沙漠化对科尔沁沙质草地生态系统碳氮储量的影响

通过野外调查,研究了沙漠化对科尔沁沙质草地生态系统碳、氮储量的影响.结果表明:沙漠化对草地碳、氮含量和储量具有显著影响,随着草地沙漠化的进程,草地碳、氮含量和储量明显下降.与非沙漠化草地相比,轻度、中度、重度和严重沙漠化草地0～100cm深土壤有机碳和全氮含量分别下降了56.06%和48.72%、78.43%和74.36%、88.95%和84.62%、91.64%和84.62%,植物组分中的碳、氮含量分别下降了8.61%和6.43%、0.05%和25.71%、2.58%和27.14%、8.61%和27.86%;轻度、中度、重度和严重沙漠化草地地上植物组分中的碳、氮储量分别下降了25.08%和27.62%、30.90%和46.55%、73.84%和80.62%、90.89%和87.31%,0～100cm深地下植物组分中碳和全氮储量分别下降了50.95%和43.38%、75.19%和71.04%、86.76%和81.48%、91.17%和83.17%.2000年科尔沁沙地沙漠化草地总面积为30152.7km2,因沙漠化损失的碳、氮总储量高达107.53和9.97Mt.草地碳、氮含量的下降主要源于风蚀过程中土壤细颗粒的损失.土壤的粗化和贫瘠化最终导致了植物和凋落物中碳、氮储量的明显下降.

Effects of desertification on C and N storages in grassland ecosystem on Horqin sandy land

Sandy grassland is widespread in northern China,where desertification is very common because of overgrazing and estrepement.However,little is known about the effects of desertification on grassland C and N storages in this region.A field survey was conducted on Horqin sandy grassland,and desertification gradients were established to evaluate the effects of desertification on C and N storages in soil,plant,and litter.The results showed that desertification had deep effects on the contents and storages of grassland C and N.The C and N contents and storages in the grassland decreased significantly with increasing desertification degree.Comparing with those in un-desertified grassland,the C and N contents in lightly,moderately,heavily,and severely desertified grasslands decreased by 56.06% and 48.72%,78.43% and 74.36%,88.95% and 84.62%,and 91.64% and 84.62% in 0-100 cm soil layer,and by 8.61% and 6.43%,0.05% and 25.71%,2.58% and 27.14%,and 8.61% and 27.86% in plant components,respectively.Relevantly,the C and N storages decreased by 50.95% and 43.38%,75.19% and 71.04%,86.76% and 81.48%,and 91.17% and 83.17% in plant underground components in 0-100 cm soil layer,and by 25.08% and 27.62%,30.90% and 46.55%,73.84% and 80.62%,and 90.89% and 87.31% in plant aboveground components,respectively.In 2000,the total area of desertified grassland in Horqin sandy land was 30152.7 km2,and the C and N loss via desertification reached up to 107.53 and 9.97 Mt,respectively.Correlation analysis indicated that the decrease of soil C and N contents was mainly come from the decreased soil fine particles caused by wind erosion in the process of desertification,and the degradation of soil texture-and nutrient status led finally to the rapid decrease of C and N storages in plant biomass and litter.