Global losses in biodiversity highlight the diverse and often dependent connections between species. The conservation of endangered plants must also consider management of associated plant and arthropod communities, including pollinators, that facilitate sexual reproduction. We conducted targeted pollination studies on Willamette daisy (Erigeron decumbens), a perennial endangered forb endemic to western Oregon. We tested for pollen limitation through pollen supplementation at seven sites across four years (2019–2022) and patch-level conspecific floral density-dependence of seed set at five sites in 2022. We also conducted timed observations of floral visitors to daisies at nine sites to document the potential pollinator fauna. We found that pollen supplementation increased seed set 30% overall but varied in magnitude across sites and years. Seed set generally increased with higher floral density. Insect communities were diverse (>140 taxa) and also differed substantially across sites and years. Management of prairie ecosystems to benefit pollinators will likely have positive effects on the long-term viability of Willamette daisy. In turn, conservation introductions of Willamette daisy may benefit from planting in dense patches to attract pollinators.
Cascadia Prairie-Oak Partnership
Providing coordination for the technical prairie community in the Willamette Valley, Puget Trough, Georgia Basin (WPG) ecoregion and beyond.