THE IMPACT OF TERRESTRIAL ECOSYSTEMS ON CARBON ASSIMILATION AND OXYGEN PRODUCTION IN THE GUANZHONG-TIANSHUI ECONOMIC REGION OF CHINA

摘要

The balance between carbon removal and oxygen production plays a key role in global biogeochemical carbon cycles. Therefore, carbon flows through an ecosystem are an important determinant of its ability to act as a carbon sink. Using remote-sensing images and precipitation, temperature and total solar radiation data from 1998 to 2007, and a light use efficiency model, we study the effects of changes in these parameters and land use and cover types on removing carbon and producing oxygen value in Guanzhong-Tianshui Economic Region. The results show that carbon removal value is 3.62 $ B a(-1) in Guanzhong-Tianshui Economic Region. Over the ten year period considered, the highest value of carbon removal is in 2005 at 4.83 $ B a(-1) and the minimum is in 2002 at 2.54 $ B a(-1). The average value of producing oxygen is 3.84 $ B a(-1), more than 0.23 $ B a(-1) of which is carbon removal. The amount of carbon removal in the Guanzhong-Tianshui economic region decreased between 2007 and 1998. There is a gradual decrease in the average level of carbon removal and oxygen production travelling from the south of the study area towards the north, in a way that mirrors the elevation of the land. From the perspective of land use types, forestland > grassland > cultivated land > other types. From space distribution perspective, unit value of carbon removal and oxygen production in southern counties is higher than northern counties: in general, the value decreased gradually from south to north.