雪被厚度对色季拉山急尖长苞冷杉林土壤线虫群落的影响

Effects of snow cover on soil nematode community in Abies georgei var.smithii forest in Sejila Mountain

为了解雪被覆盖对青藏高原高寒森林土壤线虫群落的影响,选取藏东南色季拉山急尖长苞冷杉林为研究区,采用高通量测序技术分析不同雪被厚度0、10、20、30 cm下土壤线虫群落特征。结果表明:随着雪被增厚,有机质和全氮含量显著降低(P<0.05),全钾含量显著升高(P<0.05)。雪被增厚对线虫群落Shannon指数、Simpson指数、Pielou指数以及成熟度指数、线虫通路比值(NCR)均未产生显著影响,但NCR值有升高的趋势。雪被增厚使刺嘴纲(Enoplea)及食细菌性线虫的相对丰度增多,同时使20 cm和30 cm雪被下土壤线虫群落结构发生显著变化(P<0.05)。土壤有机质、全氮和全钾含量是影响土壤线虫群落的最关键的3个土壤环境因子。研究表明雪被厚度会对青藏高原色季拉山急尖长苞冷杉林土壤线虫群落产生影响,雪被增厚意味着较为稳定和温暖的土壤环境,利于土壤细菌数量增加,继而利于土壤有机质分解及钾的释放,为刺嘴纲及食细菌性线虫的增多提供了资源与环境条件。目前仍需对青藏高原地区土壤进行系统调查,以更深入的了解该生态脆弱区土壤线虫分布及其响应环境变化的规律。

To examine the effects of snow cover on soil nematode communities in alpine forests on the Tibetan Plateau,an Abies georgei var.smithii forest in the Sejila Mountains of southeastern Tibet was selected as the study area.Soil nematode communities were characterized at different snow cover thicknesses of 0,10 cm,20 cm,and 30 cm using high-throughput sequencing.The results showed that soil organic matter and total nitrogen content decreased significantly(P<0.05)and total potassium content increased significantly(P<0.05)with the thickening of snow cover.Snow cover thickening did not significantly affect the Shannon index,Simpson index,Pielou index,MI(maturity index),and NCR(nematode channel ratio)indicators of the nematode community,but the NCR values tended to increase.Snow cover thickening increased the relative abundance of Enoplea and Bacterivores nematodes,and also caused significant changes(P<0.05)in soil nematode community structure under 20 cm and 30 cm snow cover.Soil organic matter,total nitrogen,and total potassium content were the three most critical soil environmental factors affecting soil nematode communities.This study revealed that snow cover thickness affected soil nematode communities in the Abies georgei var.smithii forest,and the thickening of snow cover means a more stable and warm soil environment,which is conducive to the increase of soil bacteria and then to the decomposition of soil organic matter and the release of potassium,providing resources and environmental conditions for the increase of Enoplea and Bacterivores nematodes.A systematic survey of the soils in the Tibet region is still needed to better understand the distribution of soil nematodes and their response to environmental changes in this eco-fragile area.