“碳中和”背景下碳输入方式对森林土壤活性氮库及氮循环的影响  

Responses of forest soil labile nitrogen pool and nitrogen cycle to the changes of carbon input under “carbon neutrality”

作　　者：谢君毅 徐侠 蔡斌 张惠光 XIE Junyi;XU Xia;CAI Bin;ZHANG Huiguang(College of Biology and the Environment,Nanjing Forestry University,Nanjing 210037,China;Center for Scientific Research and Monitoring,Wuyishan National Park,Wuyishan 354300,China)

机构地区：[1]南京林业大学生物与环境学院,江苏南京210037 [2]武夷山国家公园科研监测中心,福建武夷山354300

出　　处：《南京林业大学学报（自然科学版）》2022年第2期1-11,共11页Journal of Nanjing Forestry University：Natural Sciences Edition

基　　金：国家自然科学基金青年科学基金项目(31700376);江苏省高等学校自然科学研究重大项目(17KJA180006);江苏省“六大人才高峰”项目(JY-041&TD-XYDXX-006);南京林业大学“5151”人才计划;江苏省研究生科研与实践创新计划项目(KYCX21-0868)。

摘　　要：森林生态系统具有碳源和碳汇双重功能,调控森林中碳输入方式对于实现我国“碳中和”目标具有重要意义。作为森林土壤有机碳(SOC)的主要来源,不同碳(C)输入方式(如地上凋落物、地下植物根系等)对森林生态系统土壤氮(N)循环的影响一直是相关学者的研究重点。笔者综述了目前国内外不同C输入方式对土壤活性N库、土壤N矿化、硝化过程及氧化亚氮(N_(2)O)排放的影响研究现状,分析了森林土壤活性N库及N转化过程对不同C输入变化的响应,发现:(1)地上C排除可以降低土壤有效态氮(主要包括NH_(4)^(+)-N和NO_(3)^(-)-N)的含量,但地下C排除却增加了土壤NH_(4)^(+)-N含量。C输入方式的改变对土壤微生物生物量氮(MBN)含量影响具有不确定性,这可能与生态系统类型、树种组成、时间尺度等因素相关。此外,地下C排除对土壤可溶性氮(DON)含量的影响较地上C排除的大,地下根系可能是影响土壤DON含量的主要贡献者。(2)地上C输入对土壤N矿化及硝化速率的影响在短期内较大,而长期影响较小。其主要是通过间接改变土壤微生物活性从而影响了土壤N矿化及硝化过程,地下C排除增加了土壤N矿化速率,且随着时间尺度的增加表现更加明显。(3)地上C输入通过改变硝化和反硝化微生物的可利用C源而间接影响了N_(2)O的排放,且受到树种影响显著,而地下C输入对N_(2)O的影响因根系质量等的差异而发生改变。综上可知,森林土壤活性N库及N循环过程对不同C输入具有不同的响应机制,且受生态系统类型、物种、时间等因素影响较大。目前关于两种乃至多物种不同C的输入对森林土壤N影响的研究较少,且定性研究较为普遍;对优化森林生态系统地上地下C输入动态模型和精准预算不足,尚未建立完整的碳减排生态补偿机制。今后的研究亟须定量了解不同森林生态系统不同的C输入及其两者或者多�The forest ecosystem has the dual functions of carbon source and carbon sink, and regulating the carbon input mode in forest is of great significance for realizing the goal of “carbon neutrality” in China. The effects of changes in carbon(C) inputs(such as above-ground litter and under-ground roots) on soil nitrogen(N) cycling have long been a research focus in forest ecosystems. Based on previous studies worldwide, this paper reviews the research progress on the effects of different C inputs on the responses of the forest soil active N pool and N transformation processes, including soil active N pools, soil N mineralization, nitrification processes, and nitrous oxide(N_(2)O) emissions. We found:(1) Above-ground C removal reduced soil available nitrogen contents(mainly NH_(4)^(+)-N and NO_(3)^(-)-N). However, under-ground C removal increased the soil NH_(4)^(+)-N content. Changes in different C inputs showed inconsistent effects on soil microbial biomass nitrogen(MBN), which may be related to the ecosystem type, tree species composition, timescale, and other factors. In addition, the influence of under-ground C removal on soil soluble nitrogen(DON) was greater than that of above-ground C removal, and the under-ground root system may be the main contributor to soil DON.(2) The effects of above-ground C inputs on soil N mineralization and nitrification rates were greater in the short but less in the long term. Soil N mineralization and nitrification processes were affected indirectly by changes in soil microbial activity. The under-ground C removal increased soil N mineralization rates, and the effect was more obvious with an increase in a time scale.(3) Above-ground C inputs indirectly affected N_(2)O emissions by changing the available C sources of nitrifying and denitrifying microorganisms and was significantly affected by tree species. However, the effect of the under-ground C inputs on N_(2)O varied with the root quality. Current research mainly focuses on the impacts of a certain type of above-and under-g

关 键 词：森林生态系统 凋落物及根系C输入 土壤活性N库 N矿化 N_(2)O排放 N循环 碳中和 

分 类 号：S718[农业科学—林学]