Nutrient and salt relations of <Emphasis Type="Italic">Pterocarpus officinalis</Emphasis> L. in coastal wetlands of the Caribbean: assessment through leaf and soil analyses |
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Authors: | Ernesto Medina Elvira Cuevas Ariel Lugo |
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Institution: | (1) Centro de Ecología, IVIC, Apartado 21827, Caracas, 1020-A, Venezuela;(2) International Institute of Tropical Forestry, USDA Forest Service, Río Piedras, PR 00926-1119, USA;(3) Department of Biology, University of Puerto Rico, Río Piedras, PR, USA |
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Abstract: | Pterocarpus officinalis L. is a dominant tree of freshwater coastal wetlands in the Caribbean and the Guiana regions. It is frequently associated
with mangroves in areas with high rainfall and/or surface run-off. We hypothesized that P. officinalis is a freshwater swamp species that when occurring in association with mangroves occupies low-salinity soil microsites, or
alternatively that it possesses mechanisms preventing accumulation of salt in photosynthetic tissues. To test this we compared
the mineral composition of soils and leaves of several species in two Pterocarpus forests in Puerto Rico associated with coastal mangroves, Sabana Seca and Punta Viento. Results indicate that (1) Sabana
Seca has low soil salinity values even in the P. officinalis and Laguncularia
racemosa mixed zone. In Punta Viento, salinity in the mixed zone was higher than in the Pterocarpus forest, but much lower than in the mangrove area; (2) In both forests, leaves of P. officinalis showed much lower Na concentrations than mangrove species. The K/Na ratios were 16–20 times higher in P. officinalis, indicating preferential absorption of K against Na. The mangrove fern (Acrostichum aureum) growing side by side with P. officinalis and L. racemosa in Punta Viento also revealed high Na exclusion capacity. We found an asymmetric distribution of cations in the blade and
rachis of the P. officinalis compound leaves in both sites. The rachis accumulates more Na and Ca, but less Mg than the leaf blade. This sequestration
of Na in the rachis prevents salt damage of photosynthetic tissue in the leaf blade. |
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Keywords: | Pterocarpus officinalis Mangroves Caribbean Salt tolerance Cation compartmentation |
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