Reclamation of former mine lands in Appalachia creates persistent pockets of grassland habitat nested within forested landscapes. These patches of open habitat may act as resource islands for local plants and wildlife. In particular, reclamations may provide critical foraging habitat for native bee conservation, and thereby contribute to the stability of pollination services. In this study I determined: (1) how resources for bees change over time following reclamation of surface mines to grassland habitat; (2) the extent to which differences in resources, surrounding landscape, and other site attributes influence bumble bee nest success; and (3) which flower species in reclamations and adjacent habitats provide valuable pollen resources to bees. In summer 2014 I monitored productivity (nest size, number of workers), fitness (number of males and queens produced), and pollen resource use of 24 commercially-reared bumble bee colonies on 12 reclaimed surface mines. Sites were classified into four categories representing ecological age post-reclamation: (1) 0 -10 years post-reclamation, (2) 11-20 years, (3) >20 years, but mowed for hay, and (4) >20 years and undisturbed. Once every three weeks, I collected pollen loads from returning foragers at each nest site and performed surveys of floral diversity and abundance.
Results/Conclusions
19 colonies survived the duration of the study (mid-May to early August). Nest fitness from male and queen production varied greatly by colony, regardless of site age and resources. Multiple linear regression models that included both Shannon diversity of floral resources on the reclamation habitat and landscape heterogeneity within 2km of sites were significant predictors of total colony weight (which included males, queens, workers, and other nest material; p<0.001) and number of new queens produced (p=0.009). Queen production was also strongly correlated with floral evenness (p=0.020) and the diversity of pollen collected by the colony (p=0.001). Species composition of both floral communities and bee pollen loads clustered significantly by time of season on NMDS ordination plots. Although floral community composition was significantly influenced by site age class, it did not translate to differences in bee pollen use by age of site. However, composition of pollen used by bees differed among sites (p=0.002).
Reclamations complemented resources offered by adjacent natural habitats; bees utilized a mix of pollen plants from both habitats. Tracking which wildflowers bees rely on in mine-impacted landscapes will allow us to recommend to reclamation project managers practices that encourage native pollinators.