土壤C/N对蚯蚓氮矿化效应的调控机制研究

The effect of earthworm on nitrogen mineralization has become the focus of soil ecology. This effect of earthworm changes with the change of soil ratio of carbon to nitrogen (C/N), and soil C/N is considered to be an important regulatory factor. However, how soil C/N regulates the effect of earthworm on soil nitrogen mineralization has not been clarified.. In this project, 5 soils with different C/N are collected (soils have been collected, woodland topsoil, soil C/N has been analyzed), and two ecological species of earthworms are introduced to the 5 soils in the lab. Through the determination of soil inorganic nitrogen, the relationship between soil C/N and earthworm effect on soil nitrogen mineralization was analyzed; through the determination of enzyme activity in earthworm intestine, nitrogen content of earthworms, inorganic nitrogen and microbial biomass nitrogen in fresh casts, how earthworms affect soil nitrogen mineralization by intestinal processes under different soil C/N was analyzed. Through the determination of soil microbial biomass nitrogen, microbial community structure and enzyme activity, how earthworms affect soil nitrogen mineralization by soil microorganisms under different soil C/N was analyzed. This study is helpful for understanding the functioning of earthworms on soil N cycling.

“ 蚯蚓氮矿化效应（蚯蚓对土壤氮的矿化效应）”已成为土壤生态领域关注的焦点。碳氮比（C/N）不同的土壤上蚯蚓氮矿化效应不同，土壤C/N被认为是蚯蚓氮矿化效应的重要调控因子。但是，土壤C/N对蚯蚓氮矿化效应的调控机制还未被阐明。. 本项目选取5个C/N不同的土壤（土壤已采集，林地表层土，C/N已分析），进行室内蚯蚓添加试验。通过测定土壤无机氮含量，分析土壤C/N与蚯蚓氮矿化效应的关系；通过测定蚯蚓肠道酶活性、蚯蚓自身氮含量、新鲜蚓粪中无机氮和微生物生物量氮，探讨不同土壤C/N下蚯蚓通过肠道过程对土壤氮的矿化效应及其作用机理；通过测定土壤微生物生物量氮、微生物群落结构和酶活性，探讨不同土壤C/N下蚯蚓通过调控土壤微生物过程对土壤氮的矿化效应及其作用机理。本研究有助于深入了解蚯蚓在土壤氮循环中的功能。

蚯蚓是通过取食、消化、排泄等活动对土壤物质循环和能量传递作出重要的贡献，被称为“生态系统工程师”。蚯蚓氮矿化效应（蚯蚓对土壤氮的矿化效应）的微小变化都对陆地生态系统氮循环产生巨大的影响。土壤 C/N 被认为是蚯蚓氮矿化效应的重要调控因子，但是，土壤 C/N 对蚯蚓氮矿化效应的调控机制还不明确。本项目发现随着碳氮比或氮磷比的降低，环毛蚓对土壤氮矿化的影响逐渐增加；在碳氮比或氮磷比最高时，赤子爱胜蚓对土壤氮矿化的影响最低，但赤子爱胜蚓对土壤氮矿化的影响最大出现在碳氮比或氮磷比为中间值；土壤C/N、N/P与蚯蚓氮矿化效应的关系与蚯蚓种类有关。此外，本项目发现随着碳氮比或氮磷比的降低，环毛蚓和赤子爱胜蚓通过肠胃对氮矿化的影响呈总体降低趋势，该矿化的降低可能与乙酰氨基葡萄糖苷酶活性降低有关；随着碳氮比或氮磷比的降低，环毛蚓对土壤真菌量和细菌量的影响总体呈上升趋势，赤子爱胜蚓对土壤真菌细菌的影响呈波动变化，这可能是蚯蚓增加土壤氮矿化的原因。这些结果有助于深入了解蚯蚓氮矿化矿化规律和作用机理。