Examination of the mechanisms of the plant community assembly at a geographical scale is an interesting topic in ecology and biogeography, which are of great significance for the understanding of species coexistence and biodiversity conservation. But so far, only a few studies have simultaneously assessed the relative roles of multiple-scale factors in shaping the phylogenetic and functional structure of plant communities at a macroecological scale. In this study, we linked modern climate, glacial-interglacial climate change, and soil properties with the phylogenetic and functional structure of shrub and herbaceous plant communities in Inner Mongolia, China, an arid and semiarid region. Our results showed that the functional structure of plant communities was more associated with modern climate and soil properties than the phylogenetic structure, especially for the soil properties. Modern precipitation was found in all the combinations of variables that were most closely related to the community structure in this arid and semi-arid region. These findings suggest that the phylogenetic and functional structure of biotic communities may be affected by processes at divergent spatial-temporal scales. That is, the functional structure is better linked with the modern and local factors while the phylogenetic structure is more associated with the historical and regional processes. This study highlights the importance of the associations between the different biodiversity dimensions and divergent drivers.

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Ostryopsis davidiana shrubland is one of the most important types of deciduous broad-leaved shrublands that widely occur on mountain sites in northern and northwestern China. Determination of the distribution and characteristics of the O. davidiana communities helps facilitate the biodiversity conservation and establishment of eco-safety buffer on the Mongolian Plateau. In this study, we investigated the O. davidiana shrubland communities across 37 sites in Nei Mongol, and identified the community characteristics, including species composition, ecological traits and classification of O. davidiana alliance based on site survey data collected during 2016-2020. A total of 300 vascular species, belonging to 158 genera from 52 families, were recorded, consisting 298 angiosperm species belonging to 156 genera from 50 families and 2 fern species belonging to 2 genera from 2 families. Perennial herbs are the dominant life form, accounting for 73% of the total species, and mesophytes are the dominant water ecological type, accounting for 65% of the total species. Temperate plants contributed largely to the geographical floristic composition, with majority of the species being East Palaearctic, followed by East Asia element. Most of plant species in the O. davidiana communities were rare species. Based on the survey data, the O. davidiana alliance in Nei Mongol could be divided into 3 association groups and 17 associations.

摘 要 锦鸡儿属(Caragana)植物是蒙古高原干旱生态系统的重要组成成分, 沿着环境梯度形成了极为明显的地理替代分 布。为了检验这些替代分布种对气候和土壤环境变化的适应性, 该研究在内蒙古地区选择了41个样地、9种锦鸡儿属植物, 测 定了这些植物的株高(h)、叶性状(叶干物质含量(LDMC)、比叶面积(SLA)、叶面积(LA)、叶片氮含量(LNC)、叶片磷含量(LPC) 和氮磷比(N:P))和茎性状(茎组织密度(STD)