Carbon budgets of wetland ecosystems in China

• Published in: Global change biology 2019-06, Vol.25 (6), p.2061-2076
• Main Authors: Xiao, Derong, Deng, Lei, Kim, Dong‐Gill, Huang, Chunbo, Tian, Kun
• Format: Article
• Language: English
• Subjects: Aquatic ecosystems; Aquatic plants; Biosphere; Carbon; Carbon dioxide; carbon emission; carbon sequestration; carbon stock; carbon uptake; climate; Climate change; Ecosystems; Emissions; Environmental changes; Geographical locations; Lakes; Marshes; Primary production; Rivers; Soil; Stocks; Surveying; Terrestrial ecosystems; Terrestrial environments; Uptake; wetland; Wetlands
• ISSN: 1354-1013; 1365-2486
• DOI: 10.1111/gcb.14621

Wetlands contain a large proportion of carbon (C) in the biosphere and partly affect climate by regulating C cycles of terrestrial ecosystems. China contains Asia's largest wetlands, accounting for about 10% of the global wetland area. Although previous studies attempted to estimate C budget in China's wetlands, uncertainties remain. We conducted a synthesis to estimate C uptake and emission of wetland ecosystems in China using a dataset compiled from published literature. The dataset comprised 193 studies, including 370 sites representing coastal, river, lake and marsh wetlands across China. In addition, C stocks of different wetlands in China were estimated using unbiased data from the China Second Wetlands Survey. The results showed that China's wetlands sequestered 16.87 Pg C (315.76 Mg C/ha), accounting for about 3.8% of C stocks in global wetlands. Net ecosystem productivity, jointly determined by gross primary productivity and ecosystem respiration, exhibited annual C sequestration of 120.23 Tg C. China's wetlands had a total gaseous C loss of 173.20 Tg C per year from soils, including 154.26 Tg CO2‐C and 18.94 Tg CH4‐C emissions. Moreover, C stocks, uptakes and gaseous losses varied with wetland types, and were affected by geographic location and climatic factors (precipitation and temperature). Our results provide better estimation of the C budget in China's wetlands and improve understanding of their contribution to the global C cycle in the context of global climate change. China's wetlands have total C stocks of 16.87 Pg C, Herein, plant C stocks is 0.22 Pg C and soil C stocks is 16.65 Pg C. Net ecosystem productivity, jointly determined by gross primary productivity and ecosystem respiration, exhibited annual C sequestration of 120.23 Tg C. Moreover, C stocks, uptakes and gaseous losses varied with wetland types. Marsh wetlands have the highest C stocks of 10.20 Pg C, following by lake, river and coastal wetlands, with the values of 4.20, 1.92 and 0.54 Pg C, respectively.