Zhao Ha-lin, Li Yu-qiang, Zhou Rui-lian
Cold and Arid Regions Environment and Engineering Institute, Chinese Academy of Sciences, Lanzhou 730000, China.
Ying Yong Sheng Tai Xue Bao. 2007 Nov;18(11):2412-7.
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.
沙地草原在中国北方广泛分布，由于过度放牧和垦殖，该地区荒漠化现象十分普遍。然而，关于荒漠化对该地区草地碳氮储量的影响却鲜为人知。本研究在科尔沁沙地草原开展了实地调查，并建立了荒漠化梯度，以评估荒漠化对土壤、植物和凋落物中碳氮储量的影响。结果表明，荒漠化对草地碳氮含量和储量有深刻影响。随着荒漠化程度的增加，草地碳氮含量和储量显著降低。与未荒漠化草地相比，轻度、中度、重度和极重度荒漠化草地0-100cm土层中的碳氮含量分别下降了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%。相应地，0-100cm土层中植物地下部分的碳氮储量分别下降了50.95%和43.38%、75.19%和71.04%、86.76%和81.48%、91.17%和83.17%，植物地上部分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%。2000年，科尔沁沙地荒漠化草地总面积为30152.7平方公里，因荒漠化造成的碳氮损失分别高达107.53 Mt和9.97 Mt。相关性分析表明，土壤碳氮含量的降低主要源于荒漠化过程中风蚀导致的土壤细颗粒减少，土壤质地和养分状况的退化最终导致植物生物量和凋落物中碳氮储量的快速下降。
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