Rare Plant Inventory at San Juan Island National Historical Park - Open Format Dataset

The aim of this project is to obtain information on rare plant species of interest in two tracts of land that were recently acquired on San Juan Island, WA by the National Park Service. This information will be used to inform a vegetation management plan that will be developed for the San Juan National Historical Park. The tracts of land that are to be investigated are Mitchell and Westcott Bay in the English Camp unit. Due to the size of the two parcels and time constraints, this project did not include formal sampling methods such as transects or grids. Instead, the focus of the surveying was on specific vegetation types with the understanding that certain species may be found in specific vegetation types. Vegetation polygons were then searched via “focused intuitive control.” We used the current trail network as our sampling path, surveying more intensely in areas where rare species are more likely and briefly surveying unlikely habitats. We also focused on the trail networks because the most likely visitor impacts are along trails and where most vegetation management will likely occur. Out of the targeted list of twenty-seven species, we found three rare plant species in the Mitchell Hill unit: true baby stars (Leptosiphon minimus), Indian valley brodiaea (Brodiaea rosea), and shortspur white plectritis (Plectritis brachystemon). We did not observe any rare vascular plant species of conservation concern on the Westcott Parcel, and most the property has extensive evidence of prior human use and habitat alteration.