内蒙古西部荒漠区短脚锦鸡儿灌丛对土壤线虫群落的影响

Influence of Caragana brachypoda shrubs on the soil nematode communities in the desert area in the Inner Mongolia Steppe

为了探究荒漠区灌丛影响下土壤线虫群落结构的特征,以内蒙古草原荒漠区短脚锦鸡儿(Caragana brachy-poda)灌丛为研究对象,从灌丛内外不同土层(0~10、10~20、30~40 cm)中分离土壤线虫并进行鉴定和计数,对线虫群落的多样性、营养结构、区系划分等进行分析,进而探讨短脚锦鸡儿灌丛对土壤线虫的影响.结果发现:①短脚锦鸡儿灌丛对土壤线虫群落的丰富度和多度影响显著;土壤深度仅显著影响土壤线虫的多度,对线虫丰富度和Shannon-Wiener指数影响均不显著;②短脚锦鸡儿灌丛显著影响了食细菌类和植物寄生类线虫的多度,其中食细菌类线虫在不同土层灌丛内、外均占据主要优势,且灌丛内的线虫多度大于灌丛外的多度,土壤深度仅对食细菌类线虫有显著影响,呈现明显的表聚性.③短脚锦鸡儿灌丛和土壤深度显著影响了c-p 2类群的丰富度,各土层c-p 2类群丰富度均表现为灌丛内大于灌丛外,无论是灌丛内还是灌丛外,表层土壤线虫丰富度最大;④短脚锦鸡儿灌丛内不同土层SI和EI组合主要分布在D象限,说明灌丛内土壤环境的干扰程度高于灌丛外.总之,短脚锦鸡儿灌丛能够促进土壤肥岛的形成,对土壤线虫群落具有正效应.

To investigate the characteristics of soil nematode communities structure under the background of shrub encroach-ment in desert area,Caragana brachypoda in the Inner Mongolia Steppe was adopted as target shrubs,and nematodes were ex-tracted from inside and outside shrub canopies at different soil depth(0-10,10-20,30-40 cm).The nematodes were counted and identified to genus level.The biodiversity features of soil nematodes were analyzed,including diversity,trophic groups structure,and divison of soil nematode flora to assess the effect of Caragana brachypoda shrubs on soil nematode communities.The results showed that:①Caragana brachypoda shrubs significantly affected the richness and the abundance of soil nema-todes;soil depth only significantly affected the abundance of soil nematodes,but did not affect its species richness and Shannon-Wiener index.②Caragana brachypoda shrubs had a significant effect on the abundance of bacterial-feeding and plant-parasitic nematode communities.The nematode communities were dominated by the bacterial-feeding species inside and outside shrub canopies at different soil depth and had higher total numbers under shrub canopies than in open areas.The soil depth only had a significant effect on the bacterial-feeding nematode communities,and the total numbers of those nematodes were the highest in the top soil layer.③Caragana brachypoda shrubs and soil depth significantly affected the richness of c-p 2 groups nematodes.The richness of c-p 2 groups in different soil layers was higher inside shrub canopies than that outside shrub canopies;Whether inside or outside shrub canopies,the richness of c-p 2 groups in the top soil layer was the highest.④The SI and EI groups of different soil layers for Caragana brachypoda shrubs were mainly distributed in the D quadrant,indicating that the degree of soil environmental disturbance is higher under shrub canopies than that in open areas.Overall,Caragana brachy-poda shrubs could enhance the formation of fertile islands and had a positive effect on soil nematode communities.