天山北麓中段拟南芥(Arabidopsis thaliana)与相邻物种的分布格局及相互关系

Spatial associations and patterns of Arabidopsis thaliana and its adjacent species in the middle part of northern Tianshan Mountain

天山山脉是世界拟南芥(Arabidopsis thaliana)及其近缘种的分布中心之一,资源优势明显。在北天山中段浅山地带选择拟南芥分布的典型样地50m×50m,分析了样地物种的结构、组成和土壤理化性质,用Ripley’sK(d)函数分析了拟南芥与相邻物种的空间特征和相互关系。发现样地由7科23个物种组成,以新疆绢蒿(Seriphidium kaschgaricum)为建群种,短命植物物种占近70%。拟南芥仅分布于北坡,在3m内聚集强度高于所有分析物种,在5m范围内与新疆绢蒿中株呈显著正关联,与十字花科的涩芥(Malcolmia africana)、藜科的散枝猪毛菜(Salsola brachiata)、木碱蓬(Suaeda dendroides)、角果藜(Ceratocarpus arenarius)呈一定尺度显著负关联。分析认为拟南芥空间分布依赖于新疆绢蒿大株、中株生长塑造的遮阴、保湿和丰富土壤有机质,生态位与藜科物种差异极大,生境特异性高于同属近缘种小鼠耳芥(Arabidopsis pumila),以及涩芥(M.africana)、庭芥(Alyssumdesertorum)、四齿芥(Tetracme quadricornis)、丝叶芥(Leptaleum filifolium)、狭果鹤虱(Lappula semiglabra)等短命植物。在干旱胁迫下,拟南芥环境选择强度大于种内作用,密度依赖的种子扩散表现不明显。扩散对策是通过大量生产种子,依靠果实不易开裂控制种子短距离扩散,充分利用原适宜生境来维持种群繁衍。

Tianshan Mountain is distribution center of Arabidopsis thaliana and its closely related species in the world. The resource advantage of this region is obvious. In shallow zone of northeru Tianshan Mountain, a typical sample plot of 50m 50m were selected to analyze the species construction and soil physicochemical properties. Ripley＇s K （d） function was used to determine the sptial pattern of A. thaliana families and 23 species were observed in the sample and relationships between A. thaliana and its adjacent species. 7 plot and 70% were ephemeral plants. Seriphidium kaschgaricum was the constructive species. A. thaliana in this plot mainly took on aggregated distribution in northern slope, and had a higher L（d） value than other species within 3m scale. The sptial distribution of A. thaliana was positively correlated with middle size S. kaschgaricum under a range of 5m, while negatively correlated with Malcolmia africana, Salsola brachiata, Suaeda dendroides and Ceratocarpus arenarius under a certain scale. The distribution of A. thaliana depended on shading, humidity and abundant soil organic matter condition created by S. kaschgaricum. Niche of A. thaliana differed largely with chenopodiaceae. A. thaliana required a more specific habitat than A. pumila, M. Africana, Alyssum desertorum, Tetracme quadricornis, Leptaleum filifolium and Lappula semiglabra, which was a kind of ephemeral plant. In the dry stress condition, intensity of environmental selection was higher than interaction between intraspecies. Density-dependence dispersal was weak. The dispersal strategy of A. thaliana was to produce more seeds, generate fruits that were hard to crack to keep seeds disperse in a short distance, and make full use of the maternal habitat to propagate.