Prairies and Garry oak woodlands were once extensive in the lowlands of Washington and Oregon. Today, it is estimated that less than 3% of these areas still exist and many are severely degraded. The goal of the prairie monitoring project is to detect and describe changes in the extent and quality of prairie (herbaceous) communities in San Juan Island National Historical Park. The extent and distribution of prairies, oak woodlands, and forests are important attributes of the park's cultural landscape.