High carbon dioxide uptake by subtropical forest ecosystems in the East Asian monsoon region

Abstract

Temperate-and high-latitude forests have been shown to contribute a carbon sink in the Northern Hemisphere, but fewer studies have addressed the carbon balance of the subtropical forests. In the present study, we integrated eddy covariance observations established in the 1990s and 2000s to show that East Asian monsoon subtropical forests between 20°N and 40°N represent an average net ecosystem productivity (NEP) of 362 ± 39 g C m −2 yr −1 (mean ± 1 SE). This average forest NEP value is higher than that of Asian tropical and temperate forests and is also higher than that of forests at the same latitudes in EuropeAfrica and North America. East Asian monsoon subtropical forests have comparable NEP to that of subtropical forests of the southeastern United States and intensively managed Western European forests. The total NEP of East Asian monsoon subtropical forests was estimated to be 0.72 ± 0.08 Pg C yr −1 , which accounts for 8% of the global forest NEP. This result indicates that the role of subtropical forests in the current global carbon cycle cannot be ignored and that the regional distributions of the Northern Hemisphere's terrestrial carbon sinks are needed to be reevaluated. The young stand ages and high nitrogen deposition, coupled with sufficient and synchronous water and heat availability, may be the primary reasons for the high NEP of this region, and further studies are needed to quantify the contribution of each underlying factor.

Spatial variation in annual actual evapotranspiration of terrestrial ecosystems in China: Results from eddy covariance measurements

“…At each site, the meteorological variables including solar radiation, air temperature and relative humidity were measured at a frequency of 2 s and then recorded at 30-min intervals. Further details of the monitoring systems were presented by Chen et al (2013) and Yu et al (2014).…”

Primary estimation of Chinese terrestrial carbon sequestration during 2001–2010

“…In general, the NPP was regarded as the material basis of aboveground and belowground biomass in plant communities, whereas the NEP was directly defined as the net carbon sequestration of natural ecosystems and was considered the climate-based potential carbon source/ sink in the absence of anthropogenic and natural disturbances [26].…”

“…Currently, the methods used in the determination of ecosystem productivity and the evaluations of the carbon budget at different spatial and temporal scales include eddy covariance [11], resource inventory [12,13], airborne laser scanning [14], remote sensing evaluation based on resource satellite observations [15], remote sensing inversion of carbon satellites [16,17], geographical statistical modeling [18,19], analysis based on process-based models [20][21][22] and atmospheric inversion [23,24]. These technologies have improved continually with their own appropriate spatiotemporal scales, and researchers have also performed meta-analyses based on multi-source data from different approaches [25,26]. Additionally, comprehensive assessments were conducted on the ecosystem productivity or carbon source/sinks at national, continental and global scales by data-model fusion [7,27,28].…”

Construction and progress of Chinese terrestrial ecosystem carbon, nitrogen and water fluxes coordinated observation

“…Global analysis of carbon fluxes indicated that East Asian monsoon subtropical forests between 20°N and 40°N have high strength of carbon uptake and it attributes to the combined effects of the young stand ages, high nitrogen deposition and sufficient and synchronous water and heat availability ( Yu et al, 2014c). Integrative analysis of global carbon fluxes data showed that GPP and RE co-varied at the spatial pattern from regional to global scale (Yu et al, 2013b;Chen et al, 2013;Chen et al, 2015b) .…”