Navegando por Assunto "Temperatura do solo"

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Acesso aberto (Open Access)
Fluxos de CO2 do solo na Floresta Nacional de Caxiuanã, Pará, durante o experimento ESECAFLOR/LBA
(2013-03) SILVA JUNIOR, João de Athaydes; COSTA, Antonio Carlos Lôla da; AZEVEDO, Pedro Vieira de; COSTA, Rafael Ferreira da; METCALFE, Daniel B.; GONÇALVES, Paulo Henrique Lopes; BRAGA, Alan Pantoja; MALHI, Yadvinder Singh; ARAGÃO, Luiz Eduardo Oliveira e Cruz de; MEIR, Patrick
The ESECAFLOR/LBA experiment was carried out at the Caxiuanã National Forest, Pará State, and this article intends to investigate the effect of hydrological stress on the total soil respiration. Two adjacent 1 hectare plots were defined in January 2002. One plot remained in its natural conditions and was used as a control (A), while in the exclusion plot (B) plastic cover panels were installed in order to drain about 70% of the total rainfall to outside of the plot. Accumulated monthly rainfall was recorded from 2005 January to December. During 2005 the rainfall over the ECFPn was 2,211.6 mm, or 9.96% above the mean of 2,011.2 mm. The average soil moisture was 15.6±9.2 and 9.5±3.4% in the plots A and B, respectively. The average soil temperature was 25.6±0.4 and 25.7±0.5 ºC, for the A and B plots, respectively. The average soil CO2 flux was 3.46±0.44 and 3.21±0.84 μmolCO2 m-2s-1 in the A and B plots, respectively. With the exclusion of part of rain in plot B, it had a reduction of 7.23% in the soil CO2 flux (0.25 μmolCO2 m-2s-1), 39.1% in the soil humidity (6.1p.p.), and an increase of 0.39% in the soil temperature (0.1ºC). The soil moisture in parcel B was lesser than in the parcel A, due to the exclusion system of rain. However at the beginning of the year, site B undergone some changes causing the measuring values to be about the same on both areas.
Acesso aberto (Open Access)
Observações e estimativas de propriedades térmicas do solo sob floresta e pastagem no leste da Amazônia
(2013-09) CARVALHO, Saulo Prado; SOUZA, José Ricardo Santos de; MAKINO, Midori
Temperature and heat flux variations in soils, at sites of the Caxiuanã native forest and a natural pasture in Marajó Island, were continuously monitored in the period between December, 2001 and February, 2005. The objective was to compare the thermal responses to the daily heating, of the soils of these two types of ecosystems present in eastern Amazonia, in order to subsidize regional climate models and the evaluation of deforestation effects. Besides the field measurements of the above mentioned variables, at three levels down to 0.50 m depth, this work presents estimates of the heat flux and soil properties such as: thermal diffusivity and conductivity, damping depth and propagation speed of the daily heating pulse, determined by analytical methods. The results showed the seasonal contrast and other significant differences between the responses of the two studied sites, especially regarding the role of the water contents on the vertical temperature profiles of each soil type. The observed fitting between the measurements and the computed values of the variables, indicates the possibility of generalization of the results to other similar ecosystems sites in Amazonia.
Acesso aberto (Open Access)
Variação temporal do efluxo de CO2do solo em sistemas agroflorestais com palma de óleo na Amazônia Oriental
(Instituto Nacional de Pesquisas da Amazônia, 2016-03) SILVA, Carolina Melo da; VASCONCELOS, Steel Silva; OLIVEIRA JUNIOR, Moisés Cordeiro Mourão de; KATO, Osvaldo Ryohei; SILVA JUNIOR, Alberto Cruz da; CASTELLANI, Débora Cristina
The soil carbon dioxide (CO2) efflux dynamics and its controlling factors of Amazonian agroforestry systems are poorly understood. The objective of this study was to evaluate the temporal variation of soil CO2 efflux in oil palm-based agroforestry systems and the relation between efflux and biotic (microbial and total soil carbon, microbial respiration, fine roots, individual components of agroforestry systems (AFS)) and abiotic factors (soil moisture and temperature). The measurements were taken during the less rainy (December 2010) and rainy (May 2011) periods. The soil CO2 efflux was highest during the rainy season, probably due to increased microbial activity influenced by climatic factors coupled with biotic factors. The soil CO2 efflux correlated positively with soil moisture and microbial biomass carbon and negatively with soil temperature and metabolic quotient, but these correlations were weak. The soil CO2 efflux was sensitive to the type of agroforestry system and to rainfall seasonality.
Acesso aberto (Open Access)
Variação temporal do efluxo de dióxido de carbono CO² do solo em sistemas agroflorestais com palma de óleo (Elaeis guineensis) na Amazônia Oriental
(Universidade Federal do Pará, 2013-09-20) SILVA, Carolina Melo da; VASCONCELOS, Steel Silva; http://lattes.cnpq.br/0719395243841543
The Amazon region has been subjected to continuous deforestation and expansion of land use for the implementation of activities such as cattle ranching, logging, agriculture, mining and urbanization. The burning and decomposition of forest biomass releases gases that contribute to global warming, such as carbon dioxide (CO2). In this context, there is interest in assessing the dynamics of soil CO2 efflux in the Amazon, especially in oil palm (Elaeis guineensis) agroforestry systems, due to the current large expansion of this crop in the state of Pará, which has become one of the largest producers of the country. This study aimed to investigate the dynamics of soil CO2 efflux in palm oil cultivation in agroforestry systems in the Amazon considering temporal and biotic and abiotic factors that directly influence this process. We quantified biotic factors: microbial biomass, total soil carbon, soil basal respiration, fine root and soil zone of influence of planted species, and abiotic factors: moisture and soil temperature, in two oil palm-based agroforestry systems (adubadeiras and biodiverso systems), during the dry and rainy periods. The results showed that the highest soil CO2 efflux occurred during the rainy season, probably due to increased microbial activity during this period influenced by climatic factors coupled with biotic factors. The biodiverso system showed higher soil efflux than the fertilizer adubadeiras system, probably due to increase biological activity in former system. The soil CO2 efflux showed no strong correlation with the tested variables. It was concluded that the soil CO2 efflux was influenced by rainfall seasonality only. The fact that the systems were be too young (~3 yr-old) may represent the main factor for a lack of stronger relationship of soil CO2 efflux and the variables analyzed.