Walt Dineen Society Annual Conference '97
|Session VII: Marine Ecology
||Abstract #: 97706
PATTERNS OF GROWTH AND RECRUITMENT IN MANGROVE FORESTS FOLLOWING
CATASTROPHIC DISTURBANCE IN RELATION TO SOIL NUTRIENTS
Smith III, T.J., Wiebe, W.J. & Merickel, J.A.
Biological Resources Division, U.S. Geological Survey, Miami, FL
and University of Georgia, Athens, GA.
Hurricane Andrew passed over the southwest coast of Florida in August 1992 causing a gradient of disturbance in mangrove forests from minor to catastrophic. We established a series of permanent plots from Rookery Bay in the north to Flamingo in the south to measure initial patterns of mortality, continuing storm related mortality, and the growth of survivors and new recruits. Soil porewater nutrients (nitrogen and phosphorus), sulphide and salinity were measured over time at a subset of plots. Initial mortality was both size and species dependent. Larger individuals of all species were killed and Rhizophora suffered higher initial mortality than either Avicennia or Laguncularia. Continuing mortality has also been concentrated in
larger size classes and has been greater for Avicennia and Laguncularia. Recruitment at most, but not all, plots has been dominated by Laguncularia. Rhizophora dominated recruitment at a single plot and Avicennia has recruited in very low numbers in all plots. Growth, measured as basal area increase, has been greatest for all species in plots subjected to intermediate levels of disturbance and least in plots suffering either catastrophic disturbance or little disturbance at all. Soil nutrient pools appear to have played a secondary role. Plots with higher levels of phosphorus had slightly higher growth rates and plots with high sulphide levels had decreased rates of growth. After five years, areas of catastrophic disturbance are not
close to approaching prestorm levels of forest biomass.