Chapter 4 Habitats
adapted to long periods of inundation. More large floods might mean increased river areas with increased instability of bars. This would come at the expense of forests along the river banks, which are often the least altered forests in the floodplains. If flood frequency increases, it might also cause the boundaries between bottomland hardwoods and cypress-gum swamp to shift. Effects on species composition are unknown, but changes to the overall community structure are likely, especially in lower reaches that may eventually convert to marsh. Sea Level Rise. Saltwater intrusion associated with sea level rise is expected to have significant adverse effects on lower reaches of blackwater floodplains where it is likely to affect long-term survivability of canopy species. Saltwater intrusion will affect long-term survivability of canopy species in the lower floodplain reaches. Wetlands close to the Cape Fear River near Wilmington and the lower portion of the Scuppernong River near Columbia have already been impacted. No expansion of this community type is possible upstream and expansion into the Piedmont is not possible for this ecosystem. Consequently, the net effect from climate change will be an overall loss of acreage. Because there is not substantial potential for the floodplain systems to expand inland, there will be a net loss in area. 4.3.4.4 Climate Change Compared to Other Threats Comparing climate change to other ecosystem threats can help define short- and long-term conservation actions and recommendations. While climate change is not the most severe threat, a combination of synergistic effects with other existing conditions could stress these systems to the point where several species are unable to persist. Changes in flood regimes and rising sea level are the most important climate effects. Most Coastal Plain wetland communities, including blackwater systems, may be moderately vulnerable to climate change, depending on importance of precipitation and riverine flooding for hydrologic inputs. Direct loss of wetlands due to sea level rise is expected to be the greatest threat in coastal landscapes (DeWan et al. 2010) . However, these systems will remain common. Table 4.3.4-1 summarizes the comparison of climate change with other existing threats.
Table 4.3.4-1 Comparison of climate change with other threats to blackwater floodplains.
Rank Order
Threat
Comments
Flood Regime Alteration
1
Effects of changed flooding regime are very uncertain. If floods become more extreme, channels may begin to migrate more. Levee communities, where present, are the forested floodplain community most likely to be affected by changes in flooding regime and channel stability. Increased canopy gaps may result from increased storm wind damage and from flood scouring. Logging will remain a large source of altered canopy age and structure. This might benefit species that depend on canopy openings.
Logging/Exploitation 1
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2025 NC Wildlife Action Plan
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