Poster Session # 11: Disturbance Ecology.

Tuesday, August 5 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.

Sedimentation influences on fine root dynamics and vegetation composition and structure in riparian forests.

Cavalcanti, Guadalupe*,1, Lockaby, Graeme1, 1 School of Forestry and Wildlife Science, Auburn, Alabama, USA

ABSTRACT- One of the most important functions of riparian zones is the ability to improve water quality by trapping sediment leaving agricultural fields and other disturbed areas. Many studies have quantified sediment deposition and identified sources of sediments in riparian ecosystems. However, little information exists regarding the impacts of sediment deposition from disturbance on belowground processes within these ecosystems. As a result of sediment deposition, one might expect a decrease in fine root production due to reductions of soil O2, which will lead to alterations in belowground net primary productivity. In the long-term, such alterations can compromise nutrient levels in forest soils resulting in decreased ANPP. Studies have also indicated that sedimentation promotes decreases in plant community richness and diversity. This study is conducted at Fort Benning, Georgia where intense disturbance caused by heavily military traffic has generated significant sediment movement into riparian forests associated with ephemeral drains. Effects of sediment deposition on fine root production and, alterations in vegetation composition and structure in riparian forests are the focus of this study. Since February 2002, nine catchments have been monitored. Based on vegetation inventory and visual evidence of sediment, catchments were classified as highly or moderate disturbed and reference. Within each drainage, samples are collected in paired plots, one in the upper extremity (disturbed plot), which receives greater amounts of sediments due the proximity of unpaved roads and another (control plot) located further down the catchment beyond the reach of deposition. Preliminary results show significant differences in fine root production and ANPP between paired plots in highly disturbed catchments. No difference was observed in moderately disturbed and reference areas.

Key words: sedimentation, fine root, riparian forests