Sebastião Venâncio Martins

Estrutura da vegetação arbustivo-arbórea colonizadora de uma área degradada por mineração de caulim, Brás Pires, MG

This study aimed to analyze the floristic composition of shrub-tree vegetation colonizing an area degraded by kaolin mining in Bras Pires, MG, compare it with other forest fragments and characterize ecological aspects of species and soil of the area. The sampled area was 0.5 ha subdivided in 50 grid plots of 10x10 meters each. All individuals included had CAP equal or larger than 10cm. The floristic composition is the result of the sampled area plus species collected outside of it. A total of 64 species was obtained, distributed in 50 genera and 30 families. The families with the greater number of species were Leguminosae (11), Annonaceae (5), Lauraceae e Melastomataceae (4), while the richest genus was Machaerium (3). The soil analysis revealed that it had not impaired the vegetation colonization. The main dispersal syndrome was zoochorous, showing the importance of remnant individuals, surroundings forest fragments and its fauna. The greatest floristic similarity occurred in Cruzeiro, SP, being both areas at the same successional stage.

Caracterização morfométrica da bacia hidrográfica do rio Debossan, Nova Friburgo, RJ

The objective of this work was to perform a morphometric characterization based on some physical parameters. In order to do so, a Hydrologically Consistent Digital Elevation Model (HCDEM) was generated from IBGE topographical maps, scale 1:50.000, using as database and analysis the system of geographic information, by means of the ArcVIEW and Arc/INFO version 8.3 systems. From this, some morphometric parameters of a previous study on the hydrologic behavior of the watershed were calculated. The drainage area was 9,9156 Km2 and 17,684 km in perimeter. The Debossan river watershed was proven not easily subject to floods as the compacity coefficient was far from the unit (1.5842) and its shape factor presented a low value (0.3285). Such fact can still be proven by the circularity index value (0.3985). The drainage density was 2,3579 Km/Km2, showing that the watershed has average draining capacity. The drainage system forms a dendritic pattern. This pattern occurs in high lands, in which the regolith and the parent rock relatively provide a uniform resistance to erosion. The more elongated watershed shape, as the circularity index, shape factor and compacity coefficient, indicates that the rainwater volume that falls within the watershed is concentrated in different points, contributing to reduce rain intensities that could cause greater flow variations.

Uso de parcelas de areia para o monitoramento de impacto de estradas sobre a riqueza de espécies de mamíferos

Faunal monitoring is an essential procedure to evaluate the efficiency of a conservation unit. The aims of this paper were to evaluate the use of sand-plots to record mammal tracks for estimating species richness in habitats crossed by roads and to analyze the applicability of this method to propose a monitoring program. The survey was carried out in Rio Doce State Park, MG, in two sampling grids composed by 3 parallel transects at different distances from the forest (12, 82 and 152 m ), monitored from March to November 2000. Species richness estimates were obtained by applying the EstimateS program and the MONITOR program to calculate the power of the analysis to estimate a probability of detection (p=0.90) of a decline (5%)in the number of species on the road borders. Species richness estimates in the transects varied between 5.99 (SD 0.99) and 15.07 (SD 1.75). The results indicate that a monitoring program needs at least 3 surveys per year during 4 consecutive years using the same sampling protocol to detect a 5% decline in species richness on the road, with 0.90 probability. The use of sand plots is an easy-to use method that can be applied to estimate mammal species richness, and provide important information to management and conservation of these species.

Banco de sementes como indicador de restauração de uma área degradada por mineração de caulim em Brás Pires, MG

Este estudo teve como objetivo caracterizar o banco de sementes sob vegetacao secundaria em uma area degradada por mineracao de caulim em Bras Pires, MG. Foram coletadas 40 amostras de solo de 0,5 x 0,5 m ate a profundidade de 5,0 cm. As amostras foram mantidas em viveiro por quatro meses, sendo metade em sombreamento de 11,5% (luz) e metade em sombreamento de 60% (sombra). A germinacao das sementes foi comparada nas duas condicoes de sombra (11,5% e 60%), utilizando-se o teste t para amostras independentes. Foram amostradas 36 especies pertencentes a 17 familias botânicas. As familias com maior riqueza especifica foram Asteraceae, com nove especies, Rubiaceae com cinco e Poaceae com quatro. A maioria das especies (66,7%) e dos individuos (82,2%) amostrados no banco foi de herbacea. As especies com maior numero de individuos germinados do banco foram as herbaceas Urochloa decumbens (Stapf) R.D. Webster, Cenchrus sp. e Eragrostis sp. e a arbustiva Leandra niangaeformis Cogn. Entre as arboreas, destacaram-se em numero de individuos Luehea grandiflora Mart. e Trema micranta (L.) Blume. A maior densidade de ervas daninhas oriundas de areas antropizadas do entorno indicou baixa resiliencia da vegetacao presente na area degradada em caso de ocorrer alguma perturbacao severa.

Nutrient cycling in two sites of semideciduous forest in mata do paraíso forest reserve in Viçosa, MG, Brazil.

A Semideciduous Seasonal Forest in different successional stages (initial forest and mature forest), in Vicosa, Minas Gerais State, in the southeast region of Brazil, was studied aiming at quantifying litter annual production, decomposition, N, P, K, Ca, and Mg contents and use efficiency. The annual litter production was 6,310 kg.ha-1 for the initial forest and 8,819 kg.ha-1 for the mature forest. Nutrient annual deposition in the litter was estimated at 137 and 180 kg.ha-1 N, 5 and 8 kg.ha-1 P, 17 and 45 kg.ha-1 K, 89 and 179 kg.ha-1 Ca, 21 and 26 kg.ha-1 Mg for the initial forest and mature forest, respectively. The average forest floor biomass was 4,647 kg.ha-1 for the initial forest and 7,006 kg.ha-1 for the mature forest. The instantaneous decomposition rate (k) was estimated at 1,36 for the initial forest and 1,26 for the mature forest, with a turn over time of 270 and 288 days, respectively. The smallest litter production in the initial forest reflects the less developed structure in the site of forest in initial successional stage, with litter production of lower quality compared to the mature forest, but with faster renovation and efficient use of the nutrients.

Produção de serapilheira em dois estádios sucessionais de floresta estacional semidecidual na Reserva Mata do Paraíso, em Viçosa, MG

RESUMO – Dois trechos de floresta em distintos estadios sucessionais (floresta inicial e floresta madura) foram avaliados quanto a producao de serapilheira durante o periodo compreendido entre novembro/ 2003 e outubro/2004. Os objetivos foram estimar a producao anual de serapilheira, verificar a variacao temporal de deposicao da serapilheira e investigar a existencia de correlacoes entre a estrutura da vegetacao e a producao de serapilheira. O estudo foi realizado na Reserva Mata do Paraiso, em Vicosa, MG, onde foram instalados 20 coletores de 1 m², colocados a 20 cm acima da superficie do solo. Os coletores foram distribuidos no centro de parcelas de for mato retangular, medindo 10 x 30 m cada um, e cada trecho de floresta recebeu 10 coletores. A serapilheira coletada mensalmente foi separada nas fracoes folhas, ramos, flores e frutos/sementes. A producao anual de serapilheira foi estimada em 6.310 kg.ha -1 na floresta inicial e 8.819 kg.ha -1 na floresta madura. A fracao predominante foi a foliar (64,6% e 55,9%), seguida das fracoes ramos (31,2% e 36,4%), frutos e sementes (3,2% e 6,2%) e flores (1,0% e 1,5%), nas florestas inicial e madura, respectivamente. A producao de serapilheira total foi continua ao longo do periodo analisado, apresentando modelo sazonal, com os maiores valores no periodo da primavera. Na fracao foliar, o pico de producao foi verificado em setembro, no final da estacao seca. A producao de serapilheira esteve mais relacionada a densidade de individuos nas parcelas e a sua biomassa do que a presenca de especies pioneiras nos ambientes estudados.

Transposição do banco de sementes do solo como metodologia de restauração florestal de pastagem abandonada em Viçosa, MG

This study had as its objective to compare the transposition of the soil seed bank of two successional stages of Seasonal Semideciduous Forest for a Melinis Minutiflora P. Beauv site, in an abandoned pasture of the Mata do Paraiso Forest Reserve, Vicosa, MG. Ten parcels had been placed in each successional site of forest and withdrawals of the center of each parcel sample of 1 m² and 5 cm of superficial depth of soil, being carried afterwards to the abandoned pasture site. Two hundred and thirty one individuals had been registered in the two treatments (initial forest and mature forest), consisting of 31 shrubs and 200 trees. The individuals are distributed by 13 families, 17 kinds and 22 species. The most abundant species had been Vernonia polyanthes, with 108 individuals and Senna multijuga, with 39 individuals. The soil seed bank coming from the site of initial secondary forest (Fi) registered more individuals (120) than the bank coming from the site of the mature forest (Fm), with 111 individuals. The parcels witnesses had been colonized by herbaceous and mainly by the exotic grass Melinis Minutiflora. The number of germinated seeds was only greater in the Fm treatment in the months of july/2008 and january/2009. Significant differences were observed with 1% probability, between the treatments, for the variable wealth of species and density of individuals. The present study showed that it is recommendable and viable to adopt the technique of transposition of the seed bank as a methodology of forest restoration of abandoned pasture.

Síndromes de dispersão de sementes em três trechos de vegetação ciliar (nascente, meio e foz) ao longo do rio Pindaíba, MT

Este estudo foi desenvolvido visando identificar as proporcoes entre as sindromes de dispersao e os tipos de frutos encontrados em tres areas: nascente (Cerrado Rupestre), meio e foz (mata ciliar Floresta Estacional Semidecidual) ao longo do Rio Pindaiba, MT. No trecho de nascente, 55,6% das especies amostradas eram zoocoricas, 43% anemocoricas e apenas 1,4% autocoricas, respectivamente. No trecho do meio, 85,7% das especies eram zoocoricas, 11,7% anemocoricas e apenas 1,3% autocoricas. Na foz do Rio Pindaiba foram encontradas 77,5% de especies zoocoricas, 20% de anemocoricas e apenas 2,5% de autocoricas. A hipotese levantada neste estudo foi de que em areas abertas (nascente) a proporcao de especies anemocoricas seria maior do que em ambientes fechados (meio e foz), onde predominaria a zoocoria. Entretanto, nao houve diferenca significativa nas proporcoes de especies anemocoricas e zoocoricas na nascente (Cerrado Rupestre), enquanto no meio e na foz (mata ciliar) as proporcoes de zoocoria foram maiores. Ambientes florestais, estruturalmente mais complexos com menor circulacao do vento e menor incidencia luminosa, requerem estrategias de dispersao mais direcionadas e previsiveis como a zoocoria.

Composição florísitca de uma área de cerrado sensu stricto no município de Senador Modestino Gonçalves, Vale do Jequitinhonha (MG) e análise de similaridade florística de algumas áreas de cerrado em minas gerais

Studies on factors influencing species distribution are necessary because of the accelerated agricultural advancement over these species. Thus, this study aimed to assess Senador Modestino Goncalves floristic composition and possible cerrado floristic connections in Minas Gerais. Twenty-eight areas were assessed for floristic similarity, including Senador Modestino Goncalves. Sfrensen index was used in comparative analyses. Floristic analysis identified 91 species, 65 genera and 38 families. Greater richness was represented by Leguminosae (13), Malpighiaceae (11), Myrtaceae (7), Vochysiaceae (4), Sapindaceae (4), and Rubiaceae (4). A strong floristic similarity was found in cerrado vegetation, with six groups being formed with superior similarities for 0.5. However, the factors influencing this distribution could not be verified, but geographical proximity and altitude seem to have a strong influence on some of these groups.

Caracterização hidroambiental da bacia Hidrográfica do rio Debossan, nova friburgo, rj

The objective of this work was to characterize the hydrological behavior and the volume of water entering and leaving the Debossan river watershed, where an important water captation plant is situated, managed by the Nova Friburgo Water and Sewage Treatment Company LTDA (CAENF), within the Macae de Cima Ecological Reserve, Nova Friburgo-RJ. Data of daily flow and precipitation were collected from January/2002 to December/2004. Starting from these data, some hydrological parameters were calculated, such as specific flow and flow. The average rainfall for the period was 2,163.66 mm, being that the months december/2002 and january/2003 presented the greatest values. The annual average flow for the period was 0.86 m3/s, with December/2002 having the highest index and September/2004 the lowest. The average annual hydrological balance for the three years of measurements showed 1.923,04 mm of evapotranspiration, which was 88% of the conventional precipitation. This shows that the forest ecosystem works like a buffer effect on the amount of watershed water, keeping water in the months of higher rainfall and releasing it in the months of less rainfall. Analyzing the relation between the water entering in the watershed, the current use of the soil, and the amount of produced water, it was concluded that a well-preserved watershed is crucial to keep the flow constant during the year, besides the evident participation in the water quality.