民勤绿洲荒漠过渡带植物群落数量分类和排序研究

绿洲-荒漠过渡带作为绿洲与荒漠的连接区域,在干旱区生态环境退化与恢复研究中具有重要意义。该研究以民勤绿洲荒漠过渡带为例,在47个植物群落调查样地的基础上,应用双向指示种分类法(TWINSPAN)和除趋势对应分析法(DCA)对研究区典型植物群落进行数量分类和排序,并讨论了影响植物群落类型及空间分布的环境因子。结果表明:(1)研究区植物群落结构简单,植物种以旱生耐盐植物为主。(2)TWINSPAN分类将研究区的植物群落划分为11个群丛类型,即白刺+盐生草群丛、白刺+芦苇群丛、白刺+盐爪爪群丛、盐爪爪+黑果枸杞群丛等,分类结果在空间上反映了民勤绿洲荒漠过渡带植物群落的演替变化趋势。(3)DCA排序结果验证了TWINSPAN分类结果的合理性,同时指出制约民勤绿洲荒漠过渡带植物群落类型及空间分布的重要环境因子是地下水埋深和地貌形态。

Quantitative Classification and Ordination Analysis on Vegetation in the Minqin Oasis-Desert Ecotone

Due to the special role as connection corridor between oasis and desert,oasis-desert ecotone was a key area to carry out research on ecosystem degradation and recovery in arid region.As the result of dry climate,fragile environment system and long-term human activities,Minqin oasis and its surrounding areas had degraded seriously.In this study,the desert plant communities in the oasis-desert ecotone of Minqin (Minqin ODE) were selected as case study.We obtained valuable data on 19 major plant species from 47 study plots of desert plant communities in Minqin ODE and analyzed that by the means of two-way indicator species analysis (TWINSPAN) and detrended correspondence analysis (DCA) in order to identify the main plant associations and environment gradient correlated to their distribution.The results show that:(1)In Minqin ODE,the structure of desert vegetation communities is simple and the species of plants have the characteristics of drought resistance and salt tolerance (2)The outcome of TWINSAN shows that the desert plant communities in Minqin ODE were composed of 11 plant associations and its rationality was verified by DCA ordination.Meanwhile,the succession trends of Minqin ODE are also reflected spatially in the classification result.The main associations include Nitraria tangutorum+Halogeton glomeratus,N.tangutorum+Phragmites australis,N.tangutorum+Kalidium foliatum,K.foliatum+Lycium ruthenicum et al.(3)The result of DCA ordination shows that the groundwater table and landforms are the leading factors which decide the association type and spatial distribution of desert plant communities in the Minqin ODE.