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FERNANDEZ HONAINE mariana
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Título:
Silicophytoliths and calcium oxalate crystals in plants and soils of Brazil mangrove environments
Autor/es:
BORRELLI, NATALIA; OSTERRIETH, MARGARITA; GOMES COE, HELOISA; ALTAMIRANO, STELLA MARIS; FERNÁNDEZ HONAINE, MARIANA
Lugar:
Colorado
Reunión:
Encuentro; 8th International meeting on phytolith research; 2011
Institución organizadora:
•PaleoResearch Institute (PRI), Golden, Colorado
Resumen:
In plants, silicophytoliths (SiO2Nh2O) and calcium oxalate crystals (CaC3Or.nH2O, COC) are the most common types of biomineralizations. These biomineralizations become part of the soil once the organic matter has been degraded. The silicophytoliths remain on the soil while calcium oxalate crystals, due to their high susceptibiliry to weathering, quickly degrade. The study of both rypes of biomineralizations has relevance for botany, taxonomy, pedological, paleobotan¡ and biogeochemistry. Mangrove ecosystems are considered very productive and have great ecological and socioeconomic imporance. Nevertheless, almost no information exists concerning the production of biomineralizations and their content in mangrove soils, so the aims of this study are to: l) describe and quantifr the silica and calcium biomineralizations in leaves of vegetal species characteristics of these ecosysrems, and 2) describe the phytolith assemblages of mangrove soil developed in the municipality of Casemiro de Abreu, fuo de Janeiro, Braztl. \We worked wirh Rhizophora mangle (Rhizophoraceae), Auicennia schaueriana (Avicenntaceae), Laguncularia racemlsrt (Combretaceae), and Auostichurn l¿ureuTn (Pteridaceae). The silicophytoliths were exrracred from the leaves by calcination method; calcium oxalate crystals were analyzed by diaphanized and cross sections. In each soil site, samples were taken 5cm below the surface to analyze the proportion of silicophytoliths regarding the total mineralogical components of the soil. For this purpose, iron, organic marter, and clay minerals were removed by routine analysis. Siiicophytoliths were observed in A. schauerirtna, A. Aureum, and L. racem¿s¿. Predominant morphotypes were tabular polygonal phytoliths and cylindrical sulcate tracheids in A, schaueriana; xomaral complexes and jigsaw phytoliths in 14. aureum, and a few fragments of tissues with cell walls siliciñe d in L. racemosa. Druses (COC) were observed in hypodermis and phloem in R. mangle; and spongy parenchvma and associated to vascular bundles in L. racemosa. A superficial soil sample was collected under a R. mangle and A. schaueriana mixed mangrove, with few Z. racernosa. A lot of sponge spicules and diatoms, characteristic of hydromorphic environments, were observed, but very few phytoliths, all very weathered and broken. Predominant morphowpes n'ere globular echinate, globular granulate, point shape, elongate, and debris of unidentifiable phr.tolirhs. Ther- are all associated with terrestrial vegetation developed around the mangroves. Probabl¡ the silicophvroliths senerated from the plant species associated to mangroves are not reflected in the soil due to i¡s lorl'producrion and/or state of silicification.