苜蓿-荒漠草地交错带步甲昆虫多样性

Diversity of carabid beetles community across alfalfa- desert grassland ecotone in Yanchi of Ningxia,China

选取宁夏东部盐池县苜蓿-荒漠草地交错带为研究样地,以距离梯度形式,利用巴氏诱罐法对步甲科昆虫群落多样性进行了调查,共采集步甲昆虫1944头,分属11属22种。结果表明,直角通缘步甲Pterostichus gebleri个体数量占总个体数的67.90%,为该地区的优势种类。物种多样性和均匀度沿苜蓿草地、边缘到荒漠草地依次升高,步甲个体数量沿苜蓿草地、边缘到荒漠草地则依次降低,且显著差异。主成分PCo A排序表明边缘与苜蓿草地和荒漠草地都有部分相似,苜蓿草地内部和荒漠草地间的步甲群落组成差异较大,反映了苜蓿草地内部与荒漠草地内部的群落组成开始明显分化。从季节动态看,苜蓿草地和边缘物种多样性、均匀度季节变化相似,荒漠草地和苜蓿草地的优势度季节变化相似,3种生境步甲物种丰富度、活动密度季节变化相似。边缘效应强度分析呈现边缘正效应。多元回归分析说明植被密度是影响步甲的Shannon-Wiener多样性和优势度,植被密度和植被盖度是影响整个群落步甲和优势种直角通缘步甲活动密度的决定因素。

Carabid beetles of planting Medicago sativa- desert grassland edge gradient were sampled to determine seasonal dynamics and the effect of the edge on spatial patterns of carabid beetles species and community structure using pitfall traps from June to October in 2012 in a desert- steppe in Yanchi of Ningxia,Northwestern China. During the field research,a total of 1944 carabid beetles were collected belonging to 22 species and 11 genera. Of these beetles,Pterostichus gebleri was the dominant species in the area,accounting for 67. 90% of the total number of individuals. From alfalfa grassland interior to the edge and desert grassland interior respectively,Shannon- Wiener diversity and eveness of carabid beetles increased in sequence, and individuals of carabid beetles decreased in sequence, and there are significant differences. Ordinations of principal coordinate analysis（ PCo A） showed that community assemblage of carabid beetles in the artificial planting alfalfa grassland interior was significant differentiation with desert grassland interior,the edge was partly similar to alfalfa grassland interior and desert grassland interior respectively. Seasonal dynamics of carabid beetles Shannon- Wiener diversity and eveness in alfalfa grassland interior was similar to the edge, and dominance of alfalfa grasslandinterior was similar to desert grassland interior. Activity density and abundance of carabid beetles in the three habitats had the similar seasonal changes. Intensity of edge effect analysis showed the positive effect of the edge. Multiple linear regression analysis showed that vegetation density contributed to Shannon-Wiener diversity and dominance of carabid beetles,vegetation density and plant coverage were important factors in determining the activity density of carabid beetles community and dominant species.