Understanding A Mutualistic Relationship
There is strong evidence that Taylor’s checkerspot butterfly (TCB) population numbers are dramatically declining across many sites, particularly in the center of its range. While this decline may be due in part to direct impacts of extreme weather events (extended spring-summer drought, late winter freeze events, the 2021 ‘heat dome’, etc.), it is also hypothesized that decreases in oviposition and larval host plant abundance in occupied sites are contributing factors.
Very little information exists around the microsite conditions needed to support the primary host plant species throughout the different life stages of the butterfly. With the projected increase in the frequency of extreme weather events, including extensive and intensive spring-summer droughts throughout the PNW, it is imperative to understand the conditions that support climate-resilient populations of Taylor’s checkerspot host plants to meet recovery goals for this endangered butterfly species. In addition to identifying and creating supportive microsite conditions, we also need to select the genetics that will thrive in the range of conditions expected in the future. Testing seeds sourced from different local and regional sites will provide the information needed to create resilient populations of host plants in the future.
Our Objectives
1) identify the microsite conditions that promote TCB host plant (P. lanceolata and Castilleja sp.) patch persistence and density that meet TCB oviposition habitat requirements,
2) evaluate the effects of microsite conditions on the phenology of Castilleja sp. and P. lanceolata that maximize both pre- and post-diapause larval food resources,
3) evaluate the effects of seed provenance on P. lanceolata establishment, growth and reproduction within different microsites, and
4) communicate project progress and outcomes to local and regional partners, military personnel, researchers and practitioners through reports, regional and national conferences, and peer-reviewed publications.
To actualize these objectives, we are collaborating with Institute for Applied Ecology and Pacific Rim Institute to monitor soil moisture, temperature, and phenology of host plants on long-term plots in identified microsites, and conduct a common garden trial crossing seed source by microsite.
Activities are being conducted at three sites occupied by host plants (and in some cases, TCB) in each of three regions that span the U.S. distribution of TCB (9 sites total): the North Puget Sound, South Puget Sound (including on JBLM) in Washington, and the Willamette Valley in Oregon.