Hurricanes are a chaotic major force that structure mangrove forests. The extent of initial damage depends not only on physical factors such as the strength/duration of winds, the depth/period of flooding and sediment characteristics but also on biological factors such as the mangrove species, tree size and the successional stage of the forest. Additional damage occurs over the longer term as injured trees perish. Both initial and later effects of hurricanes can have strong impacts on the recovery of mangrove forests, which is dependent on both the survival of existing trees and recruitment and survival of seedlings. Changes in sediment elevation include initial deposition/erosion and the later collapse of mangrove root peat with tree death. Much loss of foliage, branches, trees and canopy cover occurs early with the passage of the hurricane, but loss of trees often occurs months later. Further, these variances in sediment elevation and light subsequently alter the biogeochemical and microbial characteristics of the soil.
Results/Conclusions
On the west and east coasts of south Florida (FL) damage from a series of hurricanes have caused both initial and longer term impacts on mangrove forests. Hurricanes Frances and Jeanne swept through swaths of forests in southeast Florida. At Hutchinson Island Where the eyewalls hit, winds shattered trees and floodwaters deposited over a meter of sand that smothered trees. Slightly inland, large Avicennia trees that had been twisted by shear winds perished more than a year later and sediment in these patches could no longer support planted seedlings. Where greatest canopy cover loss occurred, soil salinity increased to levels above the tolerance of seedling tolerance. In southwest FL, alteration of the canopy by a hurricane precluded survival of seedlings more than a decade after the event. In Jobos Bay, Puerto Rico Hurricane Maria caused extreme damage extending 5-10 m into fringe forests. On the many islands, trees were uprooted or stripped of foliage. With the loss of mangroves, the diverse epibiotic communites of Rhizophora roots were also decimated. The devastation caused by hurricanes long outlasts the immediate apparent effects of its passing.