A pest is a pest is a pest? The dilemma of neotropical leaf-cutting ants: Keystone taxa of natural ecosystems

Leaf-cutting ants of the genera Acromyrmex and Atta are considered the principal polyphagous pests of the Neotropics. Although some members of these genera are of economic importance, have a broad geographic distribution, and are extremely good colonizers, others are endemic and closely interact with native ecosystems. Control is generally practiced against any colony, irrespective of its taxonomic status. Indiscriminate control coupled with habitat destruction threatens endemic species with extinction, and, through habitat simplification, favors other pest species. As nests of Atta are large, having several square meters of nest surface, the endemic taxa can be easily used as environmental indicators for natural ecosystems. Likewise, the pest species can be used to detect environmental disturbance. As these ants are keystone species and easily identified by nonspecialists, efforts should be made to integrate these into viable conservation programs.

Solar energy budgets in central Amazonian ecosystems: a comparison between natural forest and bare soil areas

In order to estimate the deforestation consequences on the actual solar energy budget of the Central Amazon Region, two ecosystems of different characteristics were compared. The present conditions of the region were represented by a typical 'terra firme' forest cover located at INPA's Ducke Forest Reserve, where the measurements necessary to evaluate its solar energy balance were carried out. The second ecosystem, simulating a deforested area, was represented by an area about 1.0 ha without natural vegetation and situated in the same Reserve. In this area lysimeters were placed, two of them filled with yellow latosol and two others with quartzose sand soil. Both soils are representative soils in the region. Their water balances were taken into account as well as the other parameters necessary to compute the solar energy balances. The results showed that water loss by evaporation was about 41.8% of the total precipitation in the yellow latosol lysimeters and about 26.4% for the quartzose sand ones. For the forest cover it was estimated an evapotranspiration of 67.9% of the rainfall amount. In relation to solar energy balance calculated for the forest cover, it was found that 83.1% of the total energy incoming to this ecosystem was used by the evapotranspiration process, while the remaining of 16.9% can be taken as sensible heat. For bare soils, 55.1% and 31.8% of the total energy were used as latent heat by yellow latosol and quartzose sand soils, respectively. So, the remaining amounts of 44.9% and 68.2% were related to sensible heat and available to atmospheric air heating of these ecosystems. Such results suggest that a large deforestation of the Amazon Region would have direct consequences on their water and solar radiation balances, with an expected change on the actual climatic conditions of the region. © 1993.

Photosynthetic characteristics of charophytes from tropical iotic ecosystems

Responses of photosynthetic rates, determined by oxygen evolution using the light and dark bottles technique, to different temperatures, irradiances, pH, and diurnal rhythm were analyzed under laboratory conditions in four charophyte species (Chara braunii Gmelin, C. guairensis R. Bicudo, Nitella subglomerata A. Braun and Nitella sp.) from Iotic habitats in southeastern Brazil. Parameters derived from the photosynthesis versus irradiance curves indicated affinity to low irradiances for all algae tested. Some degree of photoinhibition, [β = -(0.30-0.13) mg 02 g-1 dry weight h-1 (μmol photons m-2 s-1)-1], low light compensation points (lc = 4-20 μmol photons m-2 s-1) were found for all species analyzed, as well as low values of light saturation parameter (lk) and saturation (ls) 29-130 and 92-169 μmol photons m-2 S-1, respectively. Photoacclimation was observed in two populations of N. subglomerata collected from sites with different irradiances, consisting of variations in photosynthetic parameters (higher values of α, and lower of lk and maximum photosynthetic rate, Pmax, in the population under lower irradiance). The highest photosynthetic rates for Chara species were observed at 10-15°C, while for Nitella the highest photosynthetic rate was observed at 20-25°C, despite the lack of significant differences among most levels tested. Rates of dark respiration significantly increase with temperature, with the highest values at 25°C. The results from pH experiments showed highest photosynthetic rates under pH 4.0 for all algae, suggesting higher affinity for inorganic carbon in the form of carbon dioxide, except in one population of N. subglomerata, with similar rates under the three levels, suggesting indistinct use of bicarbonate and carbon dioxide. Diurnal changes in photosynthetic rates revealed a general pattern for most algae tested, which was characterized by two peaks: the first (higher) during the morning (07.00-11.00) and the second (lower) in the afternoon (14.00-17.00). This suggests an endogenous rhythm determining the daily variations in photosynthetic rates.

Comparative study of the zooplankton composition of two lacustrine ecosystems in Southwestern Amazonia

The zooplankton communities of two lacustrine ecosystems in southwestern Amazonia (Lago Amapá and Lago Pirapora) were studied based on samples collected over an 11-month period. The general aim of the present work was to contribute to the knowledge of the zooplankton fauna in southwestern Amazonia, by studying the occurrence of certain species; and to improve the knowledge of the Rio Acre tributaries. The total number of taxa included 38 species of rotifers, 6 cladocerans and 7 copepods. Most of the species were from the rotifer family Brachionidae. Jaccard's similarity index was similar for the two lakes at 0.6964 The constancy index defined the species Keratella cochlearis, Filinia cf. terminate, Filinia opoliensis, Hexarthra intermedia braziliensis, Ceriodaphnia cornuta, Moina minuta, Diaphanosoma spinulosnm, and immature forms (nauplii and copepodites) as the constant in these lakes. The presence of zooplankton with higher number of species occupying the middle depths, during morning and night periods.

Marine Protected Areas in Brazil: An ecological approach regarding the large marine ecosystems

The objective of this study was to address the importance of implementing Coastal and Marine Protected Areas in Brazil and to examine their distribution, based on the delimitation of Large Marine Ecosystems. Out of a total of 336 protected areas identified in Brazilian coastal and marine areas, the North Platform has the largest protected area, but the ecosystem with the largest number of protected area, predominantly sustainable areas, was the East Coast followed by the South Platform. One of the reasons the eastern coast of Brazil to have more protected areas is the fact that there is a largest amount of coral reefs. Additionally there was political opportunities for the creation of protected areas for sustainable use. The coastal region of Brazil has achieved the goal proposed by the Seventh Conference of the Parties to the Convention on Biological Diversity - 7, but only then through the category V of the International Union for Conservation of Nature, which is not the best efficient means of conserving resources. The goal for marine conservation shows only the area above the recommended under protection in North Platform. The Marine portion of the East Coast and the South Platform has few protected areas, regardless of category management. We consider the coastal region the range of 12 nautical miles from baselines determined in accordance with the United Nations Convention on the Law of the Sea. As for the number of strategies permitted by law and used for the conservation of coastal and marine systems, coastal systems show a higher number when compared with the marine system. We suggest that the Brazilian government should specify strategies for the protection of marine systems and expand the protected areas of all Large Marine Ecosystems. © 2013 Elsevier Ltd.

Fenologia reprodutiva e vegetativa de arbustos endêmicos de campo rupestre na Serra do Cipó, Sudeste do Brasil

The Brazilian campos rupestres (high-altitude grasslands) are very important on the world conservation scenario because of high species richness and endemism. These grasslands are regarded as threatened ecosystems due to intense, on-going disruption by man's activities. The aim of this study was to describe the reproductive and vegetative phenological patterns of six shrub species endemic to these grasslands in the Espinhaço Range, sympatric in Serra do Cipó, MG. We tested the relationship between species phenophases and local climate seasonality. We expect that the species phenophases are strongly correlated with variations of the dry and wet seasons. Observations were conducted monthly on reproductive (flowering, fruit production and dispersal) and vegetative (leaf fall and budding) phenophases. Given the combination of reproductive phenology, vegetative phenology, and seasonality, we observed four phenological strategies for the six species. Therefore this study revealed great diversity in phenological patterns, even when considering the small number of species sampled. Moreover, all species showed a significant seasonal pattern for the reproductive phenophases, with high concentrations of species reproducing during a given season, suggesting a key role of climate in defining phenological patterns in the campo rupestre grasslands.

Longitudinal patterns of fish assemblages in mountain streams from tropical forest biome

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Persea pumila (Lauraceae), a New Species from the Brazilian Serra da Mantiqueira Mountain Range

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A new probabilistic canopy dynamics model (SLCD) that is suitable for evergreen and deciduous forest ecosystems

There are strong uncertainties regarding LAI dynamics in forest ecosystems in response to climate change. While empirical growth & yield models (G&YMs) provide good estimations of tree growth at the stand level on a yearly to decennial scale, process-based models (PBMs) use LAI dynamics as a key variable for enabling the accurate prediction of tree growth over short time scales. Bridging the gap between PBMs and G&YMs could improve the prediction of forest growth and, therefore, carbon, water and nutrient fluxes by combining modeling approaches at the stand level.Our study aimed to estimate monthly changes of leaf area in response to climate variations from sparse measurements of foliage area and biomass. A leaf population probabilistic model (SLCD) was designed to simulate foliage renewal. The leaf population was distributed in monthly cohorts, and the total population size was limited depending on forest age and productivity. Foliage dynamics were driven by a foliation function and the probabilities ruling leaf aging or fall. Their formulation depends on the forest environment.The model was applied to three tree species growing under contrasting climates and soil types. In tropical Brazilian evergreen broadleaf eucalypt plantations, the phenology was described using 8 parameters. A multi-objective evolutionary algorithm method (MOEA) was used to fit the model parameters on litterfall and LAI data over an entire stand rotation. Field measurements from a second eucalypt stand were used to validate the model. Seasonal LAI changes were accurately rendered for both sites (R-2 = 0.898 adjustment, R-2 = 0.698 validation). Litterfall production was correctly simulated (R-2 = 0.562, R-2 = 0.4018 validation) and may be improved by using additional validation data in future work. In two French temperate deciduous forests (beech and oak), we adapted phenological sub-modules of the CASTANEA model to simulate canopy dynamics, and SLCD was validated using LAI measurements. The phenological patterns were simulated with good accuracy in the two cases studied. However, IA/max was not accurately simulated in the beech forest, and further improvement is required.Our probabilistic approach is expected to contribute to improving predictions of LAI dynamics. The model formalism is general and suitable to broadleaf forests for a large range of ecological conditions. (C) 2014 Elsevier B.V. All rights reserved.

An analysis of publications on invasive macrophytes in aquatic ecosystems

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Cyanobacteria in mangrove ecosystems

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Phosphorus fractions in soils of the mangrove, restinga and Atlantic forest ecosystems from Cardoso Island, Brazil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Ecological distribution of stream macroalgal communities from a drainage basin in the Serra da Canastra National Park, Minas Gerais, Southeastern Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ecological distribution of stream macroalgal communities from a drainage basin in the Serra da Canastra National Park, Minas Gerais, Southeastern Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)