高寒草地土壤真菌的小尺度海拔分布特征

Altitudinal distribution of soil fungi at small scale in alpine grassland

为深入了解土壤真菌群落沿小尺度海拔梯度的分布特征,以青藏高原宁金岗桑峰高寒草地为研究对象,采用高通量测序技术研究了3个海拔(4902、4944、4989 m)不同土层(上表层为0~5 cm,下表层为5~20 cm)真菌群落的多样性和群落组成,并探讨了其影响因素。结果表明:上、下表层土壤真菌的多样性沿海拔梯度无显著差异,但群落组成差异显著(P<0.05);其中,上表层土壤真菌群落组成的差异主要受土壤含水量(SWC)、碳氮比(C/N)、氮磷比(N/P)、碳磷比(C/P)和植物多样性的影响;随海拔增加,SWC、N/P、C/P和植物多样性增加,C/N降低,导致子囊菌门未分类纲(Ascomycota_unclassified)在低海拔(4902 m)的相对多度显著高于中海拔(4944 m)和高海拔(4989 m);下表层土壤真菌群落组成的差异主要受地下生物量和植物多样性影响;地下生物量和植物多样性均随海拔升高而增加,导致锤舌菌纲(Leotiomycetes)在低海拔的相对多度显著高于中海拔和高海拔。子囊菌门未分类纲和锈革孔菌目(Hymenochaetales)分别是上表层土壤在纲水平和目水平的指示类群,微球黑粉菌纲未分类目(Microbotryomycetes_unclassified)和柔膜菌目(Helotiales)是下表层土壤在目水平的指示类群。本研究探讨了土壤真菌群落在高寒草地小尺度海拔梯度的分布格局及其影响因子,对于了解土壤真菌群落变化的驱动机制具有重要意义。

To understand the distribution pattern of soil fungal communities along an elevation gradient at small scale,the high-throughput sequencing technology was used to explore the diversity and composition of soil fungal communities in different soil layers(topsoil,0-5 cm;subsoil,5-20 cm)at three elevations(4902,4944,4989 m)in an alpine meadow of Noijin Kangsang Peak,Qinghai-Tibet Plateau,and the influencing factors were examined.Results showed that there was no significant difference in fungal diversity in the topsoil and the subsoil along the small scale elevation gradient,but community composition changed significantly(P<0.05).Moreover,soil fungal community composition in the topsoil was mainly affected by soil water content(SWC),carbon-nitrogen ratio(C/N),nitrogen-phosphorus ratio(N/P),carbon-phosphorus ratio(C/P),and plant diversity.With increasing elevation,SWC,N/P,C/P,and plant diversity increased,while C/N decreased,resulting in much higher relative abundance of Ascomycota_unclassified in low elevation(4902 m)than that in middle elevation(4944 m)and high elevation(4989 m).The difference in soil fungal community composition in the subsoil layer across the altitudinal gradient was mainly affected by belowground biomass and plant diversity.Both belowground biomass and plant diversity increased with elevation,resulting in higher relative abundance of Leotiomycetes at the low elevation than that in middle and high elevations.The Ascomycota_unclassified and Hymenochaetales were the indicator taxa in the topsoil at the class level and the order level,respectively.The Microbotryomycetes_unclassified and Helotiales were the indicator taxa in the subsoil at the order level.By exploring the distribution pattern and influencing factors of soil fungal community across a small-scale elevation gradient in alpine grasslands,our results provide great significance for understanding the driving mechanism of soil fungal community change.