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Registro Completo |
Biblioteca(s): |
Embrapa Cerrados. |
Data corrente: |
19/04/2001 |
Data da última atualização: |
19/04/2001 |
Autoria: |
SAN JOSE, J. J.; MEIRELLES, M. L.; BRACHO, R.; NIKONOVA, N. |
Título: |
A comparative analysis of the flooding and fire effects on the energy exchange in a wetland community (Morichal) of the Orinoco Llanos. |
Ano de publicação: |
2000 |
Fonte/Imprenta: |
Journal of Hydrology, Amsterdam, v.242, p.228-254, 2000. |
Idioma: |
Inglês |
Conteúdo: |
This work analyzes the effects of flooding and fire stress on a wetland energy balance during the dry season of the Orinoco lowlands. The effect of flooding for burning conditions is evaluated by comparing flux measurements in a flooded/burned (T1) and an unflooded/burned (T3) stand and the effect of burning for flooding conditions by distinguishing between a flooded/burned (T1) and a flooded/unburned (T2) stand. These examined factors affect the canopy features related to coverage and aerodynamic forcing conditions. The effect of flooding on the average daily radiative budget for the burned stands is to decrease the average daily albedo from 0.14 for the unflooded stand (T3) to 0.08 for the flooded stand (T1). Whereas, the effect of burning for the flooded stands decreases the average daily albedo from 0.16 for the unburned stand (T2) to 0.08 in the burned stand (T1) Furthermore, changes in surface temperature determine variations in the average daily output of long-wave ratios between stands with the most average daily net loss of long-wave radiation (-36.3 MJ m-2 day-1) corresponding to the flooded/burned stand(T1). In the stands, the changes in albedo and surface temperature lead to variation in the available energy. Thus, the average daily net radiation (Rn) is affected by burning of the flooded stands, being 15.2 MJ m- 2 day-1 in T1 and 14.7 MJ m-2 day-1 in T2.The effect of flooding on the average daily Rn is evident when compared T1 to T3 (13.1 MJ-2 day-1). The partitioning of Rn into sensible (H) and latent (LE) heat flux over the three stands is measured simultaneously using the Bowen ratio/gradient method, which is temporally corroborated by means of the eddy covariance approach. Results indicate that average daily LE to average daily Rn ratio is 0.78 and 0.80 for T1, T2 and T3, respectively. However, the partitioning of average daily LE into transpiration and evaporation is affected clearly by the analyzed factors. Thus, burning reduces the transpiration rate from -8.5 to -3.3 MJ m-2day-1 for the flooded stands (T2 and respectively). Whereas, flooding varies only a small amount the average daily transpiration rate in the burned stands (T1and T2) (-3.3 and -3.4 MJ m-2 day-1). Over the stands, the average daily H in relation To Rn for T1, T2 and T3 was 0.19. 0.21 and 0.22. respectively. In relation to the net storage heat flux (simbolo=alfa SH), the water table at or above the sediments is a small heat sink as the radiation intercepted by the canopies is relatively large. The average daily net storage heat flux is enhanced slightly in the flooded stand (T1) as compared to the unflooded/burned stand (T3). Wereas, in the surface of the unburned stand.(simbolo=alfaSH) is in thermical equilibrium. Evaluation of evapotranspiration models as a function of the hourly LE measured over the three stands, indicates that the Penman evapotranspiration model for equilibrium is appropriated for modeling long-term evapotranspiration, and therefore LE is controlled mainly by the available energy and temperature. However. the slope is above 1 (1.11, 1.12 and 1.04 for T1. T2 and T3. respectively). This possible surface control on the results is corroborated by the Penman-Monteith and Slatyer-Mcllroy model for a negligible surface resistance. The modeled values are over-predicted and consequently surface resistance affects partially the results. The effect of the areal surface resistance on wetland potential evapotranspiration is assessed as the wetland is surrounded by a dry savanna environment. The relationship between wetland potential evaporation and savanna evaporation is evaluated using the Lhomme closed-box model of the convective boundary layer. The results indicate that the savanna surface resistance enhances the wetland potential evaporation at equilibrium. The results reported in this analysis are pertinent to similar Orinoco wetlands nevertheless the controls and functioning of herbaceous wetlands under the described land-use practices are revealing commom features for wetlands surrounded by regional savannas in South America. MenosThis work analyzes the effects of flooding and fire stress on a wetland energy balance during the dry season of the Orinoco lowlands. The effect of flooding for burning conditions is evaluated by comparing flux measurements in a flooded/burned (T1) and an unflooded/burned (T3) stand and the effect of burning for flooding conditions by distinguishing between a flooded/burned (T1) and a flooded/unburned (T2) stand. These examined factors affect the canopy features related to coverage and aerodynamic forcing conditions. The effect of flooding on the average daily radiative budget for the burned stands is to decrease the average daily albedo from 0.14 for the unflooded stand (T3) to 0.08 for the flooded stand (T1). Whereas, the effect of burning for the flooded stands decreases the average daily albedo from 0.16 for the unburned stand (T2) to 0.08 in the burned stand (T1) Furthermore, changes in surface temperature determine variations in the average daily output of long-wave ratios between stands with the most average daily net loss of long-wave radiation (-36.3 MJ m-2 day-1) corresponding to the flooded/burned stand(T1). In the stands, the changes in albedo and surface temperature lead to variation in the available energy. Thus, the average daily net radiation (Rn) is affected by burning of the flooded stands, being 15.2 MJ m- 2 day-1 in T1 and 14.7 MJ m-2 day-1 in T2.The effect of flooding on the average daily Rn is evident when compared T1 to T3 (13.1 MJ-2 day-1). The parti... Mostrar Tudo |
Palavras-Chave: |
Energy exchange; Fire; Flooding; Intercambio de energia; Savana. |
Thesagro: |
Fogo; Inundação; Solo Úmido. |
Thesaurus Nal: |
savannas; wetlands. |
Categoria do assunto: |
-- |
Marc: |
LEADER 04877naa a2200277 a 4500 001 1555445 005 2001-04-19 008 2000 bl --- 0-- u #d 100 1 $aSAN JOSE, J. J. 245 $aA comparative analysis of the flooding and fire effects on the energy exchange in a wetland community (Morichal) of the Orinoco Llanos. 260 $c2000 520 $aThis work analyzes the effects of flooding and fire stress on a wetland energy balance during the dry season of the Orinoco lowlands. The effect of flooding for burning conditions is evaluated by comparing flux measurements in a flooded/burned (T1) and an unflooded/burned (T3) stand and the effect of burning for flooding conditions by distinguishing between a flooded/burned (T1) and a flooded/unburned (T2) stand. These examined factors affect the canopy features related to coverage and aerodynamic forcing conditions. The effect of flooding on the average daily radiative budget for the burned stands is to decrease the average daily albedo from 0.14 for the unflooded stand (T3) to 0.08 for the flooded stand (T1). Whereas, the effect of burning for the flooded stands decreases the average daily albedo from 0.16 for the unburned stand (T2) to 0.08 in the burned stand (T1) Furthermore, changes in surface temperature determine variations in the average daily output of long-wave ratios between stands with the most average daily net loss of long-wave radiation (-36.3 MJ m-2 day-1) corresponding to the flooded/burned stand(T1). In the stands, the changes in albedo and surface temperature lead to variation in the available energy. Thus, the average daily net radiation (Rn) is affected by burning of the flooded stands, being 15.2 MJ m- 2 day-1 in T1 and 14.7 MJ m-2 day-1 in T2.The effect of flooding on the average daily Rn is evident when compared T1 to T3 (13.1 MJ-2 day-1). The partitioning of Rn into sensible (H) and latent (LE) heat flux over the three stands is measured simultaneously using the Bowen ratio/gradient method, which is temporally corroborated by means of the eddy covariance approach. Results indicate that average daily LE to average daily Rn ratio is 0.78 and 0.80 for T1, T2 and T3, respectively. However, the partitioning of average daily LE into transpiration and evaporation is affected clearly by the analyzed factors. Thus, burning reduces the transpiration rate from -8.5 to -3.3 MJ m-2day-1 for the flooded stands (T2 and respectively). Whereas, flooding varies only a small amount the average daily transpiration rate in the burned stands (T1and T2) (-3.3 and -3.4 MJ m-2 day-1). Over the stands, the average daily H in relation To Rn for T1, T2 and T3 was 0.19. 0.21 and 0.22. respectively. In relation to the net storage heat flux (simbolo=alfa SH), the water table at or above the sediments is a small heat sink as the radiation intercepted by the canopies is relatively large. The average daily net storage heat flux is enhanced slightly in the flooded stand (T1) as compared to the unflooded/burned stand (T3). Wereas, in the surface of the unburned stand.(simbolo=alfaSH) is in thermical equilibrium. Evaluation of evapotranspiration models as a function of the hourly LE measured over the three stands, indicates that the Penman evapotranspiration model for equilibrium is appropriated for modeling long-term evapotranspiration, and therefore LE is controlled mainly by the available energy and temperature. However. the slope is above 1 (1.11, 1.12 and 1.04 for T1. T2 and T3. respectively). This possible surface control on the results is corroborated by the Penman-Monteith and Slatyer-Mcllroy model for a negligible surface resistance. The modeled values are over-predicted and consequently surface resistance affects partially the results. The effect of the areal surface resistance on wetland potential evapotranspiration is assessed as the wetland is surrounded by a dry savanna environment. The relationship between wetland potential evaporation and savanna evaporation is evaluated using the Lhomme closed-box model of the convective boundary layer. The results indicate that the savanna surface resistance enhances the wetland potential evaporation at equilibrium. The results reported in this analysis are pertinent to similar Orinoco wetlands nevertheless the controls and functioning of herbaceous wetlands under the described land-use practices are revealing commom features for wetlands surrounded by regional savannas in South America. 650 $asavannas 650 $awetlands 650 $aFogo 650 $aInundação 650 $aSolo Úmido 653 $aEnergy exchange 653 $aFire 653 $aFlooding 653 $aIntercambio de energia 653 $aSavana 700 1 $aMEIRELLES, M. L. 700 1 $aBRACHO, R. 700 1 $aNIKONOVA, N. 773 $tJournal of Hydrology, Amsterdam$gv.242, p.228-254, 2000.
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Embrapa Cerrados (CPAC) |
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Registro Completo
Biblioteca(s): |
Embrapa Milho e Sorgo. |
Data corrente: |
01/09/1992 |
Data da última atualização: |
19/10/2023 |
Autoria: |
BAHIA FILHO, A. F. de C. |
Afiliação: |
ANTONIO FERNANDINO DE CASTRO BAHIA FILHO, EMBRAPA-CNPMS. |
Título: |
Fósforo em Latossolos do estado de Minas Gerais: intensidade, capacidade tampão e quantidade de fósforo, fósforo "disponível" e crescimento vegetal. |
Ano de publicação: |
1974 |
Fonte/Imprenta: |
1974. |
Páginas: |
69 p. |
Idioma: |
Português |
Notas: |
Dissertação (Mestrado) - Universidade Federal de Viçosa, Viçosa, MG. |
Conteúdo: |
Foram coletadas amostras superficiais compostas de vinte latossolos do Estado de Minas Gerais, com o objetivo de estudar a disponibilidade de fosforo nestes solos. Para este estudo foram realizadas, em laboratorio, determinacoes do potencial de fosfato monocalcico, da capacidade tampao de fosforo, das formas de fosforo inorganico, do fosforo "disponivel" obtido pelos extratores Bray 1, IAC, Mehlich e Olsen, alem da capacidade maxima de adsorcao de fosforo. Preparou-se, tambem, laminas da fracao argila destes solos, que foram submetidas a analise de difracao dos raios-X. Em ensaio conduzido em casa de vegetacao, procurou-se verificar a resposta de aveia (Avena sativa L. var., 'Amarela') a niveis de fosforo aplicados nos vinte solos. Este ensaio constiu de um experimento faltorial 20 x 4 disposto em blocos casualizados com tres repeticoes. Cada um dos vinte solos foi adubado com quantidades crescentes de fosforo equivalentes a 0,0, 0,4, 0,8 e 1,2 da sua adsorcao maxima de fosforo. Depois de 30 dias da emergencia das plantulas de aveia, cortou-se o material, determinado-se, depois de sua secagem, o peso de materia seca e quantidade de fosforo absorvido pelo vegetal. Em decorrencia dos resultados assim obtidos, concluiu-se que: 1. as relacoes entre potencial de fosfato monocalcico e fosforo adsorvido foram, na maioria dos solos, curvilineas. 2. houve pequena variacao entre os valores de potencial de fosfato monocalcico; o mesmo nao se verificou com os valores de capacidade tampao de fosforo. 3. as diferentes........... MenosForam coletadas amostras superficiais compostas de vinte latossolos do Estado de Minas Gerais, com o objetivo de estudar a disponibilidade de fosforo nestes solos. Para este estudo foram realizadas, em laboratorio, determinacoes do potencial de fosfato monocalcico, da capacidade tampao de fosforo, das formas de fosforo inorganico, do fosforo "disponivel" obtido pelos extratores Bray 1, IAC, Mehlich e Olsen, alem da capacidade maxima de adsorcao de fosforo. Preparou-se, tambem, laminas da fracao argila destes solos, que foram submetidas a analise de difracao dos raios-X. Em ensaio conduzido em casa de vegetacao, procurou-se verificar a resposta de aveia (Avena sativa L. var., 'Amarela') a niveis de fosforo aplicados nos vinte solos. Este ensaio constiu de um experimento faltorial 20 x 4 disposto em blocos casualizados com tres repeticoes. Cada um dos vinte solos foi adubado com quantidades crescentes de fosforo equivalentes a 0,0, 0,4, 0,8 e 1,2 da sua adsorcao maxima de fosforo. Depois de 30 dias da emergencia das plantulas de aveia, cortou-se o material, determinado-se, depois de sua secagem, o peso de materia seca e quantidade de fosforo absorvido pelo vegetal. Em decorrencia dos resultados assim obtidos, concluiu-se que: 1. as relacoes entre potencial de fosfato monocalcico e fosforo adsorvido foram, na maioria dos solos, curvilineas. 2. houve pequena variacao entre os valores de potencial de fosfato monocalcico; o mesmo nao se verificou com os valores de capacidade tampa... Mostrar Tudo |
Palavras-Chave: |
Availability; Brasil; Capacidade tampao; Disponibilidade; Disponibility; Fertility; Fertilization; Minas Gerais; Quimica dos solos; Solos. |
Thesagro: |
Adubação; Fertilidade; Fósforo; Latossolo; Solo. |
Thesaurus NAL: |
Brazil; chemistry; phosphorus; soil; supply. |
Categoria do assunto: |
-- |
URL: |
https://ainfo.cnptia.embrapa.br/digital/bitstream/item/90181/1/D-Antonio-Bahia-Filho.pdf
|
Marc: |
LEADER 02565nam a2200373 a 4500 001 1472656 005 2023-10-19 008 1974 bl uuuu m 00u1 u #d 100 1 $aBAHIA FILHO, A. F. de C. 245 $aFósforo em Latossolos do estado de Minas Gerais$bintensidade, capacidade tampão e quantidade de fósforo, fósforo "disponível" e crescimento vegetal. 260 $a1974.$c1974 300 $a69 p. 500 $aDissertação (Mestrado) - Universidade Federal de Viçosa, Viçosa, MG. 520 $aForam coletadas amostras superficiais compostas de vinte latossolos do Estado de Minas Gerais, com o objetivo de estudar a disponibilidade de fosforo nestes solos. Para este estudo foram realizadas, em laboratorio, determinacoes do potencial de fosfato monocalcico, da capacidade tampao de fosforo, das formas de fosforo inorganico, do fosforo "disponivel" obtido pelos extratores Bray 1, IAC, Mehlich e Olsen, alem da capacidade maxima de adsorcao de fosforo. Preparou-se, tambem, laminas da fracao argila destes solos, que foram submetidas a analise de difracao dos raios-X. Em ensaio conduzido em casa de vegetacao, procurou-se verificar a resposta de aveia (Avena sativa L. var., 'Amarela') a niveis de fosforo aplicados nos vinte solos. Este ensaio constiu de um experimento faltorial 20 x 4 disposto em blocos casualizados com tres repeticoes. Cada um dos vinte solos foi adubado com quantidades crescentes de fosforo equivalentes a 0,0, 0,4, 0,8 e 1,2 da sua adsorcao maxima de fosforo. Depois de 30 dias da emergencia das plantulas de aveia, cortou-se o material, determinado-se, depois de sua secagem, o peso de materia seca e quantidade de fosforo absorvido pelo vegetal. Em decorrencia dos resultados assim obtidos, concluiu-se que: 1. as relacoes entre potencial de fosfato monocalcico e fosforo adsorvido foram, na maioria dos solos, curvilineas. 2. houve pequena variacao entre os valores de potencial de fosfato monocalcico; o mesmo nao se verificou com os valores de capacidade tampao de fosforo. 3. as diferentes........... 650 $aBrazil 650 $achemistry 650 $aphosphorus 650 $asoil 650 $asupply 650 $aAdubação 650 $aFertilidade 650 $aFósforo 650 $aLatossolo 650 $aSolo 653 $aAvailability 653 $aBrasil 653 $aCapacidade tampao 653 $aDisponibilidade 653 $aDisponibility 653 $aFertility 653 $aFertilization 653 $aMinas Gerais 653 $aQuimica dos solos 653 $aSolos
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