Plan community responses to aridity_Data_Ding_Eldridge

This dataset is to support the paper published in Journal of Biogeography: "Community-level responses to increasing dryness vary with plant growth form across an extensive aridity gradient". <br>Methods: We measured the abundance and size distribution (median, skewness, variance) of perennial plant communities from different growth forms (trees, shrubs and grasses), the spatial arrangement of trees in the overstorey, and both biotic (competition) and abiotic (climate, soil properties) factors at 150 sites along an extensive aridity gradient from humid to arid areas. We used regression analyses and linear models to explore variation in community structure with increasing aridity, and key driving factors for different perennial plant communities. Results: Variation in community structure differed with growth form. As aridity increased, trees had wider canopies and were spatially aggregated, shrubs became miniaturised, but highly variable in size, and grasses comprised more larger individuals. Biotic and abiotic factors exerted different effects on different growth forms, with trees and shrubs consistently affected by competition and aridity, respectively, while grasses were weakly affected by aridity, summer rainfall and soil texture. Main conclusions: Our study highlights the idiosyncratic adaptation strategies used by trees, shrubs and grasses in response to drying climates at the community level through their effect on the size distribution or spatial aggregation. The structure of different perennial growth forms was influenced by different effects from either biotic (competition) or abiotic (climate, soil) factors. Under forecasted drier climates, canopy expansion and greater aggregation of trees might enhance resource sinks and shelter for diverse biota, potentially shielding plant communities against predicted aridification.<br><br>

本数据集用于支持发表于《生物地理学杂志》（Journal of Biogeography）的论文《沿广泛干旱梯度，群落水平对干旱加剧的响应随植物生长型而异》。
方法：我们在从湿润到干旱区域的大范围干旱梯度上的150个样地中，测定了不同生长型（乔木、灌木、草本）多年生植物群落的多度与个体大小分布（中位数、偏度、方差），林上层乔木的空间分布格局，同时测定了生物因子（种间竞争）与非生物因子（气候、土壤属性）。我们采用回归分析与线性模型，探究了随干旱程度加剧的群落结构变化，以及不同多年生植物群落的关键驱动因子。
结果：群落结构的变化随植物生长型存在显著差异。随着干旱程度升高，乔木冠幅更宽且空间聚集度更高；灌木个体体型趋于小型化，但大小变异程度极大；草本群落则包含更多大型个体。生物与非生物因子对不同生长型植物的影响存在分化：乔木与灌木分别主要受种间竞争与干旱程度的调控，而草本群落受干旱、夏季降雨与土壤质地的影响较弱。
主要结论：本研究揭示了乔木、灌木与草本通过改变个体大小分布或空间聚集格局，在群落层面适应干旱气候的特异性适应策略。不同多年生植物生长型的群落结构分别受到生物（种间竞争）或非生物（气候、土壤）因子的差异化调控。在预测的更干旱气候背景下，乔木冠幅扩张与更高的空间聚集度可能会提升多样生物群落的资源库与庇护所，进而潜在地帮助植物群落抵御预期的干旱化进程。