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.

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.

A degraded riparian area in the Uberaba River basin (Brazil) was restored by local landowners using a monoculture of the exotic species Syzygium cumini (L.) Skeels over 15 years. To assess this riparian restoration, we compared this experimental site (ES) with a disturbed site (DS) and a preserved site (PS) with regard to soil organic matter, humic and fulvic acids (HA and FA), glomalin, soil aggregation and porosity. The results did not show significant differences between ES and PS with regard to soil aggregation and porosity. The cation exchange capacity and the HA and FA contents of ES were significantly different from those in PS and DS. Whereas the HA content of ES was less than that in PS, FA was significantly increased. The order of aromatic composition of humic substances by site was PS > ES > DS and contrasted with the aliphatic composition, which was DS > ES > PS. A principal component analysis based on all variables demonstrated that ES was closer to PS than to DS but that there was no overlap among sites, as PS was driven by humic aromatic substances and the experimental site by fulvic and aliphatic compounds. We concluded that there was a functional recovery of ecosystem services related to soil aggregation and porosity, but the qualitative differences in organic matter formation between the restored and preserved sites were not consistent with ES being fully restored.

The objective of this study was to evaluate the basic infiltration rate (IB), the cumulative infiltration (CI) and electrical conductivity (EC) of saturated-paste extract, in a LUVISSOLO CRÔMICO cultivated under tillage systems such as conventional tillage (CT), the minimum tillage (MT) and no-tillage (NT), on crop rotation. The infiltration basic velocity (IB) andAccumulated infiltration(CI) were determined by the ring infiltrometer; EC by thesaturated-paste method and moisture by the gravimetric method. After two and a half years of field research, the infiltration rate and cumulative infiltration was greater in NT, followed by MT and CT.Higher water infiltration rates are related to the sites where conservation practices were adopted, improving soil structure.

No abstract