Dynamics of soil respiration in Horqin semi-fixed dune and meadow wetland as a function of precipitation, temperature, and drought

Abstract

Carbon emissions from soil respiration (Rs) in arid and semi-arid regions play a crucial role in the global carbon cycle and are strongly regulated by hydrothermal factors. In this study, we examined the seasonal (May to November) and diurnal dynamics of Rs in two typical ecosystems, Artemisia halodendron communities in semi-fixed dunes (SA) and Phragmites communis communities in meadow wetlands (WP). Additionally, we investigated their responses to natural precipitation, high and low temperatures, and drought in the semi-arid Horqin Sandy Land in northern China. The results showed that the seasonal variation of Rs in SA and WP was unimodal, and peaked in humid August and dry July, respectively. Soil temperature, soil moisture and leaf area index (Ts, Ms&LAI) ternary model and Ts&Ms binary model can well simulate the Rs seasonal changes in SA and WP, respectively. It is more appropriate to use a scheme that distinguishes between pre- and post-rain conditions when simulating Rs during the growing season. Diurnal Rs generally increased with increasing temperature. However, Rs inhibition may occur under high or low temperatures and drought. The different responses of Rs in SA and WP to precipitation depend primarily on soil texture and moisture status. Incorporating several factors into carbon cycle models, including ecosystem type, vegetation growth, and precipitation, can improve the simulation and prediction of carbon emissions in arid and semi-arid regions.