Chapter 5 Threats
5.9 Natural System Modifications
Threats are from actions that convert or degrade habitat in service of “managing” natural or semi-natural systems, often to improve human welfare. This category includes suppression or increase in fire frequency and/or intensity outside natural range or variation; changing water flow patterns either deliberately or as a result of other activities; and other activities intended to ‘manage’ natural systems to benefit human welfare (Salafsky et al. 2008) . 5.9.1 Anticipated Impacts When development and land-use patterns do not take the needs of wildlife into consideration, the result is a landscape with fragmented and degraded habitats that are unable to support populations of sensitive species (NCWRC 2012) . Habitat degradation and fragmentation are landscape-scale processes in which patches of suitable habitat become smaller and more widely separated by a more or less unsuitable matrix (Stockwell et al. 2003) . Fragmentation affects all natural areas, especially forests, and it poses increasing problems for major freshwater systems (MEA 2005) . Loss of biodiversity can result when natural communities are degraded or fragmented and can lead to populations that are more susceptible to inbreeding, genetic erosion, and problematic population trends (Clark et al. 2010) . Furthermore, prescribed burning as a management tool is more difficult in fragmented areas due to difficulty with smoke management and liability issues. Destruction and degradation of habitat are widely cited as the greatest threats to aquatic species in the United States (Angermeier 1995; Warren et al. 1997; Williams et al. 1993) . Physical alterations such as channelization and dredging, aquifer depletion, impoundment and dam construction, and flow modification have contributed directly to the decline of aquatic species in the South (Walsh et al. 1995; Etnier 1997) . Increases in impervious surfaces, and subsequently stormwater flows, have caused changes in sediment transport and stream energy, which have led to limitations in the amount of suitable aquatic habitat and streambed material, especially near urban areas. The Nature Conservancy (TNC 2000; Smith et al. 2002) and NatureServe (TNC and NatureServe 2001) identify altered surface hydrology (i.e., flood control and hydroelectric dams, interbasin transfers of water, drainage ditches, breached levees, artificial levees, dredged inlets and river channels) and a receding water table as among the most significant sources of biological and ecological stress, especially in the Coastal Plain. Habitat fragmentation limits movement and gene flow of area-sensitive species and can isolate species with small home ranges, which makes populations more vulnerable to disturbance, disease, disruption to gene flow between populations, and depredation. Increased amounts of road surfaces and transportation-related projects have impacted populations and natural communities in ecologically sensitive areas. Roads can separate breeding locations and provide substantial barriers to seasonal animal migration pathways. Increased human development
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2025 NC Wildlife Action Plan
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