Carbon exchange of desert soil crust in response to simulated warming and changes of precipitation
The C exchange processes dominated by biological crusts,an important surface cover in arid desert soil,at the background of the intensified climatic change is of vital importance to access C balance at the region-al and even global scale.Despite how desert crustal C exchange responds to climatic change have received many attentions,the effects of warming and changes of precipitation as well as their interactions remain unclear.To evaluate the extent of C exchange of desert crustal soils in response to climatic change,two typical types of crust-al(moss-and algal-dominated crusts)soils in the southeastern edge of the Tengger Desert were selected,and their gross primary productivity(GPP),ecosystem respiration(ER)and net ecosystem exchange(NEE)were monitored in field with stimulated warming and five precipitation gradients(2,5,8,13,and 20 mm).The re-sults showed that:(1)warming only significantly affected daily NEE of moss-dominated crustal soil,precipita-tion significantly affected daily GPP,ER and NEE of moss-and algal-dominated crustal soil,and there was no interactions between warming and precipitation.(2)Across the five precipitation gradients,warming averagely reduced 20.8％of accumulative GPP and increased 9.9％of accumulative ER,leading to an increase in accumula-tive NEE by 102％on average for moss-dominated crustal soil.However,warming averagely enhanced 264％of accumulative GPP and increased 24.2％of accumulative ER,with a neutral effects on NEE for algal-dominated crustal soil.(3)ER and NEE of moss-dominated crustal soil were positively and negatively correlated to air tem-perature and soil moisture,respectively,while NEE of algal-dominated crustal soil was not associated with air temperature and soil moisture under warming.These results suggest climatic change might stimulate C immobili-zation of moss-dominated crustal soil,while its effects on algal-dominated crustal soil were negligible in the des-ert region.Accordingly,the distinct responses of C exchange for different crustal soils to climatic warming and precipitation should be taken in consideration when we predict the balance of carbon budget in desert ecosystems.
NETL
NSTL
万方数据
