A large-scale inventory of trees > 10cm DBH was conducted in the upland "terra firme" rain forest of the Distrito Agropecuário da SUFRAMA (Manaus Free Zone Authority Agricul tural District) approximately 65Km north of the city of Manaus (AM), Srasil. The general appearance and structure of the forest is described together with local topography and soil texture. The preliminary results of the Inventory provide a minimum estimate of 698 tree species in 53 families in the 40Km radius sampled, including 17 undescribed species. The most numeri cally abundant families, Lecythidaceae, Leguminosae, 5apotaceae and Burseraceae as also among the most species rich families. One aspect of this diverse assemblage is the proliferation of species within certain genera, Including 26 genera In 17 families with 6 or more species or morphospecies. Most species have very low abundances of less than 1 tree per hectare. While more abundant species do exist at densities ranging up to a mean of 12 trees per ha, many have clumped distributions leading to great variation in local species abundance. The degree of similarity between hectare samples based int the Coefficient of Community similarity Index varies widely over different sample hectares for five ecologically different families. Soil texture apparently plays a significant role In determining species composition in the different one hectare plots examined while results for other variable were less consistent. Greater differences in similarity indices are found for comparisons with a one hectare sample within the same formation approximately 40Km to the south. It is concluded that homogeneity of tree commu nity composition within this single large and diverse yet continuous upland forest formation can not be assumed.
RESUMO Estudo crítico e revisão taxonômica de 35 espécies do gênero Virola (Myristicaceae) ocorrentes no Brasil. Consta de uma exposição das razões que motivaram a execução desse estudo, seguida de um esboço histórico das principais contribuições para o conhecimento do gênero no País e uma descrição sucinta de sua importância econômica. Segue uma discussão da fitogeografia do gênero no Brasil e de seus principais aspectos morfológicos, anatômicos e palinológicos. Dados sobre fenologia, relações genéricas e evolução do gênero Virola são também apresentados. A principal parte deste estudo é obviamente dedicado à classificação e descrições taxonômicas do gênero e das 35 espécies consideradas válidas pelo autor. O trabalho é ilustrado com fotografias, mapas e desenhos analíticos originais de folhas, flores e frutos.
545RESUMO -A Floresta Ombrófila Mista constituiu padrão referencial da flora do Paraná. O Parque Municipal das Araucárias localiza-se no Município de Guarapuava, PR, e abriga uma área de 41ha de floresta em estado natural. Foram instaladas 32 parcelas de 10 x 10 m e mensurados 447 indivíduos com diâmetro à altura do peito (DAP) igual ou superior a 4,8 cm, ou numa média de 1.397 indivíduos/ha. A estrutura horizontal da floresta é caracterizada por cinco espécies: Araucaria angustifolia (Bertol.) Kuntze, Campomanesia xanthocarpa (Mart.) O. Berg, Casearia decandra Jac, Capsicodendron dinisii (Schwacke) Occhioni e Allophylus edulis (A. St.-Hil.) Radlk. ex Warm., que juntas somaram 64,85% do total de VI, 74,36% do valor de cobertura, 87,63% da dominância e 61,07% do número de indivíduos amostrados. Foi possível definir três estratos de altura: estrato inferior -até 5,99 m, estrato médio -entre 6,0 e 10,99 m e estrato superior -maior que 11 m. Os diâmetros dos indivíduos amostrados, distribuídos em 22 classes diamétricas, variaram de 4,8 a 114,7 cm. O índice de diversidade de Shannon-Weaver calculado foi de 2,79 nats/indivíduo e o índice de uniformidade de Pielou, igual a 0,9.Palavras-chave: Fitossociologia, floresta ombrófila mista e araucária. PHYTOSOCIOLOGICAL CHARACTERIZATION OF A MIXED OMBROPHYLOUS FOREST REMNANT IN GUARAPUAVA, PR
The densities of the breeding populations and the sex of all flowering individuals were recorded for five dioecious canopy tree species of Central Amazonian Myristicaceae, in 11 study areas of the Minimum Critical size of Ecosystems Project totalling 22.5 ha. Adult population densities were extremely low, ranging from 0.38 to 1.61 ha–1 for the five species studied. In a 10 ha study plot the mean distance to the nearest flowering conspecific ranged from 48 to 100 m, while the mean distance to the nearest opposite sex conspecific was 147 m. The two most abundant species, Iryanthera macrophylla and Virola calophylla, both showed male-biased sex ratios, of 23:9 and 20:6, respectively. The size class distribution of males, females and non-flowering individuals in V. calophylla suggests that earlier reproductive maturation of male plants may provide a partial explanation for this bias. In I. macrophylla, since 95% of the individuals were observed flowering, the observed ratio is representative of the population, and may be caused by sex shifts from male to female. The low reproductive densities, combined with the skewed sex ratios and overlapping generations of these species, create very small effective breeding populations, placing species such as these at great risk in the face of deforestation and habitat fragmentation.
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