Carbon exchange of forest plantations: global patterns and biophysical drivers

Abstract

Plantation has large carbon sequestration potential, and it plays an important role in mitigating global warming. However, the responses of carbon fluxes to biophysical factors across plantation sites are still not clear. We synthesized carbon flux data measured by the eddy covariance method over the plantations at the global scale to explore the shifts of carbon exchange with latitude, discuss the link of carbon fluxes with biophysical variables, and compare the difference in carbon sequestration between needleleaf and broadleaf plantations. Annual net ecosystem production (NEP), gross primary production (GPP) and ecosystem respiration (ER) across all plantations were 353±27, 1762±60 and 1385±46 g C m−2 yr−1, respectively. The mean annual NEP of needleleaf biomes was similar to that of broadleaf biomes. GPP and ER were 48% and 64% larger at needleleaf forests than at broadleaf forests. Annual NEP, GPP and ER decreased with the increase of latitude significantly. At the half-hourly scale, the increase of diffuse radiation enhanced carbon assimilation of needleleaf and broadleaf biomes remarkably. On the annual scale, both GPP and NEP were sensitive to mean annual temperature (MAT) and leaf area index (LAI). Annual precipitation was the dominant factor regulating the variability of GPP and ER, and it explained 34% and 47% of the variation in GPP and ER, respectively. The extension in growing season length (GSL) and rising soil water content (SWC) enhanced ecosystem photosynthesis and respiration of planted forests. However, the effect of GSL and SWC on net carbon uptake was not remarkable. These results highlight the importance of biophysical factors in regulating carbon dynamics of the plantations, and contribute to understanding of the differences in carbon sequestration between needleleaf and broadleaf biomes.