Vegetation Classification and Mapping of Morristown National Historical Park, New Jersey

Sneddon, Leslie; Zaremba, Robert; Largay, Ery; Podniesinski, Greg; Perles, Stephanie; Thompson, John

Vegetation classification and mapping of Morristown National Historical Park was conducted following U.S. Geological Survey/National Park Service (USGS/NPS) Vegetation Mapping Program protocols. After a scoping session with park staff and field reconnaissance, NatureServe developed an initial vegetation classification for the park based on NatureServe's U.S. National Vegetation Classification (USNVC) and other existing information. Twenty-two vegetation plots were sampled in the summer of 2003 and 2004, stratified across the vegetation types identified in the preliminary vegetation classification. Plot sampling included information on vegetation structure, composition, and individual species cover by vegetation stratum and on environmental setting. Quantitative analysis of the plot data, along with supplemental information, yielded fourteen vegetation associations within the park, thirteen of which were mapped. The unmapped association was small and limitations of the photography did not allow for its depiction on the map. Eleven of the fourteen associations are forested and three are herbaceous. The upland forests that characterize the area include two American beech (Fagus grandifolia) associations, a tuliptree (Liriodendron tulipifera) association, two different oak (Quercus spp.) associations, one modified successional forest association, one black locust (Robinia pseudoacacia) forest association, one Upland / Wetland Transitional Forest, and a forest formerly characterized by eastern hemlock (Tsuga canadensis) that is now dominated by oaks and hardwoods . Wetland forests include two red maple (Acer rubrum) swamp associations. Upland herb-dominated areas consist primarily of field vegetation. Wetland herbaceous associations include a skunk cabbage (Symplocarpus foetidus)-dominated community and smartweed (Polygonum spp.)-dominated impoundment. The most common forest types within the park are the Northern Piedmont Mesic Oak-Beech Forest and Successional Tuliptree Forest. Because these two forest types do not exhibit distinct signatures on aerial photography, and because they intergrade on the landscape, they are largely represented by one map class that covers 81.6% of the park. Areas of heavy land use that were not classified using the USNVC were mapped as Anderson Level II (modified) land cover classes (Anderson et al. 1976). These categories are orchard / plantation; pond / reservoir; commercial and services; and transportation, communications, and utilities. A thematic accuracy assessment was completed in August 2005. Seventy-three accuracy assessment sampling points were placed in a stratified random scheme throughout the park, resulting in an overall accuracy of 74.0%. Overall accuracy is calculated by dividing the number of correctly identified points by the total number of points. The USGS/NPS VMP standard is 80% accuracy, so total percent accuracy is somewhat lower. Accuracy of the map increases to 82% if classes are changed such that Black Locust Successional Forest and Northeastern Modified Successional Forest are combined with Northern Piedmont Mesic Oak-Beech Forest and Successional Tuliptree Forest. However, the combined map class results in a greater loss of information to the user than the does the smaller benefit gained in accuracy. One wetland forest type of note is the Montane Basic Seepage Swamp that is located in a drainage between Soldiers Hut and Aqueduct Trails and ranked G3 by NatureServe. A G3 rank is defined as “globally rare or uncommon, with generally 21–100 occurrences and either very rare and local throughout its range or found locally, even abundantly, within a restricted range or xiv vulnerable to elimination throughout its range due to specific factor(s).