Wenqi Song

Summary: Leaf length and width are key dimensions of tree leaf size and can influence leaf boundary‐layer development and leaf‐environment heat exchange. However, their global patterns and environmental correlates remain poorly understood. By integrating tree leaf traits and community data, we mapped community leaf length and width and identified their environmental correlates in global forests. Both community leaf length and width decreased toward higher latitudes, although leaf width showed an additional peak at mid‐latitudes. These asynchronous patterns contributed to geographic variation in leaf shape, with more elongated leaves in tropical and boreal forests and relatively rounder leaves in temperate forests. Soil variables and mean annual temperature were the main correlates of leaf length, whereas leaf width was mainly associated with temperature. Our results reveal distinct environmental correlates of community leaf length and width, highlight the value of multiple leaf dimensions for predicting forest distributions and function, and identify tropical regions where additional trait data are needed to reduce uncertainty.

Aim: Most seed plants are associated with one of four major types of mycorrhizal fungi: arbuscular (AM), ectomycorrhizal (ECM), ericoid (ERM) or orchid (ORM) fungi. These mycorrhizal types have evolved in close association with plant growth form (i.e., woody vs. herbaceous species). However, it remains unclear how the biogeography of mycorrhizal plants varies across different growth forms. Location: Global. Time Period: Current. Major Taxa Studied: Seed plants. Methods: By integrating newly compiled databases of species distributions, mycorrhizal types and growth forms for over 300,000 seed plant species, we demonstrated how the geographic patterns of mycorrhizal plant species and their drivers vary between woody and herbaceous species. Results: We found that the geographic patterns of mycorrhizal plants were more strongly associated with latitude and environmental variables when woody and herbaceous species were analysed separately, compared to when all species were analysed together. Specifically, in woody species, the proportion of AM species decreased towards high latitudes, while the proportion of ECM and ERM species increased. In herbaceous species, the proportion of AM species increased towards high latitudes, while the proportion of ORM species decreased. These geographic patterns of different mycorrhizal plants were primarily driven by temperature in woody species but by precipitation in herbaceous species. Interestingly, soil properties played significant roles in shaping the geographic patterns of mycorrhizal plants in both growth forms. These results suggest that mycorrhizal associations play different roles in mediating woody and herbaceous plant adaptation to environmental conditions. Main Conclusions: Our study provides the global patterns in the proportions of different mycorrhizal types and demonstrates that the drivers underlying these patterns depend on plant growth forms. We suggest that mycorrhizal symbiosis related to plant growth forms may play an important role in shaping global plant diversity patterns.

Flowering phenology has major impacts on physiological processes, survival, and reproductive success in angiosperms, serving as a critical biological indicator of climate change impacts. However, changes in flowering phenology and their determinants in subtropical montane ecosystems remain poorly quantified at continental extents. Here we investigated the determinants of flowering phenology shifts over the past century across 11 subtropical mountains in China. Based on century‐long herbarium collections of 784 flowering plant species in these mountains, we first used linear regression models to assess the magnitude and direction of changes in flowering time for each species in each mountain separately. Then, we investigated the underlying drivers of changes in flowering time, including climate changes, species traits as well as changes in species elevation range size. Our analyses revealed an average advancement in flowering phenology of 3.8 days per decade, though marked regional disparities emerged: flowering times were advanced in southeastern mountains but delayed in southwestern ones. Climate change, species functional traits, and mountain properties all had significant effects on the observed changes in flowering time. Notably, the flowering time of lowland and non‐native plants was advanced more than that of alpine and native plants. A key finding was the negative correlation between flowering time changes and elevational range expansions, supporting the hypothesis that phenological plasticity facilitates range adjustments under environmental change. These findings demonstrate that flowering phenological responses are context‐dependent, mediated by complex biotic–abiotic interactions. Our study provides the first biogeographical assessment of flowering phenology shifts in subtropical Asian mountains, offering critical insights for predicting ecosystem stability and informing biodiversity conservation strategies under ongoing climate change.

Aim: The Kunming‐Montreal Global Biodiversity Framework requires that evolutionary histories of species should be considered in conservation planning. The phylogenetic structure of species assemblages quantifies species evolutionary histories and increasingly becomes an endeavour for ecologists. Understanding the geographic patterns of phylogenetic structure of species assemblages and their drivers can provide a fundamental reference for conservation planning. Although several theoretical hypotheses based on the effects of contemporary environment, historical climate change and evolutionary niche conservatism had been widely discussed in previous studies, the relative contributions of these hypotheses on phylogenetic structure of angiosperms, especially herbaceous species, remain debated.Location: East Eurasia.Major Taxa Studied: Angiosperms.Methods: We compiled distributions of 43,023 angiosperm species in east Eurasia at spatial resolution (100 × 100 km²). Using this newly compiled database and a species‐level phylogeny, we estimated the phylogenetic structure patterns for species with different growth forms. We explored the relationships of these patterns with contemporary environment and historical climate change to test predictions of the tropical niche conservatism hypothesis (TCH) and to compare the contribution of different hypotheses using generalised linear models and hierarchical partitioning.Results: We found that phylogenetic structure of angiosperms displayed significant latitudinal gradients. Notably, phylogenetic structure patterns and their drivers differed between woody and herbaceous species. Actual evapotranspiration was the best predictor of phylogenetic structure patterns for all and herbaceous species, while the mean temperature of the coldest quarter was the best predictor for woody species. The effect of historical climate change on phylogenetic structure patterns was weak.Main Conclusions: Our results suggest that the TCH only explains the phylogenetic structure pattern of woody species, not herbaceous species. Moreover, contemporary climate influences the phylogenetic structure of angiosperms in east Eurasian by affecting herbaceous and woody species differently.

Mechanisms underlying large‐scale spatial patterns of species richness are one of the central issues in ecology. Although contemporary climate, evolutionary history, and historical climate change have been proposed as drivers of species richness patterns, variation in the relative importance of different factors remains a major challenge. Here, using newly compiled distribution data with a spatial resolution of 100 × 100 km for 43 023 angiosperms plant species in east Eurasia, we mapped species richness patterns for plants with different growth forms (i.e. woody versus herbaceous) and range sizes (i.e. wide‐ranged versus narrow‐ranged species), and compared the relative importance of the four hypotheses in explaining these patterns, i.e. freezing tolerance hypothesis, historical climate change hypothesis, Janzen's hypothesis (predicting that climate seasonality and topography determine species richness patterns), and diversification rate hypothesis. We found that species richness of all angiosperm plants presented a clear latitudinal gradient and was highest in southwestern China and Central Asian mountains. Notably, species richness patterns and their dominant drivers differed between species groups. Historical climate change was the dominant driver for richness patterns of all and herbaceous species. The freezing tolerance hypothesis dominated the drivers for all woody species, while Janzen's hypothesis dominated narrow‐ranged woody and herbaceous species. Our study suggests that different hypotheses contribute to large‐scale plant richness patterns via their effects on different plant groups. Our results did not support the diversification rate hypothesis, but demonstrated the high importance of historical climate change to plant diversity in east Eurasia, providing new perspectives on the mechanisms of plant diversity patterns in this continent.

Large-scale spatial patterns of species richness are one of the central issues in ecology. Although hypotheses based on effects of contemporary climate, evolutionary history and historical climate change have been employed to explain the mechanisms underlying species richness patterns, variation in relative contribution of different hypothesis remains a major challenge. Here, using newly-compiled distribution data with a spatial resolution of 100 * 100 km2 for 43,023 seed plant species in eastern Eurasia, we mapped species richness patterns for plants with different growth forms (i.e., woody vs. herbaceous) and range sizes (i.e., wide-ranged vs. narrow-ranged species), and compared the contribution of four hypotheses on these patterns, i.e., freezing tolerance hypothesis, historical climate change hypothesis, Janzen hypothesis and diversification rate hypothesis. We found that species richness of all seed plants presented a clear latitudinal gradient and was the highest in southwestern China and Central Asian mountains. Notably, species richness patterns and their dominant hypotheses differed between species groups. Historical climate change dominated richness patterns of overall, herbaceous and wide-ranged herbaceous species. The freezing tolerance hypothesis dominated those for all woody and wide-ranged woody species, while the Janzen hypothesis dominated narrow-ranged woody and herbaceous species. Our study suggests that different hypotheses contribute to large-scale species richness patterns via their dominant effects in different species groups. Interestingly, our study did not support the diversification rate hypothesis, but demonstrated high contribution of historical climate change to plant diversity, providing new perspectives on the mechanisms of plant diversity patterns in eastern Eurasia.

Aim: Significant changes in species elevational ranges in mountains have been repeatedly documented, yet the direction, magnitude and drivers of these shifts remain controversial. Presently, there is still lacking evidence about the general nature of species elevational range shifts in eastern Eurasia in response to anthropogenic climate change. By using historical specimen records and recent field observations for 735 seed plant species across 29 China's mountains, we assessed changes in species' elevational centroids and their drivers.Location: China.Time Period: 1950–2018.Major Taxa Studied: Seed plant species.Methods: The elevation records of all sampled occurrences in each mountain during the two time periods were estimated, and the null models were developed to test the sampling bias. Ecological niche models (ENMs) were used to evaluate the relative importance of climate factors in constraining each species distribution. Generalized linear models (GLMs) to test the relationships between the centroid elevational range shifts of species and different divers.Results: We found that 54% of the species shifting upward and 46% downhill. However, species' elevational shifts significantly differed among species and mountains. Herbaceous and lowland species moved upward faster than woody and high‐elevation species. Species in temperate mountains and in mountains with taller elevational gradients moved upward, while species in subtropical mountains and in mountains with shorter elevational gradients moved downward. Precipitation changes experienced by species, species' climatic adaptations, several species' functional traits and mountain size all contributed to explain the magnitude of species' centroid elevational range shifts.Main Conclusions: Our results highlight complex biodiversity redistribution of seed plants across Chinese mountains, not necessarily conforming to the trend of species upward shifts in elevation. Changes in precipitation regimes may blur the simplistic assumption of isotherm tracking. This study fills an important geographic shortfall for our understanding of biodiversity redistribution under anthropogenic climate change.