Dataset of CarboEastAsia and uncertainties in the CO₂ budget evaluation caused by different data processing

Abstract

The datasets of net ecosystem CO₂ exchange (NEE) were acquired from 21 forests, 3 grasslands, and 3 croplands in the eastern part of Asia based on the eddy covariance measurements of the international joint program, CarboEastAsia. The program was conducted by three networks in Asia, ChinaFLUX, JapanFlux, and KoFlux, to quantify, synthesize, and understand the carbon budget of the eastern part of Asia. An intercomparison was conducted for NEE estimated by three gap-filling procedures adopted by ChinaFLUX, JapanFlux, and KoFlux to test the range of uncertainty in the estimation of NEE. The overall comparison indicated good agreement among the procedures in the seasonal patterns of NEE, although a bias was observed in dormant seasons depending on the different criteria of data screening. Based on the gap-filled datasets, the magnitude and seasonality of the carbon budget were compared among various biome types, phenology, and stress conditions throughout Asia. The annual values of gross primary production and ecosystem respiration were almost proportional to the annual air temperature. Forest management, including clear-cutting, plantation, and artificial drainage, was significant and obviously affected the annual carbon uptake within the forests. Agricultural management resulted in notable seasonal patterns in the crop sites. The dataset obtained from a variety of biome types would be an essential source of knowledge for ecosystem science as well as a valuable validation dataset for modeling and remote sensing to upscale the carbon budget estimations in Asia.

Keywords:

• CarboEastAsia
• Carbon budget
• Intercomparison
• Net ecosystem CO₂ exchange

Acknowledgments

This study was conducted as one of A3 Foresight Program CarboEastAsia studies supported by the Japan Society for the Promotion of Science (JSPS), National Natural Science Foundation of China (NSFC), and National Research Foundation of Korea (NRF). The KoFlux was also supported by the National Research Foundation and a grant (Code: 1-8-3) from Sustainable Water Resource Research Center of 21st Century Frontier Research Program of Korea. We thank the site PIs and contributors of field measurements in ChinaFLUX, JapanFlux, and KoFlux for providing their valuable datasets and useful comments. The gap-filling analyses for all the study sites were greatly supported by CarboEastAsia members, particularly Drs. J. Hong, K. Ono, K. Ichii, K. Takahashi, T. Sasai, K. Murakami, A. Ogawa, A. Takahashi, and S. Tanaka. The study was also supported by the Environmental Research Fund (F-1101) of the Ministry of the Environment, Japan.

Notes

Electronic supplementary material The online version of this article (doi:10.1007/s10310-012-0378-6) contains supplementary material, which is available to authorized users.