| Abstract | Introduction | Methods | Future Directions | Results & Discussion | Literature Cited |
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| Intertidal Vegetation Dynamics in the Tampa Bay Estuary |
T.J. Smith III1, N. Silverman2, Jeffrey Dismukes2, G. Peery2, W. Weaver2
1: USGS/Geological Discipline
2: ETI Professionals, Inc. |
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| Click images to view enlargements. |
Methods: |
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| Figure 2. Noah Silverman (USGS/BRD), measuring diameter at breast height on stems at an Alafia River site. |
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Initial Plot Set-up: Sampling sites were located using a stratified-random sampling design. Plots were located along the large-scale salinity gradient present in each study area (Figure 1). The mangrove forest plots are circular to mimic the natural canopy gaps that are prominent feature in many forest ecosystems (Harper & White 1974, Kohyama 1993). A PVC rod was driven into the sediment to permanently mark the center of each plot. Stems, greater than 1.4m in height, within a given radius of the center, were identified to species.
They were measured for diameter at breast height (DBH) and tagged with an individually numbered aluminum tree-tag (Figure 2). The location on the stem at which DBH is measured is marked with paint to ensure accurate re-measurement. Each stem was mapped by measuring its distance and bearing (E of N) from the center stake (Figure 3).
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| Figure 3. Schematic diagram of a tree plot. |
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The plot radius is variable and depends on a visual inspection prior to establishment. The radius is large enough to ensure 20 stems. Physical parameters such as soil porewater salinity were measured at each site.
Resurveys of plots: The plots were established in the summer of 2001 and are currently being re-sampled. During a resurvey, DBH is measured at the same spot as previous surveys. Growth is calculated as the simple difference in DBH between surveys. Mortality of stems is recorded and recruitment is noted. We define a recruit as a stem that has attained the size necessary to allow a DBH measurement to be made. In this study a stem recruits when it attains a height of 1.4 m.
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