Ant-caterpillar Antagonism At The Community Level: Interhabitat Variation Of Tritrophic Interactions In A Neotropical Savanna.

Ant foraging on foliage can substantially affect how phytophagous insects use host plants and represents a high predation risk for caterpillars, which are important folivores. Ant-plant-herbivore interactions are especially pervasive in cerrado savanna due to continuous ant visitation to liquid food sources on foliage (extrafloral nectaries, insect honeydew). While searching for liquid rewards on plants, aggressive ants frequently attack or kill insect herbivores, decreasing their numbers. Because ants vary in diet and aggressiveness, their effect on herbivores also varies. Additionally, the differential occurrence of ant attractants (plant and insect exudates) on foliage produces variable levels of ant foraging within local floras and among localities. Here, we investigate how variation of ant communities and of traits among host plant species (presence or absence of ant attractants) can change the effect of carnivores (predatory ants) on herbivore communities (caterpillars) in a cerrado savanna landscape. We sampled caterpillars and foliage-foraging ants in four cerrado localities (70-460 km apart). We found that: (i) caterpillar infestation was negatively related with ant visitation to plants; (ii) this relationship depended on local ant abundance and species composition, and on local preference by ants for plants with liquid attractants; (iii) this was not related to local plant richness or plant size; (iv) the relationship between the presence of ant attractants and caterpillar abundance varied among sites from negative to neutral; and (v) caterpillars feeding on plants with ant attractants are more resistant to ant predation than those feeding on plants lacking attractants. Liquid food on foliage mediates host plant quality for lepidopterans by promoting generalized ant-caterpillar antagonism. Our study in cerrado shows that the negative effects of generalist predatory ants on herbivores are detectable at a community level, affecting patterns of abundance and host plant use by lepidopterans. The magnitude of ant-induced effects on caterpillar occurrence across the cerrado landscape may depend on how ants use plants locally and how they respond to liquid food on plants at different habitats. This study enhances the relevance of plant-ant and ant-herbivore interactions in cerrado and highlights the importance of a tritrophic perspective in this ant-rich environment.

Germinação de esporos de Polypodium pleopeltifolium: resultados preliminares

Polypodium pleopeltifolium is an epiphytic fern which occurs in cerrado vegetation of the State of São Paulo, Brazil. The species is light sensitive for germination but some spores germinate in the absence of light. Short treatments at 40 or 5ºC and alternating temperatures did not increase the germination in dark conditions. Germination was not affected by IAA but it was reduced by GA3, CEPA and ABA. Red light (short treatments) promoted germination.

Análise da estrutura de duas unidades fitofisionômicas de savana (cerrado) no sul do Brasil

The Jaguariaiva region is located at Parana State, southern Brazil, and it keeps up the last remnants of savanna vegetation in the State. Thus, it should be considered a mark of the meridional distribution limit of this vegetation type in Brazil. The Parque Estadual do Cerrado (24º09' S; 50º18' WG), whose vegetation is not solely composed by savanna forms, was the object of this study that analysed the vegetation of two dominant savanna physiognomic types (cerrado sensu stricto and campo cerrado). Twenty quadrats of 200m² (20 x 10m) were sistematicaly established in each physiognomic unit, and all the individuals having Basal Perimeter (BP) over 15 cm were sampled. The survey results indicated a low number of woody species in both units (33 species in cerrado sensu stricto and 18 in campo cerrrado). Most important species were virtually the same for both units, specially Byrsonima coccolobifolia, Acosinium subelegans, Couepia grandiflora and Stryphnodendron adstringens. The total density, total dominance and diversity were higher in cerrado sensu stricto. Moreover. there was apparently a higher lloristic resemblance with savannas of São Paulo State, specially those located in the South of thc State.

On Advertisement Call Of The Poison Frog Ameerega Berohoka (dendrobatidae, Anura) From The Brazilian Cerrado.

The poison frog genus Ameerega (Dendrobatidae) currently contains 32 species. They are distributed from central Brazil into western Amazonia to the lower Andean versant. In addition, three trans-Andean species have been allocated to Ameerega (Andrade et al. 2013; Frost 2014). Ameerega berohoka (Vaz-Silva & Maciel 2011) was described based on specimens from central Brazil (type-locality: Arenópolis, GO) and it is assumed to occur in parts of western and southwestern state of Goiás (Frost 2014). More recently, Andrade et al. (2013) extended its distribution to the state of Mato Grosso. Here we re-describe the advertisement call of A. berohoka, providing additional information regarding its temporal structure and spectral traits. Our observations also consist of a new distribution record for this species to the state of Mato Grosso.

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.

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.

Flora e aspectos auto-ecológicos de um encrave de cerrado na chapada do Araripe, Nordeste do Brasil

This study subject to investigate the floristic composition and richness, the reproductive phenological patterns, the dispersal syndromes and life forms of species of a disjunt cerrado in semiarid climate at Araripe plateau during a one year period. We found 107 species and 41 families. Fabaceae, Myrtaceae, Poaceae, Apocynaceae, Euphorbiaceae and Malpighiaceae showed the largest number of species. For 47 of the woody species found, we studied the geographical distribution based on 27 papers of the Brazilian cerrados. Twelve species are of widespread occurence in the cerrado, and 13 are restricted to the Araripe plateau. Zoocory, autocory, and anemocory are the predominant syndromes of dispersal. The predominant life forms were phanerophytes (50.7%), hemicriptophytes (14.9%) and camephytes (13.1%). The cerrado of Araripe have lower species richness than continous cerrados, but a similar pattern of reproductive phenology, dispersal syndromes and life forms in more humid zones.

Produção de serapilheira e decomposição do material foliar em um cerradão na Estação Ecológica de Jataí, município de Luiz Antônio, SP, Brasil

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.

Flora arbórea da bacia do rio Tibagi (Paraná, Brasil): Celastrales sensu Cronquist

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.

Is size structure a good measure of future trends of plant populations? an empirical approach using five woody species from the Cerrado (Brazilian savanna)

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.

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.