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Parks in Sumatra reduce deforestation to adjacent areas

We report that the establishment of protected areas on the Indonesian island of Sumatra may have helped reduce deforestation in adjacent unprotected areas. The results run counter to recent studies elsewhere that suggest the establishment of nature reserves attracts development projects and migrants to surrounding areas, undermining overall conservation efforts.

Analyzing nearly 100 LANDSAT satellite images (if you are interested in doing this too, make sure you have a good broadband connection) across Sumatra and the smaller island of Siberut from 1990 to 2000 and applying a statistical method known as "propensity score matching", we found that Sumatran protected areas have promoted protection, rather than deforestation, in adjacent unprotected land lying within 10 km of protected area boundaries.

Fig. 1. Sumatra's protected and unprotected forests in 1990 (left). Remaining forests in 2000, deforestation and logging trails occurring during the period 1990 until 2000 (right).

This result suggests that Sumatran PAs have not attracted migrants and development projects along their boundary. Instead, this study provides evidence for the presence of a 'beneficial neighborhood leakage' effect. It appears that reducing deforestation inside Sumatran protected areas has promoted protection to adjacent unprotected areas.

Whether Sumatran protected areas extend their conservation influence beyond their boundary may prove controversial, because enhanced law enforcement and ecotourism activities on private lands around protected areas are not well developed on the island of Sumatra. The unexpected presence of a beneficial leakage effect that conserves forests adjacent to protected areas may be explained by an island-wide decreasing population growth effect near Sumatran protected areas as human population moves closer to urban centers.

The success of protected areas in reducing deforestation is tempered by the continued loss of forest in Sumatra. Between 1990 and 2000 Sumatra lost at least 50,078 square kilometers of forest, 25.6 percent of its forest cover, while 49,020 kilometers of logging roads had been built in remaining forest areas. More than 35 percent of the Sumatran protected set aside to conserve biodiversity had experienced severe rates of forest loss (> 1% year) and 60% had been encroached by mechanized logging operations (Table 1).

The real question for policy makers is not whether tropical PAs have lower rates of deforestation than unprotected areas, but rather whether the long-term viability of tropical forests has been secured by establishing protected areas.

The long-term viability of Sumatran forests remains open to questions.

 

Table 1. Statistics for losses in forest cover and logging from 1990 to 2000,
shown for each conservation protected area (n=40)

 

Reference

Gaveau D.L.A, Epting J., Lyne O., Linkie M., Kumara I., Kanninen M., Leader-Williams N. 2009 Evaluating whether protected areas reduce tropical deforestation in Sumatra. Journal of Biogeography 36 2165-2175.

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