Evaluating whether protected areas reduce tropical deforestation in Sumatra

Abstract

Aim This study determines whether the establishment of tropical protected areas (PAs) has led to a reduction in deforestation within their boundaries or whether deforestation has been displaced to adjacent unprotected areas: a process termed neighbourhood leakage. Location Sumatra, Indonesia. Methods We processed and analysed 98 corresponding LANDSAT satellite images with a c. 800 m2 resolution to map deforestation from 1990 to 2000 across 440,000 km2 on the main island of Sumatra and the smaller island of Siberut. We compared deforestation rates across three categories of land: (1) within PAs; (2) in adjacent unprotected land lying with 10 km of PA boundaries; and (3) within the wider unprotected landscape. We used the statistical method of propensity score matching to predict the deforestation that would have been observed had there been no PAs and to control for the generally remote locations in which Sumatran PAs were established. Results During the period 1990–2000 deforestation rates were found to be lower inside PAs than in adjacent unprotected areas or in the wider landscape. Deforestation rates were also found to be lower in adjacent unprotected areas than in the wider landscape. Main conclusions Sumatran PAs have lower deforestation rates than unprotected areas. Furthermore, a reduction in deforestation rates inside Sumatran PAs has promoted protection, rather than deforestation, in adjacent unprotected land lying within 10 km of PA boundaries. Despite this positive evaluation, deforestation and logging have not halted within the boundaries of Sumatran PAs. Therefore the long‐term viability of Sumatran forests remains open to question.

Role of Brazilian Amazon protected areas in climate change mitigation

“…The most advanced method of PA comparison is propensity score matching, which selects paired samples inside and outside PAs with equivalent deforestation probabilities (16). This technique could not be used for the Brazilian Amazon PAs.…”

“…The well-supported argument against using buffer zones for pairwise comparison made by this second group of studies is that landscape characteristics in sampled areas are not the same: areas in the interior of PAs usually are more remote (18) and thus are less likely to be deforested than areas in their exterior (12,16,17). Conclusions from these studies regarding the inhibitory effect of PAs on deforestation also vary, from a positive effect (9,10,15) that, however, is not seen in all PA groups (11) or a positive but modest effect (12,13,16,17) to no effect (14). As a result, the terms "de jure" and "de facto" have been used to qualify PA effects (11); the latter simply expresses a bias toward PA's more remote location.…”

“…We reviewed nine studies (9-17) of PA effects on tropical deforestation, summarizing their methods, assumptions, and main conclusions (Table S2). The methods of these studies vary from simple comparisons of deforestation rates in zones inside and outside groups of PAs [all PAs of a region or groups of PAs, wallto-wall data, high or low spatial resolution, time-period or annual deforestation rates (9-11, 14, 15)] to more sophisticated statistical approaches that attempt to resolve differences in deforestation probability in samples used for comparison (12,13,16,17). The well-supported argument against using buffer zones for pairwise comparison made by this second group of studies is that landscape characteristics in sampled areas are not the same: areas in the interior of PAs usually are more remote (18) and thus are less likely to be deforested than areas in their exterior (12,16,17).…”

“…The methods of these studies vary from simple comparisons of deforestation rates in zones inside and outside groups of PAs [all PAs of a region or groups of PAs, wallto-wall data, high or low spatial resolution, time-period or annual deforestation rates (9-11, 14, 15)] to more sophisticated statistical approaches that attempt to resolve differences in deforestation probability in samples used for comparison (12,13,16,17). The well-supported argument against using buffer zones for pairwise comparison made by this second group of studies is that landscape characteristics in sampled areas are not the same: areas in the interior of PAs usually are more remote (18) and thus are less likely to be deforested than areas in their exterior (12,16,17). Conclusions from these studies regarding the inhibitory effect of PAs on deforestation also vary, from a positive effect (9,10,15) that, however, is not seen in all PA groups (11) or a positive but modest effect (12,13,16,17) to no effect (14).…”

Governance, agricultural intensification, and land sparing in tropical South America

“…In this domain, there is a vast amount of literature on the effect of protected areas on deforestation (30)(31)(32)(33)(34)(35)(36). Whereas research quantifying the effect of other aspects of environmental governance (other than the establishment of protected areas) on agricultural expansion is sparser, but indicates their potential to significantly reduce deforestation (37).…”