Changes of soil organic C and total N contents as affected by desertification in Horqin Sand Land, North China
科尔沁沙地沙漠化过程中土壤有机碳和全氮含量变化

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