A vegetation classification and map: Pecos National Historical Park

Muldavin, Esteban; Chauvin, Yvonne; Neville, Paul; Neville, Teri; Arnold, Lisa; Arbetan, Paul; Fettes, Anthony

A vegetation classification and high-resolution vegetation map were developed for Pecos National Historical Park, New Mexico as part of the U.S. Geological Survey (USGS)-National Park Service (NPS) National Vegetation Mapping Program. The monument is located in the foothills of the Sangre de Cristo Mountains in north-central New Mexico (between Santa Fe and Las Vegas). At 2,423 ha (5,988 ac) in size, the park is known for its rich tapestry of historical Native American, Spanish, and Anglo-American cultural legacies set against a backdrop of rolling plains, mesas, mountain foothills, and stream and river valleys. In this complex landscape, we find Douglas-fir and ponderosa pine forests at the higher elevations and northern aspects of the foothill canyons and ridges, pinyon-juniper woodlands extending down the south-facing slopes, and plains and mesas at the mid elevations. Intermixed among the woodlands are extensive grasslands dominated by blue grama-dominated grasslands. Much of this grassland was created and maintained by clearing ponderosa pine and pinyon-juniper woodlands in modern times. Along the stream and river courses, narrowleaf cottonwood forests and coyote willow shrublands are found, as well as small patches of herbaceous wetlands. The riparian zone of the Pecos River within the park is one of the finest examples found in northern New Mexico. We formally described this vegetation pattern following the National Vegetation Classification Standard (NVCS) and identified 46 plant associations among 13 NVC groups based on 223 field plots. The vegetation classification was used in turn to define a suite of vegetation map units. The vegetation map was developed using a combination of automated digital processing (supervised classifications and image segmentation) and direct image interpretation of 2005 high-resolution, color, aerial ortho-photography in combination with 2006 DigitalGlobe QuickBird satellite imagery. The map was designed to facilitate ecologically based natural resources management at a 1:12,000 scale with a 0.25-ha minimum map unit size. The map legend was hierarchically structured with an upper Level 1 of 10 map units; eight of these correspond to the Group Level NVCS and two are miscellaneous land-cover classes. Level 2 is a further refinement composed of 24 nested map units defined by specific plant associations in the vegetation classification that reflect variations in plant community structure as well as species composition within the broader Level 1units. Overall accuracy at Level 1 was estimated at 95.3% and 80.5% at Level 2 based on 339 independent field samples. For many natural resource management applications, Level 1 units will likely be sufficient and most appropriate, while Level 2 units provide added fine-scale information within major ecological groups. To support the map as a management tool, an annotated map legend is provided along with descriptions of each plant association, a corresponding diagnostic key, field forms, and a plant species list. The map was delivered in both hard copy and digital form as part of a geographic information system (GIS) compatible with that used in the park and the USGS-NPS mapping program. The GIS allows flexibility to update the map as new information becomes available or as major vegetation changes, such as fire, disease or other impacts, occur in the park.

A vegetation classification and map: Pecos National Historical Park

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