Weekley, Carl W. , Menges, E.S. .
Seedling Emergence and Survival in Warea carteri, a rare annual mustard.
YEAR-TO-YEAR fluctuations in the adult aboveground population size of an annual plant may be due to differential rates of seedling emergence or to differential rates of seedling survival. Warea carteri is an annual mustard characterized by boom-bust aboveground population cycles. Population booms in the year following fire indicate the presence of a persistent soil seedbank. Aboveground populations typically crash in the second year postfire with subsequent year-to-year fluctuations of varying magnitudes. Between 1998 and 2002 we followed seedling emergence and survival to reproductive age monthly in 0.25 m2 quadrats (31 < n <78) in four to five populations. We used regression analysis to determine whether the number of germinants or the percent survival was the better predictor of the number of adults. We also investigated the effect of season of emergence on survival. We found that seedlings emerged between late summer and late winter with flowering the following fall. Patterns of germination and survival varied greatly among quadrats, populations and years, with annual percent survival to reproductive age ranging from 3.9 to 24.3%. Together the number of germinants and the percent survival explained between 50% and 79% of variation in the number of adults (by year), with the percent survival being the stronger predictor. Survival to adulthood also varied by season of emergence among populations and years.
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1 - Archbold Biological Station, Plant Ecology Lab, P.O. Box 2057, Lake Placid, Florida, 33862, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Monday, July 31st, 2006
Time: 11:15 AM