Elaine Bernini

Estrutura da vegetação em florestas de mangue do estuário do rio Paraíba do Sul, Estado do Rio de Janeiro, Brasil

A structural analysis of the mangrove forest at the Paraiba do Sul river estuary was performed using the stand method. The stands were demarcated in two points both at the forest edge and interior. The results indicate that average height varied from 6.3 to 9.9m; DBH varied from 7.44 to 13.4cm; average basal area varied from 14.5 to 35.3m2.ha-1, and average density varied from 1,920 to 3,400 trunks.ha-1 (trees > 1m height). These structural parameters did not differ between the edge and the interior, but the contribution of each species varied between the zones. Avicennia germinans (L.) Stearn. was the dominant species (60%), followed by Rhizophora mangle L. (25%), and Laguncularia racemosa (L.) Gaertn. (15%). These results demonstrate that the mangroves forest at the Paraiba do Sul estuary has a better structural development than other mangrove sites found in the Rio de Janeiro State (e.g., those mangrove forests located at the Sepetiba and Guanabara bays).

Distribuição das espécies e estrutura do manguezal do rio Benevente, Anchieta, ES

The structure of the mangrove forest of the Benevente River estuary, in Anchieta, ES, was analyzed by the plot method in order to evaluate the distribution of species along the river. The results indicated a trend of species distribution, in which Avicennia schaueriana Leechm ex Stapf & Moldenke and Rhizophora mangle L. exhibited the highest dominance and relative density in areas under greater marine influence, while Laguncularia racemosa (L.) Gaertn.f. and Avicennia germinans (L.) Stearn. showed higher dominance and relative density in areas under greater influence of fresh water. The density ranged from 700 to 7,866 stems.ha-1, the basal area from 10.3 to 72.2 m2.ha-1, the average height from 2.0 to 16.4 m and average DBH (diameter at breast height) from 4.7 to 27.3 cm. Most forests exhibited distribution of trunks of the inverted iota type, with an absence of selective cutting. The contribution of the basal area was larger in diameter class ≥10 cm, indicating the high structural development of the forests studied. The forests studied exhibited good conservation.

Spatial and temporal variation of the nutrients in the sediment and leaves of two Brazilian mangrove species and their role in the retention of environmental heavy metals

A variacao espacial e temporal das concentracoes de nutrientes das folhas e do sedimento entre as raizes de Laguncularia racemosa (L.) Gaertn. f. e Rhizophora mangle L. foi analisada no manguezal do estuario do Rio Sao Mateus, Espirito Santo, Brasil. No tecido foliar, os nutrientes seguiram a ordem: N > Ca > K > Mg > S > P > Fe > Mn > Zn > Cu, havendo diferenca significativa entre especies e sitios de estudo. Em geral, os teores de K foram mais elevados no periodo seco em relacao ao periodo chuvoso, para ambas as especies analisadas, enquanto que Ca e Cu exibiram maiores concentracoes no periodo chuvoso, para Laguncularia racemosa. No sedimento, os nutrientes seguiram a ordem: Mg > Ca > Fe > K > Mn > P > Zn > Cu, em geral, com menores concentracoes no sitio onde o sedimento foi mais arenoso. Registrou-se variacao significativa das concentracoes de nutrientes do sedimento entre os periodos analisados, mas o padrao sazonal nao foi claro para todos nutrientes. Concentracoes de nutrientes determinadas nas folhas de ambas as especies nao se correlacionaram com as concentracoes dos respectivos sedimentos. O fator de concentracao foi menor que 1,0 para Fe e entre 1,0 e 3,7 para Mn, Zn e Cu. Estes resultados fornecem evidencias fisiologicas sobre a relevância destas especies arboreas para o papel dos manguezais como barreira biogeoquimica ao trânsito de metais pesados.

Photosynthetic analyses of two native Atlantic Forest species in regenerative understory of eucalyptus plantation

Gas exchange, chlorophyll afluorescence, and photosynthetic pigments of Xylopia sericeaA. St.-Hil. and Siparuna guianensis Aubl. were evaluated during the rainy season and the dry season (2009-2010) in three understories with different ecological conditions (irradiance, water availability, and temperature) located in the Uniao Biological Reserve (known as REBIO Uniao), at Rio de Janeiro State, a natural forest understory, eucalyptus understory under regeneration, and understory of eucalyptus plantation with 18-year-old trees that were removed 1 year before. The lowest values of Fv/Fme Fm/Fowere observed in the exposed understory for both seasons, with lower values in the dry season, suggesting that reduced water availability potentializes the photoinhibitory process. For both species of the exposed understory it is suggested the occurrence of photoprotection, given that an increased proportion of carotenoid pigments in relation to the chlorophylls were verified. Both species still exhibited dynamic photoinhibition after 1 year of exposure to full sunlight (exposed understory) in both seasons, but more markedly so in the dry season, though they belong to early stages of ecological succession. Based on the results, it is suggested that these species are indicated for planting in degraded areas and that the cutting of eucalyptus trees as management practice should be performed in a gradual manner, during the rainy season, in order to minimize stress on these species.

Mangrove Forest Structure in the Sao Joao River Estuary, Rio de Janeiro, Brazil

ABSTRACT Calegario, G.; Salomão, M.S.M.B.; de Rezende, C.E., and Bernini, E., 2015. Mangrove forest structure in the São João River estuary, Rio de Janeiro, Brazil. Natural and anthropic factors contribute toward the formation of environmental gradients that act as selective forces that in turn determine the distribution of the mangrove species along these gradients. The aim of this study is to characterize the structure of two mangrove forests under different conditions of salinity and compare the structural parameters between the border and inside forests in the São João River estuary. One site 11 km from the ocean (upper estuary, site 1) and another 3 km from the ocean (lower estuary, site 2) were selected along the estuary. Within each site measurements of height and diameter breast height (DBH ) of individuals ≥1 m in height, and the pore-water salinity, granulometry, and organic matter of the sediment were analyzed. The average tree height varied from 3.1 to 6.1 m, the average DBH from 3.7 to 7.0 cm, the density from 5240 to 14,720 trunks ha−1, and the basal area from 8.0 to 35.5 m2 ha−1. A pattern of zonation was observed along the estuary, with Laguncularia racemosa (L.) Gaertn. f. dominant in the upper estuary and Rhizophora mangle L. dominant in the lower estuary. We observed no zonation of species between border and inside forest, but L. racemosa exhibited higher density in the upper estuary, and R. mangle in the lower estuary, thus defining a pattern of spatial zonation along the estuary.

Ecofisiologia de duas espécies tropicais em uma plantação abandonada de eucalipto: efeito da remoção da serapilheira e sazonalidade

The effect of the removal of plant litter on photosynthetic variables (gas exchanges, chlorophyll a luorescence, and content of photosynthetic pigments) of the tropical species Xylopia sericea A. St.-Hil. and Siparuna guianensis Aubl. was evaluated in an abandoned plantation of eucalypt (Corymbia citriodora (Hook.) K.D. Hill & L.A.S. Johnson (Myrtaceae)). The study was conducted at the Uniao Biological Reserve, Rio de Janeiro State, Brazil during the rainy and dry periods, after ive years of litter removal. The removal of plant litter did not inluence the ecophysiological responses of the species. There was however signiicant seasonal variation. During the dry period, intercellular CO 2 concentration (C i ), transpiration (E), and stomatal conductance (g s ) were decreased, while intrinsic eficiency of water use (IWUE), non-photochemical quenching (NPQ), and carotenoid values increased, suggesting a protective strategy against stress. Nevertheless, the values for F v /F m (maximum quantum eficiency) and F m /F o (ratio of luorescence yields for open and closed states) indicated that even during the dry period there was no reduction in photochemical activity in these species. Only S. guianensis exhibited a reduced net photosynthetic rate (A) during the dry period. The data indicated that X. sericea was photosynthetically more eficient under conditions of low water availability and that a 5-year period of plant litter removal failed to produce differences in ecophysiological processes in the species analyzed.