DSpace Coleção: Doutorado

Fluxos superficiais de CO2 e de energia em um plantio de palma de óleo durante e após o El-Niño 2015-2016 no Leste da Amazônia

Wed, 14 Jan 2026 00:00:00 GMT

Título: Fluxos superficiais de CO2 e de energia em um plantio de palma de óleo durante e após o El-Niño 2015-2016 no Leste da Amazônia Autor(es): SILVA, Julie Andrews de França e Abstract: The 2015-2016 El Niño-Southern Oscillation (ENSO), after the 1950s, was one of the most extreme weather events ever recorded. In the Amazon, ENSO is the cause of reduced rainfall, increased solar radiation and air temperature, consequently, soil moisture is reduced, and the vapor pressure deficit is high, as variables that influence the development and production of oil palm. In this context, the objective of the thesis was to quantify the surface fluxes of CO2 and energy, defining the physical variables that control these processes seasonally and interannually in an oil palm plantation with interspecific hybrid (HIE) (Elaeis guineensis Jacq x Elaeis oleifera (Kunth) Cortés) in eastern Amazonia during the ENSO period (2015 and 2016) and in normal years (2017 and 2018). The CO2 and H2O flux data were calculated using the eddy covariance (EC) method. Photosynthetic parameters were estimated by adjusting the light response curve (LCR) using a non-rectangular hyperbole model. The averages of the Net Ecosystem CO2 Exchange (NEE) and the maximum CO2 assimilation rate (Amax) were higher during the years with ENOS, especially in the wet season. In the normal year of 2017, the greatest assimilation occurred in the dry season. The energy fluxes were higher in the years 2015 and 2016, showing high values of sensible heat flux (H) and latent heat flux (LE). Most of the net radiation (Rn) was used for evapotranspiration processes (52 to 74%). Biophysical controls such as aerodynamic conductance (Ca), surface conductance (Cs) and decoupling factor (Ω) were also calculated to better understand the behavior of the oil palm. Cs showed higher values in 2015 and 2016, indicating greater stomatal opening. Results that corroborated with the same period of the maximum found for NEE and LE. Ca was higher in the dry season, especially in 2015, favoring gas exchange. In 2015 (ENSO), Ω (in both seasonal periods) demonstrated that evapotranspiration was more influenced by vegetation. The physical variables showed weak to strong correlations with NEE, H, LE and Cs, depending on seasonality and year. The most significant were incident photosynthetically active radiation, vapor pressure deficit and soil moisture. Therefore, the interspecific hybrid was shown to be resilient to severe ENSO, with an increase in the CO2 assimilation and LE. As well, it was observed that HIE showed similar behaviors with the equatorial Amazonian forests and different to the plantations located in Southeast Asia in normal year.

O Manejo florestal como meio de conservação de espécies: uma proposta de manejo da espécie Acapu (Vouacapoua americana Aubl.)

Thu, 15 Feb 2024 00:00:00 GMT

Título: O Manejo florestal como meio de conservação de espécies: uma proposta de manejo da espécie Acapu (Vouacapoua americana Aubl.) Autor(es): JÚNIOR PEREIRA, Rodrigo Antônio Abstract: The species Vouacapoua americana Aublet (acapu or acapuzeiro), has great wood importance and, ecologically, stands out in the composition of the forests where it occurs. In the Brazilian Amazon, the species is being heavily explored without taking into account the knowledge of its ecological, structural, dynamic, silvicultural, use, economic variables, among others. The aim of this study was to contribute to the establishment of sustainable management of V. americana. The distribution zone of the V. americana populations occur in the Eastern Amazon. Dendrometric, dendrological and tree location data were obtained from Pre-Harvest Forest Inventories (IFPC) and their Continuous Forest Inventories (IFC). Information on the diametric, basal, volumetric and hypsometric structure of the species was obtained from each studied population. To evaluate the spatial distribution pattern, Ripley's K(h) function was used. To identify the ecological group of the V. americana species, two groups were considered: pioneer and non-pioneer (later successional state)For the dynamics, three stages were considered, regeneration (total height ≤30cm to DBH<2.5cm), shrub stratum (2.5cm ≤ DBH <10cm) and arboreal stratum (DBH≥10cm), and the Natural Regeneration rate (TR) was calculated. %), Ingress/recruitment (I%) and Mortality (M%). Based on the structural and dynamic characteristics, guidelines for the sustainable management of V. americana were defined. A total of 36,609 trees with a diameter varying between 10 cm and 127.32 cm were registered. Density between 6.31 trees/ha and 25.55 trees/ha. Diametric distribution showed decrease from the smallest to the largest diameter classes and when adjusted presented a distribution curve resembling a "reverse-J", a behavior reported in other studies with the species and in primary forests without disturbance anthropogenic, indicating this type of diametric distribution as a structural characteristic of the species. The basal area ranged between 0.5063m²/ha and 3.4521m²/ha, this variation was mainly influenced by the density of the species than by the DAP presented. The commercial height ranged from 2.00 m to 25.00 m, with median heights from 10 to 16 m predominating, values similar to these were observed in other studies with the species. The volume ranged from 1.6645m³/ha to 32.169m³/ha, the highest concentrations were observed in diameter classes between 40 and 80cm. V. americana was characterized in the successional group of non pionner species, having as the spatial arrangement of the trees the aggregated or grouped pattern, which was influenced by the dispersal syndrome of the species. The dynamics in the levels of seedlings, canes and trees showed variation in ingress and mortality rates, and in the arboreal population the number of trees did not vary much between measurements, indicating adaptation of the species to shading conditions in the forest. The tree population presented a diameter growth ranging from 0.22 to 0.29 cm/year, being considered low, however, in accordance with other studies for the species. The characteristics of structure, dynamics, ecology, phenology and use of V. americana provided the definition of guidelines for the sustainable management of the species: pre- exploratory forest inventory must be carried out for all trees with at least DBH ≥ 30cm; the period of exploitation of the wood product must be the months of the Amazonian summer in the region where the species occurs, before the phenophase of flowering, fruiting and seed dissemination; the minimum cut diameter (DMC) 40.00cm and the maximum cut diameter (DMxC) up to 80.00 cm; exploration intensity should be based on the adjusted diametric distribution and the observed diametric distribution; the cutting cycle must be defined by the ratio between the class interval of the diameter distribution and its growth in diameter; the selection of trees to be logged must be contained in the diameter classes of the logging interval, between the DMC and DMxC, and the density of this selection must not exceed the logging intensity; and silvicultural treatments should be based on population dynamics studies of the species.

Gestão comunitária de projetos de manejo florestal sustentável (PMFS) na Gleba Nova Olinda I, Santarém/Pará.

Thu, 08 Feb 2024 00:00:00 GMT

Título: Gestão comunitária de projetos de manejo florestal sustentável (PMFS) na Gleba Nova Olinda I, Santarém/Pará. Autor(es): MORAES, Carla Kelen de Andrade Abstract: This research aimed to understand and analyze the process of community management of PMFS through the administrative functions (planning, organization, direction and control), and specifically: identifying how communities use the forest and the logging companies relate.; and analyze the productive and / or economic practices that can be reconciled with the PMFS, aiming at generating income and / or food for the communities. The methodology used in the research was the Participatory Rapid Diagnosis (DRP), from the application of tools such as: semi-structured interview, georeferenced maps, productive calendar and flow diagram. The SWOT matrix was also used to analyze the internal and external environment of the researched organizations. The research identified that the communities do not have historical tradition with the forest management activity, but with the extraction activity, mainly for the collection of Brazil nuts and rosin. The relationship between the communities and the logging companies is contractual for the management activity, where the company is responsible for all stages of the process, passing on to the communities the values of logging. The PMFS resource management process demonstrates how a lack of knowledge of administrative functions in planning, organizing, directing and controlling acts weakens the autonomy of community organizations. Traditional production practices can be reconciled with forest management activity, but it is necessary to evaluate the opposite of this statement. “Can forest management threaten some traditional practices developed by communities?”

Fitorremediação de cádmio por Khaya ivorensis A. Chev. mitigação do estresse por silício nas modulações fisiológicas, bioquímicas e anatômicas.

Fri, 09 Feb 2024 00:00:00 GMT

Título: Fitorremediação de cádmio por Khaya ivorensis A. Chev. mitigação do estresse por silício nas modulações fisiológicas, bioquímicas e anatômicas. Autor(es): CONCEIÇÃO, Susana Silva Abstract: Among the heavy metals (MPs), cadmium (Cd) represents one of the biggest threats to the environment on a global scale, due to its high ecotoxicological potential and increasing soil indices, which contributes to the loss of carbon dioxide productivity and biodiversity of ecosystems. Fast-growing woody plants represent effective tools for Cd extraction in contaminated soil. In this sense, African mahogany (Khaya ivorensis A. Chev), a tree species belonging to the Meliaceae family, presents satisfactory characteristics for remediation given its accelerated growth, axial root system and high biomass production. However, the phytoremediation strategies and Cd tolerance mechanisms implemented by this species, associated with the improvement of nutritional status, are not clear. Given the above, this research aims to identify the modulations of silicon (Si), a beneficial micronutrient, in the physiology, biochemistry, antioxidant system and anatomy of African mahogany seedlings submitted to toxic levels of Cd and correlate these processes with increased phytoremediation potential to MP. The experimental design was a randomized block design in a 4x4 factorial scheme with five replications, and the factors constituted by increasing levels of MP (Cd 0,25, 50 and 75 mg L-1) and silicon doses (Si 0, 100, 150 and 300 mg L-1). Polynomial regression analysis, response surface was performed. Cd 50 and 75 mg L-1 concentrations were toxic and caused changes in biochemical processes with negative physiological and anatomical repercussions on K. ivorensis. There was photoinhibitory damage to PSII, where the variables of chlorophyll a, (ΦPSII), (qP) and (ETR) fluorescence, photosynthesis (A), gas exchange (gs), (Ci/Ca) and photosynthetic pigments , especially chlorophyll b, were the most affected by the highest level of the metal and presented respective minimum points by the regression adjustment of 0.05; 0.07; 0.15 µmol molar CO2 -1 ; 3.2 mmol CO2m -2 s -1; 0.1 mol H2O m-2s -1; 0.06 µmol molar CO2 and 0.18 mg g-1 and were 78%, 82%, 75%, 83%, 96%, 93% and 95% lower than the control. Disorganization in cytosolic metabolism caused lipid peroxidation. Malonoaldehyde content was increased by 69% and 63% in leaves and roots, which was accompanied by reductions in antioxidant enzyme activities. Above all, CAT had its expression decreased by 69% in the root system. Anatomical changes occurred in the tissues with marked decreases in epidermal thickness. The palisade parenchyma and root cortex were 84% and 72% less thick under that toxic Cd level. However, Si attenuated the stress promoted by the ion and modulated overexpression in those variables, which ensured the growth and development of K. ivorensis under conditions of MP contamination. Normal plant metabolism was resumed only in those submitted to treatment with Cd 50 mg L-1 and nourished with Si 150 mg L-1. Canonical analysis showed that the combination of Cd 45mg L -1 and Si 160 mg L-1 resulted in the maximum points of those parameters where the values came close to the control. Si modulation in antioxidant metabolism was confirmed by a 31% increase in SOD activity. These response patterns were related to the reduction of Cd translocation to the aerial parts due to its entrapment in the Si-induced root system. Thus, the micronutrient increased K. ivorensis tolerance and phytoremediation potential to Cd by MP phytostabilization which resulted from mechanisms of Si complexation to Cd, as well as ion restrictions imposed by the caspary striations, mediated by the beneficial mineral. Tolerance to Cd was due to improved water relations.