Comprehensive synthesis of spatial variability in carbon flux across monsoon Asian forests

• Published in: Agricultural and forest meteorology 2017-01, Vol.232, p.623-634
• Main Authors: Kondo, Masayuki, Saitoh, Taku M., Sato, Hisashi, Ichii, Kazuhito
• Format: Article
• Language: English
• Subjects: Carbon balance; Carbon flux; Monsoon Asian forests; Spatial variability; Synthesis analysis
• ISSN: 0168-1923; 1873-2240
• DOI: 10.1016/j.agrformet.2016.10.020

•MAT is related to the spatial variability of carbon fluxes in monsoon Asian forests.•GPP exerts stronger control on the spatial variability of carbon fluxes than climate.•NEP is positively related to component fluxes in high–mid latitudes.•NEP is negatively related to component fluxes in low latitudes.•Nitrogen deposition and age are potential factors in the unique variability of NEP. Forest ecosystems sequester large amounts of atmospheric CO2, and the contribution from forests in Asia is not negligible. Previous syntheses of carbon fluxes in Asian ecosystems mainly employed estimates of eddy covariance measurements, net ecosystem production (NEP), gross primary production (GPP), and ecosystem respiration (RE); however, to understand the variability within carbon cycles, fluxes such as autotropic respiration (AR), net primary production (NPP), litterfall, heterotrophic respiration (HR), and soil respiration (SR) need to be analyzed comprehensively in conjunction with NEP, GPP, and RE. Here we investigated the spatial variability of component fluxes of carbon balance (GPP, AR, NPP, litterfall, HR, SR, and RE) in relation to climate factors, between carbon fluxes, and to NEP using observations compiled from the literature for 22 forest sites in monsoon Asia. We found that mean annual temperature (MAT) largely relates to the spatial variability of component fluxes in monsoon Asian forests, with stronger positive effect in the mid–high latitude forests than in the low latitude forests, but even stronger relationships were identified between component fluxes regardless of regions. This finding suggests that the spatial variability of carbon fluxes in monsoon Asia is certainly influenced by climatic factors such as MAT, but that the overall spatial variability of AR, NPP, litterfall, HR, SR, and RE is rather controlled by that of productivity (i.e., GPP). Furthermore, component fluxes of the mid–high and low latitude forests showed positive and negative relationships, respectively, with NEP. Further investigation identified a common spatial variability in NEP and annual aboveground biomass changes with respect to GPP. The relationship between GPP and NEP in the mid–high latitudes implies that productivity and net carbon sequestration increase simultaneously in boreal and temperate forests. Meanwhile, the relationship between GPP and NEP in the low latitudes indicates that net carbon sequestration decreases with productivity, potentially due to the regional con