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Rising energy costs, decreasing soil depth, and best management practices that require on-farm water retention have led to interest in flood-tolerant bioenergy crops for production in the Everglades Agricultural Area (EAA) of Florida. Information on the effects of high water tables on sugarcane ( Saccharum spp. L.) is available; however, little is known about the bioenergy crops elephant grass ( Pennisetum purpureum Schumach.), energycane ( Saccharum spp. L.), and giant reed ( Arundo donax L.). The objective of this study was to evaluate the role of water-table depth on the yields, morphology, physiology, and early season growth of these three bioenergy species in relation to sugarcane. The species were grown in a greenhouse and subjected to three water management strategies, −40 or −16 cm constant water-table depths, and bi-weekly flooding with drainage to −40 cm. The experiment was conducted in plant-cane, first-ratoon, and successive plant-cane crop cycles. Periodic flooding relative to a −40 cm constant water table significantly reduced dry weights and leaf area index and increased aerenchyma development. Averaged among crops, dry weight declined by 32, 49, 37, and 52% while leaf area index (LAI) decreased by 31, 50, 46, and 57% for giant reed, elephant grass, energycane, and sugarcane, respectively, in response to flooding. Aerenchyma proportional area of the stalk increased by 52, 90, and 95% for elephant grass, energycane, and sugarcane, respectively, but aerenchyma in giant reed decreased by 11%. High yields and stalk populations for all water tables were observed in energycane and elephant grass. These two species show potential for bioenergy production in the EAA. Field trials are recommended to confirm production scale yield. [ABSTRACT FROM AUTHOR]

Abstract: 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 60cm) 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. [Copyright &y& Elsevier]

Periodically flooding sugarcane (Saccbarum spp.) by delaying drainage after rain in the Everglades Agricultural Area (EAA) of Florida improves soil conservation and reduces P discharge to the Everglades, but farmers are concerned that flooding recently planted or recently ratooned sugarcane reduces yields. The purpose of this study was to determine the effects of time of flood onset and flood duration on stalk, leaf, and root biomass accretion of two recently planted (plant height ∼9 cm) sugarcane cultivars. In three pot experiments, flood durations ranged from 0 to 6 wk and flood onsets were after 2 or 4 wk at a 30-cm water-table depth. Five treatments also had a second flood onset during the final 4 or 6 wk of each experiment. Increased flood durations often resulted in declines in biomass explained by linear or quadratic models. Compared with 'CP 89-2143,' leaf and stalk biomasses of 'CP 96-1252' were more tolerant of increasing flood durations, but the opposite was true for root biomass. Sugarcane leaf biomass was reduced more by flood onset following 2 rather than 4 wk at a 30-cm water-table depth, but stalk and root biomasses were similarly reduced by both flood onsets. Although previous results have indicated that well-established sugarcane in its grand-growth phase is tolerant to periodic flooding, our results suggest that the biomass of younger (recently planted) sugarcane is increasingly reduced by flood durations of 0 to 6 wk and that flood onsets after 2 or 4 wk at a 30-cm water-table depth are similarly detrimental. [ABSTRACT FROM AUTHOR]

Abstract: The present study evaluates how a prolonged artificial flooding regime in impounded mangrove forests influences the regeneration after medium-sized forest destruction created by two hurricanes in 2004 in the Indian River Lagoon, Florida, USA. Disturbance patterns, forest structure, and regeneration were investigated. We found disturbed areas, characterized by uprooted and snapped trees, and intact forests in close proximity. The canopy turnover was greater in forests in higher succession stages with median tree diameter at breast height of 7.6±5.7cm compared to the intact forest with 3.7±1.2cm. Larger trees with lower densities were more susceptible to hurricane damage. We observed that regeneration of the open patches was dominated by the flood-tolerant species Rhizophora mangle (89.9%) instead of the faster-growing pioneer species Laguncularia racemosa (7.0%). Some of the disturbed areas created by the hurricanes were not recolonized. The regeneration rate of the disturbed areas expressed by vegetation closure >50% differed between almost zero to 100% in three different impoundments. We concluded that the artificial flooding regime imposed by impoundment is the predominant selective force in the successive process according to the species composition. However, we were not able to detect the driving factors that prevented mangrove establishment in disturbed areas. [Copyright &y& Elsevier]