羽毛针禾种群中尺度的分布格局及利它作用

Spatial Pattern and Facilitating Effect of Stipagrostis pennata Population at Mid-spatial Scale

羽毛针禾(Stipagrostis pennata)是古尔班通古特沙漠流动沙丘的先锋物种,可作为流动沙丘恢复的首选植物.采用100 m×100 m的大样方,应用Ripley’s K(d)函数点格局分析方法,研究沙丘从流动到固定等不同生境下羽毛针禾种群的空间分布以及与群落内白皮沙拐枣(Calligonum leucocladum)、白梭梭(Haloxylon persicum)的空间关联性,分析该物种种群如何增长以及如何促进其它物种定居.结果表明:羽毛针禾整个种群在0～50 m呈聚集分布,在50 m以上呈随机分布.在研究尺度范围内,羽毛针禾种群内小丛(冠幅面积≤0.09 m2)和中丛(0.09 m2<冠幅面积<0.6 m2)、小丛和大丛(冠幅面积≥0.6 m2)、大丛和中丛都呈显著正相关,表明羽毛针禾种群内大、小丛之间关系紧密.种群从大丛到中丛各级别再到小丛,株丛数量差异不大,种群年增长稳定,表明羽毛针禾种群增长过程中无性繁殖起主要作用.样地内白皮沙拐枣和白梭梭呈聚集分布,而羽毛针禾与白皮沙拐枣、白梭梭在0～50 m尺度下呈显著正关联,表明了羽毛针禾对白皮沙拐枣、白梭梭两个物种种子萌发、定居和生长的促进作用.

Stipagrostis pennata is a pioneer plant in the Gurbantonggut Desert in Northern Xinjiang,China,and it can be used as an ideal plant for drift dune restoration.A typical plot of 100 m×100 m was surveyed and Ripley＇s K（d） function was applied to diagnose spatial patterns of S.pennata and spatial associations between S.pennata and Calligonum leucocladum and between S.pennata and Haloxylon persicum in different habits from drift dune to fixed dune,and to analyze the growth of the species population and its promotion to other species to be settled down.The results showed that the S.pennata population were cluster distribution pattern below 50 m and were random distribution upon 50 m.It showed all significantly positive correlation between mediun size（0.09～0.6 m2） and small size（≤0.09 m2）,large size（≥0.6 m2） and small size,medium size and large size of S.pennata populations at 0～50 m scale.S.pennata was both significantly positively associated to C.leucocladum and H.persicum at 0～50 m scale,indicating that S.pennata had obvious facilitating effect on seed germination,ecesis and growth of C.leucocladum and H.persicum.