Effects of nutrient addition and precipitation changes on the stability of aboveground and belowground biomass in desert grassland
Aims:This study aims to clarify the response of desert grassland ecosystem function and stability to changes in water and nutrient resource availability,and to elucidate the mechanisms and pathways influencing biomass stability in desert grassland.Methods:This study conducted a 5-year field control experiment on nutrient addition and precipitation changes in desert grasslands in Ningxia from 2018 to 2022.The experimental treatments included:control(Cont),N addition(N,10 g·m-2·yr-1),NPK addition(NPK,10 g·m-2·yr-1 N+10 g·m-2·yr-1 P+10 g·m-2·yr-1 K),50％reduction in precipitation(Cont-50％),50％increase in precipitation(Cont+50％),N addition+50％reduction in precipitation(N-50％),N addition+50％increase in precipitation(N+50％),NPK addition+50％decrease in precipitation(NPK-50％),and NPK addition+50％increase in precipitation(NPK+50％).The aboveground and belowground biomass,as well as species diversity,were determined.Additionally,species asynchrony,species diversity,biomass stability,and the factors affecting biomass stability were analyzed.Results:The results demonstrated that(1)nutrient addition and precipitation changes significantly impacted the biomass of desert grassland plant communities.The NPK+50％treatment led to a substantial increase in aboveground biomass(156.28％),belowground biomass(51.95％),and total biomass(75.67％).In contrast,the Cont-50％treatment resulted in a significant decrease in aboveground biomass(45.59％),belowground biomass(25.09％),and total biomass(31.41％).(2)Except for the NPK+50％treatment,the stability of plant community biomass in other treatments was notably lower than that in the control treatment.The aboveground biomass stability of the NPK+50％treatment decreased by 31.90％,while the stability of belowground and total biomass increased by 33.48％and 12.38％,respectively.(3)Furthermore,nutrient addition and precipitation changes significantly influenced species diversity(including species richness and the Shannon-Wiener diversity index)and species asynchrony.Their interaction had a notable impact on species asynchrony.(4)The change in precipitation reduced the stability of aboveground and total biomass by reducing species asynchrony.The stability of aboveground biomass had no significant direct effect on the stability of total biomass.In contrast,the stability of belowground biomass had a considerable positive impact on the stability of total biomass.Conclusion:In summary,nutrient addition and precipitation changes reduced the stability of biomass in desert grasslands,with species asynchrony(complementary effect)being the primary mechanism influencing biomass stability in desert grasslands.In desert grassland areas,the contribution of belowground biomass stability to total biomass stability was more significant than that of aboveground biomass stability.Therefore,when exploring the response patterns and mechanisms of plant community stability to nutrient addition and precipitation changes,it is essential to consider not only the aboveground parts of plants but also the changes and responses of the belowground parts.
desert grasslandnutrient additionprecipitation changesstability of belowground biomassstability of total biomass
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