Vegetation mapping inventory project: Minute Man National Historical Park, Massachusetts

Gawler, Susan; Zaremba, Robert; Cogan Technology, Inc.

Vegetation classification and mapping of Minute Man National Historical Park (MIMA) was conducted as a part of the National Park Service Vegetation Mapping Inventory (NPS-VMI) by NatureServe and the James W. Sewall Company. After a scoping session with park staff and field reconnaissance, a preliminary vegetation classification for the park based on the U.S. National Vegetation Classification (USNVC) and other existing information was developed. Thirty-nine vegetation classification plots were sampled in the summer of 2004. Plot sampling included information on vegetation structure, composition and individual species cover by vegetation stratum, and environmental setting. Quantitative analysis of the plot data, along with supplemental observations, defined the final vegetation classification for the park. Twenty-seven (27) USNVC vegetation associations were described for MIMA. The upland forests that characterize the area include three oak-dominated forest associations, a mixed pine - oak forest association, one northern hardwood forest association, and two early successional forest associations dominated by non-native tree species. Wetland forests include two floodplain forest associations and three red maple-dominated swamp associations. Upland herb-dominated areas were predominantly wooded pastures and old-field vegetation with one area of sandplain grassland. Shrub-herb wetlands included two fen associations, six herbaceous wet meadow or marsh associations (including two exotic-dominated associations), three shrub swamp associations, and one aquatic vegetation association. The Dry Oak - Hickory Forest and Red Oak - Red Maple Successional Forest are the matrix vegetation at MIMA. Forested wetlands and open marshes are regularly interspersed. Invasive species are common in both upland and wetland habitats. Natural and semi-natural vegetation patches are highly fragmented as a result of previous and ongoing land use, both within and outside MIMA. Remotely sensed mapping of the vegetation types was conducted using leaf-off (non-growing season) color infrared aerial photography and color orthophotos from the growing season. Stands representing classified vegetation associations were mapped onto acetate overlays of the aerial photos, orthorectified and converted to a Geographic Information System (GIS) polygon theme. The aerial photos were separately orthorectified into a Multiresolution Seamless Image Database (MrSID) file to aid interpretation of the vegetation map. Mapping to the association level was not always possible, and map classes representing aggregations of ecologically similar associations were created where necessary. Twenty (20) map classes were employed to represent the 27 USNVC vegetation associations and six Anderson Level II land use categories that represent cultural vegetation or non-vegetated land cover. One hundred nine accuracy assessment (AA) points were visited in the field in order to estimate the accuracy of the vegetation map. The overall map accuracy was estimated to be 67.5% at the level of the finest thematic resolution (20 map classes total) and estimated to be 85.9% when these map classes are aggregated to the thematic resolution levels of USNVC division for natural vegetation and of Anderson Level II for cultural vegetation (10 map classes total). Detailed descriptions of the local and global expressions of each vegetation association, a field key to the associations and map classes, a photointerpretation key to map classes, a plant species list, metadata for the vegetation map and the plot data, and an index to photographic documentation are included as appendixes. A geodatabase containing GIS data for the vegetation map and the spatial locations of plot and AA points, the digital orthophoto developed for MIMA, and a database containing information on vegetation classification plots and accuracy assessment observations are also products of this project.

Vegetation mapping inventory project: Minute Man National Historical Park, Massachusetts

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