摘要
Background Changes in precipitation alter soil moisture,thereby afecting the aboveground and belowground ecological processes.However,it remains unclear whether plant root systems alter these efects through rhizospheric processes.In this study,a precipitation control experiment was conducted in the alpine grassland of northern Xizang to simulate precipitation changes with a 50%decrease and 50%increase in precipitation.Nutrient and microbial biomass,root traits,and survival strategies in the rhizosphere and bulk soils of the dominant plant,Stipa purpurea,were analyzed for alterations under precipitation changes.Results Increased precipitation(IP)signifcantly decreased the rhizosphere soil total phosphorus and bulk soil ammonium nitrogen and increased the rhizosphere soil total potassium.Decreasing precipitation(DP)signifcantly increased the rhizosphere soil total potassium and decreased the bulk soil total potassium.DP signifcantly reduced microbial biomass carbon,nitrogen and phosphorus in rhizosphere soil,while IP signifcantly increased the bulk soil MBC:MBP,soil C:P imbalance,and soil N:P imbalance.Along the PC1 axis,where the contribution of the traits was relatively large,it was possible to defne the root economic spectrum.The root system of Stipa purpurea from the DP treatment was distributed on the conservative side of the economic spectrum,whereas that from the control and IP treatments were clustered on the acquisition side.Conclusions Increasing and decreasing precipitation mainly afected the contents of total phosphorus and total potassium in rhizosphere soil and the contents of ammonium nitrogen and total potassium in bulk soil of Stipa purpurea.The microbial biomass carbon,nitrogen and phosphorus were mainly afected by a decrease in precipitation.Decreasing precipitation signifcantly reduced microbial biomass carbon,nitrogen and phosphorus,but the rhizosphere MBC:MBN,MBC:MBP and MBN:MBP remained stable under the change of precipitation.Increasing precipitation exacerbated the C:P imbalance and N:P imbalance in bulk soil,and increased the demand for phosphorus by bulk microorganisms.Increased precipitation promoted root access to resources.The root system of Stipa purpurea in the context of precipitation changes was driven by rhizosphere nutrients and bulk microorganisms.This study is important for revealing plant–microbe–soil interactions in terrestrial ecosystems.
基金
funded by Sichuan Science and Technology Program(2023NSFSC0195).
