Träd i tropiska våtmarker har uppmärksammats som en viktig källa till regionala och globala metan (CH4) utsläpp, då träd fungerar som utsläppskanaler för metan som bildas i sedimenten. Dock finns det en osäkerhet gällande säsongsvariation och rumslig variation samt mängden CH4 utsläpp från träd, eftersom kunskapen kring regionala flöden är begränsad. Därför strävar vi efter att optimera provtagningsinsatser för att öka möjligheten till representativa uppskattningar för olika typer av skogsekosystem och förbättra kunskapen om rumslig och temporär variabilitet för framtida mätningar i Amazonas. Vi undersökte variabiliteten i flöden av CH4 från träd belägna i tre periodvis översvämmade platser (Solimões, Negro and Tapajós) längs Amazonfloden, med olika karaktäristiska egenskaper. Studien genomfördes in situ med slutna kammare på 36 träd vid de tre provplatserna, under olika hydrologiska säsonger. Platserna visade en stor säsongsvariation i CH4-flöden, med de största bidragen under högvattensäsong. En signifikant skillnad mellan två av platserna upptäcktes endast under högvatten och detta kan vara ett resultat av vattnets varierande fysikaliska och kemiska egenskaper. Med hänsyn till variation inom studieplatserna har indelning av zoner betydelse för mätning av CH4-flöden i träd, då vattennivån är en påverkande faktor. En stor rumslig variation upptäcktes, med lägre flöden i zonen närmast land och med det högsta flödet i zonen där förhållanden varierar mest mellan blött och torrt. Detta mönster kan beaktas genom att utföra provtagningar längs zonerna med hänsyn till vattenavståndet. / Tropical wetland-adapted trees are recognized as an important source of regional and global methane (CH4) emissions, by transport of soil gas through wetland trees. However, spatiotemporal variability and controls on the magnitude of tree-mediated CH4 emissions remain unknown as fluxes are poorly constrained. Therefore, we aim to optimize sampling efforts to yield representative emission estimates for distinct types of forest ecosystems and improve knowledge on spatial and temporal variability. We examined the variability in tree stem mediated CH4 fluxes in situ, located in three different floodplains (Solimões, Negro and Tapajós) with various characteristics, during different hydrological seasons. The sampling was conducted by measuring fluxes from 36 trees at each location using closed chambers. All the three study sites, situated in the Amazon region, displayed seasonal variability in CH4 fluxes, with the largest contributions observed during the wet season. A significant difference between Solimões and Negro was detected during the wet season and this may be a result of the different chemical and physical characteristics between the sampling locations. As for within the study sites, zones played a significant role for CH4 flux from trees since the water level influences the fluxes. A strong spatial variability (lower fluxes in the land zone, and the highest flux obtained in the zone with greatest variability between dry and wet conditions) was found. This pattern can be addressed by sampling along flooded and non-flooded zones. / The Global Methane Budget

Made available in DSpace on 2014-06-11T19:30:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-04-20Bitstream added on 2014-06-13T20:21:13Z : No. of bitstreams: 1 sartori_lr_dr_prud.pdf: 4148637 bytes, checksum: 5616600e595cbbe65fef21b03cd5309c (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O propósito deste trabalho foi avaliar o potencial dos dados PALSAR polarimétricos para discriminar e mapear espécies de macrófitas (vegetação aquática) de uma área alagável da Amazônia, a planície de inundação do Lago Grande de Monte Alegre, no estado do Pará. A coleta de dados foi realizada quase simultaneamente à aquisição dos dados de radar. Três principais espécies de macrófitas foram encontradas na área: Paspalum repens (PR), Hymenachne amplexicaulis (HA) e Paspalum elephantipes (PE). Variáveis morfológicas foram medidas em campo e usadas para derivar outras variáveis tais como a biomassa. Atributos foram gerados a partir da matriz de covariância [C] extraída da imagem ALOS/PALSAR em modo SLC (single look complex). Os atributos polarimétricos foram analisados para as três espécies e identificados aqueles capazes de discriminar as espécies. Foram aplicadas as seguintes abordagens de classificação: baseada em regras, baseada em modelos de decomposição (Decomposições de Freeman-Durden e Cloude-Pottier), baseada em estatística (Classificação supervisionada baseada na distância Wishart) e híbrida (Classificador Wishart com classes de entrada baseadas na decomposição de Cloude-Pottier). Finalmente, a variável morfológica “volume da haste” foi modelada por regressão múltipla em função de alguns atributos polarimétricos. Os resultados sugerem que a imagem polarimétrica banda L possui potencial para discriminar as espécies de macrófitas, sendo os principais atributos para isso sigma zero HH ( ), sigma zero HV ( ) e sigma zero VV ( ), índice de estrutura da copa... / The purpose of this work was to evaluate the potential of fully polarimetric PALSAR data to discriminate and map macrophyte species in the Amazon floodplain, more specifically in the Monte Alegre Lake, in the state of Pará, Brazil. Fieldwork was carried out almost simultaneously to the radar acquisition. Three main species were found in the study area: Paspalum repens (PR), Hymenachne amplexicaulis (HA) and Paspalum elephantipes (PE). Macrophyte morphological variables were measured on the field and used to derive others variables, like the biomass. Attributes were calculated from the covariance matrix [C] derived from the SLC (single look complex) data. The polarimetric attributes were analyzed for the three species and it was identified that ones capable of discriminating them. The following classification approaches were applied: a rule-based classification, model-based classifications (Freeman-Durden and Cloude-Pottier), a statistical-based classification (supervised classification using Wishart distance measure) and a hybrid classification (Wishart classifier with the input classes based on the H/a plane). Finally, the morphological variable “stem volume” was modeled using multiple regression. The findings suggest that the fully polarimetric image has potential for discriminating plant species, being the main attributes sigma-nought HH ( ), sigma-nought HV ( ) and sigma-nought VV ( ), canopy structure index ( ), HH-VV polarimetric coherence ( ), helicity of the third scattering mechanism (τ ), orientation angle of the first scattering mechanism ( ) and scattering type phase of the first mechanism ( ); among the different classifications, only the supervised (Wishart) and the rule-based discriminated the species, with overall accuracy of 75,04% and 87,18%, respectively; the stem volume was modeled using the following attributes: biomass index ( ), volumetric scattering ... (Complete abstract click electronic access below)

Resumo: O propósito deste trabalho foi avaliar o potencial dos dados PALSAR polarimétricos para discriminar e mapear espécies de macrófitas (vegetação aquática) de uma área alagável da Amazônia, a planície de inundação do Lago Grande de Monte Alegre, no estado do Pará. A coleta de dados foi realizada quase simultaneamente à aquisição dos dados de radar. Três principais espécies de macrófitas foram encontradas na área: Paspalum repens (PR), Hymenachne amplexicaulis (HA) e Paspalum elephantipes (PE). Variáveis morfológicas foram medidas em campo e usadas para derivar outras variáveis tais como a biomassa. Atributos foram gerados a partir da matriz de covariância [C] extraída da imagem ALOS/PALSAR em modo SLC (single look complex). Os atributos polarimétricos foram analisados para as três espécies e identificados aqueles capazes de discriminar as espécies. Foram aplicadas as seguintes abordagens de classificação: baseada em regras, baseada em modelos de decomposição (Decomposições de Freeman-Durden e Cloude-Pottier), baseada em estatística (Classificação supervisionada baseada na distância Wishart) e híbrida (Classificador Wishart com classes de entrada baseadas na decomposição de Cloude-Pottier). Finalmente, a variável morfológica "volume da haste" foi modelada por regressão múltipla em função de alguns atributos polarimétricos. Os resultados sugerem que a imagem polarimétrica banda L possui potencial para discriminar as espécies de macrófitas, sendo os principais atributos para isso sigma zero HH ( ), sigma zero HV ( ) e sigma zero VV ( ), índice de estrutura da copa ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The purpose of this work was to evaluate the potential of fully polarimetric PALSAR data to discriminate and map macrophyte species in the Amazon floodplain, more specifically in the Monte Alegre Lake, in the state of Pará, Brazil. Fieldwork was carried out almost simultaneously to the radar acquisition. Three main species were found in the study area: Paspalum repens (PR), Hymenachne amplexicaulis (HA) and Paspalum elephantipes (PE). Macrophyte morphological variables were measured on the field and used to derive others variables, like the biomass. Attributes were calculated from the covariance matrix [C] derived from the SLC (single look complex) data. The polarimetric attributes were analyzed for the three species and it was identified that ones capable of discriminating them. The following classification approaches were applied: a rule-based classification, model-based classifications (Freeman-Durden and Cloude-Pottier), a statistical-based classification (supervised classification using Wishart distance measure) and a hybrid classification (Wishart classifier with the input classes based on the H/a plane). Finally, the morphological variable "stem volume" was modeled using multiple regression. The findings suggest that the fully polarimetric image has potential for discriminating plant species, being the main attributes sigma-nought HH ( ), sigma-nought HV ( ) and sigma-nought VV ( ), canopy structure index ( ), HH-VV polarimetric coherence ( ), helicity of the third scattering mechanism (τ ), orientation angle of the first scattering mechanism ( ) and scattering type phase of the first mechanism ( ); among the different classifications, only the supervised (Wishart) and the rule-based discriminated the species, with overall accuracy of 75,04% and 87,18%, respectively; the stem volume was modeled using the following attributes: biomass index ( ), volumetric scattering ... (Complete abstract click electronic access below) / Orientador: Nilton Nobuhiro Imai / Coorientador: José Cláudio Mura / Banca: Evlyn Marcia Leão de Moraes Novo / Banca: Thiago Sanna Freire Silva / Banca: João Roberto dos Santos / Banca: Vilma Mayumi Tachibana / Doutor