The carbon balance of terrestrial ecosystems in China

Abstract

Global terrestrial ecosystems absorbed carbon at a rate of 1-4 Pg yr(-1) during the 1980s and 1990s, offsetting 10-60 per cent of the fossil-fuel emissions. The regional patterns and causes of terrestrial carbon sources and sinks, however, remain uncertain. With increasing scientific and political interest in regional aspects of the global carbon cycle, there is a strong impetus to better understand the carbon balance of China. This is not only because China is the world's most populous country and the largest emitter of fossil-fuel CO(2) into the atmosphere, but also because it has experienced regionally distinct land-use histories and climate trends, which together control the carbon budget of its ecosystems. Here we analyse the current terrestrial carbon balance of China and its driving mechanisms during the 1980s and 1990s using three different methods: biomass and soil carbon inventories extrapolated by satellite greenness measurements, ecosystem models and atmospheric inversions. The three methods produce similar estimates of a net carbon sink in the range of 0.19-0.26 Pg carbon (PgC) per year, which is smaller than that in the conterminous United States but comparable to that in geographic Europe. We find that northeast China is a net source of CO(2) to the atmosphere owing to overharvesting and degradation of forests. By contrast, southern China accounts for more than 65 per cent of the carbon sink, which can be attributed to regional climate change, large-scale plantation programmes active since the 1980s and shrub recovery. Shrub recovery is identified as the most uncertain factor contributing to the carbon sink. Our data and model results together indicate that China's terrestrial ecosystems absorbed 28-37 per cent of its cumulated fossil carbon emissions during the 1980s and 1990s.

Primary estimation of Chinese terrestrial carbon sequestration during 2001–2010

“…The estimates of annual carbon emissions from forest fires in China ranged from 8.55 to 13.9 TgC a -1 from 1950 to 2000 in Lü et al [73] and from 20.24 to 28.56 TgC a -1 from 1991 to 2000 in Tian et al [74,75]. However, the mean emissions from forest fires in Piao et al [25] were only 0.003 PgC a -1 between 1980 and 2000. In this study, based on the method proposed by Fu …”

“…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].…”

Potential impact of land use change on ecosystem services in China

“…The market price of agricultural production was obtained from China's statistical yearbook, the food production data from cropland for each province from China's agricultural statistics yearbook, and the forest age data around 2010 from the China's national forest inventory database during 2009-2013. The province-specific biomass densities for woodland, cropland, grassland were obtained from published literature (Fang et al 1996(Fang et al , 1998Piao et al 2007Piao et al , 2009). The physical and socioeconomic datasets used as driving factors for land use location, including elevation, slope, soil texture, temperature, precipitation, traffic, population, gross regional domestic product, and so on have been collected in one of our previous studies , and here, the datasets were directly used.…”

The Greenness of Major Shrublands in China Increased from 2001 to 2013

“…Thus, the countrywide average EVI and its temporal patterns are mostly contributed by EVGNST and DCDSTP. The contribution of shrublands to the NPP in China has been found to be comparable to the arbores forest [43]. Shrublands in China expanded in this century because of the policy-guided shrub planting after abandonment of crops in northern China [44,45].…”