Effectiveness of protected areas in reducing deforestation and forest fragmentation in Bangladesh

The establishment of protected areas has been considered a tool to battle deforestation in densely populated countries like Bangladesh. Since 2000, Bangladesh's Forest Department has declared about 41 protected areas. However, before more land is designated as a protected area, it is important to know how effective existing protected areas are in achieving conservation goals. Unfortunately, the determination of the conservation effectiveness of protected areas, such as their capacity to reduce deforestation and forest fragmentation over a considerable period at high temporal frequency (e.g., yearly), is still unavailable despite some known methods being available, for example, the System for the Integrated Assessment of Protected Areas. In this study, we processed and analyzed the Hansen dataset from 2000 to 2018 to produce yearly forest/non-forest maps of four protected areas in Bangladesh and used these maps, with a matching method, to estimate the effectiveness of protected area in reducing deforestation after controlling for potential hidden bias. We also analyzed the forest fragmentation scenario over the same time frame. The forest cover change results from 2010 to 2018 revealed a large-scale deforestation pattern in areas adjacent to the protected area boundary of Chunati Wildlife Sanctuary (CWS) and Baroiyadhala National Park-Hazarikhil Wildlife Sanctuary (together B-HWS). Using a propensity score matching (PSM) approach with a caliper of 0.25, we found that B-HWS was the best performing of the studied protected areas, and that 37% of forest pixels in B-HWS would have been deforested in 2018 if they had not been brought under protection in 2010. Similarly, the estimated avoided deforestation rates were approximately 21% and 4% for CWS and Dudpukuria-Dhopachari Wildlife Sanctuary, respectively. Despite an improvement in deforestation scenarios, during the period 2010-2018, for all protected areas, the forest fragmentation scenarios were exacerbated both inside their boundaries and in adjacent unprotected areas. Therefore, it remains questionable whether protected areas can ultimately maintain the integrity of conservation.