Reclamation of abandoned coal mines facilitates the process of succession on post-industrial barren lands, but ecological recovery depends on colonization by local plants and wildlife, as well as re-establishment of key ecosystem services like pollination. Reclaimed mines are a major component of the landscape in the Appalachian region of the eastern United States. If they support diverse pollinator and plant communities, they may serve as valuable conservation habitat. Bees are highly mobile and important pollinators that likely respond rapidly to changes in the quality and distribution of foraging habitat. Therefore, co-colonization by wildflowers and their bee pollinators is a useful biological measure of habitat quality, and can be used to assess ecological recovery on grassland-reclaimed former mines. In this study, I measured diversity, abundance, species composition, and structure of plant-pollinator interaction networks on a chronosequence of 10 reclaimed coal mines (2015-2016), as well as three managed wildflower meadows in nearby parks (2016). My objective was to evaluate the success of reclamation at promoting the recovery of plant-pollinator interactions.
Results/Conclusions
Former mines 3 - 30+ years post-reclamation had recovered basic bee communities representative of the regional bee fauna. Bee diversity did not increase in a linear fashion with time since reclamation, and rarer taxa (including nest parasite bees) were as often found on young sites as old. However, plant-pollinator interaction networks were more structured and robust on older sites, suggesting that they may support more stable pollination services. Mines reclaimed >20 years ago were comparable to recently planted park meadows in diversity and community composition on a per sample basis. Sites supplemented with native wildflowers attracted a greater diversity of bees than those planted with the standard reclamation seed mix, even though 44% of all bee visits across all sites were to two non-native species, Trifolium spp. and Lotus corniculatus. These two species, along with other non-natives legumes (Melilotus) and key native forbs (Pycnanthemum, Vernonia, and Asclepias), were highly centralized in plant-pollinator networks. Bee community re-assembly on reclaimed mines was likely driven by a combination of random colonization and the quality of flower resources. Therefore, we recommend that land managers include native bee-friendly wildflower species in the reclamation process to expedite recovery.