Safeguarding pollinators requires specific habitat prescriptions and substantially more land area than suggested by current policy

Abstract

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 insect pollinators remains unknown. Here we use comprehensive pan trap bee survey datasets from Ontario, Canada, to determine which habitat types are needed and at what spatial scales to support wild bee communities. Safeguarding wild bee communities in a Canadian landscape requires 11.6–16.7% land-cover from a diverse range of habitats (~ 2.6–3.7 times current policy guidelines) to provide targeted habitat prescriptions for different functional guilds over a variety of spatial scales, irrespective of whether conservation aims are enhancing bee species richness or abundance. Sensitive and declining habitats, like tallgrass woodlands and wetlands, were important predictors of bee biodiversity. Conservation strategies that under-estimate 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 both crops and wild plants.

Dominance of non-wetland-dependent pollinators in a plant community in a small natural wetland in Shimane, Japan

“…Therefore, many of the pollinators in their study site could be wetland species that develop in wetlands and paddy fields, whereas many of the pollinators in Akana Wetland may originate from the surrounding environment. Pindar and Raine ( 2023 ) reported that wetland are important foraging habitats for bumblebees. Stephenson et al ( 2018 ) also reported that wetland-dependent bees were less abundant in small wetlands based on a multi-site pan trap survey.…”

“…Studies on wetland pollinators have often been focusing on bees and wasps (e.g. Bartholomew and Prowell 2006 ; Hall and Ascher 2010 ; Moroń et al 2008 ; Pascarella et al 2000 ; Pindar and Raine 2023 ; Purvis et al 2020 ; Stephenson et al 2018 ; Vickruck et al 2019 ), and studies covering pollinator communities of multiple taxa are still limited (but Kato and Miura 1996 ; Mahoro et al 2008 ; Negoro 2004 ; Nkurikiyimana et al 2023 ). However, the previous studies on pollinator communities indicate that flies often dominate as pollinators in wetlands (Kato and Miura 1996 ; Mahoro et al 2008 ), unlike in forests and grasslands where bees are more prevalent (Shinjo et al 2014 ).…”