Reclaimed mined lands can persist as grasslands in a state of arrested succession. These open habitats can provide rich floral resources for bees. Nevertheless, poor soil quality prevents the growth of trees and shrubs. This paucity woody plants of may limit the suitability of reclaimed mine habitat for bee species that nest in wood. I investigated the importance of ecological and landscape factors in influencing the richness and abundance of wild bees on reclaimed mine land and whether the addition of artificial domiciles positively affected the populations of bees that use them. Over five years, I surveyed wild bees, flowers, and nesting substrates in 24 sites separated from each other by at least 1 km on a > 4000 ha reclaimed mine site in southcentral Ohio, USA. I also provided artificial domiciles for twig-nesting bee species in the family Megachilidae. Using general linear mixed models, I tested for effects of woody nesting substrate abundance and richness, bare soil, floral resource abundance and richness, and distance to the nearest forest on the abundance and richness netted wild bees and the number of nests and offspring produced by bees nesting in artificial domiciles.
Results/Conclusions
Bee richness on the reclaimed mine sites (range 0–9) increased with nesting substrate richness, flower richness, and their interaction (p<0.01), increasing with natural nesting substrate richness, except at the highest floral richness sites (10–15 species). High floral richness could attract bee species not nesting locally. Bee abundance (range 1– 57.5) increased with richness of nesting substrate, but not floral variables. The total number of nests in artificial domiciles (range 0–179) increased with the abundance of legume flowers, but not other floral or nest substrate variables. The total number of brood cells within artificial domiciles (range 1–2068) increased with legume flower abundance, but not total floral abundance. The number of bees nesting within artificial domiciles increased over the five year period, but was dominated by a non-native species. These results suggest the dual role flowers and nesting resources in limiting bee populations on reclaimed mined land. Restoration of reclaimed mines with native flowers may benefit some bee species, but may provide only partial habitat for others. Attention to nesting substrate could enhance habitat for bees. These results caution against using artificial domiciles that promote non-native over native bee species, and thus may not benefit bee diversity.