沙漠化对科尔沁沙质草地土壤呼吸速率及碳平衡的影响

EFFECTS OF DESERTIFICATION ON SOIL RESPIRATION RATE AND CARBON BALANCE IN HORQIN SANDY GRASSLAND

在科尔沁沙地测定了不同类型沙漠化草地土壤呼吸速率的日进程和季节变化,以及植物碳储量和土壤有机碳储量,分析了沙漠化对沙质草地土壤呼吸速率及草地碳平衡的影响。结果表明:(1)沙漠化可导致草地土壤呼吸速率日变化幅度变小,日均土壤呼吸速率明显降低;与非沙漠化草地相比,在生长季轻度、中度、重度和严重沙漠化草地日均土壤呼吸速率依次下降6.4%、12.8%、33.0%和39.4%;(2)受沙漠化的影响草地碳储量明显下降,与非沙漠化草地相比,4种类型沙漠化草地碳储量依次下降50.3%、74.0%、86.4%和90.2%;其中,凋落物碳储量的下降幅度最大,土壤有机碳储量下降幅度次之,植物碳储量下降幅度最小;(3)沙漠化可使草地碳平衡受到严重破坏,草地一旦沙漠化,土壤呼吸消耗碳量将超过植物固定碳量,这时土壤有机碳库将作为后备碳源来弥补土壤呼吸过程中植物固碳量的不足。为了促进沙漠化草地碳库的恢复,应加强沙漠化草地的治理,促进草地植被的恢复重建。

Plant carbon storage, soil organic carbon storage, daily and seasonal variation of soil respiration rate were measured in 2005 to understand effects of desertification on soil respiration and carbon balance in Horqin sandy grassland. Results show that （ 1 ） desertification decreased significantly daily variation of soil respiration rate and daily mean soil respiration rate; as compared with that, in the non-desertified grassland, light, moderate, heavy and severe desertification decreased daily mean soil respiration rate by 6.4% , 12.8% , 33.0% and 39.4% , respectively; （2） it also decreased carbon storage in the grassland by 50.3% , 74.0% , 86.4% and 90.2% , respectively; litter carbon storage, in particular, dropped the most drastically, and was followed by soil organic carbon storage, and plant carbon storage; and （3） it gravely disturbed carbon balance in the grassland; the amount of carbon consumed by soil respiration exceeded the amount of carbon fixed by plant photosynthesis once desertification occurred, thus turning soil organic carbon deposit into reserve carbon source to make up the shortage between carbon consumption and carbon fixation. To promote restoration of the carbon deposit in desertified grassland, it is necessary to intensify management of grassland desertification and reestablish vegetation of the grassland.