Abstract
Abstract. Urbanization is accelerating globally, causing a variety of environmental changes such as increases in air temperature, precipitation, atmospheric CO2, 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 Pinus massoniana 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.
Highlights
Urbanization is accelerating globally, with 50 % of the world’s population currently living in cities, with a projected increase to 70 % by 2050 (UNFPA, 2007)
The following environmental gradients have been related to patterns of urbanization extending from the core of Pearl River Delta (PRD) to its surrounding areas: (1) air temperature is approximately 0.5–2.0 ◦C higher in the core of PRD than in its surroundings due to the effect of “urban heat island” (Mai et al, 2011; Dou and Zhao, 2011; (2) CO2 emissions are relatively elevated in PRD, accounting for 70 % of total emissions in Guangdong Province (Liu, 2009); (3) rates of N deposition vary from approximately 46 kg ha−1 yr−1 toward the core of PRD to < 20 kg ha−1 yr−1
Two-way analysis of variance (ANOVA) showed that urbanization-induced environmental changes significantly reduced Soil organic carbon (SOC) and total nitrogen (TN) concentrations in urban sites compared with those in suburban and rural sites, in all soil depths (Table 1, all P < 0.05)
Summary
Urbanization is accelerating globally, with 50 % of the world’s population currently living in cities, with a projected increase to 70 % by 2050 (UNFPA, 2007). Numerous studies have shown air temperature (Jones et al, 1990), precipitation (Botkin and Beveridge, 1997; Gilbert, 1989), atmospheric CO2 (Idso et al, 2002; Pataki et al, 2003), and N deposition (Lovett et al, 2000; Fenn et al, 2003) to be higher in urban areas than in rural surroundings This environmental gradient may even be a useful tool for investigating how global environmental change influences forest ecosystem structure and function, since such changes in cities are known to be major drivers of global change (Carreiro and Tripler, 2005; Shen et al, 2008). This belief was supported by recent direct field measurements along an urban-to-rural
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
