科尔沁沙地沙漠化过程中土壤有机碳和全氮含量变化

通过地面调查,研究了沙漠化对科尔沁沙地农田和草地土壤有机碳和全氮含量的影响.结果表明,随着沙漠化的发展,科尔沁沙地土壤碳、氮含量明显下降.和非沙漠化农田相比,轻度、中度、重度和严重沙漠化农田土壤有机碳和全氮含量分别下降12.3%和15.3%、22.2%和24.7%、39.5%和44.7%、64.4%和63.5%;和非沙漠化草地相比,轻度、中度、重度和严重沙漠化草地土壤有机碳和全氮含量分别下降了56.3%和48.7%、78.4%和74.4%、88.9%和84.6%、91.6%和84.6%.截至2000年,科尔沁沙漠化总面积已经达到50197.5 km2,由于沙漠化而导致的土壤有机碳和全氮损失总量分别为36.39 Mt和7.89 Mt,其中草地分别占91.12%和86.06%,农田分别占8.88%和13.94%.相关分析结果表明,土壤有机碳和全氮的损失主要源于风蚀所引起的土壤粘粉粒的减少.因此,在科尔沁沙地,防治土壤风蚀对于减少农田和草地土壤碳、氮损失极为重要.

Changes of soil organic C and total N contents as affected by desertification in Horqin Sand Land, North China

data, we analyzed changes of organic C and total N contents in relation to land desertification, compare difference of organic C and total N amount lost as affected by desertification between farmland and grassland. The results showed that soil C and total N concentration decreased significantly with increased desertified degrees, which decreased by 12.3% and 15.3%, 22.2% and 24.7%, 39.5% and 44.7%, 64.4% and 63.5% in the light, moderate, heavy and severe desertified farmland compared to undesertified farmland, and by 56.3% and 48.7%, 78.4% and 74.4%, 88.9% and 84.6%, 91.6% and 84.6% in the light, moderate, heavy and severe desertified grassland compared to undesertified grassland. Desertified areas was spreaded to 50197.5 km2 in 2000 in Horqin Sand Land, which total organic C and N amount lost by desertification was 36.39 Mt and 7.89 Mt, of which account for 91.12% and 86.06% in the desertified grassland, and for 8.88% and 13.94% in the desertified farmland, respectively. Correlation analysis indicated that the loss of soil organic C and N results mainly from decreased soil fine particles caused by wind erosion in the desertification process. So combating desertification to protect the farmland and grassland against wind erosion is very importance to decrease loss of C and N store in semiarid Horqin Sand Land.Key Words: semiarid areas; land desertification; organic C and total N; storages and lost amount