南川市三泉镇岩溶区农田生态系统植被碳库的动态变化

Regime of vegetation carbon pool in karst farmland ecosystem in Sanquan town,Nanchuan city

通过农田样方观测与实验分析获得南川市三泉镇农田生态系统主要农作物的含碳率、经济系数、果实水分系数,结合该区近26年来(1980-2005)主要农作物产量与耕地面积的相关数据,用农作物产量与碳储量转换模型计算法估算和分析该区农田生态系统植被碳库的总量及构成的动态变化。结果发现:近26年来该镇农田植被碳库和碳密度略有提高,具有微弱的碳汇效应。与邻近的四川盆地非岩溶区相比,该区农田植被碳密度较低。针对农田生态系统植被碳库的构成特点和动态特征,该镇今后应进行作物结构调整,适度增加水稻等大春作物的种植和马铃薯、油菜和饲料等小春作物的种植面积,稳定小麦等作物的播种面积;加强农田基本建设,发展生态农业,以进一步提高农田生态系统植被碳库的碳储量和碳密度。

Carbon content, economic coefficient and grains＇ water content in main crops are obtained by farmland sample observation and experiment. According to data of staple crops＇ yield and cultivated land area the vegetation carbon pool and carbon density in the karst farmland ecosystem during the last 26 years are estimated and analyzed. The result shows that both vegetation carbon pool and carbon density in the karst farmland ecosystem during the last 26 years have increased slightly, and there is a carbon sink effect in farmland ecosystem in the area. Carbon density in the karst farmland ecosystem is lower than that in non-karst area in Sichuan basin during the same period. In the light of the characteristics of structure and change of vegetation carbon pool in the karst farmland ecosystem the corresponding countermeasures are put forward. Those countermeasures include adjusting crops structure, expanding sown area of spring-sown crops such as rice and sown area of autumn-sown crops such as potato and forage etc. , and correspondingly that of wheat should be fixed; enhancing capital construction on farmland to fix agriculture production and farmland vegetation carbon pool, improving agriculture production technology and management, developing eco-agriculture for increase in per unit yield, and then increasing vegetation carbon pool and carbon density for the karst farmland ecosystem.