沼泽湿地开垦对土壤水热条件和性质的影响

湿地具有重要的生态和环境功能.三江平原沼泽湿地的大面积垦殖,已对区域生态平衡及气候环境产生了一定的影响.湿地开垦后,土壤水、热条件发生较大变化,土壤温度的增高及氧化-还原条件的改变,促进了土壤有机质的分解和土壤呼吸通量的增大.土壤有机碳、氮素含量随湿地开垦及开垦年限的增加而不断降低.沼泽湿地开垦初期5～7年,土壤有机碳及其它营养元素的含量变化幅度较大,持续耕作15～20年后,土壤有机碳损失曲线趋于平缓.湿地开垦后,土壤有机质输入量的减少及分解作用加强导致土壤容重和比重的增大,其变化趋势与土壤有机碳损失趋势相一致.

Effect of Mires Reclamation on Soil Moisture, Temperature and Characters

Mires have the important ecological and environment functional, the reclamation of mires in the Sanjing plain have affected greatly the region ecological balance and climate conditions. The soil moisture and temperature have changed greatly after reclamation of mires, the rising of soil temperature and the changes of oxidation-reduction conditions increase the decomposition of the soil organic matter and soil respiration. The contents of soil organic carbon and nitrogen decrease largely with the reclamation of mires, and change greatly during early 5~7 years, then the lose of soil organic carbon show the characters of slow changes. The soil bulk specific density specific gravity increase because short of the soil organic matter after reclamation which show the characters as same as the soil organic carbon lose.