Vegetation survey and accuracy assessment of vegetation mapping at Fort Union National Monument, New Mexico

Esteban, Muldavin; Stevens, Joe; Chauvin, Yvonne; Bowder, Amanda; Neville, Terri; Seever, Kat; Talbot, Travis

The Fort Union National Monument (FOUN) is located on the western high plains of north central New Mexico and was an important military and civilian site in the development of the southwestern United States. The succession of three remote US Army Forts built at the site between 1851 and 1891 significantly impacted the natural vegetation of the site. At times the site was said to have been completely denuded by the intense human and livestock activity. A classification and map of the vegetation at FOUN were created in 2004 by ecologists with Natural Heritage New Mexico (NHNM) and published as Muldavin et al. (2004). An accuracy assessment (AA) of the FOUN vegetation map was conducted in 2009 by ecologists with the Colorado Natural Heritage Program (CNHP) and published internally as Stevens and Sever (2011). This document was compiled from those efforts by Joe Stevens and Travis Talbot, ecologists with CNHP, and includes both the vegetation inventory and the AA information reformatted to have a consistent flow and eliminate overlaps and duplications. The vegetation survey and detailed vegetation map for FOUN included the development of a comprehensive plant species list along with a classification of vegetation communities of the park based on the National Vegetation Classification System (Grossman et al. 1998). The legend for the map is based on a vegetation classification with modifications for special features of the monument. The map was developed using available digital ortho-photography and ground checking, and is designed for use at the 1:6,000 scale, with a minimum mapping unit of size 0.10 - 0.25 ha. The species list and map form the foundation of a baseline inventory of plant resources of the monument, and were developed in concert with the guidelines of the National Park Service's Inventory and Monitoring Program to aid in network-wide park natural resource management. A series of 8 plots and 19 observation points were established in homogeneous stands of vegetation and were used to classify the various plant associations found in the park. Plots were usually 400 m2 and square, with other sizes occasionally used to fit the structure of a community, especially along drainages where vegetation stands conform to the channel shape. A list of all vascular plant species and their aerial cover, stratified by life form (tree, shrub, subshrub, grass and forb layers) was compiled for each plot. In addition, several site attributes were recorded including slope percent, aspect, slope shape, surface rock type, and ground cover (percent rock, gravel, bare soil and litter), along with narratives on species composition and site conditions. Observation points were collected where only the dominants and their abundance were recorded. All plot locations were established with handheld Garmin GPS units. Accuracy is estimated to be +/- 10 m or less (see Data Addendum for examples of sampling forms and detailed survey methods). The classification included 18 associations, 6 of which are recognized within the US National Vegetation Classification system (USNVC) (an additional 8 are recognized by NHNM only and 4 are considered Park Specials). This report provides the AA of the vegetation map created in 2004.

Vegetation survey and accuracy assessment of vegetation mapping at Fort Union National Monument, New Mexico

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