BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 38 PT. I (3)


 TEMPORARY PONDS

 Defining a Temporary Pond


 Temporary wetlands can be defined as natural bodies of water which experience
a recurrent dry phase of varying duration (Williams 1987). The hydrologic
emphasis in these wetlands is on the cyclic nature of drying and re-filling as
permanent waterbodies are also capable of drying completely in exceptional years.
In addition, selection has occurred in temporary wetlands for species adapted to
this cyclic drying and filling and results in periodic bursts of productivity that fuel
these systems (Patrick and Khalid 1974; Brinson et al. 1981; Reddy and Graetz
1988).
 A temporary pond is a small (generally less than 5 hectares), isolated,
temporary wetland that is depressional in nature. There is considerable confusion
of terms in dealing with these small temporary wetlands, both among regulatory
agencies and in the literature. Terms used to describe them include flatwoods
marshes/ponds, ephemeral ponds/wetlands, highlands marshes, pineland
depressions, depression meadows/marshes, St. John's wort ponds, seasonal
marshes/ponds, intermittent ponds, and vernal pools (Holland 1988; Florida
Natural Areas Inventory and Florida Department of Natural Resources 1990;
Kushlan 1990). Some of these terms allude to the fact that temporary ponds are
difficult to identify as wetlands during their dry cycle (Means 1990).


 Hydrology


 Hydrology is the major factor influencing and maintaining the community of
wetland plants in the temporary pond basin (Mitsch and Gosselink 1986). External
water inputs transport nutrients into the system and mobilize those bound in
vegetation and soil. Water depth, duration, and frequency of flooding all influence
the formation of hydric soils and the presence of hydrophytes within the pond
(Gosselink and Turner 1978). The hydroperiod of temporary ponds is highly
variable, depending upon elevation, basin characteristics, and rainfall patterns
(Means 1990). Some ponds may fill and dry on an annual basis while others may
contain water only in the wettest years.
 When a temporary pond drains, productivity is lowered and aerobic
 decomposers begin rapidly breaking down the accumulated organic matter (Cole
 and Fisher 1979; Reddy et al. 1986). Temporary ponds are detrital systems, and
 most of the organic production decomposes before entering the detrital food chain
 (Mitsch and Gosselink 1986). The vegetation of the pond basin is readily and
 almost completely decomposed on a cyclic basis (Gopal 1986). The breakdown of