Ingalls, Stephen .
Influence of Seed Size on the Density of Arctostaphylos Seed Banks.
To test and extend current theories on life history trade-offs related to seed size, a test was done to determine how seed size influences seed density in persistent seed banks of Arctostaphylos. A large variation of seed and fruit size exists within this genus suggesting that different seed ecology strategies have been employed. To better understand these strategies, the seed banks of 10 obligate seeding Arctostaphylos species were examined and a negative correlation was found to exist between seed size and seed bank density. This correlation reflects trade-offs that have been made in overall life history strategies with regard to seed size. To determine seed bank density, soil seed banks were collected from beneath 10 different species of obligate seeding Arctostaphylos species that range in seed size from 1-10 mm (fruit from 4-15mm). For each species, 10-20 individuals were sampled and seed banks were collect at two different levels (0-2 cm deep and 2-5 cm deep) from 400 cm2 plots. Seeds were manually separated from the soil and counted, excluding seeds that showed an obvious sign of non-viability (such as those subject to herbivory). Overall seed bank density was determined from the number of seeds counted in each sample. Results show that seed size influences the density of seed banks in that larger seeded species tended to have smaller seed banks than smaller seeded species. As seed ecology is one important component in the network of life history variables, the results of this study help to provide a greater understanding of seed bank dynamics and the ecology of plant regeneration.
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1 - San Francisco State University, Biology, 1600 Holloway Avenue, San Francisco, CA, 94132, USA
Presentation Type: Poster:Posters for Sections
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM