Protected areas play a crucial part in biodiversity conservation by buffering biodiversity from human-induced threats22,34,35,36. However, the performance of protected areas in conserving species’ habitat is poorly known in many tropical countries8. Here, using Bangladesh as a case study, we showed that mean protected area coverage was very low (6.27%) for species listed on the national Red List of the country, although coverage was slightly higher for threatened species (7.36%) than non-threatened species (5.34%). Only five species met the protected area representation target, and the shortfall in protected area coverage was higher among threatened species. This finding emphasises the under-performance of protected areas, and indicate that a large portion of species’ distributions remains unprotected.
Only 4.61% of the terrestrial area (including inland waters) are now listed as protected areas in Bangladesh27. Moreover, current protected areas are highly biased towards the southwest, and most protected areas are very small: 38% (16 of 42) are < 10km2, and even more extremely, 3 protected areas are less than 1km2 [8]. The draft Post-2020 Biodiversity Framework targets suggest 30% protected area coverage by 203037. To meet this highly ambitious target, there needs to be a five-fold increase in protected area coverage in Bangladesh. Our spatial prioritisation shows that to ensure adequate representation across threatened species, Bangladesh’s government needs to protect at least 32% of the land surface, which is in close agreement with the Post-2020 Biodiversity targets. To mitigate biodiversity loss and better represent current biodiversity, these new protected areas should be established mostly in the northeast (Sylhet) and southeast (Chattogram) of the country. However, when creating new protected areas, decision-makers need to account for people, their livelihoods and biodiversity, as empowering the environmental stewardship of indigenous peoples and local communities is critical to conserving biodiversity across the planet38,39,40,41. While establishing new protected areas is an option, other effective area-based conservation measures (OECM) can be an effective solution too. Harnessing the data from Bangladesh’s national red lists can help to identify Key Biodiversity Areas (KBAs) as a first step in delineating sites of importance for biodiversity42.
Bangladesh is exceptionally endowed with a rich biodiversity and harbours many globally threatened species31,43,44,45, yet the spatial distribution of many species is poorly understood46,47. Over 17% of the nationally assessed species are Data Deficient at the country-scale31. This lack of spatial data is also prominent in global biodiversity repositories, with over 25% of our data are from social media and published resources46,48. Besides data limitations, the available data are highly concentrated on certain taxonomic groups (e.g., birds) and surrounding major cities (e.g., Dhaka)47,48,49. About 55% of the spatial distribution records of our study are from Dhaka, whereas only 1.26% are from Rangpur. Future researchers could enlighten the broader public about the importance of using citizen science applications (e.g., eBird, iNaturalist)46,50,51,52,53,54. Over one-quarter of our data are from Facebook48, where hundreds of photographers post their biodiversity photographs every day46,55,56. Future research could develop a tool to extract biodiversity data from social media (e.g., Facebook, Twitter, Flickr) and deposit it into global biodiversity repositories, such as GBIF46,55. While niche models provide a good initial mechanism to model species distributions, such additional biodiversity data are needed to verify these estimated distributions, and are also vital in confirming the potential of key biodiversity areas42.
Most of the threatened species in Bangladesh are forest species. Being a developing and densely populated country, natural resources are in high demand, impacting the forest reserves both in explicit and implicit ways7,8, 57,58,59,60. In addition, with Bangladesh being amongst the top five of inland water fisheries61, aquatic resources play an important role in nutrition, economy, employment and culture of the country31. This puts a substantial pressure on target species that is compounded by other threats such as pollution, habitat loss, invasive species and climate change31, and needs to be addressed in spatial priority setting for conservation. For example, in our analysis, threatened fish are spatially under-represented in the protected area system (Fig. 1). This could be because historically protected areas were rarely designed based on the need of aquatic species62,63. Studies elsewhere have also shown that the proportion of freshwater species with ranges substantially covered by protected areas is much smaller than for birds and mammals64. However, studies have also shown that by adequately integrating terrestrial and freshwater conservation planning, freshwater benefits were substantial increased with only a minor loss in benefits to terrestrial benefits63.
Several recently published studies from Bangladesh revealed the importance of ‘unconventional’ areas such as urban greenspaces in biodiversity conservation7,49,65,66,67,68,69 and our spatial prioritisation approach identified many important areas around major cities. Chowdhury et al.49 documented nearly 45% of the national butterfly species (305 species) in urban greenspaces of Dhaka; 40% of these 137 species were nationally threatened, and the urban protected area (National Botanical Garden) performed relatively better than other greenspaces. Designating more protected areas in urban landscapes could attract many more species and reduce species vulnerability to anthropogenic disturbances70, and perhaps such sites could constitute valuable OECMs. Besides, the current protected areas do not represent the country's diverse ecoregions; for example, only four broad forest types are designated as protected areas71. Priority areas identified here could help inform conservation decisions made by the Bangladesh government.
We assessed how protected areas in Bangladesh cover the geographic range of different taxonomic groups. We showed that the mean protected area coverage is very low, and only five species are adequately protected. However, our findings should be interpreted cautiously. For example, we did not measure the effectiveness of individual protected areas, did not calculate the rate of habitat loss inside its boundaries, and did not measure whether local habitats inside protected areas are (or will remain) suitable in an era of rapid environmental change. Specifically for freshwater species, the effectiveness of protected areas is often questioned, since freshwater needs - given their connectivity and close links with the landscape they drain - are rarely taken into account when designing and delineating protected areas29. Future studies could assess how anthropogenic climate change will impact biodiversity in tropical countries, such as Bangladesh, and find an efficient way to tackle the situation. We hope our study will create a baseline that the policymakers of Bangladesh could use to meet the Post-2020 Biodiversity Framework targets.