干旱区生态环境知识资源中心

Knowledge of soil respiration and the influencing factors in desert ecosystems is essential to understanding carbon dynamics and responses of biotic and abiotic processes in soils to climate change. In this study, soil respiration rate (R-s) for three land-cover types (shifting sandy land, sandy land with straw checkerboard barriers, and shelter forest land) in the hinterland of the Taklimakan Desert was measured in May 2015 using an automated soil CO2 flux system. The effects of soil temperature (T-s) and soil water content (W-s) on R-s were also analyzed. The results showed that R-s values in shifting sandy land, sandy land with straw checkerboard barriers, and shelter forest land were all low and exhibited obvious diurnal fluctuations. The establishment of straw checkerboard barriers in sandy land had no significant effect on R-s, while the establishment of shelterbelts significantly increased R-s. Shifting sandy land and sandy land with straw checkerboard barriers were carbon sinks at night and early morning and were carbon sources in the daytime, while shelter forest land always acted as a carbon source during the whole day. The synergistic effect of T-s and W-s could better explain the diurnal dynamics in R (s) than single factor. In shifting sandy land and sandy land with straw checkerboard barriers, W-s was identified as a limiting factor influencing the diurnal dynamics of R-s. Furthermore, a relatively strong hysteresis loop existed between R-s and T-s. In contrast, in shelter forest land, R-s was significantly influenced by T-s, and a relatively weaker hysteresis loop existed between R-s and W-s.