Vegetation classification and mapping at Marsh-Billings-Rockefeller National Historical Park, Vermont

Vegetation classification and mapping of Marsh-Billings-Rockefeller National Historical Park followed established U.S. Geological Survey (USGS) - National Park Service (NPS) Vegetation Mapping Program protocols and was conducted under its umbrella agreement with NatureServe and its network of natural heritage programs. After a scoping session with park staff and field reconnaissance, we developed an initial vegetation classification for the park based on NatureServe’s U.S. National Vegetation Classification (USNVC), Lautzenheiser’s 2002 natural community map, Keeton’s 2003 forest data, and other existing information. Thirty vegetation plots were sampled in the summer of 2004, covering the range of variation in the vegetation. Plot sampling included information on vegetation structure and composition and individual species cover by vegetation stratum and environmental setting. Seven plots were entirely new, and 23 existing forest plots established by Keeton in 2003 were re-sampled for understory vegetation. Analysis of the plot data and field notes allowed us to finalize the vegetation classification for the park and to map the vegetation onto an orthorectified composite aerial photo background using on-screen digitizing in 2005. Sixty-three accuracy assessment points were collected in 2007 to verify the accuracy of the 2005 vegetation map. The overall 2005 map accuracy and Kappa index was 76%, which fell below the USGS/NPS vegetation mapping protocol requirement of 80%. Revisions were subsequently made to the 2005 vegetation map to increase the accuracy of the final product. The final 2007 vegetation map accuracy was 85.7% and Kappa index was 84.6%. Eighteen USNVC vegetation associations were described for Marsh-Billings-Rockefeller National Historical Park: eleven upland forest types (including five plantation types), two wetland forest types, one upland woodland type, two old-field forest types, one upland herbaceous (old-field) type, and one wetland herbaceous type. Two of the upland forest types were each mapped as two map classes: in one case, separating the mixed from conifer expression; in another case, separating a unique variant occurring on limestone. The one wetland herbaceous type is a very small patch wetland within an upland forest. Areas such as the artificial pond, buildings and grounds, and active hayfields that fall outside of the scope of USNVC associations were mapped as land-cover classes. Hemlock - Northern Hardwood Forest and Northern Hardwood Forest form the dominant vegetation cover at Marsh-Billings-Rockefeller National Historical Park. Many of the plantations that are important to the history of this park show signs of conversion to Northern Hardwood Forest in the absence of management. Plant species considered uncommon in Vermont were noted where they occurred on or near the vegetation plots, as were invasive plant species. Detailed descriptions of the local and global expressions of each vegetation association, a field key to the vegetation associations, a plant species list derived from the plot and accuracy assessment data collection, metadata for the vegetation plot data, and an index to association photographic documentation are included as appendixes.