土地利用变化对盐城滨海湿地土壤有机碳库的影响

Effects of land use changes on the organic carbon storage of the soil in Yancheng coastal wetlands

以盐城滨海湿地为例，基于遥感影像提取土地利用变化信息，估算了1987-2007年盐城滨海湿地表层（0~20 cm）土壤有机碳储存量和滨海湿地土壤固碳能力现状。结果表明：表层土壤有机碳储量1992年较1987年略有增长，1992~2002年间下降33.3%，2002~2007年间增加30.5%。自然湿地面积减少是湿地土壤有机碳储量减少的主要原因，而互花米草入侵和围垦造田造成了湿地土壤有机碳储量增加。农田、芦苇滩、碱蓬滩、互花米草滩和光滩有机碳埋藏速率分别为12.90、0.30、0.80、2.92和1.68×10^4 t/a。滩涂围垦造田在短期内有利于滨海湿地土壤有机碳储量增加，但淤泥质滨海湿地生态系统在淤长过程中的自然演替过程，能使整个湿地具有更高、更持久的固碳能力。本研究建议合理控制围垦速率，才能在获取经济社会利益最大化的同时，保证湿地土壤有机碳储量持续增加。

This study estimated the organic carbon storage of surface soil （0~20 cm） in Yancheng coastal wetlands from 1987 to 2007, based on the land use change data extracted from remote sensing images, and assessed the status of the carbon sequestration capacity of the wetland soil. The results showed that： the organic carbon storage of the surface soil in 1992 slightly increased comparing to that in 1987, decreased 33.3%during 1992-2002, and increased 30.5%during 2002~2007. Natural wetlands loss might be the main driving force answered for the decrease in the organic carbon storage of surface soil, while tideland reclamation for cultivation and Spartina alterniflora plantation contributed much to more carbon acquisition. The organic carbon burial rates in farmland, Phragmites australis flat, Suaeda salsa flat, S. alterniflora flat and silt flat were 12.90, 0.91, 2.41, 2.14 and 1.68×10^4 t/a respectively. Wetland reclamation contributed to a faster organic carbon burial rate in the short run, but the natural succession process led to a higher and longer-last organic carbon burial rate in the long term. It’s necessary to control the reclamation rate in a reasonable range in order to combine the maximizing of the economic and social interests with the raising of the soil organic carbon.