BG Biogeosciences BG Biogeosciences 1726-4189 Copernicus Publications Göttingen, Germany 10.5194/bg-10-6609-2013 Changes in soil carbon sequestration in <i>Pinus massoniana</i> forests along an urban-to-rural gradient of southern China Chen H. 1 3 Zhang W. 1 Gilliam F. 2 Liu L. 1 Huang J. 1 Zhang T. 1 Wang W. 1 Mo J. 1 Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China Department of Biological Science, Marshall University, Huntington, WV 25755-2510, USA University of Chinese Academy of Sciences, Beijing 100039, China 22 10 2013 10 10 6609 6616 Copyright: © 2013 H. Chen et al. 2013 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://bg.copernicus.org/articles/10/6609/2013/bg-10-6609-2013.html The full text article is available as a PDF file from https://bg.copernicus.org/articles/10/6609/2013/bg-10-6609-2013.pdf

Urbanization is accelerating globally, causing a variety of environmental changes such as increases in air temperature, precipitation, atmospheric CO<sub>2</sub>, and nitrogen (N) deposition. However, the effects of these changes on forest soil carbon (C) sequestration remain largely unclear. Here, we used urban-to-rural environmental gradients in Guangdong Province, southern China, to address the potential effects of these environmental changes on soil C sequestration in <i>Pinus massoniana</i> forests. In contrast to our expectations and earlier observations, soil C content in urban sites was significantly lower than that in suburban and rural sites. Lower soil C pools in urban sites were correlated with a significant decrease in fine root biomass and a potential increase in soil organic C decomposition. Variation of soil C pools was also a function of change in soil C fractions. Heavy fraction C content in urban sites was significantly lower than that in suburban and rural sites. By contrast, light fraction C content did not vary significantly along the urban-to-rural gradient. Our results suggest that urbanization-induced environmental changes may have a negative effect on forest soil C in the studied region.

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