A Cost-Efficient Method to Assess Carbon Stocks in Tropical Peat Soil
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Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Biogeosciences Discuss., 9, 7049–7071, 2012 www.biogeosciences-discuss.net/9/7049/2012/ Biogeosciences doi:10.5194/bgd-9-7049-2012 Discussions BGD © Author(s) 2012. CC Attribution 3.0 License. 9, 7049–7071, 2012 This discussion paper is/has been under review for the journal Biogeosciences (BG). A cost-efficient Please refer to the corresponding final paper in BG if available. method to assess carbon stocks in A cost-efficient method to assess carbon tropical peat soil stocks in tropical peat soil M. W. Warren et al. 1,* 2,3 3,4 5 M. W. Warren , J. B. Kauffman , D. Murdiyarso , G. Anshari , Title Page K. Hergoualc’h3, S. Kurnianto3,6, J. Purbopuspito3, E. Gusmayanti5, M. Afifudin5, J. Rahajoe7, L. Alhamd7, S. Limin8, and A. Iswandi9 Abstract Introduction Conclusions References 1USDA Forest Service, Northern Research Station, 271 Mast Rd., Durham NH 03824, USA 2 Oregon State University, Dept. of Fisheries and Wildlife. Nash Hall Rm 104, Corvallis OR Tables Figures 97331, USA 3Center for International Forestry Research, Jalan CIFOR, Situ Gede, Bogor Barat 16115, Indonesia J I 4Bogor Agricultural University, Dept. of Geophysics and Meteorology, Jalan Meranti, Kampus IPB Darmaga Bogor 16680, Indonesia J I 5 Universitas Tanjungpura, Center for Wetlands People and Biodiversity, Jalan Ahmad Yani, Back Close Pontianak 78124, West Kalimantan, Indonesia 6 University of New Hampshire, Institute for the Study of Earth, Oceans and Space, Morse Hall Full Screen / Esc 8, College Road, Durham NH 03824, USA 7 Indonesian Institute of Sciences Research Center for Biology, Cibinong Science Center, Printer-friendly Version Jalan, Raya Jakarta, Bogor Km 46, Cibinong, West Java, Indonesia 8 CIMTROP, University of Palangka Raya, Kampus Tunjung Nyoho, Central Kalimantan 73111, Interactive Discussion Indonesia 7049 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 9Bogor Agricultural University, Dept. of Soil Science and Land Management, Laboratory of Soil Biotechnology, Jalan Meranti, Kampus IPB Darmaga Bogor 16680, Indonesia BGD Received: 20 March 2012 – Accepted: 16 April 2012 – Published: 14 June 2012 9, 7049–7071, 2012 Correspondence to: M. W. Warren ([email protected]) Published by Copernicus Publications on behalf of the European Geosciences Union. A cost-efficient method to assess carbon stocks in tropical peat soil M. W. Warren et al. Title Page Abstract Introduction Conclusions References Tables Figures J I J I Back Close Full Screen / Esc Printer-friendly Version Interactive Discussion 7050 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Abstract BGD Estimation of soil carbon stocks in tropical wetlands requires costly laboratory analy- ses and suitable facilities, which are often lacking in developing nations where most 9, 7049–7071, 2012 tropical wetlands are found. It is therefore beneficial to develop simple yet robust an- 5 alytical tools to assess soil carbon stocks where financial and technical limitations are A cost-efficient common. Here we use published and original data to describe soil carbon density method to assess −3 −3 (gC cm ;Cd) as a function of bulk density (g dry soil cm ;Bd), which can be used to carbon stocks in estimate belowground carbon storage using Bd measurements only. Predicted carbon tropical peat soil densities and stocks are compared with those obtained from direct carbon analysis for 10 ten peat swamp forest stands in three national parks of Indonesia. Analysis of soil car- M. W. Warren et al. bon density and bulk density from the literature indicated a strong linear relationship 2 (Cd = Bd × 0.49 + 4.61, R = 0.96, n = 94) for soils with an organic C content >40 %. Title Page As organic C content decreases, the relationship between Cd and Bd becomes less predictable as soil texture becomes an important determinant of Cd. The equation pre- Abstract Introduction 15 dicted soil C stocks to within 0.39 % to 7.20 % of observed values. When original data 2 Conclusions References were included in the analysis, the revised equation: Cd = Bd× 0.48 + 4.28, R = 0.96, n = 678 was well within the 95 % confidence intervals of the original equation, and Tables Figures tended to decrease Cd estimates slightly. We recommend this last equation for a rapid estimation of soil C stocks for well developed peat soils where C content >40 %. J I J I 20 1 Introduction Back Close Tropical wetland forests containing organic soils – mangroves and freshwater peat swamps – are significant global carbon (C) stores (Donato et al., 2011). Page et Full Screen / Esc al. (2011) estimated 88.6 PgC is stored in tropical peatlands worldwide, with 68.5 PgC (77 %) occurring in Southeast Asia. Similarly, Donato et al. (2011) estimated man- Printer-friendly Version 25 groves may contain up to 20 PgC globally. Tropical wetland forests are susceptible to large-scale C losses, due to their high C storage and rapid rates of deforestation Interactive Discussion 7051 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | (Langner et al., 2007; Miettinen and Liew, 2010a, b). Of further concern is the vul- nerability of tropical wetland C pools exacerbated by predicted consequences of global BGD climate change: ENSO-related droughts and subsequent fires, altered precipitation pat- 9, 7049–7071, 2012 terns, increasing frequency and severity of tropical cyclones, and sea level rise (Ellison 5 and Stoddart, 1991; Li et al., 2007; Field et al., 2009). Tropical wetlands are also well known for their numerous ecosystem services and A cost-efficient unique biodiversity. Because of these values and vulnerabilities tropical wetland forests method to assess are of particular interest in climate change mitigation strategies such as reduced carbon stocks in emissions from deforestation and degradation (REDD+; Murdiyarso et al., 2010; Her- tropical peat soil 10 goualc’h and Verchot, 2011). However, data deficiencies preclude the rigorous C ac- counting necessary for the successful implementation of REDD+ activities in tropical M. W. Warren et al. wetlands (IPCC, 2006). There is a pressing need for accurate C assessments in tropi- cal wetland ecosystems to establish baseline C stocks, and real and potential C losses Title Page from disturbance. 15 Belowground carbon pools of tropical wetlands are quite high. Chimner and Abstract Introduction Ewel (2005) estimated 330–775 Mg ha−1 of belowground peat C for forests on Kosrae, and 1077 MgC ha−1 were reported for riverine peat forests over shallow peat horizons in Conclusions References Tanjung Puting, Indonesia (Murdiyarso et al., 2009). Jaenicke et al. (2008) estimated up Tables Figures to 3130 MgC ha−1 for the Sebangau peat formation in Indonesia, and Page et al. (2011) −1 20 calculated a global average of 2009 MgC ha for all tropical peatlands. By compari- J I son, the soil carbon pools of upland tropical forests have been shown to range from −1 −1 76 MgC ha in dry forests with shallow soils <60 cm in depth to about 268 MgC ha J I in wet forests (Kauffman et al., 2009). Kauffman et al. (2009) reported total ecosystem Back Close C pools (aboveground + belowground pools) in upland Neotropical forests ranged from −1 −1 25 141 Mg ha in tropical dry forest to 571 Mg ha in lower montane moist forests. Full Screen / Esc Land conversion on peatlands results in immediate massive C fluxes to the atmo- sphere due to drainage, deforestation and burning followed by longer term oxidative Printer-friendly Version losses contingent on hydrological conditions (Hooijer et al., 2010; Murdiyarso et al., 2010; Hergoualc’h and Verchot, 2011). Murdiyarso et al. (2010) estimated 25 % of Interactive Discussion 7052 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | all C emissions from converting peat forest to industrial plantations (a dominant land use transition of tropical peatlands in Indonesia; Koh et al., 2011) occur from initial BGD burning to clear land. During the unusually severe fire season of 1997, drought condi- 9, 7049–7071, 2012 tions prompted opportunistic and uncontrolled burning which eventually affected over 5 2 Mha of wetland ecosystems throughout Indonesia, resulting in C losses commensu- rate with the 1.5 PgC average annual flux from global land use change from 1990–2005 A cost-efficient (Taconni, 2003; Le Quer´ e´ et al., 2009; Page et al., 2002; Langmann and Heil, 2004). method to assess The large estimates of greenhouse gas emissions from altered tropical wetlands carbon stocks in are of particular concern considering their rapid deforestation rates (Langner et al., tropical peat soil 10 2007; Miettinen and Liew, 2010a, 2010b). Langner et al. (2007) estimated that annual deforestation rates of mangroves and peat swamp forests on the island of Borneo were M. W. Warren et al. 7.92 % and 2.24 % (respectively) for the years 2002–2005. The deforestation rates of wetland forests exceeded that of any other forest type. Similarly, Posa et al. (2011) Title Page suggested that only about 37 % of Southeast Asia’s initial 182 541 km2 of peat swamp 15 forests remain, and Miettinen and Liew (2010b) estimated that half of the peat swamp Abstract Introduction forest area mapped in peninsular Malaysia, Borneo and Sumatra in 1990 had been converted to other land uses by 2008, implying large scale C emissions from land use Conclusions References change. Tables Figures The uncertainties of ecosystem carbon stocks of tropical wetlands and emissions 20 from land cover change as well as their difficulties in measurement are well known J I and recognized, and limit the accuracy of large scale C stock and flux estimates (Her- goualc’h and Verchot, 2011). The widespread estimation of soil C stocks in tropical J I wetlands has been partly limited by lack of access to suitable technical facilities and Back Close analytical equipment in remote developing areas. Induction furnace C analyzers are 25 costly and depend on infrastructure and the availability of consumables to be run prop- Full Screen / Esc erly.