Long-term thinning decreases the contribution of heterotrophic respiration to soil respiration in subalpine plantations  

作　　者：Longfei Chen Zhibin He Wenzhi Zhao Xi Zhu Qin Shen Mingdan Song Zhengpeng Li Junqia Kong Shuping Yang Yuan Gao 

机构地区：[1]Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,People's Republic of China [2]State Forestry Administration Key Laboratory of Forest Resources and Environmental Management,Beijing Forestry University,Beijing 100083,People's Republic of China [3]Academy of Agriculture and Forestry Sciences,Qinghai University,Xining 810000,People's Republic of China [4]College of Landscape Architecture,Zhejiang A&F University,Hangzhou 310000,People's Republic of China

出　　处：《Journal of Forestry Research》2024年第3期189-204,共16页林业研究（英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant Nos.41701296 and 42277481);the Natural Science Foundation of Gansu Province (GrantNo.22JR5RA058);the Youth Science and Technology Fund Program of Gansu Province (Grant No.22JR5RA087).

摘　　要：Interest in the dynamics of soil respiration(R_(S))in subalpine forest ecosystems is increasing due to their high soil carbon density and potential sensitivity to environmental changes.However,as a principal silvicultural practice,the long-term impacts of thinning on R_(S) and its heterotrophic and autotrophic respiration components(R_(h) and Ra,respectively)in subalpine plantations are poorly understood,espe-cially in winter.A 3-year field observation was carried out with consideration of winter CO_(2) efflux in middle-aged sub-alpine spruce plantations in northwestern China.A trench-ing method was used to explore the long-term impacts of thinning on Rs,Rn and R_(a).Seventeen years after thinning,mean annual Rs,Rn and R_(a) increased,while the contribu-tion of R_(h) to R_(s) decreased with thinning intensity.Thinning significantly decreased winter R,because of the reduction in R_(n) but had no significant effect on Ra.The temperature sensitivity(Q_(10))of R_(h) and R_(a) also increased with thinning intensity,with lower Q_(10) values for R_(h)(2.1-2.6)than for Ra(2.4-2.8).The results revealed the explanatory variables and pathways related to R_(n) and R_(a) dynamics.Thinning increased soil moisture and nitrate nitrogen(NO_(3)^(-)-N),and the enhanced nitrogen and water availability promoted R_(h) and R_(a) by improving fine root biomass and microbial activity.Our results highlight the positive roles of NO_(3)^(-)-N in stimulating R_(s) components following long-term thinning.Therefore,applications of nitrogen fertilizer are not recommended while thinning subalpine spruce plantations from the perspective of reducing soil CO_(2) emissions.The increased Q_(10) values of R_(s) components indicate that a large increase in soil CO_(2) emissions would be expected following thinning because of more pronounced climate warming in alpineregions.

关 键 词：Heterotrophic respiration Autotrophic respiration Long-term thinning impacts Cold seasons Subalpine plantations Temperature sensitivity 

分 类 号：S714[农业科学—林学]