This data package contains North Coast and Cascades Network (NCCN) Inventory and Monitoring Program prairie vegetation monitoring tabular data collected during 2007-2017 at the American Camp Unit of San Juan Island National Historical Park (SAJH).

The protocol, publications, and all other associated links can be found in the NCCN Monitoring Prairie Vegetation project reference at: https://irma.nps.gov/DataStore/Reference/Profile/2193720

San Juan Island National Historical Park protects some of the last remaining prairies in Washington state. Over 60% of the American Camp unit is dominated by grasslands that have persisted since the end of the Pleistocene. In 2007, the National Park Service initiated monitoring to document status and trends in cover and ecological condition of vegetation communities using repeatable, rapid assessment of physiognomic class and vegetation quality along line-intercept belt transects.

Transect-based sampling was designed to address a hierarchy of monitoring questions linked to management objectives, including the maintenance of the vegetation structure (e.g., forest versus herbaceous) associated with the cultural landscape and the continued ecological integrity of plant communities. The ecological condition of prairies is threatened by persistent, introduced grasses and exotic shrubs. Monitoring objectives included: 1) detect change in the extent of physiognomic cover types, 2) detect change in the proportion of areas dominated by exotic plant species, 3) detect change in the quality of herbaceous cover types, and 4) detect changes in composition and diversity of herbaceous cover types. Monitoring was implemented at the American Camp unit of SAJH, since 90% of all prairies are located within this section of the park. Transects proved to be an economical and reliable method for monitoring long-term trends in landscape cover with transient crews, but detailed vegetation monitoring (i.e., species frequency and relative abundance) is needed to better assess prairie condition over time.

Data within this package include point sampling locations, sampling effort and conditions, transect vegetation structure data, and phenological observations. The associated spatial transect lines and segments can be found at https://irma.nps.gov/DataStore/Reference/Profile/2305031.