Last updated: November 29, 2024
Article
Species Inventory Helps Uncover the Rare Plants of San Juan Island National Historical Park
At San Juan Island National Historical Park, a recent species inventory is giving park managers the information they need to help safeguard rare plants within the park.
NPS
Charting New Ground
San Juan Island NHP protects an incredible array of natural wonders, from lush forests teeming with diverse flora to rocky shores alive with marine life. In 2010, the park acquired Mitchell Hill, a new tract of upland forest that adjoins the English Camp unit. Since this expansion, park managers have been working to identify important features and species to protect within the new properties.Twenty-seven rare plants can be found throughout San Juan Island County, but park managers didn’t know if they were present in the recently acquired areas. Park staff sought to gain a better understanding of the whereabouts and abundance of rare and sensitive plants to make informed plans to protect them. Conservation of rare species helps maintain their genetic diversity as well as preserving the unique ecological and cultural functions they serve. In response, the park arranged for a species inventory of rare and sensitive plants in the Mitchell Hill area through the Inventory & Monitoring Division.
NPS
Surprising Finds
While surveying Mitchell Hill in 2021 and 2022, researchers found three rare plant species: true baby stars (Leptosiphon minimus), Indian valley brodiaea (Brodiaea rosea), and shortspur white plectritis (Plectritis brachystemon). Indian valley brodiaea was an especially notable find, as this species had not been seen in Washington State in 113 years. Shortspur white plectritis had never been recorded on the San Juan Islands. These survey results indicate that the open Douglas fir woodland at Mitchell Hill provides vital habitat for numerous sensitive and rare plants. However, challenges such as understory encroachment by young trees and shrubs, deer overbrowsing, and the close proximity of rare plants to heavily trafficked paths remain concerns.
NPS
Informing Conservation Action
Park staff are eager to use this information to create management plans that will help protect the park’s treasured rare plant species. They will use the data to pinpoint sensitive areas to protect from tree and shrub encroachment and invasive plants by removing select small-diameter trees and shrubs and conducting targeted herbicide treatments. Information from the inventory is also being incorporated into a project with the Samish Indian Nation Department of Natural Resources to identify special areas with culturally significant plants.
Want to learn more? See the final products from this project!