不同植被类型对滨海盐碱土壤有机碳库的影响

Effects of Different Vegetation Types on Soil Organic Carbon Pool in Costal Saline-alkali Soils of Jiangsu Province

对江苏滨海盐碱地5种不同植被类型土壤(0～40 cm)有机碳(SOC)含量、密度和表层(0～20 cm)土壤微生物量碳(SMBC)、可溶性有机碳(DOC)含量及其占总有机碳(TOC)的比例进行了分析。结果显示,随土层深度的增加,SOC含量降低,表层SOC密度占整个剖面的54.6%～75.8%。表层SOC含量和密度分别介于2.02～9.61 g/kg和5.87～21.54t/hm^2,平均值分别为4.77 g/kg和12.56t/hm^2。随着原生植被群落的演替(光滩→盐蒿→茅草),SOC、SMBC和DOC含量均依次增加。茅草荒地围垦后,稻-油轮作地和菊芋地表层SOC密度分别比茅草地的增加了55%(5.77 t/hm^2)和107%(11.15 t/hm^2);稻-油轮作地的SMBC含量及SMBC/TOC比值下降,而菊芋地的上升;围垦后土壤DOC含量及DOC/TOC比值都明显下降。结果表明,滨海盐碱地SOC主要分布在表层,原生植被群落的顺行演替使SOC库容增加且活性增强,在盐荒地围垦初期(3年),SOC库容增加但活性有所减弱。经估算,滨海盐碱非耕地具有较大的固碳潜力,但需要合理的耕作管理措施来保证农业生产的可持续发展并实现增汇减排的目标。

The content of soil organic carbon（SOC） and SOC density（0～40 cm） in the costal saline-alkali soils of Jiangsu Province under five vegetation types（Bare saline soil,BS;Artemisia wasteland,AW;Grass wasteland,GW;Rice-rape rotation,RR;and Continuous cropping of Jerusalem artichoke,CJ） were determined,and soil microbial biomass carbon（SMBC）,dissolved organic carbon（DOC） and the ratio of SMBC, DOC to TOC in topsoil（0 - 20 cm） were also analyzed.The results showed that：（1） the content of organic carbon decreased with the increase of soil depth.SOC content and stock in the topsoil was 2.02 - 9.61 g/kg and 5.87 - 21.54 t/hm^2,respectively.Topsoil SOC content and stock increased as the process of succession（BS→AW→GW） and significantly increased after three years farming in the GW soil,compared to GW,topsoil SOC stock of the RR and CJ increased by 55%（5.77 t/hm^2） and by 107%（11.15 t/hm^2）,respectively.（2） The contents of SMBC and DOC in the topsoil were 21.7 - 449.1 mg/kg and 10.8 - 43.7 mg/kg respectively.SMBC was mainly in the depth of 0～10 cm.SMBC and SMBC/TOC were highest in CJ, the followed by GW,RR,AW and BS.The DOC and DOC/TOC decreased significantly after farming.Our results suggested that,the organic carbon pool and active organic carbon component successively increased with the wild vegetation succession,SOC stock in the costal saline-alkali soils increased after agricultural use for three years,while the ratio of the active organic carbon decreased.The main reason for the variation of the active soil organic carbon pool might be the land use change.Therefore,the increase of total SOC pool in China saline-alkali lands will be significantly important to reduce CO_2 emission,however,it is worth mentioning that to take measures to improve the soil quality for ensuring sustainable productivity.