[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.
Zhao
Ha-lin
HL
Cold and Arid Regions Environment and Engineering Institute, Chinese Academy of Sciences, Lanzhou 730000, China. zhaohalin666@hotmail.com
Li
Yu-qiang
YQ
Zhou
Rui-lian
RL
D002244:Carbon / Q000032:analysis*; D002681:China; D003247:Conservation of Natural Resources; D017753:Ecosystem; D009584:Nitrogen / Q000032:analysis*; D006109:Poaceae / Q000254:growth & development* / Q000378:metabolism; D012822:Silicon Dioxide / Q000737:chemistry; D012987:Soil / Q000032:analysis
D012987:Soil; D002244:Carbon; D012822:Silicon Dioxide; D009584:Nitrogen