Body-size-dependent effects of landscape-level resource energetics on pollinator abundance in woodland remnants

Land use change reduces floral resource availability, thereby driving
declines in important pollinators. However, the severity of land use
impact varies by species, influenced by factors such as dispersal ability
and resource specialization, both of which can correlate with body size.
Here we test whether floral resource availability in the surrounding
landscape (the ‘matrix’) influences bee species’ abundance in isolated
remnant woodlands, and whether this effect varies with body size. We
sampled quantitative flower-visitation networks within woodland remnants
and quantified floral energy resources (nectar and pollen calories)
available to each bee species both within woodland and the matrix. Bee
abundance in woodland increased with floral energy resources in the
surrounding matrix, with strongest effects on larger-bodied species. Our
findings suggest important but size-dependent effects of declining matrix
floral resources on the persistence of bees in remnant woodlands,
highlighting the need to incorporate landscape-level floral resources in
conservation planning for pollinators in threatened natural
habitats.