Agenda 03-19-24; 4-a - Eno-New Hope Landscape Conservation Plan Presentation

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36 Table 3. Criteria for identifying barrier roads and potential crossing locations for each habitat guild, slightly modified from criteria provided in Ernest and Sutherland(2017)based on biological/ecological information for the species included in this project. Barrier roads were identified from data on road characteristics and roadway structures(NCDOT 2019a)and traffic volume(NCDOT 2017).Potential crossing locations were identified from barrier road—stream intersections(USGS 2018)and bridge%ulvert/pipe structure locations(NCDOT 2019b). Habitat guild Barrier road characteristics Potential crossing locations Surface width>26 feet General wet-mesic hardwood forests Shoulder curb present Intersections between barrier (Four-toed salamander) Median barrier or curb present roads and streams Striped median present Traffic volume>2000 Surface width>26 feet Dry-wet hardwood and mixed forests Shoulder curb present Intersections between barrier (Eastern box turtle, salamanders) Median barrier or curb present roads and streams Striped median present Traffic volume>2000 Sparsely settled mixed habitats Speed limit>60 miles per hour Intersections between barrier (medium-sized mammals,snake) Median barrier present roads and streams Traffic volume> 10,000 Bridges over non-barrier roads Movement cost and distance. Cost distance thresholds and the costs for movement through suitable or unsuitable habitat were derived from NatureServe's concept of separation distance(NatureServe nd). For NCNHP mapping of known species occurrences,the distance between two or more occurrences and the quality of the intervening habitat(suitable or unsuitable) determines whether the occurrences are mapped as distinct populations or as connected sub-populations. These separation distances for suitable and unsuitable habitat are determined from knowledge of species' biology and ecology, including typical or maximum dispersal distances within and between areas of suitable habitat(Table 2). For each guild, separation distances for suitable and unsuitable habitat were derived from information for species or Element Groups in Biotics(NatureServe 2019c), supplemented by information from FEIS (Abrahamson nd). Where suitable or unsuitable separation distance differed for species or Element Groups within guilds,the more limiting(lower) distance was used. A guild's cost distance threshold was scaled to the unsuitable separation distance, so that each unit of distance traveled in unsuitable habitat represented a unit of cost toward the distance threshold for unsuitable habitat. The lower movement cost in suitable habitat was then calculated as the ratio of unsuitable to suitable separation distance, so that for the same cost distance threshold,the actual distance on the ground would equal the larger suitable separation distance. Cost surface and habitat patches.The cost surface for each guild was derived by first rasterizing(where necessary),reclassifying, and combining the following GIS layers into a single raster GIS layer: • habitat(EVT vegetation, floodplains,wetlands, and non-barrier roads) • barriers(EVT developed areas,building footprints, open water, and barrier roads) • potential wildlife crossing areas(barrier road—bridge/culvert/pipe intersections and barrier road—stream intersections) The combined raster layer was then reclassified so that barriers were removed, and each unique habitat class was assigned the guild's unit movement cost value for suitable or unsuitable habitat according to a reclassification table.Potential wildlife crossing areas were also assigned the movement cost value for unsuitable habitat. Discrete areas of suitable habitat above the threshold patch size were identified and extracted as a separate habitat patch layer(shown in Figure 10 overlaid on the cost surface). A Landscape Plan for Wildlife Habitat Connectivity 23