Fluctuating deposition of ocean water drives plant function on coastal sand dunes

Tara L. Greaver, Leonel S.L. Sternberg

Research output: Contribution to journalReview article

25 Scopus citations

Abstract

Sea-level rise will alter the hydrology of terrestrial coastal ecosystems. As such, it becomes increasingly important to decipher the present role of ocean water in coastal ecosystems in order to assess the coming effects of sea-level rise scenarios. Sand dunes occur at the interface of land and sea. Traditionally, they are conceived as freshwater environments with rain and ground water as the only water sources available to vegetation. This study investigates the possibility of ocean water influx to dune soils and its effect on the physiology of sand dune vegetation. Stable isotopes are used to trace the path of ocean water from the soil to the vegetation. Soil salinity, water content and δ18O values are measured concurrently with stem water and leaf tissue of eight species during the wet and dry season and from areas proximal and distal to the ocean. Our results indicate the dune ecosystem is a mixed freshwater and marine water system characterized by oceanic influence on dune hydrology that is spatially heterogeneous and fluctuates temporally. Ocean water influx to soil occurs via salt spray in areas 5-12m from the ocean during dry season. Accordingly, vegetation nearest to the sea demonstrate a plastic response to ocean water deposition including elevated integrated water use efficiency (δ13Cleaf) and uptake of ocean water that comprised up to 52% of xylem water. We suggest physiological plasticity in response to periodic ocean water influx may be a functional characteristic common to species on the leading edge of diverse coastal habitats and an important feature that should be included in modeling coastal ecosystems. Rising sea level would likely cause a repercussive landward shift of dune species in response to encroaching maritime influences. However, human development would restrict this process, potentially causing the demise of dune systems and the protection from land erosion they provide.

Original languageEnglish (US)
Pages (from-to)216-223
Number of pages8
JournalGlobal Change Biology
Volume13
Issue number1
DOIs
StatePublished - Jan 1 2007

Keywords

  • Coastal ecology
  • Eco-physiology
  • Island ecology
  • Ocean water
  • Oxygen isotopes
  • Plant distribution
  • Sea-level rise
  • Water sources

ASJC Scopus subject areas

  • Ecology
  • Global and Planetary Change
  • Environmental Science(all)
  • Environmental Chemistry

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