The relationships between soil properties, topography and tree species distribution were analysed in a tropical riverine forest at the margins of the Rio Grande, in Bom Sucesso, state of Minas Gerais, south-eastern Brazil. The forest was sampled by three 0.18 ha plots, with each plot made up of eight contiguous 15 m X 15 m quadrats, four of which were placed at the river margin and the remaining four in the forest interior. A canonical correspondence analysis indicated that the species' density distribution was significantly correlated with some soil chemical characteristics and topographical features. The soils of the three sample plots showed statistically significant differences for the levels of Ca, Mg, K and pH, with the fertility (expressed by the cation exchange capacity) increasing from Plot I to Plot III. These variations were mainly explained by the first canonical axis while the second was strongly correlated with topographical variables, separating the quadrats into two groups: those of the higher and steeper sites from those of the lower sites. The only soil property that was significantly different in lower and upper sites was the concentration of phosphorus. No significant difference in tree species distribution was found between river margin and interior quadrats, certainly because this forest sector lies on the outer side of a curve of the river where erosion is currently building high and steep river banks and forcing the forest to retreat. A tentative ecological classification of the 30 most abundant species according to their habitat preference in terms of soil fertility and topographical sites, and to their growth strategy in the forest dynamics, is presented. It is suggested that these factors play an important role in promoting the coexistence of tree species in this type of forest.RESUMO. As relacpes entre caracteristicas do solo, topografia e distribui^ao de especies arboreas foram analisadas em um trecho de floresta riparia nas margens do Rio Grande, em Bom Sucesso, sul de Minas Gerais, Brasil. A floresta foi amostrada por tres blocos de oito parcelas contiguas com 15 m x 15 m, quatro das quais situadas na margem do no e as demais no interior da floresta. Uma analise de correspondencia canonica indicou que a distribuicao da densidade das especies estava significativamente correlacionada com certas propriedades qufmicas do solo e com a topografia. Os solos dos tres blocos mostraram diferen$as significativas, nos ni'veis de Ca, Mg, K e pH, com a fertilidade (expressa pela capacidade de troca cationica) crescendo do Bloco I para o Bloco III. Estas variac,6es foram explicadas principalmente pelo primeiro eixo de ordenac,ao, enquanto o segundo eixo expressou principalmente as variaveis topograficas, discriminando as parcelas em dois grupos: si'tios mais altos e inclinados e sitios mais baixos. A unica caracteristica dos solos que mostrou-se significativamente diferente nos sitios altos e baixos foi a concentrac,ao de fosforo. Nenhuma diferen^a significativa foi encontrada entre parcelas da ma...

The interrelationships between the distribution of woody species and environmental variables were investigated in an area of deciduous dry forest in Santa Vitöria, central Brazil. This is the first study of a vanishing type of dry forest which grows on base‐rich soils originating from the basalt bedrocks of southern Goiás and western Minas Gerais. A survey of topography, soil properties, canopy gaps and woody plants (≥5 cm diameter at the base of the stem) was conducted in 50–15 × 15 m quadrats. The soils were classified into the following soil series: Hapludolls → Haplustolls → Haplustolls → Ustropepts → Rhodustalfs. This series corresponded to a gradient of increasing elevation and effective soil depth and decreasing slope gradient, soil organic matter and total exchangeable bases. A canonical correspondence analysis and a detrended correspondence analysis indicated that plant species’abundance distribution was significantly correlated with both the relative area of canopy gaps in the quadrats and the soil‐topography gradient. Presumably, the critical factors involved in these two gradients are, respectively, light and ground water regimes. The influence of canopy gaps (i.e., light) was surprising and has not been documented previously for tropical deciduous dry forests.

Qualitative and quantitative descriptions of the woody flora and soil analyses are provided for six areas of montane semideciduous forest in the upper Rio Grande region, southern Minas Gerais, Brazil. Comparisons are made of the floristic composition of these six areas and 24 other forest areas of southeastern Brazil using ordination by detrended correspondence analysis (DCA) and hierarchical classifications, both agglomerative (upgma) and divisive (twinspan). The variation in community structure of five of the six forest areas was analysed using a two-way table yielded by twinspan. The floristic analyses indicated the strongest link between the forests of the upper Rio Grande region and other montane forest formations of southeastern Brazil as well as secondary links with the gallery forests that extend into the cerrado domain and the submontane semideciduous forests of the Rio Parana basin. Variations in community structure among the five forest areas were apparently associated mainly with riverside effects and soil fertility.

e Nilton Curi 5 RESUMO -O objetivo deste trabalho foi analisar correlações da distribuição de espécies arbóreas com variáveis ambientais em um fragmento de floresta estacional semidecidual conhecido como "Mata do Galego", o qual possui cerca de 77 ha e está localizado a 21°29'S e 44°55'W, às margens do rio Ingaí. O levantamento da comunidade arbórea, dos solos e da topografia foi realizado por meio de amostragem sistemática, em 32 parcelas de 20 x 20 m, distribuídas em três transeções, da margem do rio até a borda da mata. Foram registrados todos os indivíduos arbóreos, vivos, com circunferência à altura do peito (CAP) ≥ 15,5 cm. As variáveis químicas e físicas do solo foram obtidas das análises de amostras superficiais de solo (0-20 cm) de cada parcela. As variáveis topográficas foram obtidas por meio de um levantamento topográfico dentro e entre parcelas. Foram inventariados 2.343 indivíduos de 159 espécies, 50 famílias e 109 gêneros. As análises de gradientes, realizadas por meio de análise de componentes principais, análise de correspondência canônica e análise de correspondência retificada, indicaram que as parcelas localizadas em áreas de transição com campo de altitude foram as que mais se diferenciaram das demais. As variáveis relacionadas com a acidez e textura do solo apresentaram maior correlação com a distribuição das espécies.Palavras-chave: Floresta semidecidual, comunidade arbórea e variáveis ambientais. EFFECTS OF SOILS AND TOPOGRAPHY ON THE DISTRIBUTION OF TREE SPECIES IN A FRAGMENT OF TROPICAL SEASONAL FOREST IN LUMINÁRIAS, SE BRAZIL

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The purpose of the present study was to investigate whether variations in tree community structure and soil properties were interrelated in a fragment of semideciduous forest in Martinho Campos, south-eastern Brazil. The forest was sampled by ten plots, each of which was made up of four contiguous 15×15m quadrats (total 0.9ha). Plots were randomly distributed in the fragment with the help of grid-line coordinates. Soil samples were collected from each quadrat for chemical and textural analyses, and the soil of each quadrat was classified in conformity with the US Soil Taxonomy System. All trees with diameter at the base of the stem ≥5cm were identified and measured (circumference and height). Three soil groups were recognized: Ustifluvent, Ustropept, and Dystropept. A principal component analysis independently discriminated the soil groups in terms of their chemical and textural properties, indicating the consistency of the soil classification. Significant differences among the soil groups were also found for most soil properties. Tree community physiognomy was significantly different in Ustropept soil habitat, where trees showed more pronounced slenderness. A detrended correspondence analysis indicated that tree community structure also responded to the three soil habitats. A canonical correspondence analysis, together with Spearman's rank correlations, demonstrated that species' abundance distributions were significantly correlated with the soil properties. Differences in soil nutrient content (particularly Ca2+ and K+) and in ground water regime are apparently the leading factors determining tree species distributions within the fragment.

-(Distribution of tree and shrub species along a gradient of soils and topography in a strip of riparian forest of the São Francisco River in Três Marias, MG, Brazil). A survey of the community of trees and shrubs, topography and soils of a fragment of tropical semideciduous and tropical deciduous forests was carried aiming at assessing alleged correlations between the variations in physiognomic structure and species composition and variations in soil water regime and chemical fertility. The forest fragment, with an area of 12 ha, is situated on the right margin of the Rio São Francisco (18°05'26" S and 45°10'54" W), Três Marias municipality, Minas Gerais state, southeastern Brazil. A topographic survey and a detailed soil classification were accomplished in the forest area. Individual trees and shrubs with diameter at the base of the stem (dbs) ≥ 5 cm were sampled in 50 plots with 15 × 15 m. Samples of surface soil (0-20 cm of depth) were collected from each plot for analyses of chemical and textural properties. The survey registered 1,449 individuals belonging to 117 species, 83 genera, and 33 families, as well as three soil subgroups and five drainage classes. Canonical correspondence analysis (CCA) of the environmental variables and species abundances indicated that they are distributed in the fragment under a strong influence of drainage regime and chemical fertility of the soils, suggesting that the availability of water and mineral nutrients are the chief environmental variables determining species distribution in the forest.Key words -riverine forest, soil-vegetation relationship, tree and shrub community, tropical deciduous forest RESUMO -(Distribuição de espécies arbóreo-arbustivas ao longo de um gradiente de solos e topografia em um trecho de floresta ripária do Rio São Francisco em Três Marias, MG, Brasil). Foi realizado um levantamento da comunidade arbóreo-arbustiva, da topografia e dos solos de um fragmento de floresta estacional semidecidual aluvial e estacional decidual submontana, com o objetivo de verificar as possíveis correlações entre variações da estrutura fisionômica e da diversidade e composição de espécies e variações do regime de água e fertilidade química dos solos. O fragmento florestal, com área de 12 ha localiza-se à margem direita do Rio São Francisco (18º05'26" S e 45º10'54" W), no município de Três Marias, MG. Foram realizados um levantamento plani-altimétrico da área e uma classificação detalhada dos solos da floresta. Foram alocadas 50 parcelas de 15 × 15 m para amostrar os indivíduos arbóreo-arbustivos com diâmetro à altura do solo (DAS) ≥ 5 cm. Amostras do solo superficial (0-20 cm de profundidade) foram coletadas nas parcelas para análises das propriedades químicas e texturais. Foram registrados nas parcelas 1.449 indivíduos distribuídos em 117 espécies, 83 gêneros e 33 famílias, bem como três subgrupos de solos e cinco classes de drenagem. A análise de correspondência canônica (CCA) das variáveis ambientais e da abundância das espécies indicou que estas se distrib...

-The objective of this work was to evaluate isolates of Trichoderma harzianum regarding biocontrol of common bean seed-borne pathogens, plant growth promotion, and rhizosphere competence. Five isolates of T. harzianum were evaluated and compared with commercial isolate (Ecotrich), Carboxin+Thiram, and an absolute control. Bean seeds of the cultivar Jalo Precoce, contaminated with Aspergillus, Cladosporium, and Sclerotinia sclerotiorum, were microbiolized with antagonists, and seed health tests were carried out. Isolates were evaluated on autoclaved substrate and in field conditions. Ten days after sowing (DAS), plant length was measured. To test rhizosphere competence, isolates were applied in boxes containing autoclaved washed sand, and root colonization was evaluated at 10 DAS, using five plants per box. The most effective isolates in the seed health tests were: CEN287 and CEN289 to control Aspergillus; the commercial isolate to control Cladosporium; and CEN287 and CEN316 to control S. sclerotiorum. Isolates CEN289 and CEN290 promoted bean growth in greenhouse and field. Seed treatment with T. harzianum reduces the incidence of Aspergillus, Cladosporium, and S. sclerotiorum in 'Jalo Precoce' common bean seeds.