Safeguarding pollinators requires specific habitat prescriptions and substantially more land area than current policy suggests (original) (raw)

Habitat loss and fragmentation are major drivers of global pollinator declines, yet even after recent unprecedented periods of anthropogenic land-use intensification the amount of habitat needed to support pollinators remains unknown. Here we use comprehensive datasets to determine the extent and amount of habitat needed. Safeguarding wild bee communities in a Canadian landscape requires 11.6-16.7% land-cover from a diverse range of habitats (~1.8-3.6x current policy guidelines), irrespective of whether conservation aims are enhancing species richness or abundance. Sensitive habitats, like tallgrass woodlands and wetlands, were important predictors of bee biodiversity. Conservation strategies that underestimate the extent of habitat, spatial scale and specific habitat needs of functional guilds are unlikely to protect bee communities and the essential pollination services they provide to crops and wild plants. One sentence summary-Safeguarding wild bee communities requires 11.6-16.7% of the area in common North American landscapes to provide targeted habitat prescriptions for different functional guilds over a variety of spatial scales. Main text-Human-induced land-use changes are driving unprecedented widespread and increasing global biodiversity losses (1, 2). These alarming declines in biodiversity result in the degradation of many essential ecosystem services and functions (3, 4), including pollination. Indeed, wild bees and the pollination services they provide to crops and wild plants are experiencing global declines in response to intensive anthropogenic landscape changes, climate change, parasites and diseases, competition from invasive species, and rising agrochemical usage (5, 6). The Sustainable Development Agenda set globally agreed targets to end poverty, protect the planet, and ensure peace and prosperity for all by 2030 (7). However, less than a decade from this deadline little apparent progress has been made towards many of these key targets, including the need to 'ensure the conservation, restoration and sustainable use of terrestrial and inland freshwater ecosystems and their services' (Goal 15.1) (7). Efforts to slow, or even reverse global pollinator declines have led many countries to initiate conservation strategies in agricultural areas (8-10), urban environments (11), and other sensitive lands to mitigate the loss of vital pollinators and the ecosystem services they provide (5, 12). Selection and implementation of specific conservation strategies will strongly depend on conservation priorities and may differ substantially if the goal is to: (1) enhance pollination by pollinators visiting particular crops (13, 14), (2) maintain wider pollinator biodiversity (13) or (3) specifically target the recovery of pollinator species-at-risk (15). Most research to date has focused on adding and restoring pollinator habitat, typically by planting more abundant and diverse floral mixtures as food sources (16, 17), and by providing or enhancing nesting sites and suitable larval host plants (18). Evidence suggests these strategies can be highly effective at