A framework for assessing forest habitat connectivity loss and optimising reforestation efforts on the example of a hydropower project

The development of renewable energy, such as hydropower, often leads to the loss and fragmentation of terrestrial habitats, with significant effects on biodiversity. However, these impacts are often overlooked or underestimated in Environmental Impact Assessments (EIAs). In this study, we proposed a framework that explicitly integrates forest habitat connectivity into EIAs and environmental planning, addressing both impact assessment and recommendations for offset. The framework included (i) an evaluation of forest habitat connectivity loss by comparing before- and after-construction scenarios and (ii) a spatial analysis to prioritise reforestation activities aimed at restoring connectivity for wildlife species with varying movement abilities. We applied this framework to a proposed hydropower project in Nepal and found a major loss of forest habitat connectivity within the project footprint and up to 15 km away, indicating substantial loss of forest connectivity and a landscape-scale impact. In total, 94.1 km² of deforested areas were identified, and potential reforestation sites were ranked using the Integral Index of Connectivity across three dispersal distances (500 m, 1 km and 2 km). Priority reforestation sites were identified both at landscape-level and within riparian zones, with 15% and 36% of the sites, respectively, emerging as top priorities for reforestation across all the dispersal distances. Our findings highlight the importance of explicitly addressing habitat connectivity in EIAs and environmental planning and show how connectivity-based prioritisation can guide effective reforestation offsets, promoting a better balance between energy development and biodiversity conservation.