Study on the Carbon Fixation Model of Biological Soil Crusts in the Revegetated Desert Area
Biological soil crusts (BSC),which were significant compositions and features of desert ecosystems and arid landscapes,had played an important role in carbon source-sink exchange in the desert system.In this paper,two typical biological soil crusts (moss crusts and algae crusts) were chosen in a revegetated area of the Tengger Desert as our study materials and based on the long term continuous monitoring of soil moisture dynamics,the effective wetting time of photosynthesis and respiration were obtained and then its relationship with soil moisture,temperature and solar radiation were determined.Finally,a carbon fixation model of biological soil crusts driven by soil moisture was established.During our experimental period,through 19-25 May 2012 for example,the daily carbon fixation of the moss crusts and algae crusts were calculated and the annual carbon fixation was extrapolated based on our model.Results showed that:moss crusts and algae crusts had significant effects on the dynamics of soil moisture and temperature because of their different hydrology physical property.Rainfall was the most important trigger for biological soil crust carbon fixation,but the moss crusts had a higher carbon input than the algae crusts because it could easily absorb the non-rainfall water (condensed moisture supply from fog or dew).Preliminary estimation of the annual carbon fixation from our model was 33.33 g.m-2.a-1 for moss crusts and 14.01 g.m-2.a-1 for algae crust.The carbon fixation by non-rainfall water have reached 6.58 g.m-2 · a-1 and 2.65 g.m-2 · a-1,respectively,accounted for 19.7％ and 18.9％ of the annual total.Those results have affirmed the carbon sink by BSC in the desert revegetated area.
revegetated desert areabiological soil crustcarbon fixation modeleffective wetting time
NETL
NSTL
万方数据
维普
