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LONG-TERM VEGETATION MONITORING ALONG THE ST. CROIX NATIONAL SCENIC RIVERWAY
Suzanne Sanders, National Park Service, Great Lakes Inventory and Monitoring Network
The Great Lakes Network of the National Park Service initiated a long-term vegetation monitoring program during summer 2007. Although this program will ultimately encompass nine national parks in the Great Lakes and surrounding region, we focused on three parks this summer, including the St. Croix National Scenic Riverway. The goals of the long-term monitoring program are two-fold. First, we want to detect and quantify forest change as it relates to environmental stressors. Specific interests include detecting change in individual species, plant communities, and community structure. Second, we want to provide natural resource managers with systematically collected evidence on which to base management decisions.
Thirty-five permanent plots were established in forests within the park along both the Namekagon River and the St. Croix River, north of Stillwater, Minnesota. The forest at each plot was sampled extensively, with a heavy emphasis on saplings and the herbaceous layer. Sampling included measuring the diameter at breast height (DBH) of all trees (≥ 2.5 cm DBH) in a 900 m2 area, shrub abundance in a 150 m2 area, and herbs and seedling presence in 30 1 m2 quadrats. In addition to plants, we also assessed coarse woody debris, deer browse, and tree disease.
Each of the nine parks within the long-term monitoring program will be resampled every five years. Analyses will ultimately focus on composite indicators such as basal area, richness, and diversity as well as indices of community structure and community composition, including native:non-native species ratio, floristic quality index, and tests of biotic homogenization. This was the first season of the sampling program and some modifications of methods will be made before sampling in 2008.