Chapter 4 Habitats
Land Use Impacts . Converting land use from natural forest to agriculture or silviculture production and residential and commercial development continues to threaten stream integrity because of the loss of riparian buffers and related increases in sediment, bank erosion, and stormwater runoff containing sediment and other potentially toxic materials. Erosion and the resultant sedimentation are the largest sources of nonpoint source pollution in this system. Livestock access to streams contributes heavily to bank erosion, sedimentation, and nutrient input. Timber harvests and poorly constructed and maintained timber roads are additional sources of erosion if proper controls are not used and maintained. An increase in impervious surfaces due to roads, parking lots, homes, and businesses increases the amount and speed of runoff being delivered into aquatic systems. Decreased groundwater recharge between storms due to impervious surfaces leads to a decrease in stream base flows. Runoff from urban areas often contains higher concentrations of nutrients (such as nitrogen and phosphorus), sediment, metals, hydrocarbons, and microbes. Nonnative and Invasive Species . Nonnative species invasion is a concern for all habitats and species assemblages. In aquatic habitats the Basket Clam (formerly Asian Clam) and the Rusty and Virile Crayfishes have been collected in both cool and coldwater streams. Basket Clam populations have become established throughout the state and in some instances are extremely abundant. These may have negative effects on native species, such as competition for space and resources. With increases in water temperature, some invasive species may move into habitats that were formerly too cold for their persistence. Invasive plants in the riparian area (such as Japanese Knotweed) can have negative impacts on stream systems by creating a monoculture with poor nutrient inputs, reducing bank stability, and allowing too much sunlight to infiltrate, resulting in warmer stream temperatures. Other invasive species, such as the exotic pest Hemlock Wooly Adelgid, may be a significant factor in coldwater stream communities because of the important role that hemlock plays in these riparian areas. If hemlocks are removed from the system, nutrient inputs and temperature regimes may be disrupted, which would in turn disrupt aquatic organism life cycles and cues. Clearing and Snagging . Clearing removes standing trees and riparian vegetation from streambanks and snagging removes woody debris (logjams, snags, mid-channel bars) from within streams. These measures are often taken to lower stream discharge volume and improve drainage, especially in urban areas. Direct effects are the physical alteration of the habitat while indirect effects include changes in fluvial processes (Cobb and Kaufman 1993) . Riparian vegetation is critical to the overall stream and streambank stability and moderation of water temperatures. Lack of riparian vegetation or inadequate forested buffer widths can cause streambank erosion and sedimentation. In addition to stabilizing streambanks, riparian vegetation serves as nutrient input to the stream community, filters pollutants, and helps regulate stream temperature by providing shade. Lack of sufficient vegetation cover
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2025 NC Wildlife Action Plan
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