Determinantes locais da decomposição foliar e de raízes finais em um ecossistema semiárido do nordeste brasileiro

The decomposition process exercises an extensive control over the carbon cycle, affecting its availability and nutrient cycling in terrestrial ecosystems. The understanding of leaf decomposition patterns above the soil and fine roots decomposition below the soil is necessary and essential to identify and quantify more accurately the flow of energy and matter in forest systems. There is still a lack of studies and a large gap in the knowledge about what environmental variables act as local determinants over decomposition drivers. The knowledge about the decomposition process is still immature for Brazilian semiarid region. The aim of this study was to analyze the decomposition process (on leaves and fine roots) of a mixture of three native species for 12 months in a semiarid ecosystem in Northeast Brazil. We also examined whether the rate of decomposition can be explained by local environmental factors, specifically plant species richness, plant density and biomass, soil macro-arthropods species richness and abundance, amount of litterfall and fine root stock. Thirty sampling points were randomly distributed within an area of 2000 m x 500 m. To determine the decomposition rate, the litterbag technique was used and the data analysis were made with multiple regressions. There was a high degradation of dead organic matter along the experiment. Above ground plant biomass was the only environmental local factor significantly related to leaf decomposition. The density of vegetation and litter production were positively and negatively related to decay rates of fine roots, respectively. The results suggest that Caatinga spatial heterogeneity may exert strong influences over the decomposition process, taking into account the action of environmental factors related to organic matter exposure of and the consequent action of solar radiation as the decomposition process main controller in this region

Improving photoprotection of Beauveria bassiana conidia for biological control of the cactus pest Dactylopius opuntiae in the semiarid region northeast of Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Femur biometry, densitometry and chemical composition from Moxoto goats supplemented with concentrate in a semiarid region

The aim of study was to investigate if different intake levels of concentrate (supplementation levels) would have an influence on chemical composition, biometric aspects and bone mineral density (BMD) of femurs from Moxoto growing goats in the Brazilian semiarid region. Thirty-two castrated kids (15.69 +/- 0.78 kg initial BW) were used allocated randomly to one of the four levels of supplementation (SL) (treatments groups: 0: 5; 10 and 15 g/kg BW). When the animals of treatment group 15 g/kg BW reached 25 kg BW, the animals in the others treatments groups were also slaughtered. The increase SL resulted in linear increase (P<0.001) in the performance of animals as well as in fresh and dry weight of the femur and decrease of relative weight of the femur. The dry matter contents (g/kg) of femur increased linearly, however, the amounts of MM, ether extract, Ca, P. Mg, Na and K were not affected by the treatments. The values found in this study ranged from 134.84 to 155.90g of Ca, 48.14 to 55.95g of P. 1.69 to 1.87g of Mg, 2.87 to 3.24g of Na and 1.42 to 1.61 g of K/kg of bone in natura for animals with smaller and higher slaughter weight, respectively. The biometric and densitometric variables increased linearly with increasing treatments, except for the thickness of the sponge layer of the proximal and distal epiphysis and BMD measured in the distal epiphysis. The supplementation with concentrate did not affect the chemical composition of the femur, although it has positively influenced the structure and the bone mineral density. A BMD estimated via radiographic bone aluminum equivalent did not have correspondence with bone mineral content measured chemically. (C) 2011 Elsevier BM. All rights reserved.

Environmental Fate of Neonicotinoids and Classification of Their Potential Risks to Hypogean, Epygean, and Surface Water Ecosystems in Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Os reservatórios eutrofizados da região tropical semiárida atuam como emissores ou como sequestradores de dióxido de carbono?

The aquatic ecosystems can play a role as carbon-dioxide-source or carbon-dioxide-sink systems due to the high predominance of heterotrophic or autotrophic metabolism. The primary production can strongly affect the carbon balance (CO2) through the consumption of carbon dioxide in the photosynthesis, especially in eutrophic environment, acting as a carbon sink. The present study tested the hypothesis that the eutrophic reservoirs in tropical semi-arid region are carbon dioxide-sink systems due to the high primary productivity presented in these systems. Five Brazilian reservoirs from the semi-arid in the northeast region were monitored monthly during four years (2010 to 2013) with a prolonged drought event identified during the study. The results showed an increasing level of eutrophication over the period of prolonged drought, with the predominance of autotrophy. Significant negative correlations were observed between the partial pressure of CO2 (pCO2) (p<0,001) and chlorophyll-a in the Boqueirão, Passagem das Traíras, Dourado and Gargalheiras reservoirs, showing a pattern of the carbon dioxide-sink systems. However, this pattern was not found in Cruzeta reservoir. In summary, in the tropical semi-arid region, hydrological and morphometric variables can lead to different behaviors of the water-supply reservoirs on the carbon metabolism. The eutrophic reservoirs evaluated showed a negative relationship between pCO2 and Chl-a, which suggests that these water bodies show an autotrophic metabolism and behave as carbon dioxide- sink systems

Fungos gasteroides (Basidiomycota, Agaricomycetes) de três áreas de semiárido no Estado do Ceará, Brasil

Gasteroid fungi include several distinct lineages of basidiomycetes that were grouped by presenting some striking features in common like angiocarpic development and passive release of basidiospores. For a long period these fungi were accomodate in Gasteromycetes class. However, biochemistry and molecular studies showed the polyphyly of this group and curriently this class lies devoid of taxonomic value. These organisms influence the ecology of the various biomes, however, are poorly studied and knowledge of their diversity in neotropical ecosystems remains insufficient, despite studies that have been developed in recent years. The Brazilian semiarid region has many areas with an unexplored mycobiota. Ceará State has many areas of extreme biological importance and for this study three protected areas were chosen: Área de Proteção Ambiental da Serra da Ibiapaba, Parque Nacional de Ubajara and Área de Proteção Ambiental de Baturité. Therefore, the aim of this study was to inventory gasteroid fungi ocorring in these three areas in the semiarid region of Ceará. The expeditions, herborization and analysis of specimes were based in traditional methodology used to identify gasteroid fungi. Were identified 16 species belong to 5 families: Agaricaceae, Clathraceae, Geastraceae, Nidulariceae and Phallaceae. Morganella nuda Alfredo & Baseia is recorded for the second time in the world, Blumenavia angolensis (Welw. & Curr) Dring and Mutinus elegans (Mont.) E. Fisch. corresponds to a first record in the Brazilian Northeastern. Except for Abrachium floriforme (Baseia & Calonge) Baseia & T.S. Cabral and Geastrum lloydianum Rick, all remaining species are new records for Ceará, increasing the list of gasteroid fungi in the region of 3 for 17 species. Identified species were deposited in the collection of the Herbarium of Universidade Federal do Rio Grande do Norte. Although these areas have proved conducive to the study of gasteroid fungi, more efforts are still needed to increase knowledge of these fungi in the region

Population genetic relationships between Casearia sylvestris (Salicaceae) varieties occurring sympatrically and allopatrically in different ecosystems in south-east Brazil

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

Patterns of spatial distribution in macroalgal communities from tropical lotic ecosystems

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

LONGITUDINAL DISTRIBUTION OF MACROALGAE IN 2 TROPICAL LOTIC ECOSYSTEMS FROM SOUTHEASTERN BRAZIL

Macroalgal species richness and diversity were analysed along a longitudinal profile in small and large scales during Spring, Fall and Winter, respectively in a small stream and a mid size river in the northwest region of São Paulo State, southeastern Brazil (20 degrees 23'-20 degrees 49'S, 49 degrees 26'-51 degrees 19'W). Longitudinal variation in species richness and diversity in small scale was strongly associated with incident light. Microhabitat distribution (from data taken by quadrat technique) revealed no significant correlations. Principal coordinates analysis (PCO) indicated no consistent groupings among sampling sites in distinct seasons (Spring, Fall and Winter). Longitudinal analysis in large scale revealed different patterns in the two seasons sampled (Spring and Winter), whereas species diversity presented a consistent tl end: high upstream, low in mid reaches and higher downstream. It was associated with type of substratum in Spring, rocky substrata presenting the highest values for species richness and diversity. Weak correlations were observed in Winter. Microhabitat distribution showed significant correlations between species abundance and the following variables: positive for rocky substrata and current velocity and negative for sandyclayish substratum and macrophyte-dominated substratum. PCO delineated only one consistent grouping formed by the two headwater sites. Small scale macroalgal distribution corroborated the longitudinal pattern predicted by the River Continuum Concept, whereas the large scale approach showed a distribution more associated with substratum type than to light availability. These results showed an opposite trend in relation to the expected distributional pattern. Longitudinal distribution in macroalgal community structure has yet to be better documented, particularly for tropical streams and no generalization is possible at this stage.

Comparative sediment quality assessment in different littoral ecosystems from Spain (Gulf of Cadiz) and Brazil (Santos and Sao Vicente estuarine system)

The goal of this work was to establish comparisons among environmental degradation in different areas from Southern Spain (Gulf of Cadiz) and Brazil (Santos and Sao Vicente estuary), by using principal component analyses (PCA) to integrate sediment toxicity (amphipods mortality) and chemical-physical data (Zn, Cd, Pb; Cu, Ni, Co, V, PCBs, PAHs concentrations, OC and fines contents). The results of PCA extraction of Spanish data showed that Bay of Cadiz, CA-1 did not present contamination or degradation; CA-2 exhibited contamination by PCBs, however it was not related to the amphipods mortality. Ria of Huelva was the most impacted site, showing contamination caused principally by hydrocarbons, in HV-1 and HV-2, but heavy metals were also important contaminants at HV-1, HV-2 and HV-3. Algeciras Bay was considered as not degraded in GR-3 and -4, but in GR-3' high contamination by PAHs was found. In the Brazilian area, the most degraded sediments were found in the stations situated at the inner parts of the estuary (SSV-2, SSV-3, and SSV-4), followed by SSV-6, which is close to the Submarine Sewage Outfall of Santos - SSOS. Sediments from SSV-1 and SSV-5 did not present chemical contamination, organic contamination or significant amphipod mortality. The results, of this investigation showed that both countries present environmental degradation related to PAHs: in Spain, at Ria of Huelva and Gudarranque river's estuary areas; and in Brasil, in the internal portion of the Santos and Sao Vicente estuary. The same situation is found for heavy metals, since all of the identified metals are related to toxicity in the studied areas, with few exceptions (V for both Brazil and Spain, and Cd and Co for Brazilian areas). The contamination by PCBs is more serious for Santos and Sao Vicente estuary than for the investigated areas in Gulf of Cadiz, where such compound did not relate to the toxicity. (c) 2006 Elsevier Ltd. All rights reserved.

Yeast biodiversity from oleic ecosystems: Study of their biotechnological properties

The aim of this study was to know the yeast biodiversity from fresh olive (Olea europaea L.) fruits, olive paste (crush olives) and olive pomace (solid waste) from Arbequina and Cornicabra varieties. Yeasts were isolated from fruits randomly harvested at various olive groves in the region of Castilla La Mancha (Spain). Olive paste and pomace, a byproduct of the processing of this raw material, were also collected in sterile flasks from different oil mills. Molecular identification methodology used included comparison of polymerase chain reaction (PCR) amplicons of their 5.8S rRNA gene and internal transcribed spacers ITS1 and ITS2 followed by restriction pattern analysis (RFLP). For some species, sequence analysis of the 5.8S rDNA gene was necessary. The results were compared to sequences held in public databases (BLAST). These techniques allowed to identify fourteen different species of yeasts, belonging to seven different genera (Zygosaccharomyces, Pichia, Lachancea, Kluyveromyces, Saccharomyces, Candida, Torulaspora) from the 108 yeast isolates. Species diversity was thus considerable: Pichia caribbica, Zygosaccharomyces fermentati (Lachancea fermentati) and Pichia holstii (Nakazawaea holstii) were the most commonly isolated species, followed by Pichia mississippiensis, Lachancea sp., Kluyveromyces thermotolerans and Saccharomyces rosinii. The biotechnological properties of these isolates, was also studied. For this purpose, the activity of various enzymes (beta-glucosidase, beta-glucanase, carboxymethylcellulase, polygalacturonase, peroxidase and lipase) was evaluated. It was important that none of species showed lipase activity, a few had cellulase and polygalacturonase activities and the majority of them presented beta-glucanase, beta-glucosidase and peroxidase activities. (C) 2010 Elsevier Ltd. All rights reserved.

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.