title: Soil carbon stocks decrease following conversion of secondary forests to rubber (Hevea brasiliensis) plantations.
abstract: Forest-to-rubber plantation conversion is an important land-use change in the tropical region, for which the impacts on soil carbon stocks have hardly been studied. In montane mainland southeast Asia, monoculture rubber plantations cover 1.5 million ha and the conversion from secondary forests to rubber plantations is predicted to cause a fourfold expansion by 2050. Our study, conducted in southern Yunnan province, China, aimed to quantify the changes in soil carbon stocks following the conversion from secondary forests to rubber plantations. We sampled 11 rubber plantations ranging in age from 5 to 46 years and seven secondary forest plots using a space-for-time substitution approach. We found that forest-to-rubber plantation conversion resulted in losses of soil carbon stocks by an average of 37.4±4.7 (SE) Mg C ha(-1) in the entire 1.2-m depth over a time period of 46 years, which was equal to 19.3±2.7% of the initial soil carbon stocks in the secondary forests. This decline in soil carbon stocks was much larger than differences between published aboveground carbon stocks of rubber plantations and secondary forests, which range from a loss of 18 Mg C ha(-1) to an increase of 8 Mg C ha(-1). In the topsoil, carbon stocks declined exponentially with years since deforestation and reached a steady state at around 20 years. Although the IPCC tier 1 method assumes that soil carbon changes from forest-to-rubber plantation conversions are zero, our findings show that they need to be included to avoid errors in estimating overall ecosystem carbon fluxes.
authors.affiliation: Soil Science of Tropical and Subtropical Ecosystems, Büsgen Institute, Georg-August-Universität Göttingen, Göttingen, Germany. mblecou@gwdg.de
authors.forename: Marleen
authors.initials: M
authors.lastname: de Blécourt
authors.forename: Rainer
authors.initials: R
authors.lastname: Brumme
authors.forename: Jianchu
authors.initials: J
authors.lastname: Xu
authors.forename: Marife D
authors.initials: MD
authors.lastname: Corre
authors.forename: Edzo
authors.initials: E
authors.lastname: Veldkamp
mesh_terms: D000383:Agriculture; D002244:Carbon / Q000737:chemistry*; D002681:China; D017753:Ecosystem; D004777:Environment; D028482:Hevea; D012987:Soil / Q000737:chemistry*; D014197:Trees
chemical_list: D012987:Soil; D002244:Carbon
references.citation: J Environ Sci (China). 2004;16(2):256-61
references.pmid: 15137650
references.citation: Proc Natl Acad Sci U S A. 2011 Apr 12;108(15):6318-22
references.pmid: 21444813
references.citation: Environ Manage. 2005 Sep;36(3):394-403
references.pmid: 16132447
references.citation: Biom J. 2008 Jun;50(3):346-63
references.pmid: 18481363
references.citation: Environ Manage. 2012 May;49(5):968-79
references.pmid: 22476665
references.citation: Environ Manage. 2005 Sep;36(3):404-13
references.pmid: 15995894
references.citation: Science. 2009 May 22;324(5930):1024-5
references.pmid: 19460994