Linking stream and landscape trajectories in the southern Appalachians

Abstract

A proactive sampling strategy was designed and implemented in 2000 to document changes in streams whose catchment land uses were predicted to change over the next two decades due to increased building density. Diatoms, macroinvertebrates, fishes, suspended sediment, dissolved solids, and bed composition were measured at two reference sites and six sites where a socioeconomic model suggested new building construction would influence stream ecosystems in the future; we label these "hazard sites." The six hazard sites were located in catchments with forested and agricultural land use histories. Diatoms were species-poor at reference sites, where riparian forest cover was significantly higher than all other sites. Cluster analysis, Wishart's distance function, non-metric multidimensional scaling, indicator species analysis, and t-tests show that macroinvertebrate assemblages, fish assemblages, in situ physical measures, and catchment land use and land cover were different between streams whose catchments were mostly forested, relative to those with agricultural land use histories and varying levels of current and predicted development. Comparing initial results with other regional studies, we predict homogenization of fauna with increased nutrient inputs and sediment associated with agricultural sites where more intense building activities are occurring. Based on statistical separability of sampled sites, catchment classes were identified and mapped throughout an 8,600 km(2) region in western North Carolina's Blue Ridge physiographic province. The classification is a generalized representation of two ongoing trajectories of land use change that we suggest will support streams with diverging biota and physical conditions over the next two decades.

Urbanization Effects on Watershed Hydrology and In-Stream Processes in the Southern United States

“…For example, in the Blue Ridge Mountains of western NC, urban streams had a 3 º C greater late summer diurnal temperature range than forested streams [92]. In the southern U.S., where lowland streams are generally warm water ecosystems, increased stream temperatures could lead to an increased frequency of hypoxic or anoxic conditions during summer months.…”

Decline of a giant salamander assessed with historical records, environmental DNA and multi‐scale habitat data

“…Rivers and streams are negatively impacted by direct alteration (e.g. Deforestation and conversion of riparian zones to agricultural and urban land cover cause dramatic modifications in stream biogeochemistry, thermal regimes, hydrodynamics, and microhabitat structure due to changes in the quality and quantity of allochthonous inputs (Foster et al, 2003;Gardiner et al, 2009;Smucker et al, 2015). Deforestation and conversion of riparian zones to agricultural and urban land cover cause dramatic modifications in stream biogeochemistry, thermal regimes, hydrodynamics, and microhabitat structure due to changes in the quality and quantity of allochthonous inputs (Foster et al, 2003;Gardiner et al, 2009;Smucker et al, 2015).…”

Legacies of stream channel modification revealed using General Land Office surveys,with implications for water temperature and aquatic life

“…Tropical and subtropical rivers have experienced intense localized impacts from human settlement over several decades (Webb, 1992), with more ominous threats looming from increased interest in building large dams (Bergkamp et al, 2000; White et al, 2012). Perhaps because of a longer period of human settlement as compared to the U.S. West coupled with extensive historical documentation, land use legacies in the U.S. have been broadly implicated in degradation of streams and rivers east of the Continental Divide (Harding et al, 1998;Scott, 2006; Wenger et al, 2008;Gardiner et al, 2009; Walter and Merritss, 2008; Maloney and Weller, 2011;Einheuser et al, 2013). Land use impacts in watersheds of the U.S. West are also pervasive (McIntosh et al, 1994;Robbins and Wolf, 1994;Wallin et al, 1994), yet legacies have been described for streams and rivers in the region less frequently (see however Sedell and Froggatt, 1984;McIntosh et al, 2000; White and Rahel, 2008).…”