Riparian Forest Diversity and Structure Along an Urbanization Gradient in West Georgia, USA

"Changes in riparian woody plant assemblages are anticipated in the southeastern United States due to increases in urbanization rates. Because riparian forests serve important roles in maintaining water quality and biodiversity, understanding how they respond to urbanization is crucial. The objective of this study is to examine forest structure (leaf area index, tree density, diameter distribution, basal area) and vegetation diversity indices such as importance values, Shannon-Wiener diversity (H) and evenness (J ) of riparian woody plant species in response to an urbanization gradient in West Georgia, USA.  In each riparian community (17), woody vegetation (>2.54cm DBH) within a 3.5 ha plot was sampled. Structure and diversity of woody plant regeneration was also examined as important components of forest sustainability. Measures of forest structure and diversity were compared to measures of urbanization and land cover within each watershed.  Although Liquidambar styraciflua and Quercus nigra were dominant species in the forest stand and regeneration layer for all riparian communities, the invasive, non-native shrub Ligustrum sinense was the most dominant species observed in the regeneration layer for urban, developing, and agriculture communities. The proportion of non-native species in the forest stand and regeneration layer decreased and Shannon diversity of the regeneration layer increased with increasing distance from the urban center. Shifts in diversity may be related to anthropogenic disturbance, which might subdue the ability of diverse communities to maintain stability, productivity, and resistance to biological invasions. "[Abstract from Conference Program and Book of Abstracts]

[Concurrent Session I-E: Urbanization and Forest Structure]

[Presented at "Emerging Issues Along Urban/Rural Interfaces: Linking Science and Society", a conference held March 13-16, 2005 in Atlanta, GA (US)]