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Search Results: 1 - 10 of 391663 matches for " Flavio Antonio Ma?s dos; "
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Abundancia de ramos reprodutivos e produ??o de sementes em popula??es de Ipomoea pes-caprae (L.) R. Br. na Ilha de Santa Catarina, Brasil
Castellani, Tania Tarabini;Santos, Flavio Antonio Mas dos;
Acta Botanica Brasilica , 2005, DOI: 10.1590/S0102-33062005000200007
Abstract: the variation in the proportion of reproductive branches, fruit, and seed production of ipomoea pes-caprae (l.) r. br. (convolvulaceae) were evaluated at ten beaches on santa catarina island, state of santa catarina, brazil. three patches per beach of ipomoea pes-caprae were monitored, involving two reproductive cycles. ipomoea pes-caprae presented initially an average length of patches of 14 m, with 9.6 branches/m2 and 39% of reproductive branches. the proportion of reproductive branches varied between the cycles, but there was not noticed an alternation of reproductive effort between the subsequent cycles. there was a reduction in the percentage of reproductive branches at six localities. in four beaches where ipomoea pes-caprae populations declined, occurred reduction in the reproductive vigor, and in the seed production, being these declines associated to strong sea erosion. in another hand, in one beach with population increase, there were little reproductive branches due to the occurrence of young stolons. four patches never maturated fruits, being three of these located at small beaches. the fruit and seed productions in the patches showed values up to 40 fruits/m2 and up to 140 seeds/m2, respectively. populations with great seed production were localized in areas adjacent to great coastal plains, which may represent potential seed sources for areas with small seed production in the island.
Padr?es espaciais de Qualea grandiflora Mart. em fragmentos de cerrado no estado de S?o Paulo
Costa, Rafael Carvalho da;Santos, Flavio Antonio Mas dos;
Acta Botanica Brasilica , 2011, DOI: 10.1590/S0102-33062011000100025
Abstract: the study of spatial patterns is a helpful approach to formulating hypotheses about plant population dynamics. our aim was to search for variation in spatial patterns of q. grandiflora height classes at different scales within and among fragments of different cerrado physiognomies. spatial patterns of the number of plants in subplots (5 x 5 m) were described and compared among six 0.5-ha plots placed in four fragments. we performed moran's i correlogram analysis to describe spatial patterns and tested spatial correlations of height classes by partial mantel tests. we found 18 to 319 plants 0.5 ha-1. larger plants (height >1.5 m) had a clumped pattern in all plots, varying in numbers and magnitudes of scales independently of the physiognomy. correlogram analysis for smaller plants was possible in only three plots, where patterns were random. in two of these cases there was significant positive correlation of size classes but in the third it was not significant. abundance and spatial patterns were as different within the same fragment as in different ones. these results show that q. grandiflora spatial patterns cannot be predicted based on overall characteristics of cerrado physiognomy. the random-to-clumped transition with size and the spatial association of classes suggest that density dependent mortality does not seem to be an important driver of q. grandiflora dynamics, and that spatial structure of suitable sites for recruitment to maturity may be more important.
Geographic distribution of epiphytic bromeliads of the Una region, Northeastern Brazil
Fontoura, Talita;Santos, Flavio Antonio Mas dos;
Biota Neotropica , 2010, DOI: 10.1590/S1676-06032010000400017
Abstract: many brazilian atlantic rainforest plant and animal species are geographically restricted to southern bahia and northern espírito santo states. we investigated the geographic distribution of epiphytic bromeliads in the lowland forest of the una region (15° 17' 34' s - 39° 04' 30'' w) in southern bahia. specifically, we addressed the following questions: i) what is the extent of each species distribution?; and ii) are the bromeliaceae subfamilies distributed differently from one another? almost half of the 40 species (47.5%) occur exclusively in the southern bahia-northern espírito santo region and are herein referred as endemic species. the highest percentage of the 15 species of tillandsioideae (46.7%) occur throughout the south american continent and most of the 25 species of bromelioideae (68.0%) are mainly represented by endemic species. the una region has almost two times more species than a forested area located 40 km west, suggesting marked increases in diversity in over relatively short distances. the endemism data around una indicates that species are geographically distributed over an area spanning approximately six to seven degrees in latitude and longitude. this result contrasts with the geographic distribution of andean epiphytes, mainly represented by tillandsioideae, that have large geographical distributions. larger-scale analyses and standardized methods are necessary to verify whether the narrow geographical distribution of most epiphytic bromeliads in the una region is consistent across different forest types of the atlantic rainforest.
ASPECTOS DA VARIA O AMBIENTAL EM UMA FLORESTA DE GALERIA EM ITUTINGA, MG, BRASIL
Eduardo van den Berg,Flavio Antonio Mas dos Santos
Ciência Florestal , 2003,
Abstract: Foi caracterizada a heterogeneidade ambiental em uma área de floresta de galeria (7,55 ha), em Itutinga, MG, Brasil, pelas varia es das propriedades químicas e físicas do solo, da topografia e da abertura de dossel. As propriedades do solo e a topografia foram estudadas em 28 parcelas de 10 x 30 m utilizadas em um levantamento da comunidade arbóreo-arbustiva da área. Para a abertura do dossel utilizaram-se duas transec es de 50 m de largura, compostas por parcelas contíguas de 10 x 10 m, cruzando a floresta de lado a lado, perpendicularmente ao curso d’água. Fotos hemisféricas foram tomadas sobre estacas alternadas das extremidades das parcelas. Os dados de solo e topografia foram analisados por meio de uma PCA (Análise dos Componentes Principais) e a abertura do dossel mediante gráficos de tendência e regress o linear. A varia o mais importante em termos de solos e abertura do dossel se deu no sentido do distanciamento da borda da floresta e aproxima o do curso d’água. Nesse sentido, a abertura do dossel diminuiu (b = -0,096; R2 = 0,34) e a umidade e acidez do solo aumentaram (Eixo 1 do PCA, autovalor = 9,713). Os maiores valores da abertura do dossel próximo à borda foram explicados pela entrada de luz lateral através da borda da floresta com o campo limpo circundante.
Tree structure and richness in an Atlantic Forest fragment: distance from anthropogenic and natural edges
Ribeiro, Maíra Taquiguthi;Ramos, Flavio Nunes;Santos, Flavio Antonio Mas Dos;
Revista árvore , 2009, DOI: 10.1590/S0100-67622009000600014
Abstract: approximately 7.2% of the atlantic rainforest remains in brazil, with only 16% of this forest remaining in the state of rio de janeiro, all of it distributed in fragments. this forest fragmentation can produce biotic and abiotic differences between edges and the fragment interior. in this study, we compared the structure and richness of tree communities in three habitats - an anthropogenic edge (ae), a natural edge (ne) and the fragment interior (fi) - of a fragment of atlantic forest in the state of rio de janeiro, brazil (22°50's and 42°28'w). one thousand and seventy-six trees with a diameter at breast height > 4.8 cm, belonging to 132 morphospecies and 39 families, were sampled in a total study area of 0.75 ha. ne had the greatest basal area and the trees in this habitat had the greatest diameter:height allometric coefficient, whereas ae had a lower richness and greater variation in the height of the first tree branch. tree density, diameter, height and the proportion of standing dead trees did not differ among the habitats. there was marked heterogeneity among replicates within each habitat. these results indicate that the forest interior and the fragment edges (natural or anthropogenic) do not differ markedly considering the studied parameters. other factors, such as the age from the edge, type of matrix and proximity of gaps, may play a more important role in plant community structure than the proximity from edges.
Fenologia de Chrysophyllum gonocarpum (Mart. & Eichler) Engl. (Sapotaceae) em floresta semidecídua do Sul do Brasil
Bianchini, Edmilson;Pimenta, José Antonio;Santos, Flavio Antonio Mas dos;
Brazilian Journal of Botany , 2006, DOI: 10.1590/S0100-84042006000400009
Abstract: phenological patterns of chrysophyllum gonocarpum (mart. & eichler) engl. were investigated from may 1995 to december 1997 in a tropical semideciduous forest in southern brazil (23o27' s and 51o15' w). forty trees were monthly observed for changes on leaf fall and flushing, flowering, and fruiting. the leaf fall occurred in the dry period while leaf flushing, flowering and dispersion occurred at the beginning of the wet season. except fruiting, all phenophases were highly synchronized. the majority of individuals flowered annually, although they did not fruit annually. leaf fall was negatively associated with rainfall and temperature and flowering was positively associated with daylength.
Estrutura de estádios ontogenéticos em popula??o nativa da palmeira Syagrus romanzoffiana (Cham.) Glassman (Arecaceae)
Bernacci, Luís Carlos;Martins, Fernando Roberto;Santos, Flavio Antonio Mas dos;
Acta Botanica Brasilica , 2008, DOI: 10.1590/S0102-33062008000100014
Abstract: syagrus romanzoffiana is ecologically and economically important, including the production of good-quality hearts of palm. aiming to describe this plant's basic life cycle, we studied a natural population in the swamp forest at the santa genebra reserve, campinas municipality, s?o paulo state. observations and measurements were made, and repeated after 400 ± 3 days, in 100 randomly located plots (5×5 m) and sub-plots (2×2 m), in an area of 1 ha. six ontogenetic stages were recognized: seedling (narrow entire leaf), juvenile phase 1 (entire leaf, width > 2 cm), juvenile phase 2 (segmented leaf), immature (segmented leaf, aerial stem), virgin (aerial stem, cauligenous roots), and reproductive (cauligenous roots and periodic presence of reproductive structures). since the moment of trophic independence could not be determined in the field, leaf characteristics were used to identify seedlings. seedlings live for a long time in the low light of the understory. even though significant differences could be observed, size and leaf production overlapped among different stages. remote germination, used to explain the widespread occurrence of the species even in dry regions, and cauligenous roots that improve fixation and nutrition previous to reproduction in swamp forests, are morphological structures and properties acquired or lost in each stage that may represent adaptive advantages under different circumstances during ontogeny of s. romanzoffiana.
Efeito da explora??o madeireira sobre o número de indivíduos férteis de três espécies arbóreas comerciais na Amaz?nia oriental
Fonseca, Marisa Gesteira;Vidal, Edson;Santos, Flavio Antonio Mas dos;
Acta Amazonica , 2008, DOI: 10.1590/S0044-59672008000400011
Abstract: studies concerning the reproductive ecology of trees are important so as to better understand the impacts of logging and for the definition of guidelines to improve management practices. the aim of this study was to estimate (1) the number and proportion of reproductive individuals of chrysophyllum lucentifolium subsp. pachycarpum, lecythis lurida e pseudopiptadenia psilostachya per size class, and (2) the impact of harvesting 90% of individuals > 50 cm dbh on the number of reproductive trees. we sampled 80 l. lurida, 76 p. psilostachya and 76 c. lucentifolium trees during one reproductive season. we estimated that 14.9% of all fertile individuals of c. lucentifolium, 35.9% of l. lurida and 72.4% of p. psilostachya were > 50 cm dbh in that year. therefore, the harvest of 90% of these trees would cause a 13.4%, 32.6 %, and 65.2 % reduction in the number of fertile individuals of c. lucentifolium, l. lurida and p. psilostachya, respectively. if these proportions were stable over time, it would be necessary to keep 30% instead of 10% of individuals > 50 cm dbh in order to preserve half of the p. psilostachya fertile individuals. the results indicate that the effects of adopting a single minimum cutting diameter and of setting aside the same proportion of trees above that diameter on the proportion of remaining fertile individuals may vary by a factor of five among species.
Is size structure a good measure of future trends of plant populations? an empirical approach using five woody species from the Cerrado (Brazilian savanna)
Virillo, Carolina Bernucci;Martins, Fernando Roberto;Tamashiro, Jorge Yoshio;Santos, Flavio Antonio Mas dos;
Acta Botanica Brasilica , 2011, DOI: 10.1590/S0102-33062011000300012
Abstract: size distributions in woody plant populations have been used to assess their regeneration status, assuming that size structures with "reverse-j" shapes represent stable populations. we present an empirical approach of this issue using five woody species from the cerrado. considering count data for all plants of these five species over a 12-year period, we analyzed size distribution by: a) plotting frequency distributions and their adjustment to the negative exponential curve and b) calculating the gini coefficient. to look for a relationship between size structure and future trends, we considered the size structures from the first census year. we analyzed changes in number over time and performed a simple population viability analysis, which gives the mean population growth rate, its variance and the probability of extinction in a given time period. frequency distributions and the gini coefficient were not able to predict future trends in population numbers. we recommend that managers should not use measures of size structure as a basis for management decisions without applying more appropriate demographic studies.
Caracteriza??o dos estádios ontogenéticos de três espécies de palmeiras: uma proposta de padroniza??o para estudos de dinamica populacional
Portela, Rita de Cássia Quitete;Santos, Flavio Antonio Mas dos;
Brazilian Journal of Botany , 2011, DOI: 10.1590/S0100-84042011000400006
Abstract: the objective of this study was to identify, classify and describe the ontogenetic stages and/or size classes of three tropical palm species, astrocaryum aculeatissimum (schott) burret, euterpe edulis mart. and geonoma schottiana mart. the populations were sampled in five fragments of atlantic rain forest in 2005. all individuals had their diameter and height measured, and also the number and kind of leaf recorded in each fragment of nine 30 × 30 m plots. based on these measurements, we assigned each individual to one of five classes. astrocaryum aculeatissimum and e. edulis change their kind of leaf throughout development. geonoma schottiana has a high variation in the kind of leaf, and only the seedlings stage displays only one kind of leaf. the appearance of stem and reproductive events also represents class change. the kind of leaf, the surge of the stem and reproductive events were the main characteristics used for the ontogenetic stage identification. however, for e. edulis and g. schottiana class identification, we also used quantitative characteristic because some stages have wide size variation. studies that characterize and describe species ontogenetic stages are very important for standardization and to allow comparison between studies of population structure and dynamics.
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