Document: MIC-3-75-9

An alternative method for estimating above-ground production in mangrove communities of Biscayne National Park, Florida.

ROSS, M.S.* and P.L.RUIZ

Florida International University/Southeast Environmental Research Center, Miami, FL 33199, USA ¹

Abstract:
Total above-ground production of forest communities is usually estimated through a combination of allometry and litter collection. However, in coastal sites that are tidally influenced, or in juvenile or dwarf forests where the crown bases of dominant individuals may begin within a few decimeters of ground level, estimates of leaf production that depend on litter collection may not be feasible. We therefore developed an alternative method of estimating production in mangrove forests that overcomes this limitation. The method incorporates (a) detailed censuses of all individuals within fixed sampling plots, with (b) periodic observations of marked leaf cohorts, and is an adaptation of techniques more commonly used in grasslands. We applied the method in two South Florida forests: A fringe mangrove forest in the early stages of recovery from Hurricane Andrew (August 1992), and a dwarf forest which was not substantially damaged by the storm. During 1996-98, total above-ground production in the fringe forest was about 3 times higher than dwarf forest production. Moreover, when compared to the dwarf forest, fringe production rates were approximately eight, six, six, and two times as high as dwarf forest rates for proproots, branches, stems, and leaves, respectively. Calculations of leaf production were based on mean Rhizophora mangle leaf longevities that ranged from six to nine months, depending on cohort and site. Analysis of variance indicated that leaf life spans did not differ significantly between dwarf and fringe forests, but did differ among leaf cohorts. Based on reported values for similar mangrove forests, the method provided reasonable estimates of above-ground production of different tissues, while furnishing relevant auxiliary information on spatial and temporal variation in leaf demographic patterns.

Keywords: mangroves, productivity, hurricanes, Rhizophora mangle, leaf demography

This abstract is being presented at: 2:30 PM in session:
Oral Session #18: Mangrove Ecology.