Carbon Sources and Sinks of China Costal Farmland Ecosystem

摘要

This article estimated the size of carbon sink, emission, net carbon sink farmland ecosystem in China costal regions (including ten provinces) with statistic data from 1990 to 2010(which include crop yield and agricultural consumptions). Conclusions are as following: (1) the total carbon sink, emission and net sink of farmland ecosystem in China costal regions all increased since 1990. Carbon sink is obviously more than carbon emission, for example, total carbon sink in 2010 is 3 times more than carbon emission, which showed that the costal region is generally a "sink" region. While, because the increasing rate of carbon emission (265%) exceeded that of carbon sink (44%), the carbon sink function of farmland ecosystem in China costal regions will be saturated within several decades. (2) There were significant temporal-spatial differences in carbon sink, emission and net sink among different costal regions. Further, there are also differences in per area carbon sink, emission and net sink among different costal regions. The total and per area carbon emission increased year by year from 1990, while that of carbon sink and net sink changed drastically. The total carbon sink and net sink in relative developed regions has a down trend from 1990 to 2010. a special example: carbon emission exceeded carbon sink and caused that net carbon sink and per area net carbon sink was negative in 2010 in Shanghai, which indicated that Shanghai has been a carbon "source" region in 2010 because the decrease of cropland and increase of agricultural consumptions. (3) The proportion of carbon sinks in the main crops of farmland ecosystem in China costal regions compared with that of the whole nation decreased since 1990, which indicate that with the decrease of cropland and increase of agricultural consumptions, the carbon sink function of costal farmland is weaken.