Brazilians Mangroves have a great ecological importance, and are very importants to the survival of coastal communities that use natural resources of this ecosystem for their food and income generation. Over the years various human actions and the dynamics of this ecosystem, has encourage studies that provide a better understanding of the peculiarities of this environment. The study on the soils of mangroves are important because shows the strong influence on the distribution and degree of species development, maintaining a direct relationship with the intake of marine and river sediments. The objective of this study was to evaluate the physical and chemical characteristics of the soil in two mangrove forests located in estuarine areas of the São Francisco River and Sergipe. In each estuary were selected two (02) sites for data collection, called stations, divided into three (03) forest types (fringe, basin and transition) and collected five (05) samples consisting of 0.5 kg of soil at each sample point. In the laboratory, soil samples were subjected to chemical and physical analyzes, including pH. The soil of the estuary of the São Francisco had a sandy texture, with high amounts of organic matter and concentration of macro and micronutrients in the following order of concentration: Mg2+> Na2+>Ca2+>H+ > K+> P3-> Al3+ e Fe2+> Zn2+> Cu2+> Mn2+, respectively, with variations between woods and stations. Introducing generally, high fertility, especially in forests basin confirmed by the development of vegetation, noting a trend zoning species in relation to the fertility of the soil. The estuary of the Sergipe River presented a more silty texture and nutrient levels of macronutrients according to the following concentrations: Mg2+> Na2+> Ca2+> H+> K+> P3-> Al3+ e Fe2+> Zn2+> Cu2+> Mn2+. Both estuaries have high fertility and vegetation well developed. / Os manguezais brasileiros têm uma grande importância ecológica, além de serem fundamentais para a sobrevivência das comunidades ribeirinhas, que utilizam dos recursos naturais desse ecossistema para sua alimentação ou geração de renda. No decorrer dos anos diversas ações antrópicas e a própria dinâmica desse ecossistema, tem demandado estudos que possibilitem melhor compreensão das particularidades desse ambiente. O estudo sobre os solos dos manguezais se mostra importante pela forte influência na distribuição e no grau de desenvolvimento de espécies, mantendo uma relação direta com o aporte de sedimentos marinhos e fluviais. O objetivo deste trabalho foi avaliar as características físico-químicas do solo em duas florestas de mangue localizadas nas zonas estuarinas do rio São Francisco e do rio Sergipe. Em cada região estuarina foram selecionados 02 (dois) sítios de coleta de dados, denominados estações, divididas em 03 (três) tipos de floresta (franja, bacia e transição) e coletadas 05 (cinco) amostras compostas de 0,5 kg de solo em cada ponto amostral. Em laboratório, as amostras de solo foram submetidas às análises químicas e físicas, incluindo pH. O solo da região estuarina do rio São Francisco apresentou uma textura arenosa, com elevados valores de matéria orgânica e teores de macro e micronutrientes obedecendo à seguinte ordem de concentração: Mg2+> Na2+>Ca2+>H+ > K+> P3-> Al3+ e Fe2+> Zn2+> Cu2+> Mn2+, respectivamente, com variações entre bosques e estações. Apresent ando de maneira geral, elevada fertilidade, principalmente na floresta de bacia, confirmado pelo desenvolvimento da vegetação, observando uma tendência de zoneamento das espécies em relação à fertilidade do solo. A região estuarina do rio Sergipe apresentou uma textura mais siltosa e os teores de nutrientes de macronutrientes obedecendo as seguintes ordens de concentração: Mg2+> Na2+> Ca2+> H+> K+> P3-> Al3+ e Fe2+> Zn2+> Cu2+> Mn2+. Ambos os estuários apresentam elevada fertilidade e vegetação bem desenvolvida.

Please read the abstract in the section 00front of this document / Dissertation (MSc (Soil Science))--University of Pretoria, 2006. / Plant Production and Soil Science / unrestricted

Small peat basins (c. 10-50 m diameter) were used to obtain fine spatial resolution pollen-stratigraphic records of Holocene vegetation and land-use history in upland West Glen Affric and adjacent lowland Kintail, north-western Scottish Highlands. These data provide evidence for remarkably diverse and dynamic early to mid-Holocene vegetational mosaic and sustained later Holocene upland land-use. While acidophilous Pinus sylvestris-Betula-Calluna vulgaris communities on lower hillslopes appear comparable with other areas of the Highlands, data from floodplain and alluvial fan sediments in West Affric indicate a greater woodland diversity. Betula-dominated alluvial woods included a species-rich mix of arboreal, fen, tall-herb and ruderal herbaceous taxa, with Pinus forming small populations, confined to marginal soils. Ulmus was an important component of the lowland Betula-Alnus woods. Spatial differences in soil forming processes, particularly nutrient and base status, played a primary role in determining community composition, structure, dynamics, species diversity and stability. Inferred climatic shifts during the mid-Holocene, initially to drier, more continental conditions, followed by increased oceanicity, are suggested to have made woodland communities increasingly vulnerable to low intensity grazing disturbance and anthropogenic interference during the later Neolithic and early Bronze Age. These stresses resulted in widespread woodland decline, including that of Pinus, with the spread of blanket peat and heath on poorer hillside soils, and grassland communities on alluvial sediment. Bronze Age agricultural expansion is followed by several phases of expansion and/or intensification, with sustained pastoral and arable activity in the lowlands and on small 'islands' of richer soils in the uplands. There is little evidence for abandonment and the longevity of agricultural activity, particularly cultivation, above 250 m OD clearly indicates that the unqualified assumption of upland marginality is inappropriate. The implications for the interpretation of land-use in the Highlands from conventional palynological and archaeological records are discussed. The level of spatial and temporal detail regarding the palaeoecology of plant communities and adaptive land management evident in the present study is not afforded by conventional pollen analyses. This suggests that fine-spatial resolution palynology has the potential to contribute previously unrecognised information at scales which are directly applicable to ecological and human understanding and which can be more successfully integrated with neoecological and archaeological research, fostering closer collaboration between the disciplines.