Flooding effects on phosphorus dynamics in an Amazonian mangrove forest, Northern Brazil

Aims and methods We examined porewater salinity, soil redox potential (Eh), soil extractable phosphate (extr.-P), leaf phosphorus (leaf-P) and plant growth in relation to inundation frequency (IF) and mangrove species distributions along a 600 m transect in the Bragança Peninsula, North Brazil. Results The forest species composition changed across the tidal zone with Avicennia germinans dominating (99.1%) the high intertidal (HI) zone where the IF was 41–67 d.y−1 , Rhizophora mangle, Laguncularia racemosa and A. germinans co-occured in the mid intertidal (MI), and a mixed R. mangle (47.1%) - A, germinans (41.2%) stand occupied the low intertidal (LI) zone with an IF of 124–162 d.y−1 . Low IF resulted in high Eh levels (200 mV) in the HI zone relative to the LI where Eh ranged from 0–100 mV. The IF showed a significant positive correlation with extr.-P (r=0,89; p=0.05) and a negative association with Eh (r=−0,75; p=0.05). Conclusion An ANCOVA confirmed that Eh and extr.P were influenced by flooding. Variations in these factors were reflected in patterns of P leaf tissue concentrations across the gradient; however, a MANCOVA showed that leaf-P was not related to tree height, tree volume or basal area. Waterlogging conditions, porewater salinity, and P dynamics in the sediment appear to influence the forest structure. We suggest that P availability plays an important role in controling mangrove species distributions but not their growth.Fil: Mendoza, Ursula N.. Zentrum für Marine Tropenökologie; AlemaniaFil: Cruz, Cleise Cordeiro da. Universidade Federal Do Pará; BrasilFil: Menezes, Moirah. Universidade Federal Do Pará; BrasilFil: Lara, Ruben Jose. Zentrum für Marine Tropenökologie; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Distribution of mangrove vegetation along inundation, phosphorus, and salinity gradients on the Bragança Peninsula in Northern Brazil

Background and aims The Bragança Peninsula, in northern Brazil is characterized by macrotides (4 m) and specific edaphic conditions, which determine the local mangrove forest’s development. This study, conducted during the dry season evaluated the spatial patterns of Rhizophora mangle and Avicennia germinans species across an inundation gradient. Methods Along a transect of 700 m, measurements of structure forest, soil moisture, porewater salinity, extractable phosphorus (extr.-P) in sediments, and phosphorus in the leaves (leaf-P) were conducted. Result The A. germinans (100 %) occurred in high intertidal (HI) zone. A. germinans (59 %) and R. mangle (41 %) co-occurred in mid intertidal (MI) zone, while R. mangle (58 %) predominated in low intertidal (LI) zone, followed by A. germinans (37 %) and Laguncularia racemosa (5 %). Covariance analysis (ANCOVA) indicated that salinity and soil moisture means are significantly different between the mangrove forests, but do not correlate with inundation frequency (IF). The means of extr.-P were significantly different in mangrove forests and correlated with IF and leaf-P. Conclusion The inundation frequency, the availability of P in the sediments, phosphorus in the leaves and interstitial salinity are all important factors contributing to the distribution of the mangrove tree species A. germinans and R. mangle on the Bragança Peninsula.Fil: Cruz, Cleise Cordeiro Da. Federal University of Pará. Institute of Geosciences; BrasilFil: Mendoza, Ursula Neira. Fluminense Federal University. Department of Environmental Geochemistry; Brasil. Universidade Federal Fluminense. Departamento de Geoquímica Ambiental; BrasilFil: Queiroz, Joaquim Barbosa. Federal University of Pará. Institute for Statistics and Mathematics; BrasilFil: Berrêdo, José Francisco. Goeldi Museum. Department of Earth Sciences and Ecology; BrasilFil: Costa Neto, Salustiano Vilar Da . Amapá State Institute for Scientific and Technological Research; BrasilFil: Lara, Ruben Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto Argentino de Oceanografía (i); Argentina. Zentrum für Marine Tropenökologie; Alemani