Vegetation classification and mapping project: Niobrara National Scenic River

Baldvins, Tom; Ley, Matt; Stevens, Joe; Jones, David; Shepler, Hannah

The vegetation inventory project at Niobrara National Scenic River (NIOB) classified and mapped vegetation within the park administrative boundary and estimated thematic map accuracy quantitatively. The project was conducted over a four year period from the summer of 2015 to the winter of 2019. Located in north-central Nebraska, approximately 76 miles of the park is designated as a wild and scenic river. The vast majority of land within the NIOB administrative boundary is private or state-owned. The project follows guidance provided by the National Park Service (NPS) Vegetation Mapping Inventory (VMI) Program. The overall process includes initial planning and scoping, imagery procurement, field data collection, data analysis, imagery interpretation and classification, and accuracy assessment (AA). The initial planning and scoping meetings to develop the study plan took place in December 2009 in Valentine, Nebraska, and included representation by Niobrara National Scenic River (NIOB), NPS Northern Great Plains Network, Colorado State University, and other interested agencies and organizations. New imagery was acquired for the NIOB mapping project in early October 2015. This imagery was delivered as 30 cm 4-band (RGB and CIR) high-resolution orthoimages. Additional imagery supplementing the interpretation phase included current and historic true-color Google Earth and Bing Maps imagery. Prior to field work, the preliminary classification of the vegetation associations included 82 United States National Vegetation Classification (USNVC) associations; 36 were known to occur in the project area while the other 46 associations were potentially located in the area. Existing vegetation and mapping data combined with field-collected vegetation plot data contributed to the final vegetation classification. Vegetation data collections by field crews at 156 NIOB subjective plot locations over the summer of 2015 supported vegetation classification using hierarchical clustering and professional expertise. Other types were identified in the course of additional field work and photointerpretation reconnaissance. The final vegetation classification includes 46 USNVC associations and 13 park special types. Types include 24 forest and woodland types, 8 shrubland types, 21 herbaceous types, and 6 sparse vegetation types. The final mapping classification, which cross walks vegetation type(s) present with what can be consistently classified and mapped (i.e., interpreted), consists of 35 map classes within NIOB. Of these 35 map classes, 6 represent land use cover classes (cultivated crops, pasture/hay ground, non-vegetated barren land or borrow pit, developed open space, developed low, medium, or high intensity, and water). Of the 29 non-land use map classes, 17 map classes represent a single USNVC association or park special, five map classes represent two USNVC associations or park specials, three map classes represent three USNVC associations or park specials, two map classes represent four USNVC associations or park specials, one map class represents six USNVC associations or park specials, and one map class represents nine USNVC associations or park specials. Species dominating in forest and woodland types include eastern redcedar (Juniperus virginiana), bur oak (Quercus macrocarpa), green ash (Fraxinus pennsylvanica), hophornbeam (Ostrya virginiana), Virginia wildrye (Elymus virginicus), and Kentucky bluegrass (Poa pratensis). Dominant species in shrubland types found in NIOB are false indigo bush (Amorpha fruticosa), Kentucky bluegrass (Poa pratensis), cuman ragweed (Ambrosia psilostachya), eastern redcedar (Juniperus virginiana), and smooth sumac (Rhus glabra). Other, less extensive shrubland types are dominated by western snowberry (Symphoricarpos occidentalis). The most common species within herbaceous types include cuman ragweed (Ambrosia psilostachya), Heller’s rosette grass (Dichanthelium oligosanthes), little bluestem ...

Vegetation classification and mapping project: Niobrara National Scenic River

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