不同载畜率处理下短花针茅荒漠草原生态系统净碳交换特征
摘要
Aims Grassland ecosystem is the largest terrestrial ecosystem type in China.The dynamic changes in carbon cycle play an important role in global carbon budget balance.Grazing is the main use of grassland ecosystem.Different grazing intensity has different effects on the grassland ecosystem. MethodsIn the growing seasons (May to October) from 2014 to 2016, we used portable optical LI-6400 and the method of static chamber to measure net ecosystem carbon exchange in Stipa breviflora desert steppe with 3 different stocking rates (CK, no grazing control; LG, lightly grazing; HG, heavily grazing).At the same time, the soil temperature and moisture of 10 cm depth were also measured.The effects of stocking rate and hydrothermal factors on the carbon exchange were discussed.Important findings Stocking rate had a significant impact on net ecosystem carbon exchange.With the increase of stocking rate, the net ecosystem carbon exchange, ecosystem respiration, gross ecosystem productivity decreased by 48.6%, 35.3% and 40.4% respectively.Heavily grazing significantly reduced grassland carbon sequestration, but lightly grazing had no significant effect.The inter-annual changes in net carbon exchange was mainly controlled by precipitation.Throughout the growing season, Stipa breviflora desert steppe were carbon sinks.The contribution of soil temperature to the variations of net ecosystem carbon exchange was higher than that of soil moisture.