Bees, Bombs, and Burns: Disturbance and the Native Bee Communities of Military and Other Public Lands in Virginia

Abstract

Physical and ecological disturbances caused by military land use can create and maintain early successional habitats, which can support diverse communities of native plants and animals. These lands may serve as refugia, protecting rare, threatened, and endangered species that may have disappeared from surrounding areas, particularly those that need disturbance to survive on the landscape. This is especially true for invertebrates, who are often overlooked in management planning due to a lack of information on their natural history. In Chapter 2, we provide an introduction to topics covered in this dissertation, including ecological disturbance with an emphasis on fire, the disturbances and effects of military land usage, bee conservation, the effects of disturbance on bees, and an introduction to the Southern Plains Bumble Bee (Bombus fraternus Smith 1854) In Chapter 3, we conducted bee, plant, and habitat surveys on Marine Corps Base Quantico in Virginia, USA to determine how different combinations of disturbances generated by military land use would affect bee biodiversity. Disturbances that affected soil through exposure or soil compaction were most correlated with greater bee diversity but had negative impacts at higher levels of compaction. Fire frequency was only slightly correlated with bee diversity but had positive impacts on plant communities. In Chapter 4, we documented the collection of a Southern Plains Bumble Bee (B. fraternus) individual found at Marine Corps Base Quantico, as well as multiple specimens at Army Maneuver Training Center Fort Pickett. B. fraternus is an imperiled grassland bumblebee species that previously was known only from the southeastern region of Virginia. The species is thought to be in decline due to habitat loss/alteration, widespread pesticide use, and other factors affecting native bee populations. We also provided descriptions of the characteristics used to identify the specimens to assist other researchers. In Chapter 5, we modelled the potential range of B. fraternus in Virginia using MaxEnt predictive habitat modeling based on historic records as well as photographic records from recent years. The models indicated areas of potential habitat extending beyond the species historic range, specifically along transportation corridors, in some coastal refuges, and in areas near urban centers. We also determined that several bioclimate variables were noted as contributing significantly to two or more of the models, including Annual Mean Temperature, Isothermality, Temperature Seasonality, and Mean Temperature of the Warmest Quarter, as well as Annual Precipitation, Precipitation of the Driest Month, and Precipitation of the Wettest Quarter. More intensive surveys in patches of grassland or other open habitats within this region may be warranted to further refine our understanding of military land use and its impacts on invertebrate populations.