毛乌素沙地油蒿(Artemisia ordosica)种群空间格局对比

以空间自相关分析、半方差分析和九项轨迹方差分析等方法对比研究了毛乌素沙地优良固沙小灌木油蒿(Artemisia ordosica)在不同沙地条件下的小尺度种群格局.结果表明:在半固定沙地上油蒿种群的空间自相关性和空间异质性较强,同时斑块与斑块间隙的分化较为显著;在固定沙地上油蒿种群的空间自相关性和空间异质性较弱,同时斑块与斑块间隙的分化较轻微.半固定沙地油蒿种群的空间格局可能受控于地表风沙流,因为频繁而强烈的风沙流可以通过淘汰非聚集植株促使油蒿种群发生斑块分化.聚集斑块不仅是半固定沙地油蒿种群生存的重要形式,而且是半固定沙地油蒿种群继续发展的基础.在半固定沙地上油蒿种群的面积扩增很可能通过斑块边缘的连续性扩张过程实现.固定沙地油蒿种群缺乏斑块分化的现象可能与种群盖度高和种内竞争剧烈有关.研究结果对流沙治理具有指导意义,当把油蒿人工移栽到流动沙地时,如果将其配置为斑块与斑块间隙交替排列的格局,将有助于提高流沙固定和植被恢复重建的效率.

Comparative study on spatial patterns of Artemisia ordosica populations in the Mu Us sandy land

Artemisia ordosica is undershrub species, which dominates the vegetation of the Mu Us sandy land, north China. The spatial patterns of A. odorsica populations in different sandy lands were compared with the methods of Spatial Auto-correlation Analysis, Semi-variance Analysis and Nine-Term Local Quadrat Variance (9TLQV). The results showed that, by contrast with the A. ordosica population in fixed sandy land, the population in semi-fixed sandy land was of stronger autocorrelation and greater spatial heterogeneity, and meanwhile presented more intense differentiation between patches and patch gaps. The spatial patterns of A. ordosica population in semi-fixed sandy land are probably governed by sand drifting caused by strong winds. Drifting sand can easily put A. ordosica plants to death unless they live together in form of A. ordosica patches, where the distances between plants are small. In semi-fixed sandy land, patches are not merely the form of A. ordosica population to survive drifting sand, but also the foundation of A. ordosica population to develop and broaden their area. A. ordosica population is supposed to broaden their area through edge out-extending from the patches scattering in semi-fixed sandy land. The spatial patterns of A. ordosica population in fixed sandy land are possibly affected by intra-specific competition resulting from high plant cover. This study is ecologically useful to improve the practice of vegetation restoration from sandy lands. When transplanting A. ordosica plants to bare sandy lands, we had better arrange them in form of patches separated by patch gaps lacking A. ordosica plants. If so, it is favorable to the survival of transplanted plants, and also helpful to take advantage of the abilities of A. ordosica patches to revegetate patch gaps.