基于CCA的坡面尺度生物结皮空间分布

生物结皮是干旱半干旱地区普遍存在的活地被物,在该区生态系统中具有重要的生态功能。探讨生物结皮的空间分布规律是科学管理该资源的理论基础。选择黄土高原水蚀风蚀交错区六道沟小流域内的典型坡面,通过全面调查并应用GS+和CANOCO统计软件进行分析,探讨了坡面尺度上生物结皮的空间分布特征及其影响因子。结果表明:(1)生物结皮的分布具有明显的空间分异性。沙土区生物结皮以大面积连续分布为主,平均结皮盖度在30%以上;在黄土区则以零星分布为主,结皮盖度大都在20%以下,主要分布在坡的边缘和末端。而生物结皮厚度和抗剪强度的空间变异不大,说明其主要与生物结皮的发育年限有关。(2)典范对应分析(CCA)表明:生物结皮的空间分布与土壤、植被、地表湿度、坡度坡向等有密切关系。其中,土壤类型和生物结皮的空间分布关系最大,可以解释生物结皮空间变异的20%。其次是植被群落类型和地形湿度指数,沙蒿(Artemisia desertorum Spreng.Syst.Veg.)地和小叶杨(Populus simonii Carr.)林地是其最理想的生长环境;其他如坡度、坡向、太阳辐射等也都对生物结皮的分布有一定的影响。总体上,生物结皮具有明显的地形、土壤和植被群落的选择性,偏向于生长在较湿润的沙生植被群落当中。

The slope scale distribution regularity of biological soil crusts based on CCA

Biological soil crusts (BSCs) is a widespread ground living cover in arid and semi-arid areas, which serves an important ecological function in ecosystems of arid regions. To study its distribution regularity is the theoretical basis of scientific management and utilization of this resource. In view of this, this paper chose a typical slope in Liudaogou small watershed of Wind-Water Erosion Crisscross Region of the Loess Plateau, made a comprehensive survey and analyzed by using GS+ and the CANOCO statistical software, discussed the slope scale distribution characteristics of BSCs and its influencing factors. The results showed that: (1) the distribution of BSCs has an obvious spatial differentiation. In sand area, the BSCs mainly distributed widely and continuously, and their mean coverage is generally over 30%. While in loess area, the BSCs mainly shows a sporadic distribution pattern, and their coverage are generally below 20%; However, the spatial variation of the thickness and shear strength of BSCs are not significant, which indicates that it mainly depends on its development years. (2) Canonical correspondence analysis (CCA) showed that the distribution of BSCs has a close relation with soil, vegetation, ground surface humidity, slope and aspect ect. Among them, soil type has the closest relation with the distribution of BSCs, which can explain 20% of spatial variation of BSCs. The next is type of vegetation communities and topographic wetness index, and Artemisia desertorum Spreng land and Populus simonii Carr woodland are its most ideal growth environment. Some other environment factors such as slope, aspect and solar radiation also have some effects on the distribution of BSCs. On the whole, BSCs has an obvious topography, soil and vegetation community selectivity, and tend to develop in humid desert vegetation communities.