Managing Xeric Habitats for Native Bees, Moths, and other Species of Greatest Conservation Need

The Northeast Xeric Habitats for Pollinators project involved 20 sites from Maryland to Maine in a joint effort to measure the response of vegetation and bee communities to different habitat treatments. Bee and moth communities were also surveyed to correlate diversity and community composition with site conditions and characteristics. Although xeric sites in the region differ due to environmental factors, all sites share the habitat objective of maintaining lower percent cover of woody plants than most habitats in the northeast. A high-quality xeric habitat in the northeast U.S. typically has well-drained soils and fire-adapted vegetation with open tree canopies, abundant floral resources, and patches of bare soil. Depending on the vegetation, these habitats are referred to as sandplains, barrens, woodlands, and grasslands.

Based on the contributed information from all 20 sites, 279 plant species were identified, 262 species of bees and 1447 species of moths were collected, and we learned several important things about xeric habitats in the Northeastern U.S.:

  1. Even among sites that are self-described barrens or woodlands, environmental characteristics were important determinates of vegetation community and structure, and bee and moth communities.
  2. Habitat management is effective at restoring and/or maintaining the rare obligate species that were the target of this study. Management treatments including canopy thinning, mowing, and fire resulted in decreases in total, tree, shrub, and woody vegetation and increases in early successional flowering plants, pollinator host plant taxa, and overall plant diversity.
  3. Bees and Moths were more diverse in colder, drier sites, but moths were more diverse at sites with higher % cover, while bees were more diverse at sites that were managed for more open conditions.
  4. Bees and moths showed a slight increase in species diversity during the timeframe of this project. Reflecting longer term benefits, sites with a history of habitat management and objectives that align with maintaining quality barrens conditions had higher plant and bee species diversity and management was successful in increasing the abundance of plants that are known to be important to pollinators. In contrast long-term management was associated with lower moth richness and abundance.
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