Grewell, Brenda J. , Futrell, Caryn J. .
Seedling Emergence from Seed Banks in Ludwigia hexapetala invaded Wetlands: Implications for Restoration.
Seed banks play a critical role in the maintenance of wetland plant communities, and recruitment from seed bank may vary in response to hydrologic conditions and sediment disturbance. Seed bank recruitment also plays a role in the re-vegetation of wetlands following disturbances imposed by exotic plant invasions and subsequent eradication attempts. Analysis of the seed bank can be an important component of integrated weed management and restoration planning. Seedling emergence assays can be used to determine the potential for reinvasion of the primary weed, and to reveal the cryptic presence of invasive taxa that may emerge as secondary invaders and hinder re-establishment of native plant communities. We compared differences in species composition of standing vegetation among Ludwigia hexapetala invaded and non-invaded wetlands, and the degree of similarity between vegetation and sediment seed banks. A full factorial split plot arrangement of aquatic mesocosms in the greenhouse was used to test seed bank emergence response to inundation (flooded, moist drawdown) and sediment depth (surface, buried) among invaded and non-invaded sites. Plant species richness, evenness, and Shannon’s H’ diversity were substantially lower in standing vegetation at L. hexapetala invaded sites as compared to non-invaded sites. Over a 12-month period, a total of 69 taxa germinated from experimental seed banks. Seedling density varied among sites, but was highest (10,500 m-2) in surface sediments from non-invaded sites subjected to drawdown treatments. L. hexapetala seedlings emerged from surface and lower sediment layers in drawdown treatments suggesting the need for continued management to deplete weed seed banks. Lythrum salicaria, Alisma lanceolatum, and a number of other undesirable exotic species also emerged from seed banks and signal the need for the development and implementation of comprehensive, multiple weed management strategies to meet restoration goals.
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1 - USDA-ARS Exotic & Invasive Weeds Research, Department of Plant Sciences MS-4, University of California, Davis, 1 Shields Avenue, Davis, California, 95616, USA
invasive species management
Presentation Type: Oral Paper:Papers for BSA Sections
Location: Alpine B/Snowbird Center
Date: Tuesday, July 28th, 2009
Time: 11:00 AM