森林土壤温室气体通量对森林管理和全球大气变化的响应

Response of forest soil greenhouse gases fluxes to forest management and global atmospheric change

森林土壤是温室气体重要的源和汇。探讨不同森林管理和全球大气变化下土壤温室气体通量特征,为有效减少温室气体排放及森林可持续管理等提供参考。笔者从森林土壤温室气体(forest soil green house gases)、森林管理(forest mangement)和全球大气变化(global atmospheric change)3个关键研究点,查阅近年来相关研究成果,归纳森林管理和全球大气变化下土壤温室气体通量的一般性模式。CO_2、CH_4和N_2O是3种重要温室气体,其通量间存在协同、消长和随机型耦合关系。森林管理如火烧、采伐和造林等显著影响土壤温室气体通量。一般情况下,火烧导致土壤N_2O通量降低,CH_4吸收量增加,CO_2通量因火烧类型、火烧强度、生态系统类型不同出现增加、减低和无影响3种结果;采伐通常导致土壤CO_2、CH_4和N_2O排放增加;造林可使土壤CO_2排放减少,对N_2O和CH_4通量的影响随生态系统类型、造林树种等而改变。全球大气变化如CO_2浓度升高、氮沉降和气温升高影响森林土壤温室气体通量。通常,CO_2浓度升高导致土壤CO_2和N_2O排放量增加,CH_4吸收量降低;氮沉降促进土壤N_2O排放、抑制CH_4吸收。气温升高导致土壤CO_2和N_2O排放增加。森林管理和全球大气变化对土壤温室气体通量的综合影响是非叠加的,有效的森林管理可能改变土壤温室气体通量对全球大气变化的响应。

Forest soils are important sources and sinks of greenhouse gases （GHG）. The objectives of this study were to explore the characteristics of forest soil GHG fluxes under different forest management practices and global atmospheric change, and to provide a reference for the reduction of GHG release and sustainable forest management. Publications were searched by using China Knowledge Resource Integrated Database, Wanfang Database, Science Direct, and Springer Link, using three keywords ＂forest soil greenhouse gases＂, ＂forest management＂, and ＂atmospheric change＂. Papers reporting on forest soil GHGs were analyzed, and the general pattern of forest soil GHG fluxes under different forest management practices and global atospheric change scenarios was analyzed. CO2, CH4 and N2O are three important GHGs, and the coupling between them are complex including synergism, antagonism and random interactions. Forest soil GHG fluxes were affected by forest management practices, such as forest fire occurrence and suppression, cutting and af- forestation. Forest fire occurrence generally decreased soil N2O flux, and increased soil CH4 absorption. Forest fires could enhance, reduce or show no effects on soil CO2 flux, depending on fire type, fire intensity and ecosystem type. Forest cutting usually increased soil CO2, N2O and CH4 emission. Afforestation might reduce soil CO2 emissions, where asits effects on N2O and CH4 varied with ecosystem type, planted tree species, etc. Generally, atmospheric change impacts that may affect forest soil GHG fluxes are elevated atmospheric CO2 , nitrogen deposition, and rising temperatures. Elevated atmospheric CO2 increased soil CO2 and N2O emission, and decreased soil CH4 absorption. Nitrogen deposition stimulated soil N2O emissions, and suppressed soil CH4 absorption. Rising temperatures increased soil CO2 and N2O emissions. The combined effects of forest management practices and atmospheric change on forest soil GHG fluxes may be non-additive, and effective forest management may alter the response of soil GHG fluxes to atmospheric change.