不同土地利用方式对农田表土有机碳库的影响——以太湖地区吴江市为例

Influence of land use change on topsoil organic carbon stock:a case study of Wujiang Municipality

采用耕地质量监测资料,分析了2003年江苏省吴江市6种土地利用方式下的土壤有机碳含量的变化,并与该市1982年第二次土壤普查土壤肥力调查的结果进行了比较。结果表明,2003年吴江市土壤耕层平均有机碳密度比1982年提高(0.14±0.05)t.hm-2.cm-1;在稻田、桑园、菜地、林地、果园、旱地6种主要土地利用方式中,稻田土壤有机碳密度显著高于其他利用方式,并比1982年稻田耕层有机碳密度增加(0.21±0.06)t.hm-2.cm-1。近20多年来,吴江市水稻土的碳固定增加了1.8×103t,但由于该市的耕地面积减少而造成的总土壤表层有机碳库的减少量为14.32×105t。因此,稻田作为一种特殊的土地利用方式在陆地碳固定上有着特殊意义。

This paper deals with variation of topsoil soil organic carbon （SOC） storage under 6 major land use patterns by using the survey data of soil quality of croplands conducted in 2003. Statistical analysis was done on SOC content frequency of total sampies and also of 6 dominant soil series of Wujiang Municipality, Jiangsu Province in 2003 with comparison to those in 1982 by the 2nd national soil survey. The mean overall topsoil SOC density was shown to increase by （0. 14 ±0.05 ） t · hm^2 · cm^-1 Among the 6 major land use patterns, paddy had a higher SOC density and an increased SOC density over that in 1982 by （0.21±0.06） · hm^2 · cm^-1. As a whole result, increased topsoil SOC stock in the present paddy soils amounted to 1.8 × 103 t while a reduced stock due to paddy occupation by the newly emerged land uses being 14. 32 ×105 t. Comparatively, land use as paddy could be considered as an option for C stock enhancement and greenhouse gas mitigation.