997 resultados para Cretaceous of Brasil


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Lianas are characteristic, abundant and ecologically important members of tropical forest but they have been neglected in floristics and phytossociological studies. This work presents a floristic survey of the lianas species at Estação Ecológica do Noroeste Paulista (EENP), and a comparison of the list of species recorded in this work with those reported for other fragments of São Paulo state. The EENP (20º48'36'' S and 49º22'50'' W) is at 468 m of altitude and comprises an area of 168,43 ha, divided into three fragments of vegetation. Samples of lianas were collected in the interior and along the edges of the forest fragments. It was identified 105 species: 99 Magnoliopsida (60 genera and 22 families); six Liliopsida (three genera and three families). The richest families in species comprised 59% of the total of lianas sampled. The dendrogram of similarity showed a low similarity between the forest situated in the littoral (Atlantic Forest) and those located in the interior of the state of São Paulo. Some other authors, also analysing the similarity of forest of the interior and Atlantic Forest of São Paulo state, but considering only the trees reported similar result.

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We estimate litter production and leaf decomposition rate in a cerradão area, physiognomy little studied and very threatened in São Paulo State. During the period of study, litter production was 5646.9 kg.ha-1.year-1, which the 'leaf' fraction corresponded to 4081.2 kg.ha¹.year¹; the 'branch' fraction, to 1066.1 kg.ha-1.year-1; the 'reproductive structures' fraction, to 434.1 kg.ha-1.year-1; and the 'miscellaneous' fraction to 65.5 kg.ha-1.year-1. Litter production was highly seasonal and negatively correlated with relative humidity and air temperature. Leaf production was negatively correlated with relative humidity, rainfall, and air temperature. There was no significant difference between litter production found in this study and those in two other sites with cerradão and semideciduous forest, but these physiognomies differed significantly from the cerrado sensu stricto. Leaf decomposition rate (K) was 0.56. Half-life of the decomposing material was 1.8 years and turnover time was 2.3 years.

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Dahlstedtia Malme (Leguminosae) is a neotropical genus, native to the Brazilian Atlantic Forest, and comprises two species, D. pinnata (Benth.) Malme and D. pentaphylla (Taub.) Burk., although it has been considered a monotypic genus by some authors. Leaf anatomy was compared to verify the presence of anatomical characters to help delimit species. Foliar primordium, leaflet, petiolule, petiole and pulvinus were collected from cultivated plants (Campinas, SP, Brazil) and from natural populations (Picinguaba, Ubatuba and Caraguatatuba, SP, Brazil - D. pinnata; Antonina, PR, Brazil - D. pentaphylla). Studies on leaflet surface assessment (Scanning Electron Microscopy), as well as histology and venation analyses were carried out of dehydrated, fresh and fixed material from two species. Leaflet material was macerated for stomatal counts. Histological sections, obtained by free-hand cut or microtome, were stained with Toluidine Blue, Safranin/Alcian Blue, Ferric Chloride, Acid Phloroglucin. Secretory cavities are present in the lamina, petiolule, petiole, pulvinus and leaf primordium in D. pentaphylla, but not in D. pinnata, and can be considered an important character for species diagnosis. Other leaf characters were uninformative in delimiting Dahlstedtia species. There is cambial activity in the petiolule, petiole and pulvinus. This study, associated with other available data, supports the recognition of two species in Dahlstedtia.

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A study of the tree species of the order Celastrales sensu Cronquist from the Tibagi river basin, Paraná state, Brazil, is presented, based on herbarium material. This basin is subdivided into three zones, from north to south: lower Tibagi (BT), mid Tibagi (MT) and upper Tibagi (AT), each with different environmental conditions and vegetation types. The order Celastrales is represented in the basin by 15 tree species belonging to three families: Aquifoliaceae, Celastraceae and Icacinaceae. Icacinaceae has only two species, Citronella gongonha and C. paniculata. The former is distinguished by a glabrous ovary and leaves that usually bear thorns. Aquifoliaceae has six species: Ilex brasiliensis, I. brevicuspis, I. chamaedryfolia, I. dumosa, I. paraguariensis and I. theezans. These species are found mainly in AT and MT and are distinguished by leaf size, indument, apices and margins, and by sepal features. Celastrales is represented by seven species and two genera; Plenckia populnea, a Brazilian savannah species found only in MT, and six species of Maytenus (M. evonymoides, M. robusta, M. dasyclada, M. salicifolia, M. ilicifolia and M. aquifolia) distinguished by leaf size and margins, branch shape and number of flowers per inflorescence.

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This work aims to describe, illustrate and compare the seedling morphology of five tree species of the genera Bowdichia, Cyclolobium, Diplotropis, Ormosia, and Poecilanthe, which belong to the genistoid clade (Leguminosae Papilionoideae). Phanero-epigeal-foliaceous seedlings are found in Bowdichia virgilioides Kunth, Cyclolobium brasiliense Benth. has phanero-epigeal-reserve seedlings, while Ormosia arborea (Vell.) Harms, Diplotropis martiusii Benth., and Poecilanthe parviflora Benth. possess crypto-hypogeal-reserve seedlings. Some other relevant seedling morphological characters are discussed and compared with those of previously studied species in these genera.

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The taxonomy of the genus Heliotropium L. in Brazil was studied, revealing nine species and two varieties: H. amplexicaule Vahl, H. angiospermum Murray, H. curassavicum L., H. curassavicum var. argentinum I.M. Johnst., H. elongatum (Lehm.) I.M. Johnst., H. elongatum var. burchellii I.M. Johnst., H. indicum L., H. leiocarpum Morong, H. nicotianaefolium Poir., H. phylicoides Cham. and H. transalpinum Vell. Descriptions, illustrations, comments on relationships based on morphology and data on species distribution are presented.

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The aim of this study was to analyse seed dispersal and establishment of Solanum thomasiifolium in an area of nativo vegetation in Espirito Santo state on the southeastern Brazilian coast. Ten species of birds, the crab-eating fox (Cerdocyon thous), and one species of lizard (Tropidurus torquatus) fed on S. thomasiifolium fruits and dispersed viable seeds in their faeces. The proportional contribution of each of these groups to seed dispersal was 77% (birds), 19% (crab-eating fox) and 4% (lizards). Ants also contributed to seed dispersal. More seeds were deposited in vegetation islands than in the surrounding open areas. Germination rates of seeds collected directly from fruit (control), bird droppings, the faeces of crab-eating foxes and lizards were, respectively, 64, 64, 53, and 80 %. Differences among these rates were all significant, except between birds and control. Lizards were important as seed carriers between nearby islands and they expelled a higher proportion of viable seeds. Birds and the crab-eating foxes did not enhance seed germination, but promoted seed dispersal over a wider area. Plant architecture, fruit productivity, fruit characteristics and the diversity of frugivores are important for the success of S. thomasiifolium in habitat colonization.

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This work deals with a taxonomic study of the genus Euploca (Heliotropiaceae) in Brazil; seventeen species are recorded. A keyfor identification, descriptions, illustrations and comments, besides distribution, habitat, flowering and fruiting data for the species are presented.

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This survey aimed at describing the interactions of floral visitors and Davilla kunthii A. St.-Hil. as well as characteristics of its reproductive biology in Itacoatiara, state of Amazonas, Brazil. Tests of the breeding system were performed. The guild of visitors was described according to richness, abundance, relative frequency and constancy. The breeding system tests indicated that D. kunthii is self-compatible. The pollination system was characterized as generalist, with 39 visitor species, from three different orders. Bees were the main group of pollinators, thus some behavioural aspects were described. Th e period of highest foraging activity was between 7 and 10 am. Some species presented agonistic and monopolistic behaviour. Given the behaviour and destructive potential, the Curculionidae seem to have a greater impact as seed predators than pollinators.

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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.

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A revision of the Brazilian species of Lonchocarpus s. str. is presented. This study is based on field observation and an analysis of approximately 1,200 herbarium collections. Nine species are recognized, L. cultratus, L. hedyosmus, L. latifolius, L. macrocarpus, L. nitidus, L. pluvialis, L. sericeus, L. spiciflorus, and L. violaceus, which grow in forests and are usually associated with river banks. Lonchocarpus sericeus and L. cultratus have a wide distribution throughout Brazil, whereas L. hedyosmus, L. macrocarpus, L. spiciflorus, and L. latifolius are restricted to the Amazonian domain. Lonchocarpus pluvialis occurs in the Central-West (Mato Grosso do Sul and Goiás) and Southeast (São Paulo) regions. Lonchocarpus violaceus is found in the states of Bahia and Espírito Santo, and is reported for the first time for Brazil. Identification keys, descriptions, and illustrations, in addition to information about habitat, geographic distribution and taxonomic and nomenclatural comments, are provided for the species. Four new synonyms and five lectotypifications are proposed.

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The aim of this work was to evaluate the floristic composition, richness, and diversity of the upper and lower strata of a stretch of mixed rain forest near the city of Itaberá, in southeastern Brazil. We also investigated the differences between this conservation area and other stretches of mixed rain forest in southern and southeastern Brazil, as well as other nearby forest formations, in terms of their floristic relationships. For our survey of the upper stratum (diameter at breast height [DBH] > 15 cm), we established 50 permanent plots of 10 × 20 m. Within each of those plots, we designated five, randomly located, 1 × 1 m subplots, in order to survey the lower stratum (total height > 30 cm and DBH < 15 cm). In the upper stratum, we sampled 1429 trees and shrubs, belonging to 134 species, 93 genera, and 47 families. In the lower stratum, we sampled 758 trees and shrubs, belonging to 93 species, 66 genera, and 39 families. In our floristic and phytosociological surveys, we recorded 177 species, belonging to 106 genera and 52 families. The Shannon Diversity Index was 4.12 and 3.5 for the upper and lower strata, respectively. Cluster analysis indicated that nearby forest formations had the strongest floristic influence on the study area, which was therefore distinct from other mixed rain forests in southern Brazil and in the Serra da Mantiqueira mountain range.

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Mistletoe can have a major impact on the fitness of the host plant. If there is more than one species of mistletoe on the same host tree, the overall impact might be amplified. We report the occurrence of more than one species of mistletoe on the same host tree. Although it is not a rule in the field, to our knowledge, there have been no studies of this topic. In most cases, two species of mistletoe were recorded on the same host tree, although we recorded three species of mistletoe on one occasion. This demonstrates that different species of mistletoe can be compatible with the same host species. Therefore, compatibility (structural and physiological) might be an important factor for the occurrence of mistletoe. Recent studies have shown that if the mistletoe does not recognize the host species, the deposited seeds will germinate but the haustorium will not penetrate the host branch. This is probably the primary mechanism in the establishment of more than one species of mistletoe on the same host, which can trigger a cascade of harmful effects for the host species.

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Understanding the flow of diaspores is fundamental for determining plant population dynamics in a particular habitat, and a lack of seeds is a limiting factor in forest regeneration, especially in isolated forest fragments. Bamboo dominance affects forest structure and dynamics by suppressing or delaying the recruitment of and colonization by tree species as well as by inhibiting the survival and growth of adult trees. The goal of the present study was to determine whether dominance of the bamboo species Aulonemia aristulata (Döll) McClure in the forest understory influences species abundance and composition. We examined the seed rain at two noncontiguous sites (1.5 km apart) within an urban forest fragment, with and without bamboo dominance (BD+ and BD- areas, respectively). Sixty seed traps (0.5 m², with a 1-mm mesh) were set in the BD+ and BD- areas, and the seed rain was sampled from January to December 2007. Diaspores were classified according to dispersal syndrome, growth form and functional type of the species to which they belonged. There were significant differences between the two areas in terms of seed density, species diversity and dispersal syndrome. The BD+ area showed greater seed density and species diversity. In both areas, seed distribution was limited primarily by impaired dispersal. Bamboo dominance and low tree density resulted in fewer propagules in the seed rain. Our results suggest that low availability of seeds in the rain does not promote the maintenance of a degraded state, characterized by the presence of bamboo.

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We analyzed the structure of the understory community in the Atlantic Forest sensu lato, for which phytosociological descriptions of the understory are lacking. We delineated 50 plots of 10 × 20 m each at four sites within an Araucaria forest (a subtype of Atlantic Forest), located in the municipalities of Bananal, Campos do Jordão, Itaberá and Barra do Chapéu, all of which are in the state of São Paulo, Brazil. To sample the resident species of the understory, we randomly selected five 1 × 1 m subplots within each plot, resulting in a total sampling area of 250 m² at each site. We identified differences among the locations, mostly due to proportional differences in growth forms, in terms of species richness and the importance values within the community. Factors potentially influencing the understory structure include macroclimatic and microclimatic conditions, as well as forest fragmentation, the abundance of deciduous trees in the canopy, the surrounding vegetation and geographic location.