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Abstract: Growth, morphology and biomass allocation in response to water depth was studied in white water lily, Nymphaea odorata Aiton. Plants were grown for 13months in 30, 60 and 90cm water in outdoor mesocosms in southern Florida. Water lily plant growth was distinctly seasonal with plants at all water levels producing more and larger leaves and more flowers in the warmer months. Plants in 30cm water produced more but smaller and shorter-lived leaves than plants at 60cm and 90cm water levels. Although plants did not differ significantly in total biomass at harvest, plants in deeper water had significantly greater biomass allocated to leaves and roots, while plants in 30cm water had significantly greater biomass allocated to rhizomes. Although lamina area and petiole length increased significantly with water level, lamina specific weight did not differ among water levels. Petiole specific weight increased significantly with increasing water level, implying a greater cost to tethering the larger laminae in deeper water. Lamina length and width scaled similarly at different water levels and modeled lamina area (LA) accurately (LAmodeled =0.98LAmeasured +3.96, R 2 =0.99). Lamina area was highly correlated with lamina weight (LW=8.43LA−66.78, R 2 =0.93), so simple linear measurements can predict water lily lamina area and lamina weight. These relationships were used to calculate monthly lamina surface area in the mesocosms. Plants in 30cm water had lower total photosynthetic surface area than plants in 60cm and 90cm water levels throughout, and in the summer plants in 90cm water showed a great increase in photosynthetic surface area as compared to plants in shallower water. These results support setting Everglades restoration water depth targets for sloughs at depths ≥45cm and suggest that in the summer optimal growth for white water lilies occurs at depths ≥75cm. [Copyright &y& Elsevier]

Abstract: Historically, the Florida Everglades was characterized by a corrugated landscape of shorter hydroperiod, elevated sawgrass (Cladium jamaicense) ridges and longer hydroperiod, deep water slough communities. Drainage and compartmentalization of the Everglades have fundamentally altered this pattern, and sawgrass ridge communities have expanded at the expense of deep water slough communities throughout much of the landscape. In this study we provide a simple isotopic and nutrient characterization of major components of the slough ecosystem to elucidate physiological and nutrient differences among species and to suggest pathways for organic matter decomposition that contribute to peat development in deep water sloughs. We examined carbon (C) and nitrogen (N) isotopes and C, N and phosphorus (P) concentrations of the floating-leaved macrophytes Nymphaea odorata and Nymphoides aquatica, the emergent macrophyte Eleocharis elongata, and the submerged species Utricularia foliosa and Utricularia purpurea, as well as soil and flocculent material from the southern Water Conservation Area 3-A. Flocculent material and soils had the highest N content (4.5±0.2%) and U. foliosa and N. odorata had the highest P content (0.13±0.01% to 0.12±0.01%). The range for δ15N average±SE values was 5.81±0.29‰ (U. foliosa) to −1.84±0.63‰ (N. odorata), while the range for δ13C values was −23.83±0.12‰ (N. odorata) to −29.28±0.34‰ (U. purpurea). Differences of up to 10‰ in C isotopic values of U. foliosa and N. odorata suggest fundamental physiological differences between these species. Along a degradation continuum, enrichment of 13C and 15N and extent of decomposition was negatively related to phosphorus concentrations. A two end-member 13C mixing model suggested that Utricularia species were the primary organic source for flocculent materials, whereas organic matter derived from root decomposition of N. odorata contributed to the progressively enriched δ13C values found with depth in soils. These results illustrate the fundamentally important roles of Nymphaea and Utricularia species in ecosystem dynamics of deep water sloughs. [Copyright &y& Elsevier]

Sagittaria lancifolia leaf morphology varies in the Everglades of southern Florida, USA, from plants with broadly ovate laminae to plants with linear laminae. To understand the morphological response of S. lancifolia to increased nutrients, we (1) grew S. lancifolia plants in solutions with either 1mM or 10μM P and measured morphological responses, as well as tissue N:P content and (2) grew field-collected plants that had a range of leaf morphologies in the greenhouse and measured morphological and tissue N:P responses. Plants in high P (HP), as compared to low P (LP), were larger (biomass 48.3g HP versus 16.9g LP), produced more leaves (16.9 HP versus 10.7 LP) and inflorescences (2.9 HP versus 0.3 LP), and branched more (shoots 3.8 HP versus1.1 LP). Biomass allocation to leaves and inflorescences was greater in HP as compared to LP plants (leaves 61% HP versus 37% LP; inflorescences 15% HP versus 2% LP), while plants in LP allocated relatively more biomass to roots and rhizomes than plants in HP (roots 8% HP versus 25% LP; rhizomes 15% HP versus 35% LP). Leaf morphology changed with P-addition, so that plants in high P produced leaves with longer leaf bases (352mm HP versus 219mm LP), longer and wider blades (290mm × 49mm HP versus 176mm × 9mm LP), and a larger leaf area (99cm2 HP versus 13cm2 LP) than plants in LP, whereas plants in LP produced leaves with longer petioles (277mm HP versus 346mm LP). Leaf N:P ratios decreased in HP relative to initial ratios (43initial to 17final) and increased in LP (45initial to 86final). The direction of change in lamina width of field-collected plants grown under greenhouse conditions depended on the original leaf morphology—plants with narrow blades in the field produced wider laminae in the greenhouse, while plants with wide blades in the field produced narrower laminae. These plastic changes in leaf morphology mimic the differences in leaf morphology between S. lancifolia subsp. media and S. lancifolia subsp. lancifolia. Our results show that S. lancifolia responds rapidly to changes in environmental nutrient status, especially in lamina morphology. Blade shape thus provides a field indicator of soil/pore water nutrient status: narrow blades indicate nutrient limitation, whereas broader blades indicate nutrient enrichment. [Copyright &y& Elsevier]

• Cladium jamaicense (sawgrass) has little to no seed germination in salinities ≥ 5 ppt. • Cladium jamaicense (sawgrass) has reduced and delayed germination in salinity ≥ 5 ppt. • Seed germination in Cladium jamaicense (sawgrass) needs freshwater for ≥ 4 weeks. Sea level rise threatens coastal peatlands globally, as increased salinity can cause peat collapse and formation of brackish ponds, replacing marshes. Sawgrass, Cladium jamaicense Crantz (Cyperaceae), is the charismatic macrophyte that dominates Everglades marshes (Florida, USA). Sawgrass root growth is reduced by salinity pulses of 20 ppt, impacting soil structure and organic input into coastal peats and possibly leading to coastal marsh loss. The potential for regeneration of coastal sawgrass marsh from seeds depends on how salinity affects sawgrass germination. Although adult sawgrass plants can tolerate salinities of 10–20 ppt in the field, the effect of salinity on seed germination is not known. In this study, sawgrass seeds were exposed to salinities of 0, 5, 15, and 25 ppt and observed weekly for germination over seven months (Oct. 2017-Apr. 2018). Twenty-eight percent of seeds in 0 ppt water germinated, while only 4% of seeds in 5 ppt germinated. Seeds in 15 and 25 ppt salt did not germinate. After 3.6 months, four-fifths of the seedling trays at the two higher salinities were transferred to 0 ppt. Beginning 7 weeks after transfer, 6% (15 ppt) and 3% (25 ppt) of transferred seeds germinated, while seeds remaining at the higher salinities did not. These results indicate that sawgrass seeds have greatly reduced or no germination in elevated salinity. If salinities rise in coastal areas, this lack of germination could prevent coastal sawgrass regeneration from seed, negatively affecting coastlines as sea level continues to rise. [ABSTRACT FROM AUTHOR]

Abstract: Simulating ecological indicator responses to alternate restoration strategies provides decision support tools for resource managers and restoration planners. Our case study provides a methodology for how to utilize hydrologic suitability for native vegetation to evaluate effects of modeled restoration scenarios. We propose that hydrologic suitability of white water lily, Nymphaea odorata, an indicator species of the native Florida Everglades slough vegetation community, be used to evaluate modeled restoration scenarios in the Everglades ridge and slough landscape. Based on experimentally derived mesocosm and field studies and historical evidence, we developed a predictive performance measure to assess hydrologic suitability for N. odorata. We applied the performance measure to predict the hydrologic suitability for slough vegetation in the Everglades ridge and slough landscape using model-simulated hydrology of existing conditions, future conditions with restoration, and the predrainage Everglades. Our results indicate that Everglades restoration will provide the greatest benefits to native slough vegetation in Arthur R. Marshall Loxahatchee National Wildlife National Refuge (LNWR), Water Conservation Area (WCA) 3B, and Everglades National Park, and may degrade slough conditions within portions of WCA 2 and WCA 3A. Our analysis indicates that additional restoration efforts are needed to fully restore native slough vegetation communities throughout the Everglades ridge and slough landscape. Performance measure results for the predrainage scenario in the WCAs conflict with paleoecological data; these results indicate a need to improve the modeled predrainage topography as well as flow and evapotranspiration rates of the Natural System Model version 4.6.2 (hereinafter NSM). [Copyright &y& Elsevier]

Abstract: We have developed a comprehensive ecological indicator for invasive exotic plants, a human-influenced component of the Everglades that could threaten the success of the restoration initiative. Following development of a conceptual ecological model for invasive exotic species, presented as a companion paper in this special issue, we developed criteria to evaluate existing invasive exotic monitoring programs for use in developing invasive exotic performance measures. We then used data from the selected monitoring programs to define specific performance measures, using species presence and abundance as the basis of the indicator for invasive exotic plants. We then developed a series of questions used to evaluate region and/or individual species status with respect to invasion. Finally, we used an expert panel who had answered the questions for invasive exotic plants in the Everglades Lake Okeechobee model to develop a stoplight restoration report card to communicate invasive exotic plant status. The report card system provides a way to effectively evaluate and present indicator data to managers, policy makers, and the public using a uniform format among indicators. Collectively, the model, monitoring assessment, performance measures, and report card enable us to evaluate how invasive plants are impacting the restoration program and how effectively that impact is being managed. Applied through time, our approach also allows us to follow the progress of management actions to control the spread and reduce the impacts of invasive species and can be easily applied and adapted to other large-scale ecosystem projects. [Copyright &y& Elsevier]