Pollinator Abundance and Diversity under Differing Wet Prairie Management

Abstract

Pollinator species have seen recent declines in abundance, generating conservation concern as well as alarm about the ecosystem services they provide. A common approach to alleviate pollinator decline is through habitat management, including restoration of degraded habitats and removal of invasive species, but apparent habitat improvement does not necessarily mean an improvement in pollinator abundance and diversity. We collected pollinators in colored pan traps at three sites at the Lacamas Prairie Natural Area, Washington: remnant wet prairie, restored wet prairie, and an area invaded by reed canary grass (Phalaris arundinacea). We used model selection to assess whether site and trap color explained variation in pollinator abundance, richness, and diversity. Pollinator abundance was similar at the native and restored sites with predicted averages of 9.06 (7.15, 11.48) and 9.51 (7.52, 12.03), respectively while a heavily invaded reed canary grass site had a significantly lower predicted mean of 7.26 (5.69, 9.26). Site was not included in the top model for species richness or diversity. All three measures varied with trap color. Habitat restoration and invasive species control at Lacamas Prairie appear to have benefited local pollinator populations, but evidence for differences in pollinator richness and diversity was weak. Further work, both characterizing the response of pollinator communities to wet prairie restoration and optimizing trap colors for monitoring in this area, is warranted.