No abstract

-The objective of this work was to evaluate the feasibility of vegetative propagation through cutting technique of seven tree species with strong occurrence in the riparian forest of the Lower São Francisco River in Sergipe State, under different concentrations of indolbutiric acid at 0, 2500, and 5000 mg.L -1 , for potentialization of its use in soil bioengineering technique. It was used a complete random block design with three replicates, and a total of twenty-one treatments. The evaluation period was 120 days for each species, and the data collection was made in intervals of fifteen days, in a total of eight evaluations for each species. The evaluated parameters were: Survival Rate, callus formation, and Root Dry matter Weight. Among the studied species, Schinus terebinthifolius Raddi presented the best results related to cutting technique mainly under the indolbutiric acid concentration of 2500 mg.L -1 .

Recebido em: 09/11/2011 Aceito em: / / RESUMO Por ser um ecossistema frágil bastante susceptível as influências de origem climática os manguezais são apontados como indicadores biológicos para as modificações de linha de costa, em função da rápida resposta de suas espécies vegetais as alterações do sistema. Os principais agentes causadores de modificações ambientais estão hoje diretamente vinculados à ação humana o que acarreta ao manguezal no estuário do Rio São Francisco alterações com consequências de maior ou menor intensidade em sua estrutura. O foco deste artigo foi elaborar indicadores de sustentabilidade para o manguezal do estuário do Rio São Francisco usando como base a metodologia proposta pela OCDE adaptada pelo PNUMA. A identificação e aplicação dos indicadores fornecerão uma visão geral das condições de resiliência da floresta. Palavras-chave: Ecossistema, impactos, sustentabilidade ambiental. ABSTRACTBeing a very fragile ecosystem susceptible to weather influence, the mangrove is known as a biological indicator of coastline changes due to its plant species' fast answer to modified systems. The main causative agents of the environmental modification are nowadays linked directly to human actions which lead to less or more intense consequences in the structure of the mangrove in São Francisco River estuary. The focus of this article was to elaborate indicators of sustainability for the mangrove in the São Francisco River estuary using as its methodological basis the one suggested by OECD and adapted by PNUMA. The identification and application of these indicators will provide an overview of the forest resilience condition.

Mangrove ecosystem dynamics and diverse human activities have led to a need for studies that give us a better understanding of the peculiarities of their soils. The objective of this study was to evaluate the physical and chemical soil attributes of mangrove forests located in the São Francisco River estuary, related to local ecological conditions. Two stations, divided into three forest types (fringe, basin and transition) were selected and five composite soil samples were collected from each forest type. Soil samples were submitted for chemical and physical analysis. The soil presented a sandy texture, with high organic matter and element content in the following order: Mg 2+ >Na + >Ca 2+ >H + >K + >P>Al 3+ and Fe 2+ >Zn 2+ >Cu 2+ >Mn 2+ , respectively, with variations between the forests and stations. In general, the mangrove forests presented high fertility, especially in the basin forest, provided by vegetation development, showing a zoning trend for species in relation to soil fertility.

Santos et al.: Models for estimating the biomass of mangroves 44Allometric models for estimating the aboveground biomass of the mangrove Rhizophora mangleThe development of species-specific allometric models is critical to the improvement of aboveground biomass estimates, as well as to the estimation of carbon stock and sequestration in mangrove forests. This study developed allometric equations for estimating aboveground biomass of Rhizophora mangle in the mangroves of the estuary of the São Francisco River, in northeastern Brazil. Using a sample of 74 trees, simple linear regression analysis was used to test the dependence of biomass (total and per plant part) on size, considering both transformed (ln) and not-transformed data. Best equations were considered as those with the lowest standard error of estimation (SEE) and highest adjusted coefficient of determination (R values, probably attributed to the seasonal nature of this compartment. "Basal Area² × Height" showed to be the best predictor, present in most of the bestfitted equations. The models presented here can be considered reliable predictors of the aboveground biomass of R. mangle in the NE-Brazilian mangroves as well as in any site were this widely distributed species present similar architecture to the trees used in the present study. , o que pode ser atribuído ao caráter sazonal deste compartimento. "Área basal²×Altura" demonstrou ser o melhor preditor, presente na maioria das equações melhor ajustadas. Os modelos aqui apresentados podem ser considerados preditores confiáveis da biomassa aérea de R. mangle no manguezal do Nordeste brasileiro, bem como em qualquer local onde esta espécie de ampla distribuição assemelhe-se à arquitetura das árvores utilizadas no presente estudo. AbstrAct resumoDescritores: Equações alométricas, Biomassa aérea, Manguezal, Análises de regressão, Rhizophora mangle.

The objective of this work was characterize the floristic diversity and the phytosociological structure of the mangrove in the São Francisco River estuary in order to contribute to the conservation of this ecosystem. Thirtyfour sampling sites were selected, according to ongoing structural mosaic in the region ranging from 100 to 400 m between themselves, in a total useful area of 0.7625 ha. The evaluated parameters were: density of live and dead trunks; living and dead Basal Area; Absolute Frequency, Relative Frequency and Importance Value. Three typical mangrove species of the São Francisco estuary were found such as Avicennia germinans (L.) Stearn, Rhizophora mangle L. and Laguncularia racemosa (L.) Gaertn. F. Gaertn. The forest height ranged from 2.88 to 15.63 m, the DBH from 3.95 to 19.74 cm, live basal area from 4.22 to 47.83 m² ha-1 and dead basal area from 0.50 to 59.63 m² ha-1. The living trunks density ranged from 375.00 to 9100.00 trunks ha-1 and dead trunk density from 100-2800 trunks ha-1. The described results in this study demonstrated that the mangrove forests presents a structural variability that may be associated with environmental characteristics (marine erosion) and anthropogenic factors. The peculiarities of each site emphasize the importance of preventive actions in the ecosystem conservation.

Resumo -O uso intensivo do solo das margens do rio São Francisco em seu baixo curso, exerce influência direta na sua degradação, potencializando a ocorrência da erosão marginal e, alterando a dinâmica fluvial. O objetivo deste estudo foi caracterizar os atributos físicos e mecânicos do solo em talude fluvial, relacionando-os com à susceptibilidade a erosão no Baixo curso do rio São Francisco. O ensaio experimental foi conduzido na margem direita do rio São Francisco, localizado no Município de Amparo do São Francisco, nordeste do Brasil, em talude com solo classificado como Neossolo Flúvico. Foram realizadas coletas de amostras indeformadas e deformadas de solo com execução de sondagem a trado, até o nível freático, e a caracterização dos atributos físicos e mecânicos do solo em laboratório. A predominância de camadas mais arenosas possibilitou maior ângulo de atrito interno e consequentes diminuição da coesão e redução da resistência ao cisalhamento levando a intensificação dos movimentos de massa. Os processos de saturação e secagem, através das elevações da cota do rio, comprometeram a estabilidade do talude. A granulometria do solo do talude é determinante para a suscetibilidade ao processo erosivo, e consequentemente para o comportamento mecânico desse talude. Palavras-Chave-Cisalhamento direto, coesão, erosão marginalAbstract -The use of the riparian areas with agriculture in the Lower San Francisco has a direct effect on the degradation of these resources causing, bank erosion, and the imbalance in the river dynamics. The objective of this study was to verify the influence of soil physical and mechanical attributes in the susceptibility of the riverbanks to erosion in the lower São Francisco. The experimental area was located in the municipality of Amparo de São Francisco, located in the state of Sergipe, northeastern Brazil, in soil classified as Neossolo Flúvico. Undisturbed soil and then deformed soil samples were collected to run the auger boreholes down up to water level representing the slope layers. The predominance of more sandy layers allowed a greater angle of internal friction and consequent reduction of cohesion and reduction of shear strength leading to the intensification of soil mass movements. Saturation and drying through the elevations of the river quota compromise the slope stability. The texture of the slope material is closely related to the erosion susceptibility and the riverbank soil mechanical behavior.

No abstract