半干旱区湿地-干草原群落交错带边缘效应研究

以宁夏盐池四儿滩湿地为例,于2005年和2006年7~8月份沿湿地—干草原生境梯度按东、东北、西、西北4条样线进行实地植被调查,并采用TWINSPAN数量分类和植物群落结构指数计量研究湿地—干草原交错带边缘效应。结果表明:(1)四儿滩湿地生态系统植物群落分为沼泽植被、草甸植被、干草原植被3个类型。(2)四儿滩湿地植物群落结构指数除群落均匀度指数外,生态优势度、丰富度和物种多样性均是交错带最大,其次是旱生带,湿生带最小。(3)四儿滩湿地—干草原交错带不同方向群落结构差异较大,各项植物群落结构指数均是东北样线最大,西北样线最小。造成不同样线间边缘效应差异的主要因素是人为干扰程度和地形抬升程度不同。

Edge Effect of Wetland and Arid Grassland Community Ecotone in Semi-arid of China

The edge effect of plant communities was investigated in a wetlanddry grassland ecosystem at Siertan wetland in Yanchi county,Ningxia.Four transects lines each about 1 km long were set up in July 2005 along the biotope gradient in four directions:east,northeast,west and northwest for vegetation survey.The data were analyzed using TWINSPAN.The vegetation in Siertan wetland was classified into 3 vegetation types:halophytic marsh vegetation,meadow vegetation and grassland vegetation.Base on the calculation of the community structure indices,the edge effect was studied and revealed distinct differences among those three vegetation zones along each transect line.The ecotone had the highest richness indices(R),diversity indices(SW) and ecological dominance(SP) except evenness indices(E).As for the four transect lines,the northeast ecotone scored higher in each community structure indices than the others did,and the northwest was less.The edge effect difference between different transect lines were because of the human disturbance and topography uplift.