降水变化对荒漠草原生态系统碳氮储量及固持速率的影响OA

As an important contributor to carbon and nitrogen sinks in terrestrial ecosystems,grassland ecosystems play a crucial role in regulating global carbon and nitrogen sources,sinks,and cycling processes.This ongoing experiment is located on temperate desert grassland in Yanchi County,Ningxia,on the southern edge of the Mu Us Desert.The experiment treatments simulate five levels of precipitation using rain shelters and manual water replenishment(33%,66%,100%,133%,and 166%of natural precipitation,coded as R33,R66,CK,R133,R166,respectively).Here we report changes in vegetation,soil carbon and nitrogen storage,and retention rates from 2018 to 2024 under the different precipitation regimes.After this six year period of precipitation control:1)The carbon and nitrogen storage of surface soil(0-10 cm)has responded more than at depth to changes in precipitation;decreased precipitation has led to a decrease in surface soil carbon and nitrogen storage with this effect increasing with the number of years.Conversely,increased precipitation has led to increased surface soil carbon and nitrogen storage.2)Increased precipitation has led to increased,vegetation carbon and nitrogen storage and this effect has significantly increased over time.3)Under water addition treatment,the proportion of vegetation carbon storage in the total carbon storage of the grassland ecosystem shows an upward trend over time,peaking in 2024;while the opposite(depletion)has occurred in the 33%and 66%precipitation regimes.Therefore,an increase in precipitation contributes to an increase in carbon and nitrogen storage and sequestration rates in vegetation and soil components of this ecosystem,while a decrease in precipitation exacerbates carbon and nitrogen loss.These research results provide quantitative data and enhance understanding of the response patterns of key links in the carbon and nitrogen cycling process of steppe ecosystems in response to precipitation change.