Tree structure and richness in an Atlantic Forest fragment: distance from anthropogenic and natural edges

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.

Macroscopic description of the external and middle ear of paca (Cuniculus paca Linnaeus, 1766)

Abstract: Paca (Cuniculus paca), one of the largest rodents of the Brazilian fauna, has inherent characteristics of its species which can conribute as a new option for animal experimantation. As there is a growing demand for suitable experimental models in audiologic and otologic surgical research, the gross anatomy and ultrastructural ear of this rodent have been analyzed and described in detail. Fifteen adult pacas from the Wild Animals Sector herd of Faculdade de Ciências Agrárias e Veterinárias, Unesp-Jaboticabal, were used in this study. After anesthesia and euthanasia, we evaluated the entire composition of the external ear, registering and ddescribing the details; the temporal region was often dissected for a better view and detailing of the tympanic bulla which was removed and opened to expose the ear structures analyzed mascroscopically and ultrastructurally. The ear pinna has a triangular and concave shape with irregular ridges and sharp apex. The external auditory canal is winding in its path to the tympanic mebrane. The tympanic bulla is is on the back-bottom of the skull. The middle ear is formed by a cavity region filled with bone and membranous structures bounded by the tympanic membrane and the oval and round windows. The tympanic membrane is flat and seals the ear canal. The anatomy of the paca ear is similar to the guinea pig and from the viewpoint of experimental model has major advantages compared with the mouse ear.

Analysis of Regular and Irregular Dynamics of a Non Ideal Gear Rattling Problem

This paper presents a study on the dynamics of the rattling problem in gearboxes under non-ideal excitation. The subject has being analyzed by a number of authors such as Karagiannis and Pfeiffer (1991), for the ideal excitation case. An interesting model of the same problem by Moon (1992) has been recently used by Souza and Caldas (1999) to detect chaotic behavior. We consider two spur gears with different diameters and gaps between the teeth. Suppose the motion of one gear to be given while the motion of the other is governed by its dynamics. In the ideal case, the driving wheel is supposed to undergo a sinusoidal motion with given constant amplitude and frequency. In this paper, we consider the motion to be a function of the system response and a limited energy source is adopted. Thus an extra degree of freedom is introduced in the problem. The equations of motion are obtained via a Lagrangian approach with some assumed characteristic torque curves. Next, extensive numerical integration is used to detect some interesting geometrical aspects of regular and irregular motions of the system response.

Colonização de clareiras naturais na floresta atlântica no sudeste do Brasil

RESUMO - (Colonização de clareiras naturais na floresta Atlântica no sudeste do Brasil). Em duas florestas na encosta atlântica no sudeste do Brasil, foi analisada a colonização vegetal de 23 clareiras naturais (34-256 m²). Nos dois locais de estudo, as clareiras pequenas foram as mais abundantes, cobrindo a maior parte da superfície ocupada por este tipo de perturbação (100-66%). As clareiras apresentaram padrão comum de colonização, caracterizado pela dominância de indivíduos e espécies tolerantes à sombra, principalmente aquelas de sub-bosque. Não observou-se relação entre tamanho das clareiras, composição de guildas de regeneração e a abundância das espécies dominantes. Os resultados sugerem que a floresta atlântica possui riqueza reduzida de espécies intolerantes à sombra, principalmente as grandes pioneiras, que são pouco abundantes e pouco freqüentes. O tamanho não é o melhor preditor da composição florística e ecológica das clareiras.

Fitossociologia de um remanescente de mata mesófila semidecídua urbana, bosque John Kennedy, Araguari, MG, Brasil

RESUMO - (Fitossociologia de um remanescente de mata mesófila semidecídua urbana, Bosque John Kennedy, Araguari, MG, Brasil). Um estudo fitossociológico foi realizado no Bosque Municipal John Kennedy, município de Araguari, MG (48°11'19''W e 18°38'35''S). O bosque, com aproximadamente 11,2 ha, situa-se no perímetro urbano e é formado principalmente por uma mata mesófila semidecídua. No levantamento fitossociológico realizado, amostraram-se, em 1,2 ha, 1827 indivíduos, pertencentes a 46 famílias; 88 gêneros e 113 espécies, com um índice de diversidade de Shannon de H' = 3,75 nats/indivíduo. Os parâmetros fitossociológicos indicam as espécies mais importantes: Licania apetala, Micrandra elata, Copaifera langsdorffii, Astronium nelson-rosae e Alchornea glandulosa, e as famílias mais importantes: Chrysobalanaceae, Euphorbiaceae, Caesalpinaceae, Mimosaceae e Anacardiaceae. A ocorrência de algumas espécies incluidas entre as principais, caracteristicamente, pioneiras (Alchornea glandulosa e Piptocarpha macropoda), ou secundárias (Didymopanax macrocarpum e Maprounea guianensis), pode ser explicada pela existência de algumas áreas de clareiras, no interior dessa mata semidecídua, mas que, aparentemente, ainda não interferiram na estrutura da mata como um todo.

Produção de serapilheira em clareiras de uma floresta estacional semidecidual no município de Campinas, SP

Estudou-se a produção de serapilheira em 10 clareiras naturais da Reserva Municipal de Santa Genebra (22°49'45"S e 47°06'33"W) em Campinas, SP. Foram utilizados 30 coletores de madeira de 0,5 x 0,5 m com fundo em tela de náilon com 1,0 mm² de malha, colocados a 10 cm acima da superfície do solo. As coletas foram realizadas mensalmente de janeiro a dezembro de 1997. Em laboratório, o material depositado nos coletores foi triado nas frações folhas, ramos (até 2,0 cm de diâmetro), flores e frutos, seco em estufa a 70°C e pesado em balança analítica. A produção anual de serapilheira foi estimada para as clareiras como um todo em 5968 kg.ha­1, sendo a fração foliar dominante (75,87% do peso seco total), seguida das frações ramos com 19,27%, frutos com 3,17% e flores com 1,69%. A produção de serapilheira foi contínua ao longo do ano, apresentando um modelo sazonal, com os maiores valores no final da estação seca, atingindo valor máximo em setembro. Entre clareiras, a produção de serapilheira correlacionou-se significativa e positivamente com a dominância de espécies pioneiras.

Germination of seeds of tropical pioneer species under controlled and natural conditions

Seed germination of eight tropical pioneer species (Cecropia hololeuca, C. pachystachya, C. glazioui, Solanum gracillimum, S. granuloso-leprosum, S. tabacifolium, Croton floribundus and Miconia chamissois) was studied. In controlled conditions, alternating temperatures were tested from 5 to 25 °C. Low Red:Far Red ratios (R:FR) were also examined. In the field, germination was evaluated in gaps and under the canopy. With the exception of Croton floribundus, all other species were photoblastic in that higher germination percentages were found under light conditions (S. tabacifolium behaved as a negative photoblastic species at some temperatures). No relationship was found between germination percentage and alternating temperature. Germination was markedly reduced under low R:FR ratios. Alternating temperature is not the main factor affecting field germination. The low R:FR ratio under the canopy seems to be the crucial factor affecting germination.

Leaf optical properties of two liana species Canavalia parviflora Benth. and Gouania virgata Reissk in different light conditions

Lianas are plants that depend on support to reach some appreciable height, and they represent an important structural component of tropical forests. Although they predominate in clearings and gaps, some species survive in the understory. Changes in irradiance between these environments can affect leaf morphology and absorption of photosynthetic active radiation (PAR). We had examined the effects of different light regimes on leaf optical properties, chlorophyll content, specific leaf area, and leaf surface morphology in young seedlings of Canavalia parviflora Benth. (Fabaceae) and Gouania virgata Reissk (Rhamnaceae). The seedlings were distributed on workbenches covered by different layers of neutral shade netting, thus creating three levels of light intensity corresponding to about 40%, 10% and 1.5% of solar irradiance. Plants growing in full sun were used as a control. Both species exhibited an increase in reflectance in full sun and alterations in leaf morphology. Reduction in irradiance induced an increase in absorptance (decrease in reflectance and transmittance) in C. parviflora leaves in the green due to higher chlorophyll content. In G. virgata the spectral leaf changes were less observable. However, the efficiency of absorption was more pronounced in G. virgata than in C. parviflora leaves under 40%, 10% and 1.5% photon flux density (PFD). The greater efficiency of absorption in G. virgata was due to a larger specific leaf area (SLA) under these conditions. The adjustments in leaf optical properties can aid these species in overall carbon gain under limited light conditions.

Structure and dynamics of a woody plant community of a tropical semi-deciduous seasonal forest in the "Estação Ecológica do Panga", municipality of Uberlândia, Minas Gerais, Brazil

Studies of plant community dynamics are essential in understanding the demographic patterns of species since changes in demographic rates can affect the floristic composition and future structure. The purpose of the present study was to analyze the changes in the community structure and floristic composition of woody plants in a tropical semi-deciduous forest in Uberlândia in central Brazil, during a 10-years period. The data were collected in 1989 and in 2000 in 50 quadrats (10 m x 10 m) where all trees with a minimum circumference at breast height of 10 cm were sampled. In 1989, 93 species and 1103 individuals were registered. Over a period of 10 years, seven new species were added to the community, although eight disappeared. The main change that occurred during this period in the floristic composition was the replacement of savannah species occurring in forest gaps by those from the forest understory.

Rock outcrop vegetation in Brazil: a brief overview

This paper overviews the special issue of the Brazilian Journal of Botany dedicated to "Rock outcrop vegetation in Brazil". The main topics covered by this issue are phytogeography and vegetation ecology, plant life on shallow soils, plant reproduction and auto-ecology, morpho-physiology and plant adaptation, and finally conservation and global change. This collection of studies, in addition to other recent publications on Brazilian rocky outcrop vegetation, show that measurements of most of the relevant ecological and evolutionary parameters are under way and that scientific attention is now given to most Brazilian regions. However, there are still several gaps to be bridged: 1) inselbergs and high mountains in the Amazon and the Brazilian northeast, in particular, are still largely unknown to science; 2) long-term studies are almost totally unavailable, which hinders global change monitoring and assessment; 3) national and international networking are urgently needed to speed up scientific production about such habitats.

Pollination biology in Jacaranda copaia (Aubl.) D. Don. (Bignoniaceae) at the "Floresta Nacional do Tapajós", Central Amazon, Brazil

Jacaranda copaia (Aubl.) D. Don is a pioneer tree widespread in the Brazilian Amazon, usually found colonizing forest gaps and altered areas, and the forest fragment edges. This study investigated aspects of the floral biology, breeding system and pollinators of J. copaia trees. Flowering lasts from August to November, during the low rainfall period extending up to four weeks per tree and 3-4 months for the population as a whole, characterizing a cornucopia flowering pattern. The fruit set ends in the beginning of the rainy season, with wind dispersed winged seeds. Fruit set from open pollination was 1.06% (n = 6,932). Hand pollination using self-pollen (n = 2,099) did not set fruits. Cross-pollination resulted in 6.54% fruit set (n = 2,524), representing six times more than the natural pollination rate (1.06%, n = 6,932). Flowers excluded from insect visitation (automatic self-pollination) did not set fruits (n = 5,372). Pollen tube growth down to ovary was detected under fluorescence microcoscopy in cross-pollinated and selfed pistils. The species is an obligate allogamous plant, with late-acting self-incompatibility system. Approximately 40 species of native bees visited the flowers, but the main pollinators were medium-sized solitary bees as Euglossa and Centris species due to the compatibility between their body sizes with the corolla tube, direct contact with the reproductive structures and high frequency of visits.

Chromosome damage in underground coal miners: detection by conventional cytogenetic techniques and by submitting lymphocytes of unexposed individuals to plasma from at-risk groups

Chromosome abnormalities and the mitotic index in lymphocyte cultures and micronuclei in buccal mucosa cells were investigated in a sample of underground mineral coal miners from Southern Brazil. A decreased mitotic index, an excess of micronuclei and a higher frequency of chromosome abnormalities (fragments, polyploidy and overall chromosome alterations) were observed in the miners when compared to age-paired normal controls from the same area. An alternative assay for clastogenesis in occupational exposition was tested by submitting lymphocytes from non-exposed individuals to a pool of plasmas from the exposed population. This assay proved to be very convenient, as the lymphocytes obtained from the same individuals can be used as target as well as control cells. Also, it yielded a larger number of metaphases and of successful cultures than with common lymphocyte cultures from miners. A significantly higher frequency of chromatid gaps, fragments and overall alterations were observed when lymphocytes from control subjects were exposed to miner plasma pools. Control plasma pools did not significantly induce any type of chromosome alterations in the cultures of normal subjects, thus indicating that the results are not due to the effect of the addition of plasma pools per se.

Clastogenic effects of different Ureaplasma urealyticum serovars on human chromosomes

The possibility that Ureaplasma urealyticum might play an important role in human infertility was first raised more than 20 years ago, but this association remains speculative. Considering the hypothesis that the pathogenicity of Ureaplasma urealyticum may depend on its serotypes, the clastogenic effects of different strains of Ureaplasma urealyticum, at concentrations of 103 CCU (color changing units)/ml, 104 CCU/ml and 105 CCU/ml, were evaluated in vitro in short-term cultures of human lymphocytes. Total or partial mitotic inhibition was produced by Ureaplasma urealyticum serotypes 2, 3 and 10 independent of the concentration (103 CCU/ml, 104 CCU/ml or 105 CCU/ml) of the microorganisms employed. In contrast, the clastogenic effects observed with serotypes 1, 7 and 12 varied according to the concentration employed in the test. Mitotic alterations were observed in Ureaplasma urealyticum serotypes 5, 6, 7, 8, 9, 11 and 12. Chromatid gaps (53.0%) and chromatid breaks (13.9%) were the most frequent types of alterations observed. The results of this in vitro assay demonstrated that the clastogenic effects varied with the Ureaplasma urealyticum serotypes evaluated

Plantability and moisture content of naked and pelleted seeds of supersweet (Sh2) corn during cold storage conditions

The supersweet (Sh2) corn seeds have a thin tegument and an irregular shape, which hinder the sowing procedure. As a function of those factors, the significance of using the pelleting process to improve sowing and standardize the stand of plants in the field without the need of thinning within the row is emphasized. Although this technique has already been known for many years, little has been studied on the effect of such procedure on the plantability and on the moisture content of the supersweet corn seeds. Therefore, this research work aimed at evaluating the effects of pelleting on the moisture content of the seeds along the storing process, on the occurrence of gaps on seed deposition and on the dropping of double seeds, with the aid of a testing seeder. Other physical attributes of seeds and pellets were also evaluated through tests of fragmentation, screen retention, mass of a thousand seeds and apparent volume. Results have shown an increase on the mass and on the volume of the pelleted seeds that presented highly resistance to cracks and breaking. The pelleting was efficient on the reduction of gaps and on the deposition of double seeds at sowing, thus providing highly satisfactory results for these attributes. An increase on the seed moisture content was also observed as a function of storage with a significant reduction on this factor after the pelleting procedure. Results allow concluding that the pelleting process reduces seed moisture content and improves plantability, positively affecting the efficiency of the sowing process.

Indicadores socioambientais: evolução e perspectivas

Social-environmental indicators: evolution and perspectives. This article deals with the balance of sustainability indicators and/or sustainable development indicators. Major gaps and blocks - both conceptual and operational - still hinder the socio-environmental governance from avoiding "blind flights".