Seed germination of two cattail (Typha) species as A function of Everglandes nutrient levels

Sawgrass (Cladium jamaicense) is being replaced by cattails (Typha domingensis andTypha latifolia) in Water Conservation Area 2A (WCA 2A) of the Florida Everglades. This replacement coincides with changes in nutrients in WCA 2A. Investigating seed germination ofTypha in response to different nutrient levels, focusing on phosphate, might help in understanding how this replacement occurs. Three sets of experiments with seed germination were conducted. Series I, a pilot study, was run to set the parameters for further investigations usingTypha domingensis. Germination up to 100% was obtained. Series II used field water collected from three areas of WCA 2A that differed in the concentration of phosphate. These three areas represented high, medium, and low nutrient conditions with total phosphates that ranged from 0.200 to 0.008 mg/liter. Distilled water was used to create a zero nutrient condition.Typha domingensis andT. latifolia seeds were used. Little difference in germination percentage was found betweenT. domingensis andT. latifolia. Germination began after three days, reaching 22% to 40% in seven days. In high nutrients, however,T. latifolia germinated faster. In Series III, distilled water was used that had phosphate levels added corresponding to the concentrations found in WCA 2A. This water was used in place of the field water, which was used in Series II. In Series III, onlyT. domingensis seeds were used. No difference was found in seed germination as the phosphate concentration was varied. Germination began after three days, reaching about 40% in seven days. Seed and “fruit” traits were also measured.T. latifolia produced 1.4 times as many seeds asT. domingensis, but the mean seed weight ofT. domingensis was 3.5 times that ofT. latifolia. Results suggest that both cattail species can germinate under a variety of phosphate levels. Thus, bothT. domingensis andT. latifolia may be long-term threats to areas in the Everglades presently occupied by sawgrass.