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Diss. (sammanfattning) Umeå : Sveriges lantbruksuniv., 2007. / Härtill 3 uppsatser.

This Master's Thesis presents the results of research conducted under the Project ASSESSMENT OF POTENTIAL AS SEQUESTRANT MANGROVE FORESTS CARBON - UFRJ / UFS / UERJ (Case Study of Mangrove Forest River Estuarine Region of San Francisco - Sergipe / Alagoas), with the support of the Erosion and Sedimentation Laboratory, part of the Department of Agricultural Engineering, Federal University of Sergipe. The environmental liabilities created on account of unsustainable use of natural resources over the years has been suppressing and / or degrading a significant portion of mangroves due to the disorderly occupation and exploitation of their areas. Thus, gathering information on vegetation structure becomes a valuable tool for understanding the current state of the same. In this context, the objective of this study was to characterize the floristic, phytosociological structure and litterfall of the mangrove estuary of the river São Francisco, Sergipe. This action will provide a structural description of the community of mangrove trees and shrubs and the factors that promote change in these communities. The results show that the mangrove river São Francisco present a heterogeneous development, presenting higher in the intermediate region of the estuary, where there is less influence of anthropogenic impacts. We recorded species: schaueriana Avicennia, Avicennia germinans, Laguncularia racemosa, Conocarpus erectus and Rhizophora mangle. The average height of forests ranged from 2.88 to 15.63 m, the DBH 3.95 to 19.74 cm, basal area, live from 4.22 to 47.83 m2.ha-1 and density logs Live 375-9100 trunks.ha-1. The annual litter production was 274.43 t.ha-1.year-1 in the first year and 267.92 t.ha-1.year-1 in the second year. Generally, litter production, per compartment, submitted the following descending order: Leaves > Twigs and Branches > Stipules > Fruits and Propagating Material > Miscellaneous > Flowers. Tensors identified in the estuary, the largest impacts are promoting marine erosion and human activities, both promote the removal of large areas. / A presente Dissertação de Mestrado apresenta os resultados da pesquisa realizada no âmbito do Projeto AVALIAÇÃO DO POTENCIAL DE FLORESTAS DE MANGUE COMO SEQUESTRADORAS DE CARBONO UFRJ / UFS / UERJ (Estudo de Caso da Floresta de Mangue da Região Estuarina do rio São Francisco - Sergipe/Alagoas), com o apoio do Laboratório de Erosão e Sedimentação, vinculado ao Departamento de Engenharia Agronômica da Universidade Federal de Sergipe. O passivo ambiental criado por conta do uso não sustentável dos recursos naturais ao longo dos anos vem suprimindo e/ou degradando uma porção significativa de manguezais, principalmente no que diz respeito a ocupação e exploração desordenada de suas áreas. Dessa forma, o levantamento de informações sobre a estrutura da vegetação torna-se uma valiosa ferramenta para o conhecimento do estado atual dos mesmos. Neste contexto, o objetivo deste trabalho foi caracterizar a composição florística, estrutura fitossociológica e produção de serrapilheira do manguezal do estuário do rio São Francisco, Sergipe. Essa ação fornecerá uma descrição estrutural da comunidade arbóreo-arbustiva do manguezal e os fatores que promovem alterações nessas comunidades. Os resultados encontrados revelam que o manguezal do rio São Francisco apresenta desenvolvimento heterogêneo, apresentando-se mais elevado na região intermediária do estuário, onde é menor a influência dos impactos antropogênicos. Foram registradas as espécies: Avicennia schaueriana, Laguncularia racemosa e Rhizophora mangle. A altura média das árvores variou de 2,88 a 15,63 m, o DAP médio de 3,95 a 19,74 cm, a área basal viva de 4,22 a 47,83 m2.ha-1 e a densidade de troncos vivos de 375 a 9100 troncos.ha-1. A produção média anual de serrapilheira foi de 13,53 t.ha-1.ano-1 e 13,21 t.ha-1.ano-1, no primeiro e segundo ano, respectivamente. De modo geral, a produção de serapilheira, por compartimento, apresentou a seguinte ordem decrescente: Folhas > Galhos e Ramos > Estípulas > Frutos e Propágulos > Miscelânea > Flores. Dos tensores identificados no estuário, os que promovem maiores impactos são a erosão marinha e atividades antrópicas, ambos promovem a supressão de grandes áreas.

Thesis (MScBosb)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The characteristics and total fuel load of the forest floor (FF) and harvest residue (HR) are needed to develop tools that can be used for fuel load management, fire risk analysis and fire behaviour prediction for P. patula grown in the summer rainfall area of South Africa (SA). Forest floor depth, mass and ash-free mass were measured and there was generally a greater range in depth under sawtimber (ST) stands than under pulpwood (PLP) stands. Forest floor loads, prior to ashing, ranged from 21 - 168 t ha-1 and 27 - 72 t ha-1, for ST and PLP stands, respectively and loads increased linearly with stand age. Sawtimber and PLP stands were analysed together, which resulted in a significant correlation between depth and mass (r2 = 0.78, n = 31). A loss on ignition procedure carried out on sub-samples of the FF improved the relationship between the FF depth and the ash-free mass for the different stands, and provided a more accurate model for the prediction of mass from depth. A multiple regression analysis revealed that age, altitude and mean annual precipitation (MAP) provided the best subset and accounted for 72% of the variation in the FF mass observed. The effect of increasing FF load and increasing moisture content on the fireline intensity (FLI) was examined using the fire behaviour prediction programme, BehavePlus. Harvest residue was quantified and characterised in terms of fuel size classes, under current silvicultural regimes for ST and PLP, for the development of fuel models for this species over its planted range in SA. An investigation into the proportion (by mass) of the 1- (0.0 - 0.6 cm), 10- (0.6 – 2.5 cm), 100- (2.5 – 7.6 cm) and 1000-hr (> 7.6 cm diameter) fuel classes of the total HR mass indicated that there was a significant difference between the mass of the 1-, 10- and 1000-hr fuel classes of the two silvicultural regimes, and no significant difference for the 100-hr fuel class. Two fuel models for P. patula HR and two models for standing timber were developed using the new model (NEWMDL) programme of BEHAVE and tested in BehavePlus. Nutrient concentrations were used with FF layer and HR size class load data to estimate the quantities of nutrients held in the fuel and to describe nutrient distributions in the fuel complex. Significant differences in the nutrient concentration of the FF layers and fuel components were observed which has important implications for fuel management. The concentration of N determined in this study, relative to that determined in other similar studies on P. patula was low. Forest floor loads were predicted and nutrient pools calculated for typical ST and PLP stands at both low and high altitude to provide insight into the nutrient distributions within the fuel complex. / AFRIKAANSE OPSOMMING: Die karaktereienskappe en totale brandstoflading van die bosvloer (FF) en kaalkap oorskot (HR) word benodig om instrumente te ontwikkel wat gebruik kan word vir brandstoflading bestuur, brandgevaar ontleding en brandgedrag voorspelling vir P. patula, wat in die somer reënvalgebied van Suid-Afrika groei. Die bosvloer diepte, massa en asvrye massa is gemeet en daar was oor die algemeen ‘n groter variasie in diepte onder saaghout (ST) opstande as onder pulphout (PLP) opstande. Die bosvloerladings, voor verassing, het varieer van 21 – 168 t ha-1 en 27 – 72 t ha-1 vir ST en PLP opstande respektiwelik. Ladings het linieêr vermeerder met opstand ouderdom. Saaghout en PLP opstande is saam geanaliseer en het tot ‘n betekenisvolle korrelasie gelei tussen diepte en massa (r2 = 0.78, n = 31). ‘n Verliestydens- ontbranding prosedure is uitgevoer op die FF monsters en het die verhouding tussen FF diepte en die asvrye massa van die verskillende opstande verbeter. Dit het ook gelei tot akkurater model vir die voorspelling van massa vanaf diepte. ‘n Veelvoudige regressie analise het aan die lig gebring dat ouderdom, hoogte en gemiddelde jaarlikse reënval (MAP) die beste sub-groep verskaf, en het 72% van die variasie in die FF massa verklaar. Ondersoek is ingestel op die effek van toenemende FF lading en toenemende voginhoud op die brandlyn intensiteit (FLI) deur die brandgedrag program, BehavePlus, toe te pas. Die kaalkap oorskot is gekwantifiseer en gekarakteriseer volgens brandstof grootteklasse, onder die huidige boskultuurstelsels vir ST en PLP, vir die ontwikkeling van brandstofmodelle vir hierdie spesie oor die betrokke groeistreek in SA. ‘n Ondersoek in die verhouding (volgens massa) van die 1- (0.0 – 0.6 cm), 10- (0.6 – 2.5 cm), 100- (2.5 – 7.6 cm) en 1000-uur (> 7.6 cm deursnee) brandstofklasse van die totale HR massa het aangedui dat daar ‘n betekenisvolle verskil is tussen die massas van die 1-, 10- en 1000-uur brandstofklasse van die twee boskultuurstelsels, en geen betekenisvolle verskil vir die 100- uur brandstofklas nie. Twee brandstofmodelle is ontwikkel vir P. patula HR en twee modelle vir staande hout deur gebruik te maak van die nuwe model (NEWMDL) program van BEHAVE en getoets in BehavePlus. Voedingstof konsentrasies is gebruik, tesame met die FF laag en HR klasgrootte ladingdata, om die voedingstof inhoud van die brandstof te skat en om die voedingstof verspreiding te beskryf in die brandstofkompleks. Betekenisvolle verskille is waargeneem in die voedingstof konsentrasies van die FF lae en brandstof komponente wat belangrike implikasies inhou vir brandstofbestuur. Die konsentrasie wat vir N in hierdie studie bepaal is, was laag relatief tot ander soortgelyke studies vir P. patula. Die bosvloer ladings is voorspel en voedingstofpoele bereken vir tipiese ST en PLP opstande vir beide lae en hoë hoogtes om insig te verkry, sodat insig verkry kon word in die voedingstof verspreidings binne die brandstofkompleks.

Dans le cadre de la mission spatiale SMOS (Soil Moisture and Ocean Salinity), nous présentons dans cette thèse une nouvelle approche numérique de modélisation du calcul de l’émissivité et du coefficient bi-statique de systèmes forestiers sol-litière en Bande L. Le système sol-litière est représenté par deux couches diélectriques 3D comportant des interfaces rugueuses, une démarche qui n’apparait pas actuellement dans la littérature. Nous validons notre approche pour une seule couche en comparant les simulations de l'émissivité avec celles produites par la méthode des moments et des données expérimentales. A partir de ce nouveau modèle, nous évaluons la sensibilité de l’émissivité du système sol-litière en fonction de l’humidité et de la rugosité de la litière. Ce nouveau modèle permettra de créer une base de données synthétiques d’émissivités calculées en fonction de nombreux paramètres qui contribuera à améliorer la prise en compte de la litière dans l'algorithme d’inversion des données de la mission spatiale SMOS. / In the context of the SMOS (Soil Moisture and Ocean Salinity) mission, we present a new numerical modelling approach for calculating the emissivity and bistatic scattering coefficient of the soil-litter system found in forests, at L-band. The soil-litter system is modelled as two 3-dimensional dielectric layers, each with a randomly rough surface, which to our knowledge has not previously been achieved. We investigate the validity of the approach for a single layer by comparing emissivity simulations with results of Method of Moments simulations, and experimental data. We then use the approach to evaluate the sensitivity of the soil-litter system as a function of moisture content and the roughness of the litter layer. The numerical modelling approach which has been developed will allow us in the future to create a synthetic database of the emissivity of the soil-litter system as a function of numerous parameters, which will contribute to validating and improving the inversion algorithm used by the SMOS mission to retrieve soil moisture over forests.