亚热带森林转换对土壤有机碳、氮矿化的影响

Effects of Conversion of Natural Forests to Plantations on Mineralization of Soil Organic Carbon and Nitrogen in Subtropical China

本研究以天然阔叶林和由天然阔叶林转换而来的针阔混交人工林、马尾松人工林、杉木人工林为研究对象,采用室内培养的方法研究了天然林转换为人工林对土壤有机碳、氮矿化的影响。结果表明:天然阔叶林转换为人工林,土壤有机碳含量显著下降(P 2 kg?1d?1,天然阔叶林转换为针阔混交人工林和杉木人工林土壤有机碳矿化速率显著降低,转换为马尾松人工林土壤有机碳矿化速率显著升高;天然阔叶林转换为针阔混交人工林和杉木人工林蔗糖酶活性下降了17.8%和66.7%,转换为马尾松人工林土壤蔗糖酶活性增加了71.1%,土壤蔗糖酶活性与土壤有机碳矿化速率呈显著正相关关系。天然阔叶林转换为针阔混交人工林和马尾松人工林,土壤净氮矿化速率没有显著变化;转换为杉木林,土壤净氮矿化速率显著增加;天然阔叶林转换为人工林土壤脲酶活性均呈增加趋势,杉木人工林土壤脲酶活性显著高于其他3种林地,土壤脲酶活性与土壤氮净矿化速率呈显著正相关关系。

This study investigated the effects of forest conversion from natural forest to mixed conifer-ous-broad-leaved forest, Chinese fir plantations and Pinus massoniana plantations on the minerali-zation of soil organic carbon and nitrogen using an incubation study. The results showed that con-version from natural forests to plantations reduced soil organic carbon. The mean mineralization rate of soil organic carbon was 121.42, 95.41, 137.67, and 108.95 mg CO2 kg?1d?1 for BL, CB, MP and CF, respectively. Conversion of BL to CB and CF, the mineralization of soil organic carbon was significantly decreased and the activities of sucrase in mixed coniferous and broad-leaved plantations and Chinese fir plantations decreased by 17.8% and 66.7%. Conversion of BL to MP, the activities of su-crase was increased by 71.1%. There was a positive correlation between the mineralization of soil organic carbon and the actives of sucrose. Conversion of BL to CB and MP did not affect mineralization of soil nitrogen and conversion of BL to CF promoted soil nitrogen mineralization. There was a strong relationship between net nitrogen mineralization and the activities of urease.