Review
Transboundary Frontiers: An Emerging Priority for Biodiversity Conservation

https://doi.org/10.1016/j.tree.2020.03.004Get rights and content

Highlights

  • Transboundary frontiers overlap with important biodiversity areas and wildlife habitats.

  • Biodiversity in transboundary frontiers is threatened by construction of border infrastructure.

  • Differences in land use and policy between neighboring countries weaken conservation efforts.

  • Transboundary conservation has focused on large mammals, largely neglecting other species.

  • Strengthened coordination between neighboring countries is needed to ensure effective conservation across international borders.

The world’s biomes and their associated ecosystems are artificially fractured by geopolitical boundaries that define countries. Yet ‘transboundary’ landscapes often overlap with biodiversity hotspots, contain surprisingly important ecosystems, and provide critical habitats for threatened species. Notwithstanding, biodiversity in these landscapes is increasingly imperiled by infrastructure, including walls and fences along borders and cross-border roads that drive landscape fragmentation and the loss of ecological connectivity. Associated problems due to reduced governance (e.g., illegal wildlife trade) also undermine conservation efforts in these important regions. In this review, we distinguish positive and negative effects of transboundary frontiers on biodiversity conservation, discuss lessons from existing frameworks, and identify scenarios that can maximize opportunities for biodiversity conservation in transboundary frontiers.

Section snippets

The Importance of Transboundary Frontiers for Biodiversity Conservation

Transboundary frontiers are areas near to or bordering international political boundaries that define countries and territories, thus subjecting landforms like mountains, rivers, and lakes to differing sovereignties [1]. Many transboundary frontiers support exceptional levels of species endemism [2,3] and play important roles in ensuring ecological connectivity (see Glossary) by allowing the movement of wildlife populations. For example, over 62% of mammal species in the Americas host

Border Regions Often Overlap with Biodiversity Hotspots

Many transboundary landscapes are species rich because international borders often overlap with mountainous terrain or other geologically complex landscapes, which naturally support high richness and endemism. Of all terrestrial biodiversity hotspots, approximately one-third straddle international borders [20], including the Indo-Burma, Sundaland, Eastern Arc Mountains and Coastal Forests of Tanzania and Kenya, Western African, and Mediterranean Basin hotspots [21]. Similarly, the tripoint

Border Barriers (Infrastructure Parallel to Borders)

Border walls and fences in transboundary frontiers are often constructed for security purposes, mainly in response to managing influxes of human migrants [41], large carnivores [35], or to control the spread of wildlife disease [42]. For example, the 4053-km India–Bangladesh border and the 4710-km China–Mongolia border have been extensively fenced by wires or barbed wires [11,43]. Globally, the construction of walls, fences, and other barriers has affected over 47 000 km (>19%) of the world’s

Scenarios That Influence Biodiversity Conservation at International Borders

Many ecosystems at transboundary frontiers continue to face tremendous pressures, particularly from anthropogenic disturbance and political instability, and thus weak environmental governance. Here, we synthesize examples of transboundary frontiers that we consider as conservation friendly and contrast them with frontiers that are hostile to biodiversity conservation, paying close attention to the physical and socio-economic contexts that characterizes these transboundary landscapes.

Strengthening Biodiversity Inventories

Biodiversity and ecosystems at transboundary landscapes have historically been less studied, inventoried, or monitored than elsewhere, mainly due to inaccessibility, political instability, and tight military control. Until recently, there have only been a handful of examples of biodiversity surveys targeting transboundary frontiers, such as the tiger surveys in border regions between India and Nepal [39] and between Russia and China [29]. Most of these surveys focused on flagship large-bodied

Concluding Remarks and Future Perspectives

Our synthesis shows that while transboundary frontiers provide critical habitats for threatened and endemic species, they are increasingly threatened by: (i) construction of physical barriers, including fences, walls, roads, and associated linear infrastructure; (ii) cross-border infrastructure associated with rapid economic development; and (iii) illegal and unsustainable wildlife trade and poaching as well as armed conflicts associated with weak governance. Recognizing the inherent potential

Acknowledgments

L.G. was supported by the China Thousand Young Talents Program (K18291101), Shenzhen Government (Y01296116), the Southern University of Science and Technology (Y01296216), and the High-level Special Funding of the Southern University of Science and Technology (G02296302, G02296402). We acknowledge Lee Tibbitts, Ying Wang, and Ge Tang for helpful discussions and Lim Kim Keang and Abdelhamid Bizid for providing photos. We thank three anonymous reviewers for constructive comments which helped

Glossary

Belt and Road Initiative (BRI)
an infrastructure development project by China involving the expansion of land and maritime transportation infrastructure spanning more than 70 countries.
Border barriers
physical barriers built near international borders, mainly for security reasons.
Border fences
fences built along international boundaries, in some cases partly penetrable by small-bodied species.
Border walls
walls built along international boundaries, usually impenetrable to humans and other species.

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