坡向尺度差异对大理苍山捕食线虫真菌分布格局的影响

为了解大理苍山地区不同尺度坡向上捕食线虫真菌的分布格局及其驱动因素，利用系统采样法对大理苍山东、西坡及其次级南、北坡的捕食线虫真菌进行调查。按照五点采样法采集苍山东、西坡及其次级南、北坡土壤样品共300份。采用传统方法对捕食线虫真菌进行分离纯化，结合形态特征和分子生物学方法鉴定所得菌株，按照新分类系统进行分类，鉴定为3属12种57株捕食线虫真菌。结果表明：苍山各尺度坡向捕食线虫真菌检出率和多样性指数均是西坡大于东坡，次级南坡大于次级北坡。次级南、北坡向间捕食线虫真菌群落差异大于东、西坡向间；西坡次级南、北坡向间的群落差异最大；东、西坡向的次级南坡向间群落差异也较大；东坡次级北坡与西坡次级北坡间的群落最为相似。产黏性菌网的Arthrobotrys属、产黏性球和黏性分枝的Dactylellina属在东、西坡及其次级南、北坡间均有分布，而产收缩环的Drechslerella属仅在西坡有分布。因此，坡向是影响苍山捕食线虫真菌空间分布格局的驱动因子之一，不同尺度坡向上捕食线虫真菌分布格局存在差异；次级南、北坡间捕食线虫真菌群落差异性比东、西坡间大，小尺度坡向间地理屏障对捕食线虫真菌分布格局的影响大于大尺度坡向间环境异质性的作用；环境筛选和扩散限制均会影响到捕食线虫真菌的群落构建过程。

Slope's scale effect on the distribution patterns of nematode trapping fungi from Cangshan Mountain, Dali

In order to understand the distribution patterns of nematode trapping fungi (NTF) and driving factors of different scale of slope, systematic sampling was conducted to collect NTF from the eastern and western slopes including the northern and southern sides, respectively, in Cangshan Mountain. A total of 300 soil samples were collected using the 5-point sampling method. NTF were processed using traditional isolation and purification protocols, followed by morphological and molecular identification. According to the new classification system, a total of 57 purified NTF strains could be assigned to 3 genera and 12 species. The results show that both occurrence rate and Shannon-Wiener index on the western slope are larger than those on the eastern slope, while, those on the southern sides are larger than those on the northern sides, respectively. In addition, the heterogeneity of the NTF community structure between the western and eastern slopes is smaller than those on the southern and northern sides, respectively. Furthermore, the maximum community structure heterogeneity appears between the southern and northern sides of the western slope, while the community structure heterogeneity between the southern sides of the western and eastern slopes also show a large difference. However, the most similar community structure occurs between the northern sides of the western and eastern slopes. Genus Arthrobotrys, which produces adhesive networks, and genus Dactylellina, which produces stalked adhesive knobs and adhesive branches, occur on both the northern and southern sides of the western and eastern slopes; whereas, genus Drechslerella, which produces constricting rings, appears only on the western slope. Referring to the distribution patterns of NTF, first, different exposures may be one of the driving factors and heterogeneity in community structure may vary with different exposure scales. Second, the community structure heterogeneity between the southern and northern sides are larger than that of the western and eastern slopes suggesting that smaller scale geographical barriers have more effects on NTF distribution than do the larger scale environmental filters. Finally, the environmental filter and dispersal barrier may drive the community construction processes of NTF.