Effects of inundation on growth and nutrient allocation of six major macrophytes in the Florida Everglades

Understanding the effect of hydrological alterations on the establishment and growth of macrophytes is pivotal for restoring natural wetland plant communities and for managing constructed wetlands. Growth and nutrient storage of six native macrophytes commonly found in the Florida Everglades were studied under two inundation levels (20 and 60 cm) in experimental mesocosms receiving inflow water with a low concentration of phosphorus (P). The six species, which were planted in soils collected from P-enriched areas, included one ridge species (Cladium jamaicense), three wet prairie species (Rhynchospora tracyi, Eleocharis elongata, and Eleocharis cellulosa), one slough species (Nymphaea odorata), and one fast spreading species (Typha domingensis).Inundation level greatly affected plant survivorship, growth, and nutrient allocation. The macrophytes differed substantially in their abilities to adapt to rising inundation level and in their adaptation strategies. N. odorata exhibited a substantial increase in both biomass and nutrient storage under rising inundation and had the largest accumulation of P and nitrogen among the six species studied. Aboveground biomass (A) and belowground biomass (B) allocation varied with species. Species with a lower A/B ratio under shallow inundation (N. odorata, E. cellulosa, and T. domingensis) adapted better to deeper inundation than those with higher A/B ratios (C. jamaicense, R. tracyi, and E. elongata). Adaptation to deeper inundation was achieved either by an increase in aboveground growth (E. cellulosa and T. domingensis) or by a simultaneous increase in both aboveground and belowground growth (N. odorata). Inability to adjust the A/B ratio in response to deeper inundation was characteristic of species that experienced high mortality (R. tracyi and C. jamaicense). The results of this study, which demonstrate differences in inundation tolerance and differences in mechanisms of inundation tolerance among common and diverse wetland macrophytes, will be useful for wetland restoration and management.