2.4 Uncertainty of Future Conditions
properties and condition characteristics to evaluate their degree of resilience or vulnerabil- ity. Resilient stream and river systems are those that have the greatest potential to continue supporting biodiversity into the future despite potentially severe, and often unpredictable, impacts from climate change (Benner et al. 2014). A resilient network is a structurally intact geophysical setting that sustains a diversity of species and natural communities, maintains basic relationships among ecological features and key ecological processes, and allows for adaptive change in composition and structure (Anderson et al. 2012; Benner et al. 2014) . Te World Wildlife Fund (WWF) conducted a conservation assessment of freshwater ecore- gions of North America (Abell et al . 2000) . TNC also assessed small-scale watersheds across the country (Aldrich et al. 1998) and subsequently identifed priority areas within four freshwater ecoregions in the Southeast (Smith et al.2002) . All three eforts identify the Southeast as a key region for freshwater conservation eforts. Many of the critical areas identifed in those eforts overlap North Carolina’s borders: • Te entire South Atlantic freshwater ecoregion (southern Virginia through central Georgia) was identifed by Abell et al. (2000) as a key region in which to focus aquatic conservation eforts in North America; • Of the 327 key small watershed areas Aldrich et al. (1998) identifed across the country, 21 are found in North Carolina; • Smith et al. (2002) identifed 70 sites for priority freshwater conservation in North Carolina (14 in the Tennessee-Cumberland Aquatic Region, 56 in the South Atlantic Aquatic Region). 2.4 Uncertainty of Future Conditions Urban growth probability (as percent change) for the year 2020 to 2050 was projected by means of the Slope, Land use, Excluded, Urban, Transportation and Hillshade (SLEUTH) model, which uses cellular automata, terrain mapping, and land cover change modeling to address urban growth (Jantz et al. 2009; Project Gigapolis 2011 ). Te SLEUTH model incorpo- rates fve parameters (Dispersion, Breed, Spread, Slope, and Road Gravity) into the growth rules that project future urbanization. Te model simulates not only outward growth of existing urban areas but also growth along transportation corridors and new centers of urbanization. Figures 2.4 and 2.5 incorporate four growth rules (Spontaneous Growth, New Spreading Centers, Edge Growth, and Road-Infuenced Growth) to model the predicted rate and pattern of urbanization. Figure 2.4 depicts the change based on 12-digit Hydrologic Unit Code (HUC) boundaries (see Chapter 4.5.1 for more information on HUCs).
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2015 NC Wildlife Action Plan
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