Pollinator Ecology, Habitat Management, and Landscape Restoration on Federal and Private Lands in South-East Washington State

Holly Bowers

Shrub-steppe landscapes in the western U.S. have undergone extensive modification (e.g., ranching, farming, urbanization) and are subjected to many other ecosystem-changing forces (e.g., wild fires; invasive plants, grazing, diseases, climate change) that may influence pollinator ecology. Habitat loss and fragmentation (via fires, roads, and plant invasions) influence foraging success and population dynamics of many species of bees and other pollinators in regions of Palouse Prairie and shrub-steppe. We explored key environmental and land management policies and practices occurring on both public and private lands in south-eastern Washington with the goal of improving restoration strategies for pollinator habitats. We evaluated how the U.S. Department of Energy’s Hanford Site is currently implementing new Federal pollinator protection requirements in shrub-steppe landscapes. This policy and management analysis identified significant limitations in pollinator census and insect conservation and produced recommendations to resolve key issues and improve future pollinator conservation efforts. We also evaluated management practices on viticultural landscapes in the region as viticulture is a primary and growing agricultural land uses on private lands. Land conversion to vineyards adversely impacts pollinators by directly reducing native shrub-steppe, increasing habitat fragmentation, and by using pesticides harmful to pollinators. A case study of vineyards, including a comparison with viticultural practices in southern France, produced management recommendations to improve pollinator habitat in vineyards. Developing pollinator habitat in roadsides and infrastructure corridors, especially with milkweed species for Monarch butterflies (Danaus plexippus) is often recommended to reduce fragmentation of pollinator habitats while also increasing butterfly habitat. We studied use of 40 patches of showy milkweed (Asclepias speciosa) by Monarch butterflies in Palouse Prairie in 2016-17 and modeled ecological factors associated with caterpillar herbivory. These statistical models reveal ecological factors that may assist restoration strategies for milkweed, however, sporadic breeding events and seemingly degraded milkweed habitats in agricultural field borders and road ditches, suggest that Palouse Prairie may not be prime habitat for Monarch butterflies in the western U.S. We demonstrate that machine-learning statistical techniques have great utility to help explore and understand spatial and landscape ecology of pollinators and assist land managers interested in restoration ecology and conservation planning for pollinators.

Pollinator Ecology, Habitat Management, and Landscape Restoration on Federal and Private Lands in South-East Washington State

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