Data from: Targeting connectivity and road verge management to conserve specialist pollinators in agricultural landscapes in Sweden

Summary from article1. Agricultural intensification has driven biodiversity declines worldwide, with habitat specialists experiencing particularly severe impacts from landscape fragmentation and homogenization. Consequently, there is an urgent need to develop conservation strategies within agricultural landscapes to halt or reverse these biodiversity declines. Specialist pollinators are particularly affected, facing increasing threats, yet quantitative insights into how host plant abundance, connectivity, and topographic heterogeneity shape their metapopulations remain limited, hampering effective conservation planning in fragmented landscapes.2. We investigated the habitat requirements of Megachile lagopoda, Sweden's largest leaf-cutter bee and a specialist pollinator of Centaurea scabiosa, across 550 km² of an agricultural landscape in Östergötland, Sweden. Through systematic field surveys, we identified 120 patches containing the host plant, of which 40 (33%) were occupied by female bees. Overall, 36 patches (30%) were road verges. We parameterised an Incidence Function Model using host plant density and elevation range to adjust effective patch area and simulated future population dynamics under various road verge management and compensation scenarios.3. Connectivity was the strongest predictor of bee occurrence, followed by elevation range and host plant abundance, while soil type did not improve model fit. Road verge cutting, resulting in 90% removal of host plants from road verges, reduced metapopulation occupancy by 16% compared to baseline conditions. Uniform compensation of lost plants across all uncut patches achieved only partial recovery, while strategic compensation targeting the 20 most important patches maintained baseline population levels.4. Synthesis and applications. The two most critical factors for maintaining viable populations of specialist pollinators are connectivity—the proximity of habitat patches, which determines dispersal between sites—and topographic heterogeneity—measured here as elevation range within patches—which provides diverse nesting conditions from sun-exposed slopes to sheltered microsites. Conservation efforts, such as restoring host plants and enhancing nesting habitat, should be concentrated in well-connected patches rather than spread uniformly, as habitat improvements in these key locations have greater biological impact. For road verge management, delaying cutting until late August and concentrating host plant restoration in well-connected patches when earlier cutting is unavoidable are simple, cost-effective strategies for sustaining specialist pollinators in intensive agricultural landscapes.