Carbon pools in tropical peat forest

Transcription

1 Carbon pools in tropical peat forest Towards a reference value for forest biomass carbon in undisturbed peat swamp forests in Southeast Asia Peter van der Meer & Caspar Verwer

2 Introduction Tropical peat cover 25 mln ha in SE Asia 2.6 mln ha in Malaysia Important reservoirs of carbon, water and biodiversity 21 mln ha in Indonesia

3 Introduction Majority of carbon stored in soil : 68.5 Gt (11-14% of global peat carbon pool) (PS Konsultant 1998) Peat formation is driven by the forest vegetation but vast areas have been converted within the last decades

4 Interdependency of peat and forest Vegetation types are related to different zones on the peat dome PC1 Mixed swamp forest PC4 PC5 PC6 PC2 Alan forest PC3 PC3 Alan bunga forest PC2 PC4 Padang alan forest PC5 Tristania- Parastemon- Palaquium association; PC1 PC6 Padang keruntum

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6 Introduction

7 Introduction Logging and conversion leads to loss of biomass, but it is unknown to what extent Need to know the original (prelogging) biomass ( and potential carbon sequestration) Historical inventories (Anderson 1961)

8 Methods: historical inventories half acre (~0.2 ha) plots All trees 12 inch (~10 cm) dbh Tristania Parastemon 42 plots classified to PC Palaquium association n=2 Combretocarpus Dactylocladus association n=1 Gonystylus Dactylocladus Neoscortechinia association n=7 Shorea albida Litsea Parastemon association n=12 Shorea albida Gonystylus Stemonurus association n=12 Shorea albida consociation n=8

9 Methods Allometry and WD Aboveground biomass Inventory data Belowgroun dbiomass Anderson (1961) Basuki et al. (2009) Niiyama et al. (2010) Zanne et al. (2009) Litter:AGB ratio CWD:AGB ratio Various publications Litter biomass Coarse woody debris biomass

10 AGB (kg/tree) Methods: aboveground biomass (AGB) Chave et al 2001 Chambers et al 2001 Chave et al 2008 Brown 1997 Basuki et al 2009 Chave et al 2005 Overman 1994 Brown 1997 Moist forest Brown 1997 Wet forest Ketterings et al DBH (cm) Variety of allometrics available for wet and moist lowland forests, but not for peat forests

11 C content (t/ha) Methods: aboveground biomass (AGB) PC1 PC2 PC3 PC4 PC5 Chave et al., 2001 Chambers et al., 2001 Chave et al., 2008 Brown, 1997 Basuki et al., 2009 Chave et al., 2005 Overman, 1994 Brown, 1997 (moist forest) Brown, 1997 (wet forest) Ketterings et al., 2001 Results in high variation

12 Methods: aboveground biomass (AGB) Based on overlapping tree genera and region we applied a model by Basuki et al. (2009): ln(agb) = *ln(DBH)+0.832*ln(WD) Species specific wood densities were abstracted from the Global Wood Density Database (Zanne et al. 2009)

13 Methods: belowground biomass

14 Biomass (t/ha) Methods: belowground biomass (BGB) Lacking data on extent of root systems and carbon density in roots use DBH We applied a model by Niiyama et al. (2010): BGB = *DBH^ Aboveground biomass Belowground biomass Diameter (cm dbh)

15 Ecuador Brunei Malaysia Costa Rica Venezuela Indonesia Brazil Brazil Brazil Brazil Brazil Brazil Brazil Brazil Venezuela % of AGB CWD (t dm/ha) Coarse woody debris (CWD) Based on AGB:CWD ratios => average 18% % of AGB CWD (t dm/ha) Mor.Myr forest Dipt. hill forest Tropical wet forest Tropical moist forest

16 Litter Based on AGB:litter ratios Forest type Country % Tropical moist forest Tropical moist forest Tropical moistwet forest Venezuel a AG B Litter (t C/ha)* Reference Delaney et al., 1997 Brazil Brown et al., 1995 Brazil Nascimento and Laurance 2002 Average

17 Carbon content (t C/ha) Results Observed significant differences among peat swamp forest communities ab c c a b AGB carbon (t C/ha) BGB carbon (t C/ha) 50 0 N/A PC1 PC2 PC3 PC4 PC5 PC6 phasic community

18 Results Biomass (t dry matter/ha) Carbon content (t C/ha) Aboveground biomass Belowground biomass Coarse woody debris Range Average±SD Range Average±SD ± ± ± ± ± ±4.9 Litter ± ±0.6 Total forest

19 Conclusion More data needed from other locations Lacking technical data: Allometrics for peat swamp ecosystems Baseline data for belowground biomass (course and fine roots), CWD and litter Carbon content?? Hollow trees?? High uncertainty due to: Small sample size (# plots and plot size) Assumptions regarding allometrics, wood densities and carbon content Use of fixed ratios based on non-peat forest

20 Thank you Caspar Verwer & Peter van der Meer (2010) Carbon pools in tropical peat forest Towards a reference value for forest biomass carbon in undisturbed peat swamp forests in Southeast Asia. Alterra report 2108 Free download from (go to Alterra reports) Wageningen UR