川西北高寒地区多年生禾本科人工草地土壤线虫群落动态

Dynamics of soil nematode community in perennial gramineae artificial grasslands in Northwest Sichuan

为了查明青藏高原地区建植多年生禾本科人工草地对土壤线虫群落的影响及土壤线虫群落随人工草地建植年限增加的变化趋势,以川西北红原县2018年建植的垂穗披碱草样地(Elymus nutans)和老芒麦样地(Elymus sibiricus)为研究对象,以天然草地(Natural grassland)为对照,于2018—2020每年9月对土壤线虫群落、植被和土壤因子等进行连续监测。研究共分离到土壤线虫38470条,隶属于2纲8目65科172属,平均密度2482条/100g干土;食细菌线虫是研究样地的主要营养类群。垂穗披碱草和老芒麦样地的土壤线虫群落组成结构与天然草地间存在明显差异,但差异性随建植年限增加逐渐降低。线虫群落密度和多样性指数在垂穗披碱草、老芒麦和天然草地间均无显著差异。随建植年限增加,土壤线虫群落密度显著上升,Pielou指数显著下降,丰富度和Shannon指数无显著变化;植物寄生线虫密度和比例在第2年显著增加,并成为优势营养类群。线虫群落生态指数在不同草地类型间无显著差异,但垂穗披碱草和老芒麦样地的线虫基础指数随建植年限增加先增加,在第3年时显著降低(P<0.05)。冗余分析(RDA)与回归分析结果表明,植物群落盖度及根系的全钾、粗脂肪和粗纤维含量是影响土壤线虫群落组成结构、密度及生态指数的主要因子,其中线虫群落密度与根系的全钾和粗脂肪含量呈正相关关系,与粗纤维含量呈负相关关系。高寒地区多年生禾本科人工草地的根系营养物质含量是影响土壤线虫群落的重要因子。

The aim of this study is to investigate the effects of different perennial gramineae grasslands on soil nematode communities and the variations of soil nematode communities with increasing cultivation years of the artificial grasslands on the Qinghai⁃Tibetan Plateau.The study was conducted on two perennial gramineae monoculture grasslands of Elymus nutans and Elymus sibiricus in Hongyuan County,northwestern Sichuan,with natural grassland as the control.Soil nematode communities,plants,and soil were monitored in September from 2018 to 2020.A total of 38470 soil nematode individuals belonged into 2 classes,8 orders,65 families,and 172 genera,were extracted.The abundance of soil nematode community was 2482 ind./100g dry soil,and bacterivore was the dominant trophic group.The taxonomic composition of soil nematode communities in E.nutans and E.sibiricus plots differed from those in the natural grassland,but the difference decreased gradually with the increasing cultivation years.The abundance increased but the Pielou index decreased significantly with the increasing cultivation years,and no significant change was observed for the richness and Shannon index.The abundance and relative abundance of plant parasites increased significantly in the second year and was one of the main trophic groups.There were no significant difference in the ecological indices of nematode community among different grasslands,but the Basal index of nematode community increased and then decreased significantly with the cultivation years(P<0.05).The results from redundancy analysis and regression analysis showed that the taxonomic composition structure,abundance,and ecological index of soil nematode communities were mainly affected by the root nutrient contents of total K,ether extract,and crude fiber,with the abundance was correlated positively with the contents of total K and ether extract but negatively with the contents of crude fiber in the roots.The root nutrient content of perennial gramineae artificial grassland in alpine region is an important factor affecting soil nematode community.