基于系统发育及功能性状的不同坡向荒漠植物群落构建研究——以博湖县沙化封禁保护区为例

荒漠植物群落构建机制的研究有助于荒漠生态系统植物资源的保护及系统平衡稳定的维持。基于系统发育与功能性状相结合的方法，以博湖县沙化封禁保护区植物群落为研究对象，在研究区内纵向沙垄的不同坡向上(丘间、阴坡、阳坡)设置样方，进行植物群落物种功能性状和土壤因子的调查与测定，通过检验植物群落物种功能性状的系统发育信号，分析不同坡向植物群落物种系统发育结构和功能结构的表现模式，利用主成分分析(PCA)和线性回归模型(Linear regression model)筛选出影响物种共存的环境因子，进而揭示研究区干旱荒漠生态系统植物群落物种共存的驱动因素。结果表明：(1)研究区植被主要以耐旱的灌木和藜科草本植物为优势种；不同坡向土壤因子具有异质性，丘间、阴坡土壤养分、水分更为丰富。(2)研究区样地植物群落物种10个功能性状指标的系统发育信号K值均小于1,说明物种功能性状受系统进化影响较小，物种功能性状未表现出系统发育保守性。(3)不同坡向系统发育结构均趋于发散，限制相似性在植物分布中占主导作用；丘间和阴坡上较丰富的土壤肥力是物种功能结构发散的主要原因，阳坡物种功能结构表现为聚集效应，生境过滤为其驱动因素...

Construction of desert plant communities with different slope orientations based on phylogenetic and functional traits: Example of desertification closure reserve in Bohu County

The study of desert plant community construction mechanisms can help to protect the plant resources of the desert ecosystem and maintain the balance and stability of the system. Based on the combination of phylogeny and functional traits, the plant community of the desertification closure reserve in Bohu County was used as the research object, we set up the samples on different slope aspects (between hills, shaded slope, and sunny slope) of the longitudinal sandy monopolies in the research area, and investigated and measured the functional traits of plant community species and soil factors. Then we examed the phylogenetic signals of functional traits of plant community species, analyzed the expression patterns of phylogenetic and functional structures of plant community species in different slope aspects, and screened the environmental factors influencing species coexistence by using principal component analysis (PCA) and linear regression model. Thus we further revealed the driving factors of species coexistence in arid desert ecosystems in the study area. The results showed that:(1) the vegetation in the study area was mainly dominated by drought-tolerant shrubs and Chenopodiaceae herb; soil factors were heterogeneous in different slope aspects, and soil nutrients and water were more abundant between the hills and shaded slopes. (2) the phylogenetic signal K values of 10 functional traits of plant community species in the study area were all less than 1, indicating that the functional traits were less influenced by phylogeny and species functional traits and did not show phylogenetic conservatism. (3) the phylogenetic structure of different slope aspects tended to diverge, and the limited similarity played a dominant role in plant distribution; the richer soil fertility between the hills and on the shaded slopes was the main reason for the divergence of the functional structure of the species, while the functional structure of species on sunny slopes showed aggregation effect, and habitat filtering was the driving factor. (4) the linear regression model between functional diversity index and environmental factors showed that the effective phosphorus, soil water content, and organic matter were main environmental factors that significantly influenced the species coexistence of plant communities in the desertification closure reserve in Bohu County. This indicates that soil water and nutrients are the main constraints to plant species coexistence in arid desert ecosystems, and the drivers of ecological niche differentiation differ between slope aspects, and plants change their adaptation to environmental changes by shaping their own functional traits phenotypes. Therefore, in the process of sealing and conserving the study area, the soil moisture, nutrients, and soil seed bank of different slope aspects should be taken into account to realize the artificial afforestation and tree nurturing to achieve the improvement of the ecological environment in the area.