Douglas Antônio de Carvalho

Comunidade arbórea de um continuum entre floresta paludosa e de encosta em Coqueiral, Minas Gerais, Brasil

The purpose of the present contribution was to describe the community of trees of a continuum extending from swampy to upland forest in Coqueiral, SE Brazil, assessing the correlations between the variations of community structure and those of the environment. Sampling was carried out in 25 plots of 20 X 20 m laid on the forest fragment to survey trees with a minimum circumference of 15.5 cm (registering their circumference, height and species) as well as topographic and soil variables. Species-environment correlations were analyzed using canonical correspondence analysis (CCA) and Spearmans test. The swampy and upland habitats differed substantially in both community structure and floristic composition. The general floristic profile was similar to that of other riparian forests of the Mid and Upper Rio Grande region, whilst the swampy portion of the forest differed from what is commonly found in SE Brazil. The species distribution was correlated mainly to soil drainage and proximity to the lake. The high soil diversity and the strong soil moisture gradient found over a small area resulted in different habitats and a diverse community of trees and shrubs that combined phyto-physiognomies of semideciduous and swampy forests, along with cerrado patches.

Diversity and structure of the tree community of a fragment of tropical secondary forest of the brazilian Atlantic Forest domain 15 and 40 years after logging

Two adjacent tracts of tropical secondary forest, situated in Itambe do Mato Dentro, south-eastern Brazil, which had been regenerating for 15 and 40 years after clearing, were compared with the purpose of detecting differences in species diversity and composition, species guild composition (regeneration, stratification and dispersion), and stand structure. Four and three 1,125 m2 plots laid on the 15- and 40-year-old stands, respectively, sampled 2,430 trees with diameter at the base of the stem > 5 cm. The number of species (S = 199) was high for this forest type and significantly higher for the older stand. Tree density was significantly higher in the younger stand, particularly for smaller trees, whereas the two stands did not differ in both basal area and volume per hectare. Trees of shade-tolerant and understory species were significantly more abundant in the older stand. Though sharing a large proportion of species (49%), the two stands differed significantly in the abundance of many species. Live stumps probably contributed to the relatively quick restoration of some forest characteristics, particularly species diversity, basal area and volume.

Tree species distribution along soil catenas in a riverside semideciduous forest in southeastern Brazil

Summary The relationships between topography, soil taxonomic categories and tree species distribution were analysed in a riverside semideciduous forest on the margins of the Rio Grande, in Conquista, state of Minas Gerais, Southeastern Brazil. The forest was sampled by two transects made up of 50 contiguous 15 × 15 m2 quadrats (total 1.125 ha). Each transect started at the river margin and extended upslope so that they could include two soil catenas: the first with the sequence Ustifluvent, Haplustox and Ustorthent, and the second with Ustifluvent followed by Haplustult. A quick but more extensive survey was carried out in the whole forest fragment covering the same soil habitats in order to assess the extension of soil-species relationships found in the transects. A canonical correspondence analysis indicated that the species’ abundance distribution was significantly correlated with the soil habitats. Differences in soil drainage classes among the soils rather than their chemical properties appeared to be the leading factor: tree species distribution was strongly correlated with a wide hydrosequence ranging from poorly drained to strongly drained soils. The 55 most abundant species were classified according to their ecological group (regeneration guild) within the forest dynamics. A tentative ecological classification of those species combining their habitat preference in terms of soil drainage class and their growth strategy suggested that these factors play and important role in promoting the coexistence of tree species in that type of forest.

Plant extracts to control "Alternaria alternata" in Murcott tangor fruits

BACKGROUND Alternaria alternata causes the Alternaria brown spot disease (ABS) in many tangerines and their hybrids worldwide. Plant extracts offer an alternative method for controlling this disease, which control is based on chemical fungicides. AIMS To identify plant species with antifungal properties against A. alternata, the causal agent of the ABS. METHODS Plant extracts prepared from leaves, barks, flowers, and stalks collected from 105 plant species in the State of Minas Gerais, Brazil, were tested for activity against the fungus A. alternata in vitro and in vivo. RESULTS The most promising extract was obtained from Anadenanthera colubrina, which reduced the disease on Murcott tangor fruits to levels obtained with commercial fungicides. Artemisia annua, Cariniana estrelensis, Ficus carica, and Ruta graveolens presented moderate in vitro antifungal activity, but no effects were observed on the disease when the extracts were applied to fruits inoculated with the fungus. Besides, A. colubrina was the most active extract against A. alternata in the in vitro assay. CONCLUSIONS The results obtained in the in vitro and in vivo assays suggested that the fungal growth test, which uses 96-well polypropylene plates, seems to be appropriate for selecting potential plant species for testing new methods to control ABS.

Flora arbustivo-arbórea de uma floresta ripária no alto Rio Grande em Bom Sucesso/MG

A floristic survey was carried out in a riparian forest of the Rio Grande in Bom Sucesso, Minas Gerais, Brazil, considering the species of trees and shrubs with diameter at the base of the stem >= 5 cm. The purpose was to produce a list of indigenous species for potential use in environmental rehabilitation programs that have bee carried out on the margins of rivers and dams of this region. A list is provided with 245 species of 65 botanic families. Floristic comparisons are made with florests surveyed in the State of Sao Paulo.

Evaluation of the antifungal activity by plant extracts against Colletotrichum gloeosporioides Penz

Com vistas a contribuir para o desenvolvimento de metodos mais eficientes e menos agressivos ao ambiente que aqueles disponiveis para o controle de Colletotrichum gloeosporioides Penz, causador da mancha manteigosa em cafeeiros, buscou-se identificar especies vegetais produtoras de substâncias ativas contra o referido patogeno. Para tanto, prepararam-se extratos de 48 especies vegetais, coletadas na regiao do Alto Rio Grande, em Minas Gerais, para serem submetidos a testes in vitro com o mencionado fungo. Constatou-se que os melhores resultados foram obtidos com os extratos oriundos de Digitalis lanata Ehrh, Origanum manjorona L., Plantago lanceolata Hook. e Stevia rebaudiana (Bertoni) Bertoni que inibiram a germinacao dos esporos de C. gloeosporioides. Alguns dos extratos ativos tambem foram submetidos a diluicoes em solucao aquosa de Tween 80 a 1%, o que permitiu observar que, na proporcao de 1:2 ou 1:3 (extrato: solucao aquosa), os extratos perdiam a atividade antifungica. Verificou-se tambem que alguns dos extratos ativos nao alteraram suas atividades quando submetidos ao processo de liofilizacao. Desse modo, identificaram-se varias plantas promissoras na pesquisa por novas substâncias bioativas para o controle de C. gloeosporioides, com destaque para O. manjorona L., que inibiu 96% da germinacao dos esporos do referido fungo.

Identification of the antimicrobial substances produced by Solanum palinacanthum (Solanaceae)

To find out natural antimicrobial agents as alternative in therapeutics and to preserve food, the methanol extract of Solanum palinacanthum aerial parts was submitted to purification steps guided by antibacterial and antifungal assays. As a consequence, the flavonoid rutin and 3,5-dicaffeoylquinic acid were isolated by column chromatography and high performance liquid chromatography, and identified by mass and nuclear magnetic resonance spectrometry. Minimal inhibitory concentrations (MIC) of the quinic acid derivative against Aeromonas hydrophila, Bacillus subtilis, Staphylococcus aureus and the fungus Aspergillus ochraceus were 250, 1000, 1000 and > 568 microg/mL, respectively. Against the same microorganisms, MIC for rutin were 1000, > 1000, > 1000 and 35 microg/mL, respectively. Rutin was very promising for A. ochraceus control, since its MIC against such fungus was close to the one observed for benzalkonium chloride, which is used as a fungicide in Brazil.

Flora arbustivo-arbórea de um fragmento de mata ciliar no alto rio Grande, Itutinga, Minas Gerais

A floristic survey was carried out in an 9.450m2 fragment of riparian forest on the margin of the hydroelectric reservoir of Camargos, Itutinga, state of Minas Gerais, SE Brazil. All individuals with minimum diameter at the base of stem 5cm were surveyed in the sampled area forest. A list is provided with 253 species of trees and shrubs belonging to 66 botanic families. Floristic similarity indices were calculated in comparisons with other floristic surveys of forest in the states of Sao Paulo and Minas Gerais.

Florística, estrutura e características do solo de um fragmento de floresta paludosa no sudeste do Brasil

A survey of the tree community was conducted for an upland semideciduous riparian forest, located on the upper Rio Pardo, Santa Rita de Caldas, Minas Gerais (1156 to 1203 m altitude), in order to evaluate structural variation and environmental variables associated with the substrate. Density, basal area, tree size distribution and floristic composition were evaluated. In 25 10x40 m plots, all trees with dbh > 5 cm were sampled, topographical aspects were determined and soil samples were collected for chemical and textural analyses. A total of 2982 individuals from 50 families, 78 genera and 110 species were recorded. A sequence of three soil subgroups (Organosoil, Melanic Gleisoil and Haplic Gleisoil) was registered in a downstream direction. Floristic composition and structure the tree community was different from other swamp and alluvial forests of southern and southeastern Brazil, at lower altitudes. Canonical correspondence analysis detected a tree-species distribution gradient correlated mainly with clay content and elevation variation.

Avaliação e proposta de conectividade dos fragmentos remanescentes no campus da Universidade Federal de Lavras, Minas Gerais

Neste trabalho, objetivou-se mapear e caracterizar os fragmentos florestais existentes no dominio da UFLA e identificar potenciais corredores para maximizar a conectividade entre eles. Utilizou-se para confeccao do mapa tematico o programa SPRING 3.4, a partir de fotos aereas do ano de 2001 e de imagens de satelite Landsat 7 (marco de 2001). Os impactos sofridos pelos fragmentos foram analisados a partir da aplicacao de questionarios investigativos, a fim de levantar o historico de intervencoes humanas. A flora arbustivo-arborea dos principais fragmentos foi inventariada pelo metodo dos quadrantes, tendo como nivel de inclusao DAP > 5,0 cm. O fragmento do museu foi o que apresentou a menor area, a maior influencia dos impactos, menor indice de forma e area interna e o maior efeito de borda. Por outro lado, no fragmento da subestacao, observou-se a maior area, maior indice de forma e area interna e o menor efeito de borda. Dentre os principais impactos registrados para os fragmentos estudados, destacaram-se: lixo, estradas externas, trilhas e construcoes. Foram registrados nos quatros fragmentos e nas duas principais unidades de conectividade 544 individuos, pertencentes a 48 familias, 110 generos 161 especies. O maior valor de diversidade foi registrado no fragmento da subestacao (3,917) e o menor (2,135) para o fragmento do museu. Apos a analise dos resultados, constatou-se a possibilidade de conectividade entre os fragmentos com a recuperacao das areas de preservacao permanente no entorno dos cursos d´agua e represas e a adocao de medidas que possibilitem minimizar os impactos detectados nesses habitats.