标题：The future of forests and orangutans (Pongo abelii) in Sumatra: predicting impacts of oil
palm plantations, road construction, and mechanisms for reducing carbon emissions from
deforestation
摘要：Payments for reduced carbon emissions from deforestation (RED) are now attracting
attention as a way to halt tropical deforestation. Northern Sumatra comprises an area of
65 000 km2 that is both the site of Indonesia's first planned RED initiative, and the stronghold of 92%
of remaining Sumatran orangutans. Under current plans, this RED initiative will
be implemented in a defined geographic area, essentially a newly established,
7500 km2 protected area (PA) comprising mostly upland forest, where guards will be recruited to
enforce forest protection. Meanwhile, new roads are currently under construction, while
companies are converting lowland forests into oil palm plantations. This case study predicts
the effectiveness of RED in reducing deforestation and conserving orangutans for two
distinct scenarios: the current plan of implementing RED within the specific boundary of a
new upland PA, and an alternative scenario of implementing RED across landscapes
outside PAs. Our satellite-based spatially explicit deforestation model predicts that
1313 km2 of
forest would be saved from deforestation by 2030, while forest cover present in 2006 would shrink by
22% (7913 km2) across landscapes outside PAs if RED were only to be implemented in
the upland PA. Meanwhile, orangutan habitat would reduce by 16% (1137 km2), resulting in the conservative loss of 1384 orangutans, or 25% of the current
total population with or without RED intervention. By contrast, an estimated
7824 km2 of forest could be saved from deforestation, with maximum benefit for orangutan
conservation, if RED were to be implemented across all remaining forest landscapes outside
PAs. Here, RED payments would compensate land users for their opportunity costs in not
converting unprotected forests into oil palm, while the construction of new roads to service
the marketing of oil palm would be halted. Our predictions suggest that Indonesia's first RED initiative in an upland PA may not
significantly reduce deforestation in northern Sumatra and would have little impact on
orangutan conservation because a large amount of forest inside the project area is protected
de facto by being inaccessible, while lowland forests will remain exposed to the combined
expansion of high-revenue plantations and road networks. In contrast, RED would be more
effective in terms of its conservation impact if payments were extended to all remaining
carbon-rich tropical forests, including lowland peat swamp forests, the preferred habitat for
dense populations of orangutans, and if the construction of new roads was halted.
