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Abstract Detail

Developmental and Structural Section

Richards, Jennifer [1], Olivas, Paulo [2], Hernandez, Jonathan [3].

Variations in Cladium jamaicense (sawgrass) morphology and growth in Everglades marl and peat soils.

Cladium jamaicense, sawgrass, is the dominant macrophyte in Everglades marshes, covering 50-75% of the marsh and inspiring the region's recognition as a "river of grass". Sawgrass has been described as having two growth forms, either short and sparse or tall and dense; these could be phenotypic or genotypic morphs. Because extremes of these forms are found on different Everglades soils (short, sparse phenotype on marl soils; tall dense phenotype on peats), we hypothesized that variation in form is a result of different soil environments. Seeds collected from a single Everglades population were germinated in potting soil and allowed to grow for 3 months, then transplanted to pots with either marl or peat soils and grown in water (water level at soil surface) in outdoor mesocosms. Growth was followed for 14 months, then plants were harvested, separated into leaves, stems, and roots, dried and weighed to determine final biomass. Before drying, the abundance of dauciform roots was determined. Leaf C, N, and P were analyzed on a subset of plants, and soil TN, TC, and TP were determined for the same subset. Sawgrass seedlings grew in both soil types, but they began to differ in growth and morphology very soon after transplanting. Plants in marl had fewer live leaves after 10 days of growth, had smaller leaves after 43 days growth, and had fewer branches after 77 days growth, when plants in both treatments began to branch. After 8 mo., 85% of marl original shoots had died or were declining, with growth transferred to a branch; this phenomenon occurred to a lesser extent (46%) in peat. Plants in peat had on average 4.5x greater final total biomass than plants in marl, although investment in different plant parts was not significantly different. Marl soil had higher bulk density and pH, app. one-fourth the TN and TP of peat soils, but molar N:P was similar. Plant biomass was significantly associated with soil TP in peat but not marl soils, while it was significantly associated with plant TN in marl but not peat soil. Plants in marl had more dauciform roots, and the number of dauciform roots varied with soil TP content. These results show that sawgrass plants respond dramatically to peat and marl soils and suggest that the difference between short, sparse and tall, dense sawgrass in the Everglades is a result of environment rather than plant genetic differences.

Broader Impacts:

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1 - Florida International University, Department of Biological Sciences, 11200 SW 8th St., Miami, FL, 33199, USA
2 - Fairchild Tropical Botanic Garden, Science Village, 10901 Old Cutler Road , Coral Gables (Miami), FL, 33156, USA
3 - Florida International University, Biological Sciences, 11200 SW 8th St., Miami, FL, 33199

soil nutrients
dauciform roots

Presentation Type: Oral Paper:Papers for Sections
Session: 15
Location: Jasperwood/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 8:30 AM
Number: 15003
Abstract ID:264
Candidate for Awards:None

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