Responses of ecosystem respiration, methane uptake and nitrous oxide emission to drought in a temperate desert steppe

Abstract

Listen

Translate article

AimsDrought significantly impacts ecosystem structure and function, especially the transformation rates of soil carbon and nitrogen. This study explores how drought affects ecosystem respiration (Re), methane (CH4) uptake and nitrous oxide (N2O) emissions in temperate desert steppes and the underlying mechanisms.MethodsAn in-situ experiment was conducted in the Inner Mongolia desert steppe in northern China to study the effect of drought on Re, CH4 and N2O fluxes. Structural equation modeling (SEM) was used to establish the relationship between Re, CH4 uptake and N2O emissions and plant functional traits and environmental factors.ResultsEcosystem respiration and CH4 uptake were both significantly reduced by chronic drought (66 % precipitation reduction from 1 May to 31 August) but not by pulse drought (100 % precipitation reduction in June and July). In contrast, no significant impact on N2O emissions was observed under chronic or pulse drought. There were no significant direct effects of soil moisture on Re, CH4 uptake or N2O emissions. However, soil moisture had an important indirect effect on Re, CH4 uptake and N2O emissions, mainly through its influence on plant functional traits, plant above-ground biomass and soil nutrients. Plant biomass and soil temperature were the key indicators of Re, and plant leaf nitrogen content was the key plant trait associated with N2O emissions. In contrast, plant specific leaf area and biomass were the key traits associated with CH4 uptake.ConclusionsOverall, Re and CH4 uptake were reduced by chronic drought in this desert steppe, but there was no significant effect on N2O emissions. Ecosystem respiration, CH4 uptake and N2O emissions were associated with plant functional traits. This provides new insight for the understanding of soil carbon and nitrogen dynamics in desert steppe systems under drought conditions and an important theoretical basis for the revision of model parameters.