The area of desertified land has increased by 27.3% from 1987 to 2000 in Maduo County,northeastern Qinghai-Tibet Plateau.Driving forces of land degradation has been extensively studied in the region.Using Factor Analy...The area of desertified land has increased by 27.3% from 1987 to 2000 in Maduo County,northeastern Qinghai-Tibet Plateau.Driving forces of land degradation has been extensively studied in the region.Using Factor Analysis (FA),we evaluate contribution of human activity and natural environmental change to land degradation.Four common factors were extracted in this study.The result shows that climate related other than human-related factors,are the major inducing factors of land degradation in Maduo County.Climate change and consequent change of permafrost account for 70% to the land degradation.Increasing evaporation and declining precipitation in the beginning of the growing season hamper seedling establishment.Decreasing frozen days and rising active layer lower bound make surface soil loose and less soil moisture available for plant.展开更多
By means of ground survey and ＂3S＂ technology,taking Maduo County in three river sources areas as example,the remote sensing model between biomass and normalized difference vegetation index（NDVI） in sampling point...By means of ground survey and ＂3S＂ technology,taking Maduo County in three river sources areas as example,the remote sensing model between biomass and normalized difference vegetation index（NDVI） in sampling points was established after calculating the NDVI distribution of TM image in Maduo County,and the grade distribution map of grassland productivity in Maduo County was obtained according to the grade division of grassland productivity in Qinghai Province,so as to monitor grassland productivity step by step.The results showed that grassland coverage area in Maduo County in 2009 was about 2.22 million hm2,and NDVI was mainly from 0 to 0.5,accounting for 88.64% of total grassland area in Maduo County;there was a significant correlation between biomass and NDVI in sampling point,with the correlation coefficient of above 0.7,and their model could be quantitatively expressed as follows,namely Biomass = 552.632 × NDVI1.137;grassland productivity in Maduo County was 750-3 000 kg/hm2 which occupied 72.1% of total grassland area;the highest grassland productivity in Maduo County was 4 500-6 500 kg/hm2,but it accounted for below 1% of total grassland area.展开更多
基金funded by National Ministry of Science and Technology and the grant number is 2009CB421308
文摘The area of desertified land has increased by 27.3% from 1987 to 2000 in Maduo County,northeastern Qinghai-Tibet Plateau.Driving forces of land degradation has been extensively studied in the region.Using Factor Analysis (FA),we evaluate contribution of human activity and natural environmental change to land degradation.Four common factors were extracted in this study.The result shows that climate related other than human-related factors,are the major inducing factors of land degradation in Maduo County.Climate change and consequent change of permafrost account for 70% to the land degradation.Increasing evaporation and declining precipitation in the beginning of the growing season hamper seedling establishment.Decreasing frozen days and rising active layer lower bound make surface soil loose and less soil moisture available for plant.
基金Supported by National High Technology Research and Development Program of China(863Program)(2008AA10Z223)~~
文摘By means of ground survey and ＂3S＂ technology,taking Maduo County in three river sources areas as example,the remote sensing model between biomass and normalized difference vegetation index（NDVI） in sampling points was established after calculating the NDVI distribution of TM image in Maduo County,and the grade distribution map of grassland productivity in Maduo County was obtained according to the grade division of grassland productivity in Qinghai Province,so as to monitor grassland productivity step by step.The results showed that grassland coverage area in Maduo County in 2009 was about 2.22 million hm2,and NDVI was mainly from 0 to 0.5,accounting for 88.64% of total grassland area in Maduo County;there was a significant correlation between biomass and NDVI in sampling point,with the correlation coefficient of above 0.7,and their model could be quantitatively expressed as follows,namely Biomass = 552.632 × NDVI1.137;grassland productivity in Maduo County was 750-3 000 kg/hm2 which occupied 72.1% of total grassland area;the highest grassland productivity in Maduo County was 4 500-6 500 kg/hm2,but it accounted for below 1% of total grassland area.
