Influence of Catchment-Scale Military Land Use on Stream Physical and Organic Matter Variables in Small Southeastern Plains Catchments (USA)

Abstract

We conducted a 3-year study designed to examine the relationship between disturbance from military land use and stream physical and organic matter variables within 12 small (<5.5 km2) Southeastern Plains catchments at the Fort Benning Military Installation, Georgia, USA. Primary land-use categories were based on percentages of bare ground and road cover and nonforested land (grasslands, sparse vegetation, shrublands, fields) in catchments and natural catchments features, including soils (% sandy soils) and catchment size (area). We quantified stream flashiness (determined by slope of recession limbs of storm hydrographs), streambed instability (measured by relative changes in bed height over time), organic matter storage [coarse wood debris (CWD) relative abundance, benthic particulate organic matter (BPOM)] and stream-water dissolved organic carbon concentration (DOC). Stream flashiness was positively correlated with average storm magnitude and percent of the catchment with sandy soil, whereas streambed instability was related to percent of the catchment containing nonforested (disturbed) land. The proportions of in-stream CWD and sediment BPOM, and stream-water DOC were negatively related to the percent of bare ground and road cover in catchments. Collectively, our results suggest that the amount of catchment disturbance causing denuded vegetation and exposed, mobile soil is (1) a key terrestrial influence on stream geomorphology and hydrology and (2) a greater determinant of in-stream organic matter conditions than is natural geomorphic or topographic variation (catchment size, soil type) in these systems.

Anthropogenic disturbance and landscape patterns affect diversity patterns of aquatic benthic macroinvertebrates

“…Losses of sensitive taxa in the Plains might be a reflection of the importance of coarse woody habitat in sandy-bottom streams of the Plains (Smock et al 1989). This habitat is reduced by anthropogenic disturbance in upslope watersheds (Maloney et al 2005). In addition, our inability to detect a disturbance effect at the regional scale could have been a consequence of our use of a small subsample size (100 individuals), which is likely to produce underestimation of actual richness values.…”

“…Streams within the Plains region are characteristically low gradient with sandy substrates (Felley 1992, Maloney et al 2005, whereas streams in the Piedmont region show high variability in streambed composition and gradient (Mulholland and Lenat 1992). Thus, among-site variation in habitat (habitat heterogeneity) is likely to be higher in the Piedmont than the Plains.…”

Hydrogeomorphic Reference Condition and Its Relationship with Macroinvertebrate Assemblages in Southeastern U.S. Sand Hills Streams

“…Likewise, these conditions also were indicative of hydrologic disturbance (Maloney et al. ). As hydrologic disturbance increases, fine particles are exported from the system and bed material coarsening occurs (Helms et al.…”

Stream bed organic carbon and biotic integrity

“…Bilby and Likens, 1980;Hauer, 1989;Lepori et al, 2005;Maloney et al, 2005). This may reflect the fact that elevated levels of LW density at streams 2 and 3 were caused by accelerated inputs from the riparian zone driven by channel incision (Downs and Simon, 2001) and a large-scale LW addition project, respectively.…”