广东省1996-2012年农业用地碳汇效应及时空变化特征

Carbon Sequestration by Agricultural Land and Its Spatio-temporal Characteristics in Guangdong Province from 1996 to 2012

为了定量测定广东省农业用地碳汇效应的时空差异,运用1996-2012年的农业用地面积、主要农作物产量、年均气温和年均降水量数据以及2008年21个地级市的相关统计数据,对广东省不同农业用地植被固定CO2的量进行分析。结果表明:农业用地植被固定CO2的总量一直处于波动状态,但总体表现为增加态势,由1996年的3.43×1010 t增加到2012年的3.94×1010 t,年均增长率为0.82%。林地和园地在CO2固定过程中占绝对优势,二者固定CO2的量占全省农业用地固定CO2总量的99.95%以上,是农业用地植被固定CO2最重要的贡献者。耕地对CO2的固定主要由稻谷、糖蔗和蔬菜三大作物体现,三者固定的CO2占全省农作物固定CO2总量的90%以上。年均降水量对林地和园地固定CO2总量的影响程度要大于其面积变化的影响,而草地固定CO2的量与草地面积呈现高度一致性。广东省农业用地植被固定CO2的量具有显著的区域差异,呈现出北部山区高,珠三角地区、粤东及粤西地区低的总体特征。此外,全省农业用地固定CO2量的空间分布与林地固定CO2量的空间分布具有较高的一致性,说明一个地区林地占农业用地面积比例越大,则植被固定CO2的量越高。

In order to quantitatively study the spatio-temporal characteristics of CO2 sequestration by different kinds of agricultural lands in Guangdong Province of China,the quantities of CO2 sequestration in Guangdong Province were calculated through the statistic data of agricultural land area,the main crops yield,the annual average temperature and the annual average precipitation from 1996 to 2012and the statistic data of agricultural land of 21prefecture-level cities in 2008 in Guangdong.The results showed that the total quantity of CO2 sequestration by agricultural land ecosystems in Guangdong was zigzagging upward in 1996-2012,the total CO2 sequestration raised from 3.43×1010 t in 1996 to 3.94×1010 t in 2012 by 0.82%.Forestland and orchard were the dominant contributors for CO2 sequestration,which occupied approximately 99.95% of the total CO2 sequestration by all agricultural vegetation.Rice,sugarcane and vegetable were dominant crops for CO2 sequestration in farming lands and their CO2 sequestration amount was more than 90% of the total CO2 sequestration by the all crops.The impact of the annual average temperature on quantities of CO2 sequestration by forestland and orchard was greater than the change of land area.The quantity of CO2 sequestration by grassland was highly consistent with its area.The amounts of CO2 sequestration by agricultural vegetation in Guangdong were different among 21prefecture-level cities in 2008,and showed that they were usually higher in the north mountain areas and lower in the Pearl River Delta,the eastern and western area in Guangdong.Moreover,the spatial distribution of total CO2 sequestration by total agricultural vegetation was highly positively correlative with the CO2 sequestration by the forestlands,which indicated that the higher the proportion of forestland was,the more the CO2 sequestration.