LACLAIRE: UPLAND TEMPORARY POND VEGETATION IN FLORIDA


organic matter facilitates maintenance of a temporary pond rather than a
permanent one.


 Life History Strategies of Wetland Plants


 Three key life history traits can be used to characterize wetland species (van
der Valk 1981). These are life span, propagule longevity, and propagule
establishment requirements. Propagules may be seeds or vegetative structures, and
a single species may have both modes of reproduction which function under
different hydrologic regimes.
 Wetland plants include both annuals and perennials. Annuals may be found on
exposed soil during drawdowns or may occur as submersed or free-floating
aquatics (van der Valk 1981). Due to the ephemeral nature of annuals, perennials
may serve as better wetland indicators. The most prevalent life history strategy
among temporary pond aquatic species is represented by vegetatively reproducing
perennials (van der Valk 1981).
 Plant species may be considered drawdown species, standing water species, or
generalists relative to propagule establishment (van der Valk 1981). The majority
of emergent species germinate primarily on exposed areas free of vegetation. They
require exposure to light and/or alternating extremes of temperature. Vegetative
propagule formation may occur in response to drawdown and accompanying
temperature changes (Gopal 1986). Submersed, free-floating, and floating-leaved
species have seeds that require a flooded substrate for germination. There are also
species that can be considered generalists which germinate in both exposed and
inundated conditions (Gerritsen and Greening 1989). Relative species' abundances
fluctuate due to modes of germination and frequency and duration of wet/dry cycles
in the pond basins. Spatial gradients in seed bank density and viability may be
later expressed in spatial patterns of adult populations and can result in patterns of
zonation (Lowe 1986).


 Structure of Vegetation in Temporary Ponds


 The distribution of water in time and space is the single most important factor
influencing the occurrence of temporary pond macrophytes. Soil moisture is an
important component. Plants in the temporary pond environment demonstrate a
range of adaptations for tolerating inundation. Their distribution may follow
hydrologic patterns and result in a zonation of vegetation in the pond basin
(Laessle 1942; Lippert and Jameson 1964; van der Valk and Davis 1976;
Abrahamson et al. 1984; Bridges and Orzell 1989; Kushlan 1990). Concentric