Ecophysiological characteristics of Avicennia germinans and Laguncularia racemosa coexisting in a scrub mangrove forest at the Indian River Lagoon, Florida

Authors

M. A. Sobrado, Laboratorio de Biología Ambiental de Plantas, Departamento de Biología de Organismos, División de Ciencias Biológicas, Universidad Simón Bolívar
Sharon M.L. Ewe, Southeast Environmental Research Center, Florida International University and Smithsonian Marine StationFollow

Abstract

The purpose of this work is to increase ecological understanding of Avicennia germinans L. and Laguncularia racemosa (L.) Gaertn. F. growing in hypersaline habitats with a seasonal climate. The area has a dry season (DS) with low temperature and vapour pressure deficit (vpd), and a wet season (WS) with high temperature and slightly higher vpd. Seasonal patterns in interstitial soil water salinity suggested a lack of tidal flushing in this area to remove salt along the soil profile. The soil solution sodium/potassium (Na⁺/K⁺) ratio differed slightly along the soil profile during the DS, but during the WS it was significantly higher at the soil surface. Diurnal changes in xylem osmolality between predawn (higher) and midday (lower) were observed in both species. However, A. germinans had higher xylem osmolality compared to L. racemosa. Xylem Na⁺/K⁺ suggested higher selectivity of K⁺ over Na⁺ in both species and seasons. The water relations parameters derived from pressure–volume P–V curves were relatively stable between seasons for each species. The range of water potentials (Ψ), measured in the field, was within estimated values for turgor maintenance from P–V curves. Thus the leaves of both species were osmotically adapted to maintain continued water uptake in this hypersaline mangrove environment.

Comments

This material is based upon work supported by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research program under Cooperative Agreements #DBI-0620409 and #DEB-9910514. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Recommended Citation

Sobrado, M.A., S.M.L. Ewe. 2006. Ecophysiological characteristics of Avicennia germinans and Laguncularia racemosa coexisting in a scrub mangrove forest at the Indian River Lagoon, Florida. Trees - Structure and Function 20(6): 679-687.