Forested wetlands of low order streams in the inner coastal plain of North Carolina, USA

Abstract

We quantified geomorphic and vegetational characteristics of 22 first-to-fourth order riverine forests located in the inner coastal plain of North Carolina. We used Detrended Correspondence Analysis to compare canopy composition among sites and relate measured environmental parameters to distribution of canopy trees and stream order. Both geomorphic and vegetational attributes could be used to functionally divide first-to-fourth order riverine systems into 17 headwater (first and second order streams) and 5 midreach systems (third and fourth order streams). As expected, stream order was found to be positively correlated (P<0.003) with drainage basin size, floodplain width, and channel width. The canopy of headwater reaches was dominated by various combinations ofLiquidambar styraciflua, Nyssa biflora, andAcer rubrum, while midreach systems were typically dominated byTaxodium distichum and/orNyssa aquatica. Canopy composition was similar to other low order stream floodplains in the southeastern USA from Alabama to Maryland. However, the canopy composition of bottomlands differed in that the generaFraxinus, Quercus, andUlmus were generally less important in the North Carolina bottomlands than elsewhere in the Southeast. Metrics obtained from these relatively unaltered ecosystems could be used to develop standards for assessing of wetland condition and provide appropriate criteria for designing restoration of altered low order riverine ecosystems.