PARENT SESSION
Oral Session #2: Riparian Ecology.
Presiding: M. Dixon
Monday, August 5. 8:00 AM to 11:30 AM. Greenlee Meeting Room, TCC.
Process and pattern: hydrogeomorphology and biodiversity in forested wetlands on the Chesapeake Bay coastal plain.
Alexander-Augustine, Lauren*,1,2, Hupp, Cliff2, 1 Harvard University, Cambridge, MA2 U.S. Geological Survey, Reston, VA
ABSTRACT- Unique ecotonal properties and unusually diverse plant communities characterize riparian landscapes. Bottomland forested wetlands are one type of riparian system, and processes of periodic inundation and sediment deposition typify floodplain ecotones. This research investigates relationships between hydro-geomorphic processes and patterns of plant composition and diversity in forested wetlands across the Chesapeake Bay coastal plain. Field observations in 15 1-ha sites on six floodplains were conducted to describe and quantify plant composition, frequency and duration of flood events, sedimentation, and floodplain surface microtopography. Field methods include inventories of vegetation composition in three 400-m2 plots at each site, quarter point analysis for woody species, surveyed surface elevations and derivation of hydroperiod values from long-term discharge records. Results show that hydro-geomorphic conditions and patterns of plant distribution change across the coastal plain. Hydroperiod ranges from 3 to 255 days/year; elevational range increases from 0.62 m to 2.62 m; and sediment deposition rates register between 2mm/yr and 26 mm/yr. Plant diversity increases with hydroperiod and microtopographic heterogeneity. Relationships of plant pattern at the plot scale (400-m2) differ significantly from relationships at the site scale (1-ha) in some cases; true alluvial streams differ from original blackwater systems, and western shore sites from eastern shore sites. These relationships are quantified and graphically and spatially presented.
KEY WORDS: biodiversity, forested wetland, floodplain, hydro-geomorphology