杉木叶和细根诱导的土壤有机碳分解激发效应及其对氮添加的响应  

Priming effect of soil organic carbon decomposition induced by Cunninghamia lanceolate leaf litter and fine root and its response to nitrogen addition in subtropical forests

作　　者：王梁 赵学超 杨少博 王清奎 WANG Liang;ZHAO Xue-Chao;YANG Shao-Bo;WANG Qing-Kui(Anhui Provincial Key Laboratory of Forest Resource and Silviculture,School of Forestry&Landscape Architecture,Anhui Agricultural University,Hefei 230036,China;Huitong Experimental Station of Forest Ecology,CAS Key Laboratory of Forest Ecology and Management,Institute of Applied Ecology,Chinese Academy of Sciences,Shenyang 110016,China)

机构地区：[1]安徽农业大学林学与园林学院安徽省林木资源培育重点实验室,合肥230036 [2]中国科学院沈阳应用生态研究所森林生态与管理重点实验室会同森林生态实验站,沈阳110016

出　　处：《植物生态学报》2024年第11期1434-1444,共11页Chinese Journal of Plant Ecology

基　　金：国家自然科学基金(32171752和31830015);湖南省自然科学基金(2022JJ30468)。

摘　　要：激发效应是指外源碳输入引起的土壤有机碳分解速率的短期变化,是全球陆地生态系统碳循环的重要过程,对全球土壤碳储量及其动态变化具有重要影响。凋落叶和细根作为森林土壤碳输入的主要途径,调控土壤有机碳分解的激发效应,而大气氮沉降引起的土壤氮有效性的增加也是影响激发效应的重要因素。然而,凋落叶和细根的输入引起的激发效应的差异及它们对土壤氮有效性增加的响应机理尚不清楚。该研究将^(13)C标记的杉木(Cunninghamia lanceolate)叶覆盖在杉木人工林土壤表面,细根则混合在土壤中,以尽可能模拟它们在野外林地中的存在状态,同时添加氮以增加土壤氮有效性,通过室内模拟培养35天,测定土壤释放CO_(2)的量及其^(13)C丰度值,并在培养结束时测定土壤养分和微生物群落结构。主要结果:1)杉木叶促进了土壤有机碳分解,即产生了正激发效应(1.69 mg C·kg^(-1)·d^(-1)),而杉木细根则产生了负激发效应(^(-1).26mgC·kg^(-1)·d^(-1));2)土壤氮有效性增加使杉木叶引起的正激发效应的强度降低了38.7%,但使杉木细根引起的负激发效应的强度增加了16.6%;3)添加杉木叶降低土壤真菌细菌比(22.9%),添加杉木细根增加了真菌生物量(30.8%);同时土壤氮有效性增加提高了真菌细菌比和真菌生物量。该研究发现了凋落叶和细根对激发效应的影响存在差别,且土壤氮有效性增加降低了激发效应强度,研究结果为氮沉降背景下森林土壤有机碳库的预测与管理提供理论支持。Aims Priming effect(PE),as the change in the decomposition rate of soil organic carbon(SOC)caused by exogenous carbon(C)input,plays important roles in regulating the storage and dynamics of global SOC.Leaf litter and fine root are the main sources of SOC in forest ecosystems,which can significantly affect PE.In addition,increased soil nitrogen(N)availability caused by atmospheric N deposition also impacts PE.However,the differences between the PE induced by leaf litter and fine root differ and their response to increased soil N availability remain unclear.Methods In this study,we conducted a 35-days incubation experiment by adding^(13)C-labelled leaf litter and fine root into Cunninghamia lanceolate soil.Leaf litter was covered on soil surface and fine root was mixed in the soils to simulate their natural field conditions.The amount and carbon isotope composition(δ^(13)C)value of soil CO_(2)were measured during the experiment,and soil nutrient contents and microbial community composition were also measured after incubation.Important findings 1)Leaf litter addition promoted the SOC decomposition,that is,leaf litter induced a positive PE,with the magnitude of 1.69 mg C·kg^(-1)·d^(-1),while fine root addition induced a negative PE with the magnitude of^(-1).26 mg C·kg^(-1)·d^(-1).2)N addition reduced the magnitude of positive PE induced by leaf litter addition by 38.7%,while it increased the magnitude of negative PE induced by fine root addition by 16.6%.3)Leaf litter addition reduced fungi bacteria ratio by 22.9%,while adding fine root increased the fungal biomass by 30.8%.Furthermore,N addition increased the fungal bacterial ratio and the fungal biomass.Our results demonstrated the differences in the PE induced by leaf litter and fine root addition,and provided theoretical support for the prediction and management of SOC in forests under the scenario of increasing atmospheric N deposition.

关 键 词：土壤有机碳分解 激发效应 氮沉降 森林凋落物 土壤微生物群落组成 

分 类 号：S71[农业科学—林学]