Effects of Sediment Deposition on Fine Root Dynamics in Riparian Forests

Abstract

One of the most important functions of riparian zones is their ability to improve water quality by trapping sediment leaving agricultural fields and other disturbed areas. However, few data exist quantifying the impacts of sediment deposition from anthropogenic disturbance on belowground processes within these ecosystems. This study was conducted at Ft. Benning, GA, where disturbance caused by military training has generated a range of sedimentation levels in riparian forests near ephemeral streams. Nine ephemeral streams, exhibiting different levels of sediment deposition, were selected for study. Two paired treatment plots (upper and lower) were established along each catchment to represent potentially disturbed and control conditions, respectively. On highly and moderately disturbed catchments, upper plots had received varying rates of sediment from erosion along unpaved roads. Biomass, turnover, productivity, and nutrient contents of fine roots were compared within and across catchments. Temporal fluctuations in biomass of live and dead fine roots were observed for both treatments in the three disturbance categories, except for upper plots of highly disturbed catchments, where biomass remained fairly low and constant throughout the study. Fine root productivity declined sharply with sediment rates as low as 0.3 cm yr−1 Nutrient contents of live and dead fine roots followed a similar trend to that of root biomass. These data suggest that fine root dynamics may be affected by sediment deposition rates commonly occurring in some wetland forests, and the water filtration function performed by these ecosystems may be at risk.

Groundwater Denitrification Capacity of Riparian Zones in Suburban and Agricultural Watersheds1

“…Microbial and plant dynamics are not well understood in these types of recent deposits. Cavalcanti and Lockaby (2005) observed that riparian fine root productivity dropped sharply with increased riparian deposition caused by anthropogenic disturbance.…”

Stratifying soils into pedogenically similar categories for modeling forest soil carbon

“…Buried horizons are often found in Cumulic Regosols, which commonly result from intermittent flooding and deposition (Soil Classification Working Group 1998). Hydroperiod is generally accepted to be the dominant controlling process on forested wetlands (Baker III et al 2001a) and research has shown that hydrological fluctuations can influence fine root turnover (Baker III et al 2001a;Cavalcanti and Lockaby 2005), litter decay rates (Baker III et al 2001b;Shaw et al 2001) and storage of highly stable C in buried horizons (Shaw et al 2001;Blazejewski et al 2005).…”

Comparing two tools for ecosystem service assessments regarding water resources decisions

“…While the considered decision contexts are hypothetical, they are realistic both in terms of the types of tools that people are using to assess the ecosystem response for ES assessments, and for the types of regulations and investments ES approaches are being used to support. [Cavalcanti and Lockaby, 2005;Cohen et al, 2006]. Approximately 65% of the base is classified as forest, 17% as range, 6% each as agriculture and wetlands, and 4%…”