Approximately 17% of global greenhouse gas emissions come from the clearing and burning of forests (van der Werf et al. 2009). Tis is more than all the emissions from the world’s transport sector com- bined. To keep average global temperature increases to less than 2 °C by 2050, global emissions must be reduced by 85% from 2000 levels, and must peak no later than 2015 (IPCC 2007). But rather than slowing down, greenhouse gas emissions are still increasing, and even accelerating (Canadell et al. 2007). Indonesia can play an important role in mitigating global emissions, because as a result of forest loss and especially the subsequent burning of peatlands, Indonesia is the third largest emitter of carbon in the world after China and the US (Hooijer et al. 2006). Vigorous efforts are need- ed to reverse this trend, and doing so will be impossible without addressing carbon losses from deforestation (Trumper et al. 2009).
Managing these ecosystems can be a highly cost-effective means of limiting carbon emissions (Stern 2006). When evaluating the role of Sumatran orangutan habitat in carbon sequestration, it is necessary to distinguish between the relative contributions made by the above-ground and below-ground carbon stocks.
Forests vary in the amount of carbon they store above-ground, depending, in particular, on the abundance of very large trees of species with a high wood density, as these trees store the most carbon (Baker et al. 2004). Nevertheless, it is generally accepted that the total carbon stored in the above-ground woody biomass of a tropical forest varies between 170 and 250 tonnes of carbon per hectare (tC/ha) Malhi et al. 2006; Chave et al. 2008; Lewis et al. 2009) (Map 21).