All Green, But Equal? Morphological Traits And Ecological Implications On Spores Of Three Species Of Mosses In The Brazilian Atlantic Forest.

Spores of the tropical mosses Pyrrhobryum spiniforme, Neckeropsis undulata and N. disticha were characterized regarding size, number per capsule and viability. Chemical substances were analyzed for P. spiniforme and N. undulata spores. Length of sporophyte seta (spore dispersal ability) was analyzed for P. spiniforme. Four to six colonies per species in each site (lowland and highland areas of an Atlantic Forest; Serra do Mar State Park, Brazil) were visited for the collection of capsules (2008 - 2009). Neckeropsis undulata in the highland area produced the largest spores (ca. 19 µm) with the highest viability. The smallest spores were found in N. disticha in the lowland (ca. 13 µm). Pyrrhobryum spiniforme produced more spores per capsule in the highland (ca. 150,000) than in lowland (ca. 40,000); longer sporophytic setae in the lowland (ca. 64 mm) than in the highland (ca. 43 mm); and similar sized spores in both areas (ca. 16 µm). Spores of N. undulata and P. spiniforme contained lipids and proteins in the cytoplasm, and acid/neutral lipids and pectins in the wall. Lipid bodies were larger in N. undulata than in P. spiniforme. No starch was recorded for spores. Pyrrhobryum spiniforme in the highland area, different from lowland, was characterized by low reproductive effort, but presented many spores per capsule.

Metacommunity Versus Biogeography: A Case Study Of Two Groups Of Neotropical Vegetation-dwelling Arthropods.

Biogeography and metacommunity ecology provide two different perspectives on species diversity. Both are spatial in nature but their spatial scales do not necessarily match. With recent boom of metacommunity studies, we see an increasing need for clear discrimination of spatial scales relevant for both perspectives. This discrimination is a necessary prerequisite for improved understanding of ecological phenomena across scales. Here we provide a case study to illustrate some spatial scale-dependent concepts in recent metacommunity studies and identify potential pitfalls. We presented here the diversity patterns of Neotropical lepidopterans and spiders viewed both from metacommunity and biogeographical perspectives. Specifically, we investigated how the relative importance of niche- and dispersal-based processes for community assembly change at two spatial scales: metacommunity scale, i.e. within a locality, and biogeographical scale, i.e. among localities widely scattered along a macroclimatic gradient. As expected, niche-based processes dominated the community assembly at metacommunity scale, while dispersal-based processes played a major role at biogeographical scale for both taxonomical groups. However, we also observed small but significant spatial effects at metacommunity scale and environmental effects at biogeographical scale. We also observed differences in diversity patterns between the two taxonomical groups corresponding to differences in their dispersal modes. Our results thus support the idea of continuity of processes interactively shaping diversity patterns across scales and emphasize the necessity of integration of metacommunity and biogeographical perspectives.

The Neuromuscular Activity Of Bothriopsis Bilineata Smaragdina (forest Viper) Venom And Its Toxin Bbil-tx (asp49 Phospholipase A2) On Isolated Mouse Nerve-muscle Preparations.

The presynaptic action of Bothriopsis bilineata smaragdina (forest viper) venom and Bbil-TX, an Asp49 PLA2 from this venom, was examined in detail in mouse phrenic nerve-muscle (PND) preparations in vitro and in a neuroblastoma cell line (SK-N-SH) in order to gain a better insight into the mechanism of action of the venom and associated Asp49 PLA2. In low Ca(2+) solution, venom (3μg/ml) caused a quadriphasic response in PND twitch height whilst at 10μg/ml the venom additionally induced an abrupt and marked initial contracture followed by neuromuscular facilitation, rhythmic oscillations of nerve-evoked twitches, alterations in baseline and progressive blockade. The venom slowed the relaxation phase of muscle twitches. In low Ca(2+), Bbil-TX [210nM (3μg/ml)] caused a progressive increase in PND twitch amplitude but no change in the decay time constant. Venom (10μg/ml) and Bbil-TX (210nM) caused minor changes in the compound action potential (CAP) amplitude recorded from sciatic nerve preparations, with no significant effect on rise time and latency; tetrodotoxin (3.1nM) blocked the CAP at the end of the experiments. In mouse triangularis sterni nerve-muscle (TSn-m) preparations, venom (10μg/ml) and Bbil-TX (210nM) significantly reduced the perineural waveform associated with the outward K(+) current while the amplitude of the inward Na(+) current was not significantly affected. Bbil-TX (210nM) caused a progressive increase in the quantal content of TSn-m preparations maintained in low Ca(2+) solution. Venom (3μg/ml) and toxin (210nM) increased the calcium fluorescence in SK-N-SH neuroblastoma cells loaded with Fluo3 AM and maintained in low or normal Ca(2+) solution. In normal Ca(2+), the increase in fluorescence amplitude was accompanied by irregular and frequent calcium transients. In TSn-m preparations loaded with Fluo4 AM, venom (10μg/ml) caused an immediate increase in intracellular Ca(2+) followed by oscillations in fluorescence and muscle contracture; Bbil-TX did not change the calcium fluorescence in TSn-m preparations. Immunohistochemical analysis of toxin-treated PND preparations revealed labeling of junctional ACh receptors but a loss of the presynaptic proteins synaptophysin and SNAP25. Together, these data confirm the presynaptic action of Bbil-TX and show that it involves modulation of K(+) channel activity and presynaptic protein expression.

Environmental Controls In The Water Use Patterns Of A Tropical Cloud Forest Tree Species, Drimys Brasiliensis (winteraceae).

Trees from tropical montane cloud forest (TMCF) display very dynamic patterns of water use. They are capable of downwards water transport towards the soil during leaf-wetting events, likely a consequence of foliar water uptake (FWU), as well as high rates of night-time transpiration (Enight) during drier nights. These two processes might represent important sources of water losses and gains to the plant, but little is known about the environmental factors controlling these water fluxes. We evaluated how contrasting atmospheric and soil water conditions control diurnal, nocturnal and seasonal dynamics of sap flow in Drimys brasiliensis (Miers), a common Neotropical cloud forest species. We monitored the seasonal variation of soil water content, micrometeorological conditions and sap flow of D. brasiliensis trees in the field during wet and dry seasons. We also conducted a greenhouse experiment exposing D. brasiliensis saplings under contrasting soil water conditions to deuterium-labelled fog water. We found that during the night D. brasiliensis possesses heightened stomatal sensitivity to soil drought and vapour pressure deficit, which reduces night-time water loss. Leaf-wetting events had a strong suppressive effect on tree transpiration (E). Foliar water uptake increased in magnitude with drier soil and during longer leaf-wetting events. The difference between diurnal and nocturnal stomatal behaviour in D. brasiliensis could be attributed to an optimization of carbon gain when leaves are dry, as well as minimization of nocturnal water loss. The leaf-wetting events on the other hand seem important to D. brasiliensis water balance, especially during soil droughts, both by suppressing tree transpiration (E) and as a small additional water supply through FWU. Our results suggest that decreases in leaf-wetting events in TMCF might increase D. brasiliensis water loss and decrease its water gains, which could compromise its ecophysiological performance and survival during dry periods.

Variação na cobertura vegetal nativa em São Paulo: um panorama do conhecimento atual

Studies in several countries have shown the occurrence of forest transition, when forest cover increase overcomes the loss by deforestation. In Brazil, although deforestation is still higher than afforestation, this relationship may be inverse in some regions. Recent assessments suggest the tendency of the state of São Paulo towards forest transition. Aiming to analyze forest transition evidence and facilitate the use of existing information, we review data on native vegetation cover variation in São Paulo from four data sources (Instituto Florestal, SOS MataAtlântica/INPE, IBGE and CATI/IEA). Our results indicate that discrepancies among these assessments may be accounted by differences in methodologies and objectives. We highlight their common grounds and discuss possibilities to harmonize their information.

Composição florística da floresta semidecídua de altitude do Parque Municipal da Grota Funda (Atibaia - Estado de São Paulo)

A floristic survey was carried out in the Grota Funda Municipal Park, Atibaia Municipality, Sao Paulo State (45º45 - 46º 45'W and 23º10 - 23º15'S), a mountainous region from 900 to 1400 meters above sea level. The climate is characterized by two seasons a hot, moist period from October to March and a dry, cold period from April to August, with frequent frosts. The sandy soil is low in fertility and highly acid at the surface. The study was done from April 1987 to November 1988. A total of 415 species were collected and identified: 362 dicotyledons belonging to 84 families and 224 genera, and 53 monocotyledons beloging to 15 families and 43 genera. Species richness in Atibaia can be attributed to environmental diversity, edaphic variation, and slight disturbance of the vegetation. A comparison with other floristic surveys in mountain forests was made and a list of the most common species of this kind of forest is presented.

Fisionomia e organização da vegetação do carrasco no planalto da Ibiapaba, estado do Ceará

Is the carrasco on the Ibiapaba plateau a unique plant formation? To answer this question the vertical height (except of climbers) and the stem basal diameter (from 3cm on) of woody plants were measured, and soil extracts (0-50 and 50-100cm depth) were taken from 100 random plots (10x10m) at Jaburuna (3º54'34S and 40º59'24W, altitudes near 830m), municipality of Ubajara, Ceará State. Data on climate, soil, diameter height, density, basal area, and physiognomy were compared with those surveyed by other researchers from the carrasco, caatinga, and cerrado in Northeastern Brazil. The carrasco occurs under an annual rainfall of between 668 and 1,289mm and temperatures from 22 to 24ºC, on alic Quartz Sand soils, at altitudes between 700 and 900m: it has a larger density and a smaller basal area than the caatinga and the cerrado, small and similar diameters, and an average vertical height between 3,7 and 5,4m. It differs from the caatinga, cerrado (and cerradão) and secondary forest in many items of lhe ecotope, organization and physiognomy, thus being a unique plain formation, which can be characterized as a deciduous, high, closed, and unistratified shrubland intermingled by lianas, with an irregular canopy and sparse, emergent trees.

Lianas da estação ecológica do Noroeste Paulista, São José do Rio Preto/Mirassol, SP, Brasil

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.

O Complexo Vegetacional da Zona Litorânea no Ceará: Pecém, São Gonçalo do Amarante

Due to its geographical location, the northeastern Coast of Brazil (Litoral Setentrional do Nordeste - LSN) is a hotter and drier climate than the eastern coast. In addition, because of its proximity to caatinga and cerrado, the LSN contains species from these vegetation biomes and from the restinga on the coast, which comprise different plant formations and creates a vegetation complex. Despite the great importance of this ecotone, there are few studies about its flora. The objective of this work was to contribute to what is known about the floristic and phytosociological composition of this region. We made a floristic survey in the area (between 2007 and 2011), consulted herbaria data from the region and made a phytosociological study in a stretch of coastal semideciduous forest (mata de tabuleiro). The study recorded 382 plant species from 96 families. In the phytosociological survey (0.32 ha) we recorded 2,970 individuals and 52 species. The most abundant plants surveyed were the trees Manilkara triflora, Chamaecrista ensiformis and Guapira nitida and the shrubs Cordiera sessilis and Maytenus erythroxyla (average height 3.8 m, average diameter 6.2 cm, basal area 39.28 m²/ha). The local flora includes floristic elements of caatinga, cerrado and restinga, corroborating the idea that the plant community of the coastal region of Ceará has an ecotonal nature.

Mixed rain forest in southeastern Brazil: tree species regeneration and floristic relationships in a remaining stretch of forest near the city of Itaberá, Brazil

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.

Seed rain in areas with and without bamboo dominance within an urban fragment of the Atlantic Forest

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.

Isotopic view of vegetation and carbon and nitrogen cycles in a cerrado ecosystem, southeastern Brazil

Carbon and nitrogen biogeochemical cycles in savannas are strongly regulated by the seasonal distribution of precipitation and pulses of nutrients released during the wetting of the dry soil and are critical to the dynamics of microorganisms and vegetation. The objective of this study was to investigate the spatial and temporal variability of C and N isotope ratios as indicators of the cycling of these elements in a cerrado sensu stricto area, within a protected area in a State Park in the state of São Paulo, Brazil. The foliar δ13C and δ15N values varied from -33.6 to -24.4 ‰ and -2.5 to 4.5 ‰, respectively. The δ13C values showed a consistent relationship with canopy height, revealing the importance of structure of the canopy over the C isotopic signature of the vegetation. Carbon isotopic variations associated with the length of the dry season indicated the importance of recent fixed C to the integrated isotopic signature of the leaf organic C. The studied Cerrado species showed a depleted foliar δ15N, but a wide range of foliar Nitrogen with no difference among canopy heights. However, seasonal variability was observed, with foliar δ15N values being higher in the transition period between dry and rainy seasons. The variation of the foliar C and N isotope ratios presented here was consistent with highly diverse vegetation with high energy available but low availability of water and N.

Respostas fisiológicas de plantas amazônicas de regiões alagadas às mudanças climáticas globais

Conforme previsões do último relatório do IPCC (Intergovernmental Panel of Climatic Change) em 2007, até meados deste século haverá um aumento na concentração de CO2 na atmosfera podendo chegar a 720 μmol mol-1. Consequentemente haverá uma elevação da temperatura de até +3 °C, o que ocorrerá em conjunto com mudanças no padrão de precipitação. O mesmo relatório sugere que isto poderá acarretar uma substituição gradual da floresta tropical por vegetação similar a uma savana na parte oriental da Amazônia, porém nada é conclusivo. Diante dessas possibilidades, pergunta-se - Como as espécies de árvores que compõem as regiões de alagamento da Amazônia irão responder às alterações climáticas por vir? Apesar dessas previsões serem pessimistas, o alagamento ainda ocorrerá por vários anos na Amazônia e é de grande importância compreender os efeitos do alagamento sobre as respostas fisiológicas das plantas num contexto das mudanças climáticas. Os principais efeitos sobre a sinalização metabólica e hormonal durante o alagamento são revisados e os possíveis efeitos que as mudanças climáticas poderão ter sobre as plantas amazônicas são discutidos. As informações existentes sugerem que sob alagamento, as plantas tendem a mobilizar reservas para suprir a demanda de carbono necessário para a manutenção do metabolismo sob o estresse da falta de oxigênio. Até certo limite, com o aumento da concentração de CO2, as plantas tendem a fazer mais fotossíntese e a produzir mais biomassa, que poderão aumentar ainda mais com um acréscimo de temperatura de até 3 °C. Alternativamente, com o alagamento, há uma diminuição geral do potencial de crescimento e é possível que quando em condições de CO2 e temperatura elevados os efeitos positivo e negativo se somem. Com isso, as respostas fisiológicas poderão ser amenizadas ou, ainda, promover maior crescimento para a maioria das espécies de regiões alagáveis até o meio do século. Porém, quando a temperatura e o CO2 atingirem valores acima dos ótimos para a maioria das plantas, estas possivelmente diminuirão a atividade fisiológica.

Allometric models for estimating the phytomass of a secondary Atlantic Forest area of southeastern Brazil

The purpose of this study was to develop and validate equations to estimate the aboveground phytomass of a 30 years old plot of Atlantic Forest. In two plots of 100 m², a total of 82 trees were cut down at ground level. For each tree, height and diameter were measured. Leaves and woody material were separated in order to determine their fresh weights in field conditions. Samples of each fraction were oven dried at 80 °C to constant weight to determine their dry weight. Tree data were divided into two random samples. One sample was used for the development of the regression equations, and the other for validation. The models were developed using single linear regression analysis, where the dependent variable was the dry mass, and the independent variables were height (h), diameter (d) and d²h. The validation was carried out using Pearson correlation coefficient, paired t-Student test and standard error of estimation. The best equations to estimate aboveground phytomass were: lnDW = -3.068+2.522lnd (r² = 0.91; s y/x = 0.67) and lnDW = -3.676+0.951ln d²h (r² = 0.94; s y/x = 0.56).

Diversidade de abelhas (Hymenoptera, Apidae) ao longo de um gradiente latitudinal na Mata Atlântica

A Mata Atlântica é um dos ambientes mais ricos e ameaçados do mundo, o que deveria ter estimulado em muito o estudo e a conservação do Bioma, mas a fauna de Hymenoptera permanece ainda relativamente pouco conhecida. Em especial, a fauna de abelhas da floresta ombrófila densa é pouco estudada em comparação à fauna das áreas abertas brasileiras. O projeto temático "Biodiversidade de Hymenoptera e Isoptera: riqueza e diversidade ao longo de um gradiente latitudinal na Mata Atlântica - a floresta úmida do leste do Brasil", integrante do Programa Biota-Fapesp, foi idealizado com o objetivo de catalogar térmitas, formigas e famílias selecionadas de vespas ao longo da Mata Atlântica, disponibilizando dados que permitam melhor embasar a conservação deste bioma. O protocolo de amostragem aplicada para a coleta de himenópteros (excluindo as formigas) empregou armadilhas Malaise, pratos-armadilha de cor amarela e esforço similar na varredura de vegetação ao longo de 17 localidades selecionadas, representando um gradiente de quase 20° de latitude na Mata Atlântica, dos Estados da Paraíba até Santa Catarina. Este protocolo foi definido para otimizar a coleta de vespas, sendo as abelhas um produto secundário da amostragem (levantamentos de abelhas em geral utilizam captura em flores ao longo das estações do ano). No entanto, devido à escala regional do projeto e ao grande esforço de amostragem, uma expressiva quantidade de abelhas foi coletada durante o projeto, incluindo novos registros de abelhas para a Mata Atlântica. Foi amostrado um total de 797 espécimes distribuídos em 105 espécies de abelhas; o grupo de abelhas mais rico e abundante foi Meliponina. Uma análise de correspondência "destendenciada" ('detrended correspondence analysis') aplicada à uma matriz de presença ou ausência de Meliponina revela a relativamente fraca influência do gradiente latitudinal na composição das assembléias de abelhas de Mata Atlântica. Uma listagem das espécies amostradas por localidade, com suas freqüências relativas, é apresentada e discutida.