide. We found that larger glacial-interglacial temperature change was strongly associated with lower spatial turnover (species replacements) and higher nestedness (richness changes) components of beta-diversity across all three biodiversity facets. Moreover, phylogenetic and functional turnover was lower and nestedness higher than random expectations based on taxonomic beta-diversity in regions that experienced large temperature change, reflecting phylogenetically and functionally selective processes in species replacement, extinction, and colonization during glacial-interglacial oscillations. Our results suggest that future human-driven climate change could cause local homogenization and reduction in taxonomic, phylogenetic, and functional diversity of angiosperm trees worldwide.

In a meta-analysis, we use an unprecedented dataset, representing 556 unique locations worldwide, distributed across 44 countries and six continents to show for the first time that lianas (woody vines) thrive relatively better than trees when forests are disturbed, temperature increase, precipitation decrease, and particularly in tropical lowlands. We demonstrate that liana dominance can persist for decades post-disturbance and hinder the recovery of disturbed forests, especially when climate favours lianas. With implications for the global carbon sink, our findings suggest that degraded tropical forests with environmental conditions favouring lianas should be the highest priority to consider for restoration management.

Significance We explore an extended view of the tropical conservatism hypothesis to account for two often-neglected components of climatic stress: drought and the combined effect of seasonal cold and drought—the latter being a common feature of extratropical dry environments. We show that evolutionary diversity of angiosperm assemblages in extratropical dry biomes is even lower than in biomes subject to only one type of climatic stress. We further show that evolutionary diversity in many assemblages from eastern North America is higher or comparable to that of tropical moist forests, suggesting that some extratropical moist biomes have accumulated angiosperm lineages over deep evolutionary timescales with their flora assembled from lineages that represent the entirety of the angiosperm tree of life.

AbstractThe functional composition of plant communities is commonly thought to be determined by contemporary climate. However, if rates of climate‐driven immigration and/or exclusion of species are slow, then contemporary functional composition may be explained by paleoclimate as well as by contemporary climate. We tested this idea by coupling contemporary maps of plant functional trait composition across North and South America to paleoclimate means and temporal variation in temperature and precipitation from the Last Interglacial (120 ka) to the present. Paleoclimate predictors strongly improved prediction of contemporary functional composition compared to contemporary climate predictors, with a stronger influence of temperature in North America (especially during periods of ice melting) and of precipitation in South America (across all times). Thus, climate from tens of thousands of years ago influences contemporary functional composition via slow assemblage dynamics.

AbstractThe species abundance distribution (SAD) is one of the few universal patterns in ecology. Research on this fundamental distribution has primarily focused on the study of numerical counts, irrespective of the traits of individuals. Here we show that considering a set of Generalized Species Abundance Distributions (GSADs) encompassing several abundance measures, such as numerical abundance, biomass and resource use, can provide novel insights into the structure of ecological communities and the forces that organize them. We use a taxonomically diverse combination of macroecological data sets to investigate the similarities and differences between GSADs. We then use probability theory to explore, under parsimonious assumptions, theoretical linkages among them. Our study suggests that examining different GSADs simultaneously in natural systems may help with assessing determinants of community structure. Broadening SADs to encompass multiple abundance measures opens novel perspectives in biodiversity research and warrants future empirical and theoretical developments.

La déconstruction de la variation et de la co-variation des traits fonctionnels dans un large éventail de conditions environnementales devrait améliorer la compréhension mécaniste des processus d'assemblage de la communauté et améliorer le paramétrage actuel des modèles de végétation dynamique. Ici, nous présentons une étude qui déconstruit la variation et la co-variation des traits foliaires aux composantes iithin-species, taxonomic-interspecific et plot-environment en comparant trois gradients environnementaux tropicaux au Pérou, au Brésil et au Ghana. Nous avons mesuré les traits photosynthétiques, chimiques et structurels des feuilles à l'aide d'un protocole d'échantillonnage standardisé, totalisant plus de 1 000 individus appartenant à 367 espèces échantillonnées. La variation associée à l'ensemble de la composante taxonomique interspécifique (espèce+genre+famille) pour la plupart des caractères était relativement constante dans tous les gradients environnementaux, mais la variation intra-spécifique dans l'espèce et la variation parcellaire-environnementale dépendaient fortement du gradient environnemental. La co-variation trait-trait était également fortement liée au gradient environnemental où les traits étaient mesurés, bien que certains traits aient des composantes de co-variation cohérentes indépendamment du gradient environnemental. Nos résultats démontrent que le filtrage le long des gradients est principalement exprimé par la variation taxonomique intra- et interspécifique des traits, mais que la co-variation des traits dépend fortement de l'environnement local et que, par conséquent, les relations globales de co-variation des traits peuvent ne pas toujours s'appliquer à des échelles plus petites. La deconstrucción de la variación y covariación de los rasgos funcionales en una amplia gama de condiciones ambientales debería aumentar la comprensión mecanicista de los procesos de ensamblaje comunitario y mejorar la parametrización actual de los modelos dinámicos de vegetación. Aquí, presentamos un estudio que deconstruye la variación del rasgo foliar y la covariación a los componentes iithin-specie, taxonómico-interspecífico y de parcela-ambiente comparando tres gradientes ambientales tropicales en Perú, Brasil y Ghana. Medimos los rasgos fotosintéticos, químicos y estructurales de las hojas utilizando un protocolo de muestreo estandarizado, totalizando más de 1.000 individuos pertenecientes a 367 especies muestreadas. La variación asociada con todo el componente taxonómico interespecífico (especie+género+familia) para la mayoría de los rasgos fue relativamente consistente en todos los gradientes ambientales, pero la variación intraespecífica dentro de la especie y la variación parcela-ambiente dependieron en gran medida del gradiente ambiental. La covariación rasgo-rasgo también estuvo fuertemente vinculada al gradiente ambiental donde se midieron los rasgos, aunque algunos rasgos tenían componentes de covariación consistentes independientemente del gradiente ambiental. Nuestros resultados demuestran que el filtrado a lo largo de los gradientes se expresa principalmente a través de la variación taxonómica intra e interespecífica del rasgo, pero que la covariación del rasgo depende en gran medida del entorno local y, por lo tanto, las relaciones de covariación del rasgo global no siempre se aplican a escalas más pequeñas. Deconstructing functional trait variation and co-variation across a wide range of environmental conditions should increase the mechanistic understanding of community assembly processes and improve current parameterization of dynamic vegetation models. Here, we present a study that deconstructs leaf trait variation and co-variation to iithin-species, taxonomic-interspecific, and plot-environment components comparing three tropical environmental gradients in Peru, Brazil and Ghana. We measured photosynthetic, chemical and structural leaf traits using a standardized sampling protocol, totalling more than 1,000 individuals belonging to 367 species sampled. Variation associated with the whole interspecific taxonomic component (species+genus+family) for most traits was relatively consistent across environmental gradients, but intra-specificwithin-species variation and the plot-environment variation was strongly dependent on the environmental gradient. Trait-trait co-variation was also strongly linked to the environmental gradient where the traits were measured, although some traits had consistent co-variation components irrespective of environmental gradient. Our results demonstrate that filtering along gradients is mostly expressed through trait intra- and interspecifictaxonomic variation, but that trait co-variation is strongly dependent on the local environment, and thus global trait co-variation relationships might not always apply at smaller scales. يجب أن يؤدي تفكيك تباين السمات الوظيفية والتباين المشترك عبر مجموعة واسعة من الظروف البيئية إلى زيادة الفهم الميكانيكي لعمليات تجميع المجتمع وتحسين المعلمات الحالية لنماذج الغطاء النباتي الديناميكية. هنا، نقدم دراسة تفكك تباين سمة الورقة والتباين المشترك مع أنواع الإيثين، والمكونات التصنيفية بين النوعية، ومكونات بيئة الأرض التي تقارن ثلاثة تدرجات بيئية استوائية في بيرو والبرازيل وغانا. قمنا بقياس سمات الأوراق الضوئية والكيميائية والهيكلية باستخدام بروتوكول موحد لأخذ العينات، بلغ مجموعها أكثر من 1000 فرد ينتمون إلى 367 نوعًا تم أخذ عينات منها. كان التباين المرتبط بالمكون التصنيفي الكامل بين الأنواع (الأنواع+الجنس+العائلة) لمعظم السمات متسقًا نسبيًا عبر التدرجات البيئية، ولكن التباين داخل الأنواع وتباين بيئة الأرض كان يعتمد بشدة على التدرج البيئي. كما ارتبط التباين المشترك في السمات ارتباطًا وثيقًا بالتدرج البيئي حيث تم قياس السمات، على الرغم من أن بعض السمات تحتوي على مكونات تباين مشترك متسقة بغض النظر عن التدرج البيئي. تُظهر نتائجنا أن التصفية على طول التدرجات يتم التعبير عنها في الغالب من خلال التباين التصنيفي داخل الصفات وبين الصفات المحددة، ولكن هذا التباين المشترك في السمات يعتمد بشدة على البيئة المحلية، وبالتالي قد لا تنطبق علاقات التباين المشترك في السمات العالمية دائمًا على نطاقات أصغر.

A large fraction of Earth’s plant species are faced with increased chances of extinction.