贺兰山冲积扇荒漠草地拟步甲群落小尺度空间格局动态

为探讨贺兰山冲积扇荒漠草地拟步甲群落小尺度空间格局动态特征,本研究于2019年5—10月每月采用陷阱法调查200 m×200 m空间尺度的拟步甲昆虫群落,基于地统计分析方法,研究拟步甲昆虫群落的空间格局,并分析空间格局与地形因子的关系。6次调查共捕获拟步甲科成虫7属10种1086只,群落组成具有较明显的空间和时间变异性。其中,拟步甲群落多样性以5月最大,7月最低。Moran I指数表明,拟步甲优势种空间自相关性具有明显的季节波动性,在5月、9月和10月表现为显著空间正相关。拟步甲群落和优势种具有较强的空间异质性,主要由结构性因素决定。普通克里金插值表明,不同季节群落空间格局梯度分布存在明显差异,夏季群落空间格局比较简单。交叉方差函数分析显示,优势种物种间大多表现为正空间关联性,且主要受结构性因素单一调控。典范对应分析(CCA)结果表明,坡度和海拔显著影响昆虫分布。本研究揭示了拟步甲昆虫群落小尺度空间异质性具有明显的季节变异,为研究贺兰山冲积扇生境地表甲虫物种多样性空间格局及维持机制奠定基础。

Spatial pattern dynamics of darkling beetle communities at small scale in a desert grassland of alluvial fans in Helan Mountain,Northwest China

To understand the dynamics of spatial pattern of darkling beetle communities at the small scale, we surveyed the darkling beetle community using pitfall in a desert grassland of alluvial fans in Helan Mountain from May to October 2019. Based on the geostatistical analysis, we divided the 200 m×200 m study area equally into 100 grid squares and analyzed the spatial autocorrelation, spatial heterogeneity, spatial distribution pattern, and its relationship with topographic factors of the darkling beetle community. A total of 1086 individuals belonged to 10 species and 7 genera were collected. Community composition of darkling beetle had significant spatial and temporal variation. The diversity index of the community was the highest in May and lowest in July. The spatial autocorrelation of dominant species had obvious seasonal fluctuation, with a significantly spatial positive correlation in May, September, and October. Communities of darkling beetle and the dominant species showed strongly spatial heterogeneous, which were mainly determined by structural factors. The ordinary Kriging interpolation showed that the gradient distribution of beetle communities was obviously different among seasons, being the simplest in summer. The results of the cross variogram showed that the spatial relationships between different dominant species groups were mostly positive, and were mainly regulated by structural factors. Results of the canonical correspondence analysis (CCA) showed that the slope and elevation significantly affected the distribution of darkling beetles. Our results showed that the spatial heterogeneity of the darkling beetle showed significant seasonal variation, and thus provided a basis for understanding the mechanism and biodiversity of ground-dwelling beetle community in a desert grassland of alluvial fans.