Laboratorio Of Ecologia Vegetal

Laboratorio Of Ecologia Vegetal

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Peixoto K.S.,Laboratorio Of Ecologia Vegetal | Marimon-Junior B.H.,Laboratorio Of Ecologia Vegetal | Marimon-Junior B.H.,Mato Grosso State University | Marimon B.S.,Laboratorio Of Ecologia Vegetal | And 8 more authors.
Acta Oecologica | Year: 2017

The transition region between two major South American biomes, the Amazon forest and the Cerrado (Brazilian savanna), has been substantially converted into human-modified ecosystems. Nevertheless, the recovery dynamics of ecosystem functions in this important zone of (ecological) tension (ZOT) remain poorly understood. In this study, we compared two areas of cerradão (a forest-woodland of the Brazilian savanna; Portuguese augmentative of cerrado), one in secondary succession (SC) and one adjacent and well preserved (PC), to test whether the ecosystem functions lost after conversion to pasture were restored after 22 years of regeneration. We tested the hypothesis that the increase in annual aboveground biomass in the SC would be greater than that in the PC because of anticipated successional gains. We also investigated soil CO2 efflux, litter layer content, and fine root biomass in both the SC and PC. In terms of biomass recovery our hypothesis was not supported: the biomass did not increase in the successional area over the study period, which suggested limited capacity for recovery in this key ecosystem compartment. By contrast, the structure and function of the litter layer and root mat were largely reconstituted in the secondary vegetation. Overall, we provide evidence that 22 years of secondary succession were not sufficient for these short and open forests (e.g., cerradão) in the ZOT to recover ecosystem functions to the levels observed in preserved vegetation of identical physiognomy. © 2017 Elsevier Masson SAS

De Souza V.C.,Federal University of Paraiba | Agra P.F.M.,Federal University of Paraiba | De Andrade L.A.,Laboratorio Of Ecologia Vegetal | De Oliveira I.G.,Federal University of Paraiba | De Oliveira L.S.,Federal University of Pernambuco
Semina:Ciencias Agrarias | Year: 2010

The work had as objectives to evaluate the influence of the light, temperature, and chemical scarification on the germination of seeds of S. virgata, species still little studied and that is invasive in several niches of the caatinga ecosystem. The seeds of S. virgata were collected in the municipal district of Natuba-PB in March/2008. Eight treatments were used as follows: intact seeds in the presence and absence of light, at 25°C; intact seeds in the presence and absence of light, at 30°C; submerged seeds in sulfuric acid for five minutes in the presence and absence of light, at 25°C; submerged seeds in sulfuric acid for five minutes in the presence and absence of light, at 30°C. The germination tests were accomplished in germination cameras under light and continuous darkness at constant temperatures of 25°C and 30°C, in a 12 hours photoperiod. The seeds were put to germinate in plastic boxes (gerbox) with filter paper. The seeds of S. virgata have tegument dormancy and show low germination tax when intact, which is a strategy for seed banks formation. The acid scarification increased germination percentage and speed germination index.

Cardoso F.C.G.,Laboratorio Of Ecologia Vegetal | Marques R.,Federal University of Paraná | Botosso P.C.,EMBRAPA - Empresa Brasileira de Pesquisa Agropecuária | Marques M.C.M.,Laboratorio Of Ecologia Vegetal
Plant and Soil | Year: 2012

Background and aims: Phenological variations in tropical forests are usually explained by climate. Nevertheless, considering that soil water availability and nutrient content also influence plant water status and metabolism, soil conditions may also be important in the regulation of plant reproductive and vegetative activities over time. We investigated whether phenological patterns and stem growth differ in trees growing in two types of soil that display contrasting water and nutrient availability, namely, Gleysol (moist and nutrient-poor) and Cambisol (drier and nutrient-rich). Methods: Phenological observations (flushing, leaf fall, flowering and fruiting) and stem diameter growth were recorded for 120 trees fitted with fixed dendrometer bands, at 15 days intervals, for 1 year. Two species of contrasting deciduousness were investigated: Senna multijuga (semi-deciduous) and Citharexylum myrianthum (deciduous). Results: Both species were seasonal in all phenophases, regardless of soil type. However, frequency, mean date and intensity of phenophases varied according to soil type. Girth increment of C. myrianthum was four times greater in Cambisol than in Gleysol, whereas the type of soil had no significant effect on that of S. multijuga. Conclusions: These results show that soil characteristics also play an important role in determining phenological patterns and growth and must be considered when analysing phenological patterns in tropical forests. © 2011 Springer Science+Business Media B.V.

Mejia-Recamier B.E.,National Autonomous University of Mexico | Vazquez I.M.,National Autonomous University of Mexico | Callejas-Chaveros A.,Laboratorio Of Ecologia Vegetal | Estrada-Venegas E.G.,Colegio de Mexico
Experimental and Applied Acarology | Year: 2013

Agroecosystems are altered systems whose soil structure has changed affecting the dynamics of soil organisms. This paper aims at evaluation of the effects of garlic farming practices on phenology, richness, abundance, composition and diversity of soil-dwelling Cunaxidae. Ten pilot plots in Guanajuato State were sampled from August 2002 to July 2005, every month, 8 months per year. Ten soil samples (1 kg) were taken from each plot and extracted in Berlese-Tullgren funnels. A total of 108 cunaxids were found, belonging to 11 species. Neocunaxoides andrei was the most abundant, and Cunaxa evansi and Armascirus sp. were least abundant. Relative abundance was highest after harvesting and during plant growth, and lowest during planting. Dactyloscirus nicobarensis and D. candylus were present from planting to harvesting. According to Sörensen's similarity coefficient between cultivation stages, Cunaxidae communities were similar during plant growth and harvesting, sharing 80 % of the species. The highest abundance and diversity were found in 2004, during and after harvesting. Cunaxid species increased over 100 % from planting to the harvesting phase, suggesting that they play an important role in the soil agrosystems food web. Species composition and diversity in cunaxid communities present in garlic crop fields varied with agricultural phase, but little change was observed among the years studied. All species found in this study are new records for the state of Guanajuato and for the garlic crop fields. © 2013 Springer Science+Business Media Dordrecht.

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