Impacts of cultivated land conversion on the vegetation carbon storage in the Huang-Huai-Hai Plain
黄淮海平原耕地转移对植被碳储量的影响

Land use changes influence the distribution and structure of terrestrial ecosystems,and also change their carbon storage.Cultivated land,an important part of our country,affects not only the crop productivity,but also the spatial distribution pattern of vegetation carbon storage.According to the GLO-PEM model and by using the NOAA/AVHRR data acquired in 1988,this paper estimates the net primary productivity of the Huang-Huai-Hai Plain.Then the amounts of the vegetation carbon storage associated with the various land uses are estimated by subtracting the quantities of litter.The key findings show that there are differences in vegetation carbon storage among the various land uses and over space.The density of vegetation carbon storage in forest area is the biggest,and the smallest is the unused land.According to the decoded land use information from Landsat TM/ETM digital imagines,we traced the land conversions in the period between 1988 and 2000 and analyzed the changes between cultivated land and other land types and find it interesting that different land types can be transferred to each other.But the net change will be various.With the development of economy,built-up area gradually expanded,and the amount of cultivated land around the city were occupied.A total of 5.3 107hm2 of land were transferred to cultivated land in the Huang-Huai-Hai Plain.Based on the above data,we calculated the impacts of cultivated land conversions on the vegetation carbon storage.It is found out that that the vegetation carbon storage decreased by 0.25% due to the land conversions between cultivated land and other land uses.The cultivated land conversion to built-up area caused a decrease of 4.57 103tC released to air.We overlapped the agro-ecological zones and the vegetation carbon storage,and calculated the total changes in every agro-ecological zone.The vegetation carbon storage of the Huang-Hai Plain decreased by 0.89 103t.With the population increase,59% of the cultivated land was transferred to residential area.This is the main reason for the substantial decrease in the vegetation carbon storage.The research results provide valuable information for the formulating of the carbon management policies at a regional extent.