根茎禾草沙鞭的克隆生长在毛乌素沙地斑块动态中的作用

Role of clonal growth of the rehizomatous grass Psammochloa villosa in patch dynamics of Mu Us sandy land

毛乌素沙地沙化景观是由众多不同类型和大小的斑块镶嵌而成的 ,许多生态学过程影响着这些斑块的动态 ,根茎禾草沙鞭的克隆生长就是其中之一。通过对有沙鞭生长的 3块 1 hm2 风蚀样地的野外调查和染料饲喂实验 ,研究了沙鞭的克隆生长在毛乌素沙化景观斑块动态中的作用。每块样地均被划分为 62 5个 4 m× 4 m的格子 ,在 3块样地的流沙斑块出现的植物中 ,沙鞭占据了最多的格子数。沙鞭根茎扩展的主要方向是从半固定斑块到流沙斑块 ,染料饲喂实验测量了沙鞭扩展到风蚀流沙斑块中的分株数、根茎分枝数、根茎长度和地上生物量。将不同斑块土壤含水量和沙鞭根茎在土壤中的分布进行比较发现 ,在沙鞭根茎分布集中的地下 3 0～ 5 0 cm处 ,流沙斑块的土壤含水量显著地高于半固定斑块。

Mu Us sandy landscape is a mosaic of many different patches.A number of ecological processes at landscape level control the dynamics of these patches.Clonal growth of the rhizomatous grass Psammochloa villosa is one of the ecological processes not well known up to now.In this paper,the role of clonal growth of P.villosa in the patch dynamics in Mu Us sandy landscape was examined by means of field investigation in three 1hm 2 wind\|eroded plots and by methods of the acid fuchsin application.Each plot was divided into 625 4m×4m quadrats.The plant species occupied most of the quadrats in the mobile sandy patches of the three plots.Its rhizomes extended from the semi\|fixed sandy patches to the mobile sandy patches.Number of ramets,number of rhizome branches,length of rhizome and aboveground biomass of P.villosa extending from the semi\|fixed sandy patches to the mobile sandy patches were measured.In both the mobile and semi\|fixed sandy patches, P.villosa plants usually distributed most of their roots belowground from 30cm to 50cm depth.The soil water content in 30～50cm depths belowground was higher in the mobile sandy patches than in the semi\|fixed sandy patches.In Mu Us sandy land,the wind\|erosion and the rainfall regime discouraged the plant seeds' generation and survival.However,the heterogeneous environments caused by the wind\|erosion may benefit the clonal growth. P.villosa extended its rhizomes towards the mobile sandy patches where the soil water contents were high.Clonal integration between the ramets in the different patches promoted the plant growth.This result suggests clonal growth of P.villosa played an important role in stabilizing wind\|eroded patches.