Response of everglades plant communities to nitrogen and phosphorus additions

Abstract

Nitrogen (N) and phosphorus (P) were applied to sawgrass (Cladiumjamaicense), mixed sawgrasscattail (Typha domingensis), and slough (shallow water communities dominated by Utricularia spp., Eleocharts spp., and Panicum spp.) communities in the Everglades for two years to test for N or P limitations and to investigate the plant community response. Nitrogen (as NH4 + ) and P (as PO, 3-) were applied singly and in combination at rates of 0.6, 1.2, and 4.8 g P.m --2-yr ' and 5.6 and 22.4 g N.m 2 .yr ~. Plant response was quantified by measuring aboveground standing crop biomass and tissue N and P concentrations each year. Everglades plant communities are P limited. Phosphorus additions at the highest rate (4.8 g.m 2.yr ') resulted in increased P uptake and biomass production by emergent vegetation. Tissue P concentrations of sawgrass and cattail were significantly higher in response to the high P (329-684 ug-g ') and high N+ P (371-594 ug.g ~) treatments (control=94-256 ug-g-') in both years after the initiation of nutrient additions. Aboveground biomass also increased in response to the highest rate of P at the sawgrass (2618-3284 g/m2; control -1158 g/rn 2) and mixed (1387-1407 g/m2; control = 502 g/m 2) communities, but only after two years. At the slough site, the high P and high N + P treatments resulted in a significant decline of the Utriculariaperiphyton mat after only one year of nutrient additions (16-74 g.m 2; control=364 g.m-~'). During the second year, the macroalga, Chara, expanded in these plots and replaced the floating mat as the major nonemergent component of the plant community. In all three communities, P additions at the highest rate resulted in a significant increase in bicarbonate-extractable and total soil P (0-5 cm depth). There was no effect of N additions on biomass production, nulrient uptake, or N enrichment of the peat during the twoyear study. We observed no significant change in macrophyte species diversity or expansion of cattail in plots receiving nutrient additions during the two year study. However, the decline of the Utricularia-periphyton mat (and the subsequent increase in C'hara) in slough plots receiving 4.8 g P.m -2-yr -t may serve as an early indicator of P enrichment in the Everglades.

Phenolic content and growth of wetland macrophytes: Is the allocation to secondary compounds driven by nutrient availability?

“…Their growth and response to nutrient increase have been well described (Craft et al 1995;Rejmánková et al 1996;Richardson et al 1999;Rejmánková 2001;. My main question was: How do growth and phenolic compounds of these two species respond to different levels of nitrogen and phosphorus?…”

“…Yet many aspects of this impact are poorly understood. While growth responses leading to changes in community structure have been widely studied (Aerts and Berendse 1988;Craft et al 1995;Miao and Sklar 1998;, far less is known about changes in plant secondary metabolites following increased input of nutrients. They may have important consequences for ecological interactions and processes such as herbivory and decomposition (Aerts and de Caluwe 1997;Peñuelas and Estiarte 1998;Hättenschwiler and Vitousek 2000;Wong et al 2010;Kagata and Ohgushi 2011).…”

Short-Term Effects of Drying-Rewetting and Long-Term Effects of Nutrient Loading on Periphyton N:P Stoichiometry

“…The Comprehensive Everglades Restoration Plan (CERP) aims to address the major impacts of these hydrological diversions and impoundments and to ecologically restore this wetland by, e.g., increasing clean freshwater flow into ENP (evergladesrestoration.gov). To inform such restoration efforts, various authors have been studying the effects of drying frequency on mat primary production [42,43] and on nutrient fluxes in plant and algal communities [29,31,44,45 Figure 1) and randomly assorted into 72 beakers (400 mL) that were kept in cool, dark conditions until the start of the experiment. The mats in this region are representative of the "short-hydroperiod" (6-9 months flooding duration and more than one wet-dry cycle per year) of the upstream areas of the TS/Ph and SRS drainages [25,32].…”

Quantitative Comparison of Plant Community Hydrology Using Large-Extent, Long-Term Data

“…The two WCAs have different water management regimes (Fennema et al 1994;Light and Dineen 1994) and different nutrient inputs. In particular, WCA 2A receives excess phosphorus (DeBusk et al 2001), which is the limiting nutrient in the historic Everglades (Craft et al 1995;Noe et al 2001;Childers et al 2003;Gaiser et al 2005). These additional abiotic differences have led to differences in plant community abundances and distributions, reflected in different patterns of conditional density and density deviations for Cladium and Typha along hydrologic gradients in the two WCAs.…”