Analysis of floristic composition and structure of a tract of terra firme forest and of an adjacent mangrove stand on the Ajuruteua peninsula in Bragança, Pará

The current article provides data about floristic composition and forest structure of a terra firme forest fragment and a mangrove stand on Ajuruteua Peninsula, Bragança, Pará. The fragment is situated next to mangrove forest, without being exposed to tidal inundation. Compared to the mangrove, density and basal area are distinctly higher in terra firme forest (2320.0±736.1/417.7±349.6 indiv..ha-1; 25.2±11.0/9.1±5.3 m2.ha-1 for terra firme and mangrove forest, respectively). Three tree species form the mangrove forest, Rhizophora mangle, being the dominant species. Among the 40 families (71 species) found in terra firme, Arecaceae, Burseraceae (represented exclusively by Protium heptaphyllum) and Simaroubaceae (represented by Simarouba amara reach high importance values. Terra firme forest differs in species composition and complexity from restinga dune forest found in other parts of the peninsula. The high importance of palms in the terra firme forest could indicate influence of man in the past

Investigations of Mangrove Forest Dynamics in Amazonia, North Brazil

The north coast of the Brazilian states of Para, and Maranhao, presents a large continuous belt of mangroves, covering an area of about 700 000 ha. Although mangroves in this region are relatively well preserved, expanding tourism, intensification of fisheries and of urban growth in the region may endanger this important coastal ecosystem. In spite of the immense area covered by mangrove forest, very few is known about species distribution and forest ecology in the region. The present study focuses on the growth dynamics of the mangrove species Rhizophora mangle L. under different conditions of inundation frequency, salinity and rainfall regime on the north coast of Brazil. The study concentrates on: 1) evidence of seasonality in primary production, reflected in phenology, litter fall and interactions with herbivores; 2) application of dendrochronological methods on R. mangle, including determination of tree age and influence of climatic and site-specific factors on tree growth; 3) applying these findings in an analysis of forest structure and dynamics on Ajuruteua Peninsula. Wood samples for dendrochronology were taken at three points along the coast of Para: Viseu, Sao Joao de Pirabas and Braganca. Detailed studies of phenology and litter fall, herbivory, forest structure and forest evolution were developed at different sites on Ajuruteua Peninsula, Braganca district.A study on litter fall and phenology demonstrated that rainfall seasonality is reflected in mangrove tree primary production. The description of a severe infestation by moth larvae in mangrove forests demonstrated that, besides climate and site-specific conditions, herbivory can be substantially influence the primary production.The wood of all studied specimens of R. mangle showed distinct rings. The rings were formed by a light and a dark layer. The light layer, formed at the end of the rainy season, is the result of a higher density of vessels; the dark layer, formed at the end of the dry season. The increase or decrease of vessels may be a reaction to seasonal salinity variation. Radiocarbon analysis showed that growth rings are annual. This allowed to the determination of tree age. The oldest tree was 111 years old.Growth curves revealed a linear growth (absence of trend-age). Growth rates varied strongly. The highest (however, not significantly different) rates were found at the sector of the Para coast with the highest tidal amplitudes, suggesting an influence of the tide on tree growth. The relationship between rainfall and growth was not easily interpretable, however, growth was positively correlated to rainfall in some areas. A presumed influence of rainfall may have been superimposed by the impact of other factors as salinity and input of fresh water.Growth rates on Ajuruteua Peninsula were highly variable. Trees were tentatively divided in three groups (fast, medium and slow growth). Although trees from each study sitecould occur in more than one group, there is an obvious trend that trees from frequently inundated areas dominate the group with the highest growth rate. Considering that all sites are submitted to similar climatic conditions, the absence of fast growing trees at certain sites may be due to the influence of local factors (e. g. salinity, inundation frequency or also neighbourhood competition among trees). It is assumed that neighbourhood competition is an important source of within-site variability of growth rates.The determination of the age of forest stands in combination with a classical study of forest structure allowed to propose a model of forest succession. This study demonstrated that the combination of forest structure surveys and dendrochronological methods provided informations concerning trees growth and forest development that were up to now not available. The application of these informations in mangrove forest management and preservation is suggested. In spite of the weak correlations between tree growth and climatic factors, dendrochronology may also help to understand changes of coastal vegetation within the past decades

Untersuchungen von Mangrovenwälder-Dynamiken in Amazonien, Nord-Brasilien

The north coast of the Brazilian states of Para, and Maranhao, presents a large continuous belt of mangroves, covering an area of about 700 000 ha. Although mangroves in this region are relatively well preserved, expanding tourism, intensification of fisheries and of urban growth in the region may endanger this important coastal ecosystem. In spite of the immense area covered by mangrove forest, very few is known about species distribution and forest ecology in the region. The present study focuses on the growth dynamics of the mangrove species Rhizophora mangle L. under different conditions of inundation frequency, salinity and rainfall regime on the north coast of Brazil. The study concentrates on: 1) evidence of seasonality in primary production, reflected in phenology, litter fall and interactions with herbivores; 2) application of dendrochronological methods on R. mangle, including determination of tree age and influence of climatic and site-specific factors on tree growth; 3) applying these findings in an analysis of forest structure and dynamics on Ajuruteua Peninsula. Wood samples for dendrochronology were taken at three points along the coast of Para: Viseu, Sao Joao de Pirabas and Braganca. Detailed studies of phenology and litter fall, herbivory, forest structure and forest evolution were developed at different sites on Ajuruteua Peninsula, Braganca district.A study on litter fall and phenology demonstrated that rainfall seasonality is reflected in mangrove tree primary production. The description of a severe infestation by moth larvae in mangrove forests demonstrated that, besides climate and site-specific conditions, herbivory can be substantially influence the primary production.The wood of all studied specimens of R. mangle showed distinct rings. The rings were formed by a light and a dark layer. The light layer, formed at the end of the rainy season, is the result of a higher density of vessels; the dark layer, formed at the end of the dry season. The increase or decrease of vessels may be a reaction to seasonal salinity variation. Radiocarbon analysis showed that growth rings are annual. This allowed to the determination of tree age. The oldest tree was 111 years old.Growth curves revealed a linear growth (absence of trend-age). Growth rates varied strongly. The highest (however, not significantly different) rates were found at the sector of the Para coast with the highest tidal amplitudes, suggesting an influence of the tide on tree growth. The relationship between rainfall and growth was not easily interpretable, however, growth was positively correlated to rainfall in some areas. A presumed influence of rainfall may have been superimposed by the impact of other factors as salinity and input of fresh water.Growth rates on Ajuruteua Peninsula were highly variable. Trees were tentatively divided in three groups (fast, medium and slow growth). Although trees from each study sitecould occur in more than one group, there is an obvious trend that trees from frequently inundated areas dominate the group with the highest growth rate. Considering that all sites are submitted to similar climatic conditions, the absence of fast growing trees at certain sites may be due to the influence of local factors (e. g. salinity, inundation frequency or also neighbourhood competition among trees). It is assumed that neighbourhood competition is an important source of within-site variability of growth rates.The determination of the age of forest stands in combination with a classical study of forest structure allowed to propose a model of forest succession. This study demonstrated that the combination of forest structure surveys and dendrochronological methods provided informations concerning trees growth and forest development that were up to now not available. The application of these informations in mangrove forest management and preservation is suggested. In spite of the weak correlations between tree growth and climatic factors, dendrochronology may also help to understand changes of coastal vegetation within the past decades

Vegetação de manguezais na Amazônia: uma revisão dos estudos da costa dos Estados Pará e Maranhão, norte do Brasil

The present study is a compilation of the literature about vegetation of mangrove forest of the north coast of Brazil. It synthesizes the knowledge about this important ecosystem and lists the currently available literature. The study focuses on the coast of Pará and Maranhão states, which are covered by a continuous belt of mangroves. The mangrove flora comprises six mangrove tree species and several associated species. Mangrove tree height and stem diameter vary as a function of abiotic local stand parameters. Seasonal variation in rainfall and salinity affect the species' phenology and litter fall. Local population use products derived from mangrove plants for different purposes (e.g. fuel; medicinal; rural construction). The increase in the coastal population has given rise to conflicts, which impact on mangrove forest.CNPq - Conselho Nacional de Desenvolvimento Científico e TecnológicoO presente estudo apresenta uma compilação da literatura sobre a vegetação dos manguezais da costa norte do Brasil, apresentando uma síntese do conhecimento e listando a literatura disponível. O estudo se concentra na costa dos estados do Pará e Maranhão que formam um cinturão contínuo de manguezais. Foram contabilizadas seis espécies arbóreas exclusivas de mangue e várias outras associadas. A altura e o diâmetro das árvores de mangue variam em função de parâmetros abióticos locais. As variações sazonais do regime de chuvas e da salinidade afetam a fenologia das espécies e a produção de serapilheira. A população costeira utiliza a flora do manguezal para diferentes fins (ex: combustível, medicinal, construção rural). O aumento da ocupação costeira inicia um processo de impacto para as florestas de mangue e a disponibilidade de seus recursos.MENEZES, M. P. M. Universidade Federal do Par

Structure of mangrove stands on the Bragança peninsula, Pará, Brazil

The study describes the forest structure of three mangrove stands (Acarajó, Furo do Meio and Furo Grande) on Bragança peninsula, north-eastern Pará state, Brazil, using the point centered quarter method (PCQM). Three typical mangrove tree species were found: Rhizophora mangle, Avicennia germinans and Laguncularia racemosa. At all stands, R. mangle reached the highest importance values. At AC, we found individuals of various size classes, indicating possibly a constant rejuvenation process. At Furo do Meio, there were various individuals of medium size, indicating a peak of renovation event in the past. Furo Grande was characterised by a stand still in development, with mainly medium-sized trees and few larger specimens. The relationship between dbh and height showed that height growth is size limited. Tree density appeared low in comparison to other reports; however, examination of the dbh size class distribution reveals that the stands of the present investigation are mainly composed of comparatively large trees. Cluster analysis separated two groups, segregating Furo do Meio from both other sites (Acarajó, Furo Grande)

Native plants used by Vila dos Pescadores community, Caeté-Taperaçu Marine Extractive Reserve, Amazon coast, Brazil

This study identifies the native plant species used by the inhabitants of Vila dos Pescadores, Caeté-Taperaçu Marine Extractive Reserve, Bragança, Pará, Brazil. By means of semi-structured interviews with 30 inhabitants, a socio-economic profile of the people interviewed was done; useful plant species and their respective usage were recorded. A total of 23 species were cited. Of these, 20 species are native to mangrove or sand dune (restinga) ecosystems. The remaining 3 species are considered "native" by village inhabitants, although they are in fact introduced exotic species. Most of the restinga species are used for food, while most mangrove species are employed in a broad range of usage types, mainly associated with "construction" and "technical applications" categories. The fishing profession was evident in plant species usage, especially for the mangrove species. The Shannon diversity index was high (H'=2.3) due to the large number of reported uses of mangrove species. The results indicate that, due to the great utility of native plant species, the management, use and preservation policies of Marine Extractive Reserves should pay more attention to the exploitation of plant resources, especially those from mangrove forests.O presente estudo identifica as espécies vegetais nativas utilizadas pelos moradores da Vila dos Pescadores localizada na RESEX Marinha Caeté-Taperaçu, em Bragança, Pará. Através de entrevistas baseadas em protocolos semi-estruturados realizadas com 30 moradores, foi traçado o perfil sócio-econômico dos entrevistados, identificadas as espécies vegetais úteis e seus respectivos usos. No total foram citadas 23 espécies, sendo que 20 espécies são oriundas dos ecossistemas manguezal ou restinga e as outras 3 espécies são consideradas nativas pelos moradores, apesar de serem espécies não típicas da região. As espécies de restinga são utilizadas principalmente como alimento, enquanto as espécies do manguezal apresentam um amplo espectro de utilidades, com destaque nas categorias "construção" e "tecnologia". O ofício de pescador ficou evidente nos usos dos recursos vegetais, principalmente das espécies de manguezal. O valor do índice de diversidade de Shannon foi alto (H'=2,3) por causa da grande citação de usos das espécies de mangue. Os resultados indicam que devido à grande utilidade das espécies vegetais nativas, a gestão e políticas de uso e preservação das RESEX Marinhas devem dar mais atenção à exploração dos recursos vegetais, principalmente de manguezal

Vegetação de restinga do Estado do Pará, Amazônia Brasileira: uma síntese

The present article reviews studies (some unpublished) of the vegetation of coastal sandy soils (restinga) along the coast of Pará State, northern Brazil. A total of 411 higher plant species are reported; Fabaceae, Poaceae, Cyperaceae, Rubiaceae and Myrtaceae are the most species-rich families. Nearly half of the restinga species (48%) are terrestrial herbs; palms, trees and shrubs account for 39% of the species, the remainder being lianas and epiphytes. Species are frequently wide-spread and occur in coastal areas of Southeastern Brazil as well as at inland sites in the Amazon region. Only two species appear to be exclusively coastal; whereas other species appear to exhibit a preference for sandy soils. Plant assemblages are commonly classified by means of "formations" associated with certain habitats but current data do not allow the description of well-defined plant associations. The species composition at different sites along the Pará coast does not show any clear regional grouping pattern. Seasonal changes in the composition of restinga vegetation are most probably linked to variation in ground water level. Restinga forest is mostly low and open; among the dominant tree species are Humiria balsamifera Aubl., Pouteria ramiflora (Mart.) Radlk., Anacardium occidentale L., Byrsonima crassifolia (L.) Kunth, and Tapirira guianensis Aubl.Este artigo apresenta uma revisão dos estudos (alguns não publicados) da vegetação de restinga da costa do Estado do Pará, na região norte do Brasil. Ao todo foram registradas 411 espécies de plantas vasculares, sendo as famílias Fabaceae, Poaceae, Cyperaceae, Rubiaceae e Myrtaceae as mais ricas em espécies. Dentre as espécies da restinga, 48% são ervas terrestres, 39% são palmeiras, árvores e arbustos, sendo o restante constituído por lianas e epífitas. As espécies são amplamente distribuídas ocorrendo inclusive em ambientes costeiros de outras regiões brasileiras, como a região sudeste, assim como em ambientes não costeiros da Amazônia. Apenas duas espécies parecem ser exclusivamente costeiras, já outras espécies parecem ter preferência por ambientes de solo arenoso em geral. Diferentes associações de plantas são descritas e agrupadas em diferentes tipos de "formações vegetais" associadas à certos habitats, mas os dados da literatura não permitem identificar com precisão tais associações em toda a costa. Análises estatísticas mostraram que a distribuição das espécies ao longo da costa não apresentam nenhum padrão de agrupamento. Mudanças na composição da vegetação de restinga nas estações seca e chuvosa são mais provavelmente ligadas à variação do nível do lençol freático. As florestas de restinga são, em sua maioria, abertas e de pequeno porte. Entre as espécies arbóreas dominantes estão: Humiria balsamifera Aubl., Pouteria ramiflora (Mart.) Radlk., Anacardium occidentale L., Byrsonima crassifolia (L.) Kunth e Tapirira guianensis Aubl

Structural analysis of two mangrove stands, Cajutuba river, municipality of Marapanim, Pará, Brazil

The present study describes the structural characteristics of the mangrove forest of the Cajutuba river, municipality of Marapanim, Pará state, Brazil. The point centered quarter method (PCQM) was used to analyze two transects at two different study sites (C1, C2). Three mangrove species were found: Rhizophora mangle L., Avicennia germinans (L.) L. and Laguncularia racemosa C. F. Gaertn. At C1, all three species were registered. C2 is an almost monospecific R. mangle forest (one single tree of A. germinans). At C1, tree heights varied between 4 and 21 m, while diameter ranged between 8,6 and 108,3 cm. At C2, tree height varied between 10 and 22 m, stem diameter between 10,5 and 97,1 cm. C2 presented the highest basal area values. At C1, numerous individuals had intermediate diameters, but small trees also occurred. At C2, 76% of the trees had diameters between 25 and 30 cm, but small trees were almost absent. Diameter and height of mangrove trees at C2 are significantly larger than those at C1. Salinity results are not enough to take conclusive results