垦殖对湿地土壤有机碳垂直分布及可溶性有机碳截留的影响

通过测定和计算兴凯湖地区沼泽湿地及由其垦殖而来的旱田和水田土壤剖面有机碳含量和密度及土壤剖面不同深度土壤溶液中可溶性有机碳含量,分析了垦殖对兴凯湖周边沼泽湿地土壤有机碳垂直分布及土壤剖面截留可溶性有机碳的影响.结果表明,垦殖显著影响湿地0～40 cm土壤有机碳含量,大豆田和水稻田0～10、10～20、20～30、30～40 cm土壤有机碳含量与湿地相比分别降低了79.07%和82.01%、79.01%和82.28%、79.86%和92.90%、37.49%和78.05%;40 cm以下土层土壤有机碳含量垦殖前后差异不显著.大豆田和水稻田有机碳密度相比沼泽湿地分别降低了25.50%和47.35%,但三者1 m深土壤中大部分的有机碳均是储存在0～50 cm土层中.垦殖前后土壤有机碳含量与深度之间的关系均可用指数函数来描述,垦殖改变了土壤有机碳含量但并未改变其随土壤深度的变化规律.垦殖为大豆田土壤剖面对可溶性有机碳的截留效果较湿地和水稻田更明显,沼泽湿地和水稻田对可溶性有机碳的截留效果大致相当.

Effect of Reclamation on the Vertical Distribution of SOC and Retention of DOC

Contents and density of soil organic carbon (SOC) in soil profiles and dissolved organic carbon (DOC) of soil solution in different soil depths in wetland, soybean and paddy field reclaimed from the wetland around Xingkai Lake were determined to investigate how reclamation of wetland for soybean and rice farming impacts vertical distribution of SOC and retention of DOC. SOC contents in 0-40 cm soil layers were significantly influenced. SOC contents in 0-10, 10-20, 20-30 and 30-40 cm soil layers in soybean and paddy field were 79.07% and 82.01%, 79.01% and 82.28%, 79.86% and 92.90%, 37.49% and 78.05% respectively lower than those in wetland. Before and after reclamation, SOC contents in soil layers deeper than 40 cm were not significantly different. SOC densities in soybean and paddy field were 25.50% and 47.35% respectively lower than those in wetland. However, either in wetland or farm land, most of the SOC storage in 0-100 cm soil layer was stored in 0-50 cm soil layer. The relationships between SOC content and soil depth in wetland and two farm lands all could be described by exponential functions; cultivation did not change the variation of SOC content with soil depth. The retention of DOC was more obvious for soybean farming than wetland and rice farming, and that was roughly the same for wetland as rice farming.