50 resultados para pedology


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A new site with Lateglacial palaeosols covered by 0.8 - 2.4 m thick aeolian sands is presented. The buried soils were subjected to multidisciplinary analyses (pedology, micromorphology, geochronology, dendrology, palynology, macrofossils). The buried soil cover comprises a catena from relatively dry ('Nano'-Podzol, Arenosol) via moist (Histic Gleysol, Gleysol) to wet conditions (Histosol). Dry soils are similar to the so-called Usselo soil, as described from sites in NW Europe and central Poland. The buried soil surface covers ca. 3.4 km**2. Pollen analyses date this surface into the late Aller0d. Due to a possible contamination by younger carbon, radiocarbon dates are too young. OSL dates indicate that the covering by aeolian sands most probably occurred during the Younger Dryas. Botanical analyses enables the reconstruction of a vegetation pattern typical for the late Allerod. Large wooden remains of pine and birch were recorded.

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Understanding the response of humid mid-latitude forests to changes in precipitation, temperature, nutrient cycling, and disturbance is critical to improving our predictive understanding of changes in the surface-subsurface energy balance due to climate change. Mechanistic understanding of the effects of long-term and transient moisture conditions are needed to quantify
linkages between changing redox conditions, microbial activity, and soil mineral and nutrient interactions on C cycling and greenhouse gas releases. To illuminate relationships between the soil chemistry, microbial communities and organic C we established transects across hydraulic and topographic gradients in a small watershed with transient moisture conditions. Valley bottoms tend to be more frequently saturated than ridge tops and side slopes which generally are only saturated when shallow storm flow zones are active. Fifty shallow (~36”) soil cores were collected during timeframes representative of low CO2, soil winter conditions and high CO2, soil summer conditions. Cores were subdivided into 240 samples based on pedology and analyses of the geochemical (moisture content, metals, pH, Fe species, N, C, CEC, AEC) and microbial (16S rRNA gene
amplification with Illumina MiSeq sequencing) characteristics were conducted and correlated to watershed terrain and hydrology. To associate microbial metabolic activity with greenhouse gas emissions we installed 17 soil gas probes, collected gas samples for 16 months and analyzed them for CO2 and other fixed and greenhouse gasses. Parallel to the experimental efforts our data is being used to support hydrobiogeochemical process modeling by coupling the Community Land Model (CLM) with a subsurface process model (PFLOTRAN) to simulate processes and interactions from the molecular to watershed scales. Including above ground processes (biogeophysics, hydrology, and vegetation dynamics), CLM provides mechanistic water, energy, and organic matter inputs to the surface/subsurface models, in which coupled biogeochemical reaction
networks are used to improve the representation of below-ground processes. Preliminary results suggest that inclusion of above ground processes from CLM greatly improves the prediction of moisture response and water cycle at the watershed scale.

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Le cycle du carbone (C) est, depuis la révolution industrielle, déstabilisé par l’introduction dans l’atmosphère de C autrefois fossilisé. Certaines mesures de mitigation prometteuses impliquent la séquestration accrue du CO2 atmosphérique dans les sols via le développement du réseau racinaire des arbres. Ce projet de recherche visait à : 1) quantifier la biomasse racinaire ligneuse produite annuellement par unité de surface par le Salix miyabeana cultivé en régie intensive à courtes rotations, 2) doser la concentration en C et en N des racines de saule en fonction de leur profondeur et de leur diamètre et 3) déterminer l’influence des propriétés pédoclimatiques du milieu sur la séquestration du carbone organique (Corg) par les racines. Pour y arriver, six souches de saules ont été excavées à partir de huit sites (n=48) et neuf carottes de recolonisation ont été implantées à cinq sites (n=45) pour évaluer la productivité racinaire fine. Les échantillons séchés ont été pesés pour quantifier la biomasse racinaire produite, et ont été analysés pour le C et le N. La productivité en biomasse racinaire ligneuse du saule en plantation pour tout le réseau d'échantillonnage varie de 0,7 – 1,8 Mg/ha/an. La proportion de C dans la biomasse racinaire s’étend de 31,3% à 50,4% et sa variance dans les tissus est expliquée par le diamètre racinaire et par les conditions environnementales des sites de provenance. Les conditions climatiques constituent la principale influence sur la production de biomasse racinaire. La variance de la biomasse racinaire est significativement contrôlée (p :0,004) par la quantité de précipitation de l’été et de l’année qui contrôlent ensemble 83,4 % du r2 ajusté. La précipitation de l’été est inversement liée à la productivité racinaire puisque les protéines expansines des racines sont stimulées par les carences hydriques du sol. La production de racines fines des plantations (1,2 à 2,4 Mg/ha/an) est, elle, plus fortement contrôlée par les conditions pédologiques du site qui expliquent 36,5% de la variance de productivité des racines fines contre 37,5% de la variance expliquée par les facteurs pédoclimatiques. Le P et le N du sol ont des rôles prépondérants sur la production de racines fines. Une disponibilité en P accrue dans le sol stimule la biomasse racinaire fine alors qu’une quantité supérieure de N dans le sol limite la croissance racinaire tout en favorisant la croissance des parties aériennes de la plante. Ce projet a permis d’améliorer notre compréhension des conditions pédologiques et climatiques qui engendrent, au Québec méridional, une productivité et une séquestration en Corg accrue dans le réseau racinaire du saule.

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O conceito de superfície geomórfica permite uma interligação entre os diferentes ramos da ciência do solo, tais como geologia, geomorfologia e pedologia. Esta associação favorece a compreensão da distribuição espacial dos solos na paisagem, e torna possível compreender o comportamento dos atributos do solo, que estão principalmente relacionadas com a estratigrafia e formas do relevo. Assim, este estudo visa à aplicação da estatística multivariada para categorizar superfícies geomórficas em uma litossequência arenito-basalto, de modo a fornecer uma base para a avaliação do solo em áreas afins. A área de estudo está localizada no município de Pereira Barreto, São Paulo, Brasil. A área escolhida possui 530 hectares, onde foram localizadas e mapeadas três superfícies geomórficas (I, II e III). Na área, 134 amostras foram coletadas nas profundidades de 0,0-0,2 m e 0,8-1,0 m, foram determinados os conteúdos de areia, silte e argila, pH em CaCl2, conteúdo de MO, P, Ca, Mg, K, Al e H+Al. Com base nos resultados, foram realizadas a análise univariada e multivariada de variância, clusters e principal componente, a fim de comparar as três superfícies geomórficas. A análise estatística univariada dos atributos do solo não foi eficiente na identificação das três superfícies geomórficas. Utilizando-se os atributos físicos e químicos do solo, as técnicas estatísticas multivariada permitiram à separação dos três grupos de corpos naturais do solo que foram equivalentes as três superfícies geomórficas mapeadas. Estes resultados são interessantes, pois demonstram a viabilidade da utilização de classificação numérica das superfícies geomórficas para ajudar no mapeamento de solo.

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The semi-arid Northeast region are coming through changes since its formation causing changes in the landscape and increased degradation. The economic dynamics which was established at the Potiguar semiarid had for a long time settled in livestock, subsistence agriculture and cotton, however, these economies decline from the year 1970. Thus, the Potiguar spaces are undergoing by a process of space reordering marked by the growth of agricultural activities and the process of urbanization. In the Potiguar western region these changes weaken significantly transform the landscape. In these areas, the process of urbanization and agricultural activities have caused changes in the hinterland landscape changing the natural dynamics of the caatinga biome that has been subject to negative interference with the indiscriminate removal of vegetation. In this case, the specific study area of the watershed of Cajazeiras Creek located in the cities of Pau dos Ferros, Água Nova, Encanto and Rafael Fernandes, changes in the landscape has led to degradation and environmental fragility. From this perspective, the research objective is to assess the dynamics of the landscape of the watershed of Cajazeiras Creek, semiarid region of the state of Rio Grande do Norte, identifying the degrading factors, the most degraded areas and/or susceptible to degradation and environmental fragility. The research investigated the phenomena of light geosystems theory that emphasizes the integration of elements in shaping the landscape. During this reporting period, it was carried out exploratory and bibliographical research, and geoprocessing techniques to assess the social and environmental conditions of the researched area and its environmental fragility. To do so, first, it was made an multitemporal analisis on the basis of the years 1984, 1996 and 2009 demonstrating that the dynamics of use and land cover in the watershed of Cajazeiras Creek showed a significant change in the landscape, especially in the caatinga vegetation. This has been recovering in various areas of the watershed, especially in its upper course in the mountains of Bom Sera, in Encanto city. The analysis showed the need to develop policies and programs for the maintenance, restoration and preservation of the caatinga vegetation of the river network and of water bodies. In addition, it was identified the most degraded areas of the watershed, environmental fragility and potential emerging that take into account the landscape components such as climate, topography, geology, pedology, geomorphology and the use and occupation of the soil in an integrated manner. The results show that the landscape of the watershed has medium and high environmental fragility throughout its area, especially on the banks of the river network provided by the use and occupation of the soil in an inadequate way with the environmental conditions of the watershed

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This paper studies the applicability of a model to the evolutive dynamics of Pantanal physiography. The Miranda-Aquidauana Pantanal has developed as a pre-existent fluvial plain in the beginning, from Paraguay river, whose ancient marks, recognized by weathering alteration volumes, show components that make possible its relative age determination and consequently permit the comprehension of the ancient and recent dynamic evolutions, that are responsible for the present physiographic form.

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The fractal and multifractal approaches in the geographical analysis. This paper results from a bibliographical research showing the applications of the fractal and multifractal approaches in the geographical studies. At first describes some text books about fractals and, after, focuses the works did concerned with Physical Geography, Meteorology, Climatology, Geomorphology, Pedology and Human Geography.

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The highways are enterprises of great longitudinal extension that cross several types of lands, that possess different geologic, geomorphologic, pedologic and vegetation conditions. In the environmental management of highways the importance of the use of Engineering Geological Maps of Susceptibility was noticed, for being documents that inter-relates several information of the environment. This way, this research objectified the elaboration of this type of map and the indication of lines of direction for the conservation of the Highway Marechal Rondon - SP-300. For its elaboration the Map of Declivity, the delimited Homogeneous Physiographic Units, the processes of the superficial dynamics mapped and the use of the ground was used. Its elaboration evidenced its importance for the environmental management of highways, in view of the prevention, the monitoring and the correction of the adverse processes that can occur in this type of enterprise.

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Pós-graduação em Geociências e Meio Ambiente - IGCE