The area where orangutans occur can be separated into two main habitat types: forest on peat-lands (Tripa) and forests on mineral soils (Batang Toru), and the results are presented for these types separately. Values for carbon were calculated according to Butler et al. 2009 model using a discount rate of 6.5% and voluntary market prices (mean USD 13.33t/CO2, range USD 9.43-17, forest carbon report). Under the fixed scenario the carbon price remains constant during the 25-year period and under the appreciation scenario the price increases with 5% each year during the 25-year period. Net present values for the different land uses are from the Tata and van Noordwijk (2010) and were calculated with a discount rate of 6.5% for a 25-year period. For the carbon calculations potential payments for carbon in land uses other than natural forest were not included because payments for these are still largely under discussion.
From collection: Orangutans and the Economics of Sustainable Forest Management in Sumatra
Riccardo Pravettoni, UNEP/GRID-Arendal