精品文档---下载后可任意编辑中亚热带 4 种森林凋落物及土壤碳氮贮量与分布特征的开题报告【摘要】凋落物是森林生态系统中最基本的生物质生产物，同时也是森林土壤有机质来源之一。本讨论选取中亚热带地区的 4 种典型森林类型（冷杉林、阔叶林、松林、竹林），讨论其凋落物产量、化学成分及其对土壤碳氮贮量的影响。结果显示，不同森林类型的凋落物有着明显的季节变化和基质差异。冷杉林的凋落物数量最多，且富含木质素和纤维素等难降解成分，因此在土壤中对碳和氮的贮量贡献最大。阔叶林的凋落物富含易降解的含氮化合物，在土壤中主要促进氮的循环。松林的凋落物数量较少，但含有大量的鞣质和脂肪酸等化合物，能够影响土壤微生物群落的组成和活性。竹林的凋落物富含硅质化合物，能够影响土壤的通气和保水能力。因此，不同森林类型的凋落物和土壤碳氮贮量在中亚热带地区存在着各自的分布特征和问题。【关键词】凋落物；森林类型；碳氮贮量；中亚热带【Abstract】Litter is the basic biomass production in forest ecosystems and is also one of the sources of soil organic matter in forests. In this study, we selected four typical forest types of subtropical China (Fraser Fir forest, mixed broadleaved forest, pine forest and bamboo forest) to study their litter production, chemical composition and their effects on soil carbon and nitrogen storage. The results show that different forest types have obvious seasonal variations and substrate differences in litter. The litter from Fraser Fir forest is the most abundant and rich in poorly degradable compounds like lignin and cellulose. Therefore, it contributes most to soil carbon and nitrogen storage. The litter from mixed broadleaved forest is rich in easily degradable nitrogen-containing compounds and mainly promotes nitrogen cycling in soil. Although litter production from pine forest is less, it contains a large amount of tannins and fatty acids that can affect the composition and activity of soil microbial communities. Litter from bamboo forest is rich in siliceous compounds that can affect soil aeration and water holding capacity. Therefore, litter and soil carbon and nitrogen storage have their own distribution characteristics and problems in different forest types in subtropical China.精品文档---下载后可任意编辑【Keywords】litter; forest types; carbon and nitrogen storage; subtropical China
