Agostinho Lopes de Souza

Composição florística de dois trechos em diferentes etapas serais de uma floresta estacional semidecidual em Viçosa, Minas Gerais

This study was carried out in two sites of a semideciduous forest, under different stages of secondary succession in Vicosa, MG to verify qualitative variations in floristic composition. In each site, ten plots of 10 m x 20 m were delimited, with all woody individuals with circumference at 130 cm height from the soil larger than or equal to 5 cm being listed. Floristic similarity among parcels was evaluated through clustering analysis, using the Sorensen index. Sixty-seven species were sampled in the 15-year-old area, and 69 species in the 30-year-old area. Among the exclusive species, 38 were placed in the younger site and 40 in the older. The families Annonaceae, Leguminosae Caesalpinioideae and Sapindaceae, with five, four and four species, respectively, and the genus Nectandra, with two species, were better represented in the 15-year-old site. On the other hand, the families Flacourtiaceae, Meliaceae and Myrtaceae, with four, three and four species, respectively, and the genus Ocotea, with three species, were better represented in the 30-year-old site. Floristic similarity among plots from the same area was considered high, being related to spatial proximity, which reflects similar bakgrounds of disturbance and regeneration, consequently resulting in similar floristic compositions and secondary succession stage.

MORFOMETRIA DA BACIA HIDROGRÁFICA DA CACHOEIRA DAS POMBAS, GUANHÃES - MG 1

RESUMO – O objetivo deste trabalho foi estudar a morfometria da bacia hidrografica da Cachoeira das Pombas, localizada no Municipio de Guanhaes, MG. A base de dados foi disponibilizada pelo convenio SIF/CENIBRA/ UFV e consistiu dos dados matriciais Modelo Digital de Elevacao Hidrologicamente Consistente (MDEHC), rede hidrografica e direcoes de escoamento. As caracteristicas morfometricas e delimitacao da bacia e subbacias hidrograficas foram obtidas automaticamente pelo software Hidrodata 2.0. A area de drenagem encontrada foi de 6,981 km² e o perimetro de 14,864 km. De forma geral, constatou-se que a area estudada possui forma alongada, com baixa densidade de drenagem, relevo forte-ondulado e declividade media de 33,9%. Esses parâmetros possuem grande influencia sobre o escoamento superficial e, consequentemente, sobre o processo de erosao, que resulta em perda de solo, agua, materia orgânica, nutrientes e microfauna, que podem vir a provocar o assoreamento e eutrofizacao dos corpos d´agua. Quanto a orientacao do terreno, pode-se se constatar que 41% do terreno da bacia hidrografica esta exposto a face norte-oeste, e 33% de sua area total encontra-se sombreada. Para um estudo mais detalhado, procuraram-se caracterizar suas sub-bacias, onde cada uma foi analisada individualmente, concluindo-se que as cinco sub-bacias apresentam deficiencia de densidade de drenagem e forma alongada. Em termos de declividade media, os valores variaram entre 29,6 e 40,4%, representando o relevo forte-ondulado. Pode-se constatar, tambem, que a morfometria diferenciada entre as sub-bacias evidencia a necessidade de um manejo especifico de cada uma delas.

Modelo de distribuição diamétrica para povoamentos de Eucalyptus sp. submetidos a desbaste

Data used for this study are from a thinning essay established in stands of eucalypt carried out in the Copener Florestal enterprise, in the Northeast region of Bahia State, Brazil. Data were collected in 48 rectangular permanent plots, with an area of 2,600 m2. The first thinning was made at 58 months. Various percentages of basal area reductions were used. The objective of the study was to build and quantitatively evaluate, through statistical tests, a growth and yield model by diameter class for thinned eucalypt stands. The theoretic redistribution of diameters by class was made through equations that include both linear and non-linear relations between the Weibull function parameters in a future age (b2 and g2) and the parameters at the present age (b1 and g1) and with some stand characteristics at the present and future age. Three equations systems were analyzed. The equations were analyzed through the adjusted determination coefficient, the correlation coefficient and the graphical analyses of the residues. Tests were performed to verify the compatibility of the systems and the identity among them. The selected system is compatible and assures the property that when the future age (I2) is equal to the present age (I1), the diametric distribution at the future age is equal to the diametric distribution at the present age. This system generated accurate and consistent estimates of growth and yield per diameter class.

DINMICA DA ESTRUTURA FITOSSOCIOL"GICA DA REGENERA˙ˆO NATURAL EM SUB-BOSQUE DE Mimosa scabrella Bentham EMREA MINERADA, EM POOS DE CALDAS, MG 1

Como estrategia de reabilitacao de area minerada foram realizados, no ano agricola 1982/1983, hidrossemeadura de gramineas e leguminosa e o plantio puro de Mimosa scabrella Bentham em Pocos de Caldas, MG. Em 1997 foi implantado um conjunto de 19 parcelas permanentes de 50 m2 nessa area, para caracterizacao inicial do processo de regeneracao natural. Em 2000, foi realizado o segundo inventario nas parcelas, para caracterizacao do processo de dinâmica da regeneracao natural, que e o objeto deste trabalho. O processo de dinâmica da regeneracao natural foi caracterizado mediante analises quantitativas e qualitativas da composicao floristica e da estrutura horizontal e vertical. O povoamento florestal do Retiro-Branco esta sobre intensa atividade de estruturacao, caracterizando o estagio inicial do processo de sucessao. O declinio do povoamento puro de Mimosa escabrella esta modificando a ordem anteriormente estabelecida para o processo de sucessao da area, provocando a diversificacao de condicoes de sitio e, assim, selecionando a ocupacao deste em funcao dos grupos ecologicos, sendo as especies pioneiras as mais favorecidas. As especies secundarias sao as de maior dominância nas maiores classes de altura e de diâmetro, sendo as principais responsaveis pela edificacao do estrato superior, em especial a especie Miconia sellowiana. As especies que apresentaram melhor desempenho na colonizacao e estruturacao da regeneracao natural do Retiro-Branco, nos dois inventarios, foram Miconia sellowiana, Psychotria sessilis, Leandra melastomoides, Clethra scabra, Myrsine umbellata, Miconia pepericarpa, Tibouchina candolleana, Cordia superba, Cestrum amictum, Alchornea triplinervia, Casearia sylvestris, Blepharocalyx salicifolius, Myrcia rostrata e Schinus terebinthifolius, sendo indicadas como especies para uso nos programas de reabilitacao de areas mineradas em condicoes semelhantes sobre a estrategia sucessional.

Influence of Soil Physical Properties on Plants of the Mussununga Ecosystem, Brazil

Distribution ranges of plant species are related to physical variables of ecosystems that limit plant growth. Therefore, each plant species response to physical factors builds up the functional diversity of an ecosystem. The higher the species richness of an ecosystem, the larger the probability of maintaining functions and the higher the potential number of plant functional groups (FGs). Thus, the richness potentially increases the number of functions of the highly diverse Atlantic Rainforest domain in Brazil. Severe plant growth limitations caused by stress, however, decrease species richness. In the Spodosols of the Mussununga, an associated ecosystem of Atlantic Rainforest, the percentage of fine sand is directly related to water retention. Moreover, the depth of the cementation layer in the Mussununga’s sandy soil is a physical factor that can affect the plants’ stress gradients. When a shallow cementation layer depth is combined with low water retention in soils and with low fine sand percentage, the double stresses of flooding in the rainy season and water scarcity in the dry season result. This study aimed to identify FGs among Mussununga plant species responding to water stress gradients of soil and to verify the effects of the gradients on plant species richness of the Mussununga. A canonical correspondence analysis (CCA) of species abundance and soil texture variables was performed on 18 plots in six physiognomies of the Mussununga. Species richness rarefactions were calculated for each vegetation form to compare diversity. The two main axes of the CCA showed two FGs responding to soil texture and cementation layer depth: stress tolerator species and mesic species. Physical variables affect plant diversity, with species richness rising as the fine sand proportion also rises in the Mussununga. The effect of the cementation layer is not significantly related to species richness variation.

Comparação entre florestas de várzea e de terra firme do Estado do Pará

RESUMO – Foram analisados agrupamentos floristicos entre comunidades arboreas localizadas em diferentes locais do Estado do Para, por meio de um banco de dados composto por 24 inventarios em florestas de terra firme e 10 em floresta de varzea. Utilizaram-se o indice de Jaccard no calculo da matriz de similaridade floristica, que foi transformada em matriz de distância euclidiana, e o Metodo de Ward na definicao dos grupos. Pelos resultados, foi possivel concluir que as composicoes floristicas das florestas de varzea e terra firme sao bem distintas. Poucas especies ocorrem nos dois ecossistemas; a floresta de terra firme apresenta maior riqueza de especies arboreas que a floresta de varzea; houve tendencia das florestas de terra firme em se agruparem mais pela situacao antropica e proximidade geografica do que as florestas de varzea; em geral, as florestas agruparam-se em ordem decrescente de importância dos fatores: saturacao hidrica do solo, situacao antropica e proximidade geografica.

Quantificação de biomassa e estimativa de estoque de carbono em uma floresta madura no município de Viçosa, Minas Gerais

The objective of this study was to quantify the stem biomass without bark and the carbon stock in a mature forest located in the municipal district of Vicosa (MG). The biomass quantification was performed using the non-destructive method, by the use of a mean wood density of species of greater importance value. Three hundred and nineteen tree species were registered, belonging to 177 genera and 60 families. The quantification of the biomass resulted in 166,67 t.ha-1, which corresponds to 83,34 tC.ha-1. The estimates obtained for the mature forest can be used as a reference for the establishment of afforestation/reforestation projects in the scope of the Clean Development Mechanism.

Valoração ambiental de áreas de preservação permanente da microbacia do ribeirão São Bartolomeu no Município de Viçosa, MG

The objective of this work was to estimate an economic value for the Permanent Preservation Areas in Sao Bartolomeu watershed, located in Vicosa, MG. The Contingent Valuation Method was used to estimate the true willingness-to-pay (WTP) of the city of Vicosa residents for the restoration or preservation of these areas. The monthly true WTP was estimated at R

Individual Growth Model for Eucalyptus Stands in Brazil Using Artificial Neural Network

27.98 per residence, which results in an approximated total value of R

Comparação de métodos de amostragem para análise estrutural de florestas ineqüiâneas

3.863.926.08 or R