Seasonal plant water uptake patterns in the saline southeast Everglades ecotone

Sharon M L Ewe, Leonel Sternberg, Daniel L. Childers

Research output: Contribution to journalArticle

60 Citations (Scopus)

Abstract

The purpose of this study was to determine the seasonal water use patterns of dominant macrophytes coexisting in the coastal Everglades ecotone. We measured the stable isotope signatures in plant xylem water of Rhizophora mangle, Cladium jamaicense, and Sesuvium portulacastrum during the dry (DS) and wet (WS) seasons in the estuarine ecotone along Taylor River in Everglades National Park, FL, USA. Shallow soilwater and deeper groundwater salinity was also measured to extrapolate the salinity encountered by plants at their rooting zone. Average soil water oxygen isotope ratios (δ 18O) was enriched (4.8 ± 0.2‰) in the DS relative to the WS (0.0 ± 0.1‰), but groundwater δ 18O remained constant between seasons (DS: 2.2 ± 0.4‰; WS: 2.1 ± 0.1‰). There was an inversion in interstitial salinity patterns across the soil profile between seasons. In the DS, shallow water was euhaline [i.e., 43 practical salinity units (PSU)] while groundwater was less saline (18 PSU). In the WS, however, shallow water was fresh (i.e., 0 PSU) but groundwater remained brackish (14 PSU). All plants utilized 100% (shallow) freshwater during the WS, but in the DS R. mangle switched to a soil-groundwater mix (δ 55% groundwater) while C. jamaicense and S. portulacastrum continued to use euhaline shallow water. In the DS, based on δ 18O data, the roots of R. mangle roots were exposed to salinities of 25.4 ± 1.4 PSU, less saline than either C. jamaicense (39.1 ± 2.2 PSU) or S. portulacastrum (38.6 ± 2.5 PSU). Although the salinity tolerance of C. jamaicense is not known, it is unlikely that long-term exposure to high salinity is conducive to the persistence of this freshwater marsh sedge. This study increases our ecological understanding of how water uptake patterns of individual plants can contribute to ecosystem levels changes, not only in the southeast saline Everglades, but also in estuaries in general in response to global sea level rise and human-induced changes in freshwater flows.

Original languageEnglish
Pages (from-to)607-616
Number of pages10
JournalOecologia
Volume152
Issue number4
DOIs
StatePublished - Jul 1 2007

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ecotones
ecotone
water uptake
salinity
Cladium mariscus subsp. jamaicense
groundwater
Sesuvium portulacastrum
Rhizophora mangle
shallow water
water
oxygen isotope ratio
salinity tolerance
sedge
xylem
rooting
chronic exposure
wet season
macrophytes
water use
soil profile

Keywords

  • Mangrove ecotone
  • Plant water use
  • Seasonal water uptake

ASJC Scopus subject areas

  • Ecology

Cite this

Seasonal plant water uptake patterns in the saline southeast Everglades ecotone. / Ewe, Sharon M L; Sternberg, Leonel; Childers, Daniel L.

In: Oecologia, Vol. 152, No. 4, 01.07.2007, p. 607-616.

Research output: Contribution to journalArticle

Ewe, Sharon M L ; Sternberg, Leonel ; Childers, Daniel L. / Seasonal plant water uptake patterns in the saline southeast Everglades ecotone. In: Oecologia. 2007 ; Vol. 152, No. 4. pp. 607-616.
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