Bibliographies thématiques / Transitional soils

Littérature scientifique sur le sujet « Transitional soils »

Auteur : Grafiati
Publié le 10 mars 2023

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Articles de revues sur le sujet "Transitional soils"

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Elkamhawy, Elsayed, Huabin Wang, Tarek N. Salem, František Vranay et Martina Zelenakova. « Soil Fabric and Transitional Behavior in Completely Decomposed Granite : An Example of Well-Graded Soil ». Journal of Marine Science and Engineering 9, no 10 (23 septembre 2021) : 1046. http://dx.doi.org/10.3390/jmse9101046.

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Unlike sedimentary soils, limited studies have dealt with completely decomposed granite (CDG) soils, even though they are plentiful and used extensively in several engineering applications. In this paper, a set of triaxial compression tests have been conducted on well-graded intact and disturbed CDG soils to study the impact of the fabric on soil behavior. The soil behavior was robustly affected by the soil fabric and its mineral composition. The intact soil showed multiple parallel compression lines, while a unique isotropic compression line was present in the case of disturbed soil. Both the intact and disturbed soils showed unique critical state lines (CSL) in both the e-log p′ and q-p′ spaces. The intact soil showed behavior unlike other transitional soils that have both distinct isotropic compression lines ICLs and CSLs. The gradient of the unique ICL of the disturbed soil was much more than that of the parallel compression lines of the intact soil. In the intact soil, the slope of the unique CSL (M) in the q-p′ space was higher than that of the disturbed soil. The isotropic response was present for both the intact and disturbed soils after erasing the inherited anisotropy as the stress increased with irrecoverable volumetric change. Soil fabric is considered the dominant factor in the transitional behavior and such a mode of soil behavior is no longer restricted to gap-graded soil as previously thought.
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Pan, Yii‐Wen, et Sunirmal Banerjee. « Transitional Yielding Approach for Soils under General Loading ». Journal of Engineering Mechanics 113, no 2 (février 1987) : 153–69. http://dx.doi.org/10.1061/(asce)0733-9399(1987)113:2(153).

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Xiao, Yang, M. R. Coop, Hong Liu, Hanlong Liu et Jingshan Jiang. « Transitional Behaviors in Well-Graded Coarse Granular Soils ». Journal of Geotechnical and Geoenvironmental Engineering 142, no 12 (décembre 2016) : 06016018. http://dx.doi.org/10.1061/(asce)gt.1943-5606.0001551.

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Prosyannikov, E. V., V. B. Osipov et G. V. Chekin. « Behavior of 137Cs in soils of transitional bogs ». Russian Journal of Ecology 37, no 6 (décembre 2006) : 408–13. http://dx.doi.org/10.1134/s1067413606060075.

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Zabielska-Adamska, Katarzyna. « Characteristics of Compacted Fly Ash as a Transitional Soil ». Materials 13, no 6 (19 mars 2020) : 1387. http://dx.doi.org/10.3390/ma13061387.

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Cohesive and non-cohesive soils show a number of properties typical of a given category. Cohesive soils are characterized by cohesion, and the properties of compacted soils closely depend on moisture at compaction. However, many researchers have found the existence of so-called mixed or transitional soils. Compacted transitional soils, macroscopically recognized as non-cohesive, are characterized by mechanical properties and hydraulic conductivity which are strictly dependent on the moisture content at compaction. The aim of this work is to show the influence of the content of fine particles in fly ash on the variation of California Bearing Ratio (CBR) values as a parameter strictly dependent on initial compaction. The CBR values were interpreted in terms of moisture at compaction, void ratio and intergranular void ratio. Three different research samples were selected with fine contents of 45%, 55% and 70%; all samples corresponded in terms of grading with sandy silt. Fly ash containing only non-plastic fines behaved as cohesive soils despite the lack of plasticity. The CBR values decreased with increasing moisture at compaction or void ratio. The CBR values, plotted as a function of the intergranular void ratio, have lower penetration resistance together with fine content.
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Bijak, Szymon. « Selected properties of organic soils under boreal mire spruce forest in the Romincka Forest, NE Poland ». Soil Science Annual 68, no 4 (1 décembre 2017) : 182–88. http://dx.doi.org/10.1515/ssa-2017-0023.

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Abstract The paper presents selected properties of the organic soils developed in boreal mire spruce forests (Sphagno girensohnii-Piceetum) in the Romincka Forest (NE Poland). Additionally, the relationship between soil fertility and forest stand productivity was investigated. Data from 12 soil profiles, differing in terms of peatland ecological type (raised bog, transitional bog and fen) was used. The significance of the differences in soil properties among peatland types was assessed with the Kruskal-Wallis test. Soil fertility was described using soil trophic index (SIGo), whereas stand productivity according to site index (SI) value. The properties of the analysed soils varied significantly in terms of peatland type. Soils from fens were more fertile (SIGo 25–31), less acidic (pH > 5.7), with lower total potential acidity (36–40 cmol(+)·kg−1), higher base saturation (77–79%), Ca2+ content (116–136 cmol(+)·kg−1) and base exchange capacity (123–145 cmol(+)·kg−1) than soils from transition or raised bogs. No significant effect of soil fertility on the site index of stands growing on analysed soils was observed (r = 0.385, p = 0.216).
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Tkach, E. P. « The content of manganese in soddy brown soils of the Transcarpathian Mountain Valleys ». Fundamental and Applied Soil Science 16, no 1-2 (24 mars 2015) : 60–65. http://dx.doi.org/10.15421/041506.

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The soil covering of Transcarpathia, which is used for cultivation of crops, is rather heterogeneous as to genetic features of soils. This is mostly caused by the climatic conditions of corresponding natural zones. Brown mountain soils, soddy brown soils, meadow brown soils and mountain meadow soils have originated in mountainous areas on mountain ranges and slopes of different altitude, which are different in terms of mechanical makeup and are well drained. They are characterized by high content of inaccessible humus (in which fulvic acids predominate), acid reaction of soil solution and evident diversity in provision of mobile forms of nourishing chemicals. On the average, the reaction of soil solution is 4,60 pH of a salt solution, in the case of hydrolytic acidity – 4, 28 me/100g of soil, which characterizes them as semi-acidic. The aim of our thesis is to research the level of manganese, which is one of essential and toxic elements for plants, depending on its concentration in soil, in soddy brown soils of the mountainous zone of Thranscarpathia, and also its distribution in profile of soil horizons. To carry out this aim, samples of soil were chosen by random selection. Total manganese in the soil was determined by the method of mass spectrometery. The samples were extracted by hydrogen peroxide, chlorohydric and azotic acids (ext. p.). Dissolution of the samples was carried out using microwave sample preparation system. Active forms of manganese were extracted by generally accepted extragents: water-soluble extragent – deionized water; free forms of manganese – ammonium acetate buffer solution рН 4.8 according to M. K. Krupskyi and H. М. Alexandrova. Afterwards, the samples of soil were analysed using the method of mass spectrometery. According to the results of the research, the max. total of the manganese is observed in the mineral upper humus-accumulative horizon, but if you make a transition to the parent rock, it decreases. According to the quantitative research on determining free forms of manganese, it can be observed that soddy brown soils of the researched region are provided with the mobile forms of manganese both in the upper humus horizon and in lower transitional humus horizon. Moreover, the humus horizon of the observed region has a high content of mobile forms of manganese, which constitutes >20,1, and in the transitional horizon to the parent rock the provision index is high. A considerable increase in the water-soluble manganese in the upper humus horizon was also observed. Its concentration is considerably decreased with a transition to the lower humus horizon. The research data confirms that soddy brown soils of the observed region are contaminated with manganese compounds.
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Rusakova, E. S., I. V. Ishkova, I. I. Tolpeshta et T. A. Sokolova. « Acid-base buffering of soils in transitional and transitional-accumulative positions of undisturbed southern-taiga landscapes ». Eurasian Soil Science 45, no 5 (mai 2012) : 503–13. http://dx.doi.org/10.1134/s1064229312050110.

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Taruna, Yulian, Salampak Salampak, Nina Yulianti, Haiki Mart Yupi, Sustiyah Sustiyah et Fahrul Indrajaya. « Pengaruh Penyiraman Air Tanah Terhadap Perubahan Sifat Kimia Tanah dan Air Gambut di Kalimantan Tengah ». soilrens 19, no 1 (10 août 2021) : 58. http://dx.doi.org/10.24198/soilrens.v19i1.35092.

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This study observed the changes in chemical properties of peat soil and ground water after irrigation of two peat types: inland and transition peat. The research was carried out in the Basic and Analytic Laboratory of Palangka Raya University. Inland peat and water samples were obtained from Palangka Raya City, meanwhile and transitional peatland was taken from Pulang Pisau Regency, Central Kalimantan Province. Research methods consisted of survey and experimental test with complete randomized design (CRD) consisted of groundwater irrigation treatment and was repeated 3 times. The experimental parameters are soil chemical properties such as Ash Content, Base Saturation (KB), Nitrogen (N), Phosphor (P), Exchangeable Potassium (K-dd), Interchangeable Sodium (Na-dd), Interchangeable Calcium (Ca-dd), Interchangeable Magnesium (Mg-dd), Cation Exchange Capacity (CEC), Aluminum Saturation, Iron (Fe), Sulfate (SO₄), Hydrogen Concentration (pH), and Electrical Delivery Power (EDP), and water chemical properties such as pH, EDP, cation, and anions.. The results showed that there has been an increase in the value of CEC, P, Na-dd, SO₄, pH, and decreased of Ash Content, N, K-dd, Ca-dd, and EDP on transitional peat soils. Meanwhile, the inland peat soils showed an increase of Ash Content, N, P, Mg-dd, a saturation of Al and Fe, and decreased in the value of CEC, Ka-dd, Na-dd, Ca-dd, SO₄, pH, and EDP. There were similar effect of groundwater irrigation, towards soil chemical properties, with an exeption of iron levels (Fe). Iron levels (Fe) in transitional peat increase, but decreased in inland peat.
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deBortoli, Leah A., Bradley D. Pinno, M. Derek MacKenzie et Edith H. Y. Li. « Plant community composition and tree seedling establishment in response to seeding and weeding treatments on different reclamation cover soils ». Canadian Journal of Forest Research 49, no 7 (juillet 2019) : 836–43. http://dx.doi.org/10.1139/cjfr-2018-0363.

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The majority of plant diversity in North American boreal forests is comprised of understory plant communities undergoing continuous interspecific competition. Anthropogenic activities, particularly surface mining, have introduced higher severity disturbances that not only remove vegetation, but also modify soil. During reclamation, soils used to cap overburden materials have inhibited native plant growth and increased weed invasion. This study aimed to examine the effectiveness of seeding and weeding treatments for promoting the establishment of native understory plant communities, as well as a common deciduous tree species, on three different reclamation cover soils (forest floor – mineral mix, peat–mineral mix, and transitional). The broadcasting of a native forb seed mix was not successful on any of the cover soils, whereas weeding affected each cover soil differently. With weeding, the forest floor – mineral mix and transitional cover soils experienced a decrease in the relative abundance of introduced forbs and an increase in the relative abundance of graminoids. The increase in graminoid cover on the forest floor – mineral mix was mostly attributed to the expansion of Calamagrostis canadensis (Michx.) P. Beauv. Overall, weeding effectively eliminated introduced plant species, allowing competitive native grasses to establish. However, weeding may have unintentionally hindered the development of a native understory plant community via the over-establishment of grass on reclamation sites.
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Thèses sur le sujet "Transitional soils"

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Shipton, Barbara. « The Mechanics of Transitional Soils ». Thesis, Imperial College London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.517638.

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Lopes, Bruna de Carvalho Faria Lima. « Microstructural-based approach to the interpretation of clays and transitional soils behaviour ». reponame:Repositório Institucional da UnB, 2016. http://repositorio.unb.br/handle/10482/20465.

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Tese (doutorado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Civil e Ambiental, 2016.
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O futuro da prática da engenharia é a incorporação de aspectos da microestrutura nas características macroestruturais dos solos de modo a simplificar e tornar mais realistas as análises geotécnicas. Consequentemente, é de fundamental importância que se entenda a estrutura dos solos em diferentes estados (inderformado, reconstitutído, remouldado, compactado, etc.) e se correlacionem os mesmos, já que se sabe que o estado inicial do solo dita o seu comportamento. Neste sentido, esta pesquisa está focada no desenvolvimento do entendimento das mudanças na estrutura do solo através dos tamanhos dos seus poros e sua distribuição quando submetido a carregamentos mecânicos assim como a determinação do estado mais apropriado para descrever um estado de referência do comportamento do solo. Os solos testados foram duas argilas: Caulinita e Ball; e um solo tropical transicional: Solo de Brasília. A partir dos solos estudados foram produzidas amostras com pH 9, reconstituídas, remoldadas e indeformadas, esta última somente para o solo de Brasília. Cada uma destas amostras foi submetida à compressão unidimensional combinada no oedometro e aparelho de taxa constante de deformação a diferentes tensões: 2, 90, 360, 2.000, 5.000 e 11.000kPa. Em seguida as amostras foram congeladas e secas pelo processo de liofilização e por último foram submetidas ao ensaio de porosimetria por intrusão de mercúrio. Adicionalmente, mediu-se a sucção inicial de algumas das amostras dos três solos estudados. A partir dos resultados dos ensaios realizados foram propostos dois modelos conceituais um para as argilas e outro para o solo transicional. Os resultados do ensaio de adensamento foram modelados usando uma adaptação do modelo constitutivo SCLAY-1S (Koskinen et al., 2002) na qual a variável x descreve os efeitos da estrutura ao invés de cimentação como proposto originalmente. Além disto, a amostra pH 9 foi considerada a amostra de referência, assim para este estado x = 0 e todas as outras amostras tem estrutura, de acordo com a metodologia aqui proposta. Os resultados mostraram que a metodologia proposta para obtenção das amostras é adequada. A sucção inicial foi satisfatoriamente correlacionada à tensão de preadensamento. Resultados das análises de porosimetria confirmam que o estado da estrutura das amostras com pH 9 é mais adequado para representar um estado de referência que o estado das amostras reconstituídas. As amostras com pH 9 apresentam uma estrutura dispersa já que as laterais da partícula de caulinita são carregadas negativamente assim como as faces. Dessa forma com o aumento do carregamento não há muitas configurações possíveis, a estrutura da amostra irá ficar cada vez mais orientada e alinhada paralelamente. O mesmo acontece com as amostras em outros estados. A amostra indeformada apresenta inicialmente a estrutura mais aberta, seguida da reconstituída e remouldada. À medida que o carregamento aumenta a estrutura destas outras amostras tende para uma configuração dispersa com as partículas de caulinita orientadas e alinhadas paralelamente. A modelagem constitutiva se mostrou apropriada, embora ainda haja necessidade de aprimoramento nos estudos para que o parâmetro ax possa ser correlacionado com a variável x. _________________________________________________________________________________________________ ABSTRACT
The future of engineering practice is to incorporate aspects of the microstructure into the macroscopic characteristics of soils in order to simplify and make the geotechnical analysis more realistic. Therefore, it is fundamentally important to understand the structure of soils in various states (undisturbed, reconstituted, remoulded, compacted, etc.) and correlate them, as it is already known that the initial state of the soil dictates its behaviour. Hence, this research focuses on developing an understanding of the changes in the soil structure through its pore sizes and distribution under mechanical loading, as well as determining which state is appropriate to describe a reference state of the soil behaviour. The soils tested were the two clays: Kaolin and Ball; and the tropical transitional soil: Brasilia Soil. From the studied soils, samples with pH9, reconstituted, remoulded and undisturbed (for the Brasilia Soil only), were produced. Each of these samples was subjected to uniaxial compression combined with oedometer and Constant Rate of Strain (CRS) apparatus up to: 2, 90, 360, 2,000, 5,000 and 11,000 kPa. Specimens of these samples were then freeze-dried by the lyophilization process and lastly subjected to the Mercury Intrusion Porosimetry (MIP) test. Additionally, the initial suction of a few samples of the three soils was measured. From the results of the laboratory tests carried out, two conceptual models were proposed: one for the clays and one for the transitional soil. The results of the consolidation test were modelled using an adaptation of the constitutive model, SCLAY-1S (Koskinen et al., 2002), in which the variable x describes the structure rather than bonding as originally proposed. Furthermore, the pH9 sample was considered the reference state; thus this state has x = 0, while all other states have some structure, according to the methodology herein proposed. Results showed that the methodology proposed for obtaining the specimens is adequate. The initial suction measured was satisfactorily correlated to the preconsolidation stress. Results of the MIP confirmed that the pH9 state is the most suitable to represent a reference state, rather than the reconstituted state. The pH9 state presents a disperse structure, as the edges of the kaolinite particle are charged negatively as well as the faces. Therefore, as the loading increases there are not many possible configurations for this sample, hence the structure will orient in a preferential direction. The same happens for the samples in other states. The undisturbed sample has the most open structure, followed by the reconstituted and remoulded states. As the loading progresses, the structure of these samples tends towards the dispersed configuration with the kaolinite particles well-oriented and aligned in parallel with each other. The constitutive modelling is appropriate; however, there is still room for improvement studies to correlate the parameter ax with the state variable x.
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Marcosanti, Agnese <1982&gt. « Experimental study of the transitional behaviour of the silty soils from the Venice Lagoon ». Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/4167/1/marcosanti_agnese_tesi.pdf.

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Marcosanti, Agnese <1982&gt. « Experimental study of the transitional behaviour of the silty soils from the Venice Lagoon ». Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/4167/.

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Carrión, Carmona Miguel Ángel. « The effects of the structure on the mechanical behaviour of young Holocene alluvial materials from the Bormida River (Italy) and Turia River (Spain) ». Doctoral thesis, Universitat Politècnica de València, 2016. http://hdl.handle.net/10251/63470.

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[EN] The understanding of the mechanical behaviour of natural intact soils is central to engineers when designing new structures. The research carried in this thesis focused on investigating the effects of the naturally occurring in-situ structure on the mechanical behaviour of two shallow recently deposited Holocene alluvial materials, the Bormida River silts (BRS) from Italy and the Valencia silty soils (VSS) from the alluvial plains of the Turia River, Spain. These types of deposits are frequently characterised by highly heterogeneous in-situ structures. A large range of soils with different size distributions from sands to silty clays were investigated. Oedometer and triaxial tests were carried out on intact, slurry and compacted samples. The first step was to characterise the behaviour of the materials at their reconstituted state to define the reference framework for investigating the effect of the in-situ structure of the intact specimens. The effects of the sample preparation technique on the mechanical behaviour were examined, in particular its influence on the uniqueness of the normal compression line and critical state line. The initial structure created during the preparation of the specimens was totally removed after compression and shearing regardless of the sample preparation method. Only one soil displayed a clear effect of the sample preparation technique, the oedometer compression lines of which remained parallel to each other even at a very high stress levels for the case of the slurry samples. This result showed that contrary to what is stated in the literature the sample preparation technique can created very robust initial structures resulting in a transitional behaviour. Clears effects of the in-situ structure of the intact samples of the BRS and VSS were observed on the oedometer compression behaviour even at very high stress levels with stress sensitivity values still larger than unity at the end of the tests. It appeared that the effects were more noticeable as the degree of heterogeneity inside the specimens increased at a meso-structure level as it was the case of some samples of the VSS materials which exhibited a certain layering. Small effects of the in-situ structure were seen at large shearing strains and only on the wet side of the critical state.
[ES] El conocimiento del comportamiento mecánico de los suelos en su estado natural es de importancia capital para los ingenieros a la hora de diseñar nuevas obras. La investigación desarrollada en esta Tesis se centra en descubrir los efectos que tiene la estructura del suelo en su estado natural en la respuesta mecánica de dos suelos aluviales holocenos, depositados superficialmente: los limos del río Bormida (BRS) en Italia y los suelos limosos provenientes de la llanura aluvial del río Turia (VSS) en España. Este tipo de suelos se caracterizan frecuentemente por una estructura inicial altamente heterogénea. Se ha ensayado una gran variedad de muestras con diferentes granulometrías, desde arenas a arcillas limosas en las que se han realizado ensayos edométricos y triaxiales en muestras intactas, compactadas y en muestras reconstituidas (slurry). En una primera etapa de la investigación se caracterizó la respuesta del material en su estado reconstituido para definir un marco de referencia con el que poder comparar la respuesta de las muestras intactas tomadas in situ y que preservan su estructura natural (inalteradas). Se ha analizado la influencia del modo de preparación de las muestras en su comportamiento mecánico, y, en particular, en la unicidad de las curvas de compresión noval y de estado critico. Se ha comprobado que la estructura inicial inducida durante el proceso de preparación desaparece completamente tras someter la muestra a compresión y corte, independientemente del método de preparación utilizado. Únicamente un suelo mostró, de un modo nítido, el efecto de la técnica de preparación, de modo que las líneas de compresión edométrica se mantuvieron paralelas incluso a niveles de tensión elevados en el caso de muestras reconstituidas (slurry). Este resultado demostró, contrariamente a la opinión aceptada en la bibliografía, que el sistema de preparación de la muestra puede crear una potente estructura inicial dando lugar a un comportamiento de tipo transicional. En los ensayos de compresión edométrica se ha podido comprobar un claro efecto positivo de la estructura inicial de las muestras intactas, incluso a niveles altos de tensión, observándose índices de sensitividad tensional superiores a uno al final de los ensayos, de modo que para igualdad de índice de huecos, la tensión efectiva vertical de la muestra intacta es superior a la correspondiente en la muestra reconstituida. Aparentemente, este efecto es tanto más significativo cuanto mayor es el grado de heterogeneidad interno de la muestra a nivel de meso-estructura, como se pudo observar en algunas muestras de los suelos (VSS) que presentaban niveles de laminación horizontal. En los ensayos de corte la influencia de la estructura intacta fue relativamente pequeña y únicamente en el lado húmedo del estado critico.
[CAT] Conèixer el comportament mecànic dels sòls en el seu estat natural és d'importància capital per als enginyers a l'hora de dissenyar noves obres. La investigació desenvolupada en aquesta Tesi se centra a descobrir els efectes de l'estructura del sòl en el seu estat natural en la resposta mecànica de dos sòls al¿luvials holocens, dipositats superficialment: els llims del riu Bormida (BRS) a Itàlia i els sòls llimosos provinents de la plana al¿luvial del riu Túria (VSS) a Espanya. Aquests tipus de sòls es caracteritzen sovint per una estructura inicial altament heterogènia. S'ha assajat una gran varietat de mostres amb diferents granulometries, des d'arenes fins a argiles llimoses amb les quals s'han realitzat assajos edomètrics i triaxials en mostres intactes, compactades i en mostres reconstituïdes (slurry). En una primera etapa de la investigació es va caracteritzar la resposta del material en el seu estat reconstituït per a definir un marc de referència amb el qual poder comparar la resposta de les mostres intactes preses in situ i que preserven la seua estructura natural (inalterades). S'ha analitzat la influència del mètode de preparació de les mostres en el seu comportament mecànic i en particular, en la unicitat de les corbes de compressió noval i d'estat crític. S'ha comprovat que l'estructura inicial induïda al llarg del procés de preparació desapareix completament després de sotmetre la mostra a compressió i tall, independentment del mètode de preparació utilitzat. Únicament un sòl va mostrar clarament l'efecte de la tècnica de preparació, de manera que les línies de compressió edomètrica es van mantenir paral¿leles fins i tot a nivells de tensió elevats en el cas de mostres reconstituïdes (slurry). Aquest resultat va demostrar, contràriament a l'opinió acceptada en la bibliografia, que el sistema de preparació de la mostra pot crear una potent estructura inicial donant lloc a un comportament de tipus transicional. Als assajos de compressió edomètrica s'ha pogut comprovar un clar efecte positiu de l'estructura inicial de les mostres intactes, inclús a nivells alts de tensió, observant-se índexs de sensitivitat tensional superiors a la unitat al final dels assajos, de manera que per a igualtat d'índex de buits, la tensió efectiva vertical de la mostra intacta és superior a la corresponent en la mostra reconstituïda. Aparentment, aquest efecte és més significatiu quant major és el grau d'heterogeneïtat intern de la mostra a nivell de meso-estructura, com es va poder observar en algunes mostres dels sòls (VSS) que presentaven nivells de laminació horitzontal. Als assajos de tall la influència de l'estructura intacta va ser relativament petita i únicament en el costat humit de l'estat crític."
Carrión Carmona, MÁ. (2016). The effects of the structure on the mechanical behaviour of young Holocene alluvial materials from the Bormida River (Italy) and Turia River (Spain) [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/63470
TESIS
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Giusti, Ilaria Verfasser], et Joachim [Akademischer Betreuer] [Stahlmann. « Improvement of piezocone test interpretation for partial drainage conditions and for transitional soils / Ilaria Giusti ; Betreuer : Joachim Stahlmann ». Braunschweig : Technische Universität Braunschweig, 2019. http://d-nb.info/1175894958/34.

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Giusti, Ilaria [Verfasser], et Joachim [Akademischer Betreuer] Stahlmann. « Improvement of piezocone test interpretation for partial drainage conditions and for transitional soils / Ilaria Giusti ; Betreuer : Joachim Stahlmann ». Braunschweig : Technische Universität Braunschweig, 2019. http://d-nb.info/1175894958/34.

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Savioli, Valentina. « Indagine sperimentale sul comportamento transizionale di miscele granulari ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amslaurea.unibo.it/2276/.

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Rezgui, Cyrine. « Etude du potentiel d'introduction de la culture du pois d'hiver dans les successions culturales en Normandie : conséquences sur les communautés microbiennes du sol et les flux d'azote Impacts of the winter pea crop (instead of rapeseed) on soil microbial communities, nitrogen balance and wheat yield Quantification et analyse des exsudats racinaires de pois, de blé et de colza : mise au point d’une méthodologie de collecte des exsudats racinaires N rhizodeposition quantification and root exudates characterization of pea (Pisum Sativum L.), rapeseed (Brassica napus L.) and wheat (Triticum aestivum L.) under controlled conditions Linking soil microbial community to C and N dynamics during crop residues decomposition ». Thesis, Normandie, 2020. http://www.theses.fr/2020NORMR047.

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La transition agroécologique vise la triple performance agronomique, écologique et sociétale des exploitations agricoles. Un certain nombre de pratiques agricoles permet d’envisager la construction et le développement de systèmes de culture répondant à ces contraintes. Les légumineuses, par leur capacité à fixer l’azote atmosphérique, sont une alternative intéressante aux intrants azotés. Outre l’absence de fertilisation lors de leur culture, elles fournissent de l’azote à la culture suivante. Il existe cependant un manque de références sur certaines légumineuses à graines et notamment la culture du pois d’hiver. En effet, si des données acquises dans différentes régions françaises sont disponibles, aucune référence n’a été publiée pour la Normandie où la culture du pois d’hiver connaît un récent regain d’intérêt. Cette thèse propose d’évaluer, sur une période de deux ans, l’effet du remplacement du colza par le pois d’hiver en tête de rotation en réalisant une analyse comparative de ces deux successions (pois d’hiver-blé et colza-blé). L’objectif était d’évaluer l’effet de ce changement de tête de rotation (pois d’hiver vs colza) sur l’état biologique du sol et les flux d’azote à différentes échelles spatiotemporelles. Les résultats ont révélé une forte variabilité spatio-temporelle dans la réponse des communautés microbiennes du sol, et mis en évidence l’importance du contexte pédoclimatique dans le déterminisme de l’abondance et de l’activité des communautés microbiennes du sol. Ils ont montré par ailleurs, l’effet positif du pois d’hiver sur la disponibilité de l’azote minéral au cours du cycle cultural et pour les cultures suivantes, ici le blé puis l’orge. Les apports d’azote minéral dans le sol lié à la contribution des parties racinaires via la rhizodéposition et à la dégradation des résidus de culture après récolte ont été évalués au cours de ce travail de thèse. En effet, si la rhizodéposition s’est révélée plus importante sous pois d’hiver, elle n’a pas eu d’impact significatif sur les communautés microbiennes rhizosphériques. Contrairement à ces observations, la dégradation des résidus de culture a significativement modifié la composition des communautés bactériennes en lien avec leur composition biochimique initiale. La succession culturale incluant le pois a enrichi le sol en azote minéral mais des risques de perte d’azote par lixiviation de l’ordre de 23 kg N. ha-1 ont été estimés. Ces constats soulignent l’importance d’adapter la conduite des systèmes de culture incluant le pois d’hiver, en limitant les pertes d’azote par lixiviation et en maximisant son utilisation par les cultures suivantes. Les résultats de ces travaux ont confirmé la diminution des quantités d’engrais azoté utilisées dans la succession contenant le pois, sans préjudice de productivité, ni pour le pois, ni pour la culture suivante, ici, le blé. Finalement, introduire le pois d’hiver dans la rotation de culture en région Normandie, semble permettre de répondre à la problématique d’augmentation du coût des intrants, et aux enjeux de transition agroécologique et d’autonomie protéique régionale
The agroecological transition targets triple agronomic, ecological, and societal performance of farms. Some new agricultural practices had emerged to develop a new cropping system to respond to these constraints. Legumes constitute an interesting alternative. Indeed, legumes are advantageous for soils due to their symbiotic relationship with nitrogen-fixing bacteria. The presence of compatible rhizobia combined to nitrogen-limited conditions promotes symbiosis which is the most efficient way for legumes to acquire more nitrogen. Compared with non-nodulated plants, symbiosis provides a competitive advantage by increasing soil nitrogen pool. However, some grain legumes, notably winter pea, are rarely studied, especially in the Normandy region where no reference has been published for this crop. The objective of this study is to compare two crop successions for a period of two years (winter pea-wheat and rapeseed-wheat), in order to assess the effect of replacing rapeseed by winter pea at the head of the rotation .We evaluated the effect of these two crops (winter pea vs rapeseed) on the biological state of the soil and nitrogen fluxes at different spatio-temporal scales. The results showed a significant spatio-temporal effect on the response of soil microbial communities and highlighted the importance of the pedoclimatic context in determining the abundance and activity of soil microbial communities. A positive effect of winter pea has been demonstrated on the availability of mineral nitrogen during the crop cycle and for following crops (wheat and barley). The supply of nitrogen to the soil is linked to the rhizodeposition of nitrogen via plants roots and the degradation of crop residues after harvest. Our results showed that winter pea exhibited the greatest amount of nitrogen rhizodeposition. However, rhizodeposition did not have a significant impact on rhizospheric microbial communities. Contrary to these observations, the degradation of crop residues significantly modified the composition of bacterial communities linked to their initial biochemical composition. Crop succession including winter pea enriched the soil with mineral nitrogen but simulation with STICS software revealed a nitrogen leaching around of 23 kg N. ha-1 during the cropping cycle. These findings underline the importance of adapting an adequate crop management system, including winter pea, to limit nitrogen losses. The results showed also that wheat yields after winter pea without the use of nitrogen fertilizers were equivalent to those obtained after rapeseed. However, rapeseed required significant nitrogen fertilization. Including winter pea in crop rotation in Normandy region may be a key to enhance productivity, to respond to the challenges of agroecological transition, regional protein autonomy, and to reduce environmental and economic costs, by reducing notably, the costs of fertilizers production and uses
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Carnes, Jennifer L. « Response of Soils and Soil Ecosystems to the Pennsylvanian-Permian Climate Transitionin the Upper Fluvial Plain of the Dunkard Basin, Southeastern Ohio, USA ». Ohio University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1493571336373265.

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Livres sur le sujet "Transitional soils"

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International Erosion Control Association. Conference. Erosion control : Technology in transition. Steamboat Springs, CO : International Erosion Control Association, 1990.

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(Germany), Wissenschaftlicher Beirat der Bundesregierung Globale Umweltveränderungen. World in transition : The threat to soils : 1994 annual report. Bonn : Economica Verlag, 1995.

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Beyond the edge : Spiritual transitions for adventurous souls. London : SPCK Publishing, 2013.

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Zerwekh, JoAnn Graham, et Jo Carol Claborn. Nursing today : Transition and trends. 2e éd. Philadelphia : Saunders, 1997.

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Rorke, Bryan, dir. Soil erosion, land degradation and social transition : Geoecological analysis of a semi-arid tropical region, Kenya. Cremlingen, Germany : Catena, 1994.

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1978-, Snell Patricia, et Smith Christian 1960-, dir. Souls in transition : The religious and spiritual lives of young adults. Oxford : Oxford University Press, 2009.

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D, Allen Sarah, U.S. Fish and Wildlife Service. Research and Development et University of Rhode Island. Dept. of Natural Resources Science, dir. Soil-vegetation correlations in transition zones of Rhode Island red maple swamps. Washington, DC : U.S. Dept. of the Interior, Fish and Wildlife Service, Research and Development, 1989.

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D, Allen Sarah, U.S. Fish and Wildlife Service. Research and Development et University of Rhode Island. Dept. of Natural Resources Science, dir. Soil-vegetation correlations in transition zones of Rhode Island red maple swamps. Washington, DC : U.S. Dept. of the Interior, Fish and Wildlife Service, Research and Development, 1989.

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D, Allen Sarah, U.S. Fish and Wildlife Service. Research and Development. et University of Rhode Island. Dept. of Natural Resources Science., dir. Soil-vegetation correlations in transition zones of Rhode Island red maple swamps. Washington, DC : U.S. Dept. of the Interior, Fish and Wildlife Service, Research and Development, 1989.

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D, Allen Sarah, U.S. Fish and Wildlife Service. Research and Development. et University of Rhode Island. Dept. of Natural Resources Science., dir. Soil-vegetation correlations in transition zones of Rhode Island red maple swamps. Washington, DC : U.S. Dept. of the Interior, Fish and Wildlife Service, Research and Development, 1989.

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Chapitres de livres sur le sujet "Transitional soils"

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Kaltekis, K., et J. Peuchen. « A CPT-based method for estimation of undrained shear strength of sands and transitional soils ». Dans Cone Penetration Testing 2022, 486–90. London : CRC Press, 2022. http://dx.doi.org/10.1201/9781003329091-68.

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Kaltekis, K., et J. Peuchen. « A CPT-based method for estimation of undrained shear strength of sands and transitional soils ». Dans Cone Penetration Testing 2022, 486–90. London : CRC Press, 2022. http://dx.doi.org/10.1201/9781003308829-68.

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Silla, Cesare. « Souls in transition ». Dans The Rise of Consumer Capitalism in America, 1880–1930, 48–59. 1 Edition. | New York : Routledge, 2018. | Series : Contemporary liminality : Routledge, 2018. http://dx.doi.org/10.4324/9781315399669-3.

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Gad-el-Hak, Mohamed. « Transition Control ». Dans Advances in Soil Science, 319–54. New York, NY : Springer New York, 1990. http://dx.doi.org/10.1007/978-1-4612-3430-2_38.

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Zang, Thomas A., Norbert Gilbert et Leonhard Kleiser. « Direct Numerical Simulation of the Transitional Zone ». Dans Advances in Soil Science, 283–99. New York, NY : Springer New York, 1990. http://dx.doi.org/10.1007/978-1-4612-3432-6_23.

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Speziale, Charles G. « Group Summary : Transition Modeling ». Dans Advances in Soil Science, 451–52. New York, NY : Springer New York, 1990. http://dx.doi.org/10.1007/978-1-4612-3432-6_34.

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Reshotko, Eli. « Transition Research Using Flight Experiments ». Dans Advances in Soil Science, 88–90. New York, NY : Springer New York, 1990. http://dx.doi.org/10.1007/978-1-4612-3430-2_12.

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Spalart, P. R. « Computation of Instability and Transition ». Dans Advances in Soil Science, 192–99. New York, NY : Springer New York, 1990. http://dx.doi.org/10.1007/978-1-4612-3430-2_23.

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Herbert, Thorwald. « Theory of Instability and Transition ». Dans Advances in Soil Science, 20–31. New York, NY : Springer New York, 1990. http://dx.doi.org/10.1007/978-1-4612-3430-2_4.

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Smith, Frank T. « Theory on Instability and Transition ». Dans Advances in Soil Science, 32–40. New York, NY : Springer New York, 1990. http://dx.doi.org/10.1007/978-1-4612-3430-2_5.

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Actes de conférences sur le sujet "Transitional soils"

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Athanasios Alexandrou, Deborah Stinner et Mohammad Reza Mosaddeghi. « A Comparison Of Penetration Resistance Of Transitional Organic And Conventional Soils ». Dans 2004, Ottawa, Canada August 1 - 4, 2004. St. Joseph, MI : American Society of Agricultural and Biological Engineers, 2004. http://dx.doi.org/10.13031/2013.17652.

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King, Fraser, Russell Given, Robert G. Worthingham et Greg Van Boven. « Effect of Transitions in the Water Table and Soil Moisture Content on the Cathodic Protection of Buried Pipelines ». Dans 2006 International Pipeline Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/ipc2006-10171.

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Buried pipelines can be subject to transitional environments due to changes in soil type or moisture content. Changes in the height of the water table, for example, will affect not only the availability of water but also the access of oxygen to the pipe surface. Transitions between different soil types will also result in different exposure conditions for different parts of the pipe. These variations can affect the distribution of potential on the pipe surface and the ability of the CP system to provide adequate protection. A combination of laboratory-scale soil box tests and field measurements on operating pipelines has been used to study the effect of varying moisture content and water level on the level of cathodic protection and on pipe-depth environmental conditions. In both laboratory tests and field trials, the degree of protection depends on the availability of cathodic reactants (O2 and/or H2O). Ingress of O2 results in a positive shift in potential as more current is required to electrochemically reduce the oxidant and the pipe is less easily polarized. Under some circumstances the ingress of water has the same effect. Although more aerobic conditions lead to more-positive potentials the pipe is not necessarily less well protected. In many dry and/or high resistivity soils the pipe surface may well be passive because of the high interfacial pH and/or high O2 concentration.
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Zatserkovnyi, V. I., P. I. Trofymenko, O. V. Zubova, N. V. Trofimenko et I. V. Karas. « The remote diagnosis of organic carbon content in Polissya transitional zone soils of Ukraine by using the multispectral images Sentinel-2 ». Dans 16th International Conference on Geoinformatics - Theoretical and Applied Aspects. Netherlands : EAGE Publications BV, 2017. http://dx.doi.org/10.3997/2214-4609.201701876.

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Mironov, Valery L., Igor V. Savin, Yuri I. Lukin et Andrew Yu Karavaisky. « Phase transition analysis in freezing moist soils carried out on the basis of phase transitions characteristic to the different types of soil water ». Dans IGARSS 2012 - 2012 IEEE International Geoscience and Remote Sensing Symposium. IEEE, 2012. http://dx.doi.org/10.1109/igarss.2012.6350472.

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Rodionova, Natalia. « Identification of thawed and frozen soil state in some Siberia regions by multi-temporal Sentinel 1 radar data in 2017-2018 ». Dans Information Technology and Nanotechnology 2019. IP Zaitsev V.D., 2019. http://dx.doi.org/10.18287/1613-0073-2019-2391-1-10.

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The paper deals with the identification of thawed/frozen soils in the topsoil layer for three stations in Siberia: Salekhard, Tiksi and Norilsk by using Sentinel 1B C-band radar data for the period of 2017-2018. Determination of the frozen/thawed soil state is carried out in three ways: 1) by multi-temporal radar data on the basis of a significant in 3-5 dB difference in the backscatter coefficient 0 in the transition of freezing/thawing soil state, 2) by finding the threshold value of 0 at which the temperature in the topsoil layer falls below 00C, 3) by texture features. The first method allows determining the period of time during which the process of freezing/thawing of the soil occurs. The second and third methods allow making local maps of frozen/thawed soils. It is shown that for the studied areas the Spearman correlation coefficient between 0 and air temperature for cross - polarization exceeds the correlation coefficient for co-polarization. The graphs of the AFI (air freezing index) for the period of 2012-2018 are constructed based on the archive data of air temperature for the study areas.
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Badache, M., Z. Aidoun, J.-M. Hardy et V. Rondeau. « An interactive interface of isotherms for Canada’s soil temperature ». Dans 2nd Geoscience & Engineering in Energy Transition Conference. European Association of Geoscientists & Engineers, 2021. http://dx.doi.org/10.3997/2214-4609.202121083.

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Boukpeti, Nathalie, David White, Mark Randolph et Han Eng Low. « Characterization of the Solid-Fluid Transition of Fine-Grained Sediments ». Dans ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79738.

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Characterization of the strength of fine-grained sediments as they evolve from an intact seabed material to a remolded debris flow is essential to adequately model submarine landslides and their impact on pipelines and other seabed infrastructure. In the current literature, two distinct approaches for modelling this material behavior have been considered. In the soil mechanics approach, fine-grained soils are characterized by the undrained shear strength, su. The critical state framework proposes a relation between su and the water content, or void ratio of the soil. In addition, rate effects and strain softening effects are described by multiplying a reference value of su by a function of the shear strain rate or the accumulated shear strain respectively. In the fluid mechanics approach, slurries of fine-grained material are characterized by a yield strength and a viscosity parameter, which describes the change in shear stress with shear strain rate. Empirical relationships have been proposed, which relate the yield strength and the viscosity to the sediment concentration. This paper demonstrates that the two modelling approaches are essentially similar, with only some formal differences. It is proposed that the strength of fine-grained sediments can be modelled in a unified way over the solid and liquid ranges. To support this unified approach, an experimental campaign has been conducted to obtain strength measurements on various clays prepared at different water content. The testing program includes fall cone tests, vane shear tests, miniature penetrometers (T-bar and ball) and viscometer tests. Rate effects and remolding effects are investigated over a wide range of water contents spanning the domains of behavior that are usually defined separately as soil and fluid. The present paper focuses on analyzing the results of fall cone, vane shear and viscometer tests. Analysis of the results shows that the variation in shear strength over the solid and liquid ranges can be described by a unique function of water content — suitably normalized — for a given soil. Furthermore, the effect of strain rate and degree of remolding can be accounted for by multiplying the basic strength parameter by appropriate functions, which are independent of the current water content.
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Phillips, Ryan, Arash Nobahar et Joe Zhou. « Trench Effects on Pipe-Soil Interaction ». Dans 2004 International Pipeline Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/ipc2004-0141.

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Trenched pipelines subjected to large lateral soil movements were studied to quantify mitigative effects of trench geometry, backfill soil material and strength on the force-displacement behaviour in cohesive soils. Experimental and numerical models show a good agreement in terms of undrained ultimate forces, which are also consistent with design guidelines and previous studies. Undrained lateral pipe resistance factors, are assessed in terms of soil strength and soil weight in uniform soil. A normalised pipe displacement rate characterizes a transition in the lateral resistance from undrained to drained conditions is presented. The presence of a trench backfilled with material weaker than the native soil softens the lateral load-deformation (p-y) response compared to that of the same pipe buried in native soil. An increase in the trench width increases the pipe displacement to peak load. The lateral interaction force is much lower in a pipe with a wider trench than a narrower trench prior to reaching the peak load. The peak load occurs after pipe touches the trench wall and is controlled by the native soil strength. It decreases slightly with increase in the trench width because of upward movement of pipe prior to reaching trench wall. The mitigative effects of trench wall inclination are also demonstrated. A simple approach to determine the p-y response for a trenched pipeline backfilled with material weaker than the native soil is proposed.
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MOROZ, Hryhorii. « AGROPEDOGENIC TRANSFORMATION OF PHYSICAL PROPERTIES OF SOILS OF MEDIUM-DRY STEPPE PEDO-ECOTONE IN THE NORTHWEST OF THE BLACK SEA REGION ». Dans RURAL DEVELOPMENT. Aleksandras Stulginskis University, 2018. http://dx.doi.org/10.15544/rd.2017.184.

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The anthropogenic transformation of soil physical properties of the transition stripe from the dry to the middle steppe in the Northwest of the Black Sea region is considered and analyzed on the basis of comparison of indicators characterizing the properties of the cultivable and subcultivable horizons. The signs of negative influence of agricultural use on the most important indices of physical properties of soils are investigated. Significant degradation of the physical properties of the arable horizons (in comparison with tillable and subcultivable horizons), as well as deterioration of the water resistance of the structure of the tillable horizons (compared to the arable) was revealed. The geographic regularities of agrogenic evolution of sodic and residual-sodic calcic chernozems and gypsic kastanozems are established.
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Hembree, Daniel. « EARLY EFFECTS OF THE LATE PALEOZOIC CLIMATE TRANSITION ON SOILS AND SOIL ECOSYSTEMS OF THE APPALACHIAN BASIN (CONEMAUGH, MONONHAHELA, AND DUNKARD GROUPS) ». Dans GSA Connects 2022 meeting in Denver, Colorado. Geological Society of America, 2022. http://dx.doi.org/10.1130/abs/2022am-381715.

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Rapports d'organisations sur le sujet "Transitional soils"

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Truex, Michael J., Dave Becker, Michelle A. Simon, Martinus Oostrom, Amy K. Rice et Christian D. Johnson. Soil Vapor Extraction System Optimization, Transition, and Closure Guidance. Office of Scientific and Technical Information (OSTI), février 2013. http://dx.doi.org/10.2172/1097942.

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Chefetz, Benny, et Baoshan Xing. Sorption of hydrophobic pesticides to aliphatic components of soil organic matter. United States Department of Agriculture, 2003. http://dx.doi.org/10.32747/2003.7587241.bard.

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Sorption of hydrophobic compounds to aliphatic components of soil organic matter (SOM) is poorly understood even though these aliphatic carbons are a major fraction of SOM. The main source of aliphatic compounds in SOM is above- and below-ground plant cuticular materials (cutin, cutan and suberin). As decomposition proceeds, these aliphatic moieties tend to accumulate in soils. Therefore, if we consider that cuticular material contributes significantly to SOM, we can hypothesize that the cuticular materials play an important role in the sorption processes of hydrophobic compounds (including pesticides) in soils, which has not yet been studied. The overall goal of this research was to illustrate the mechanism and significance of the refractory aliphatic structures of SOM in sorbing hydrophobic compounds (nonionic and weakly polar pesticides). The importance of this study is related to our ability to demonstrate the sorption relationship between key pesticides and an important fraction of SOM. The specific objectives of the project were: (1) To isolate and characterize cuticular fractions from selected plants; (2) To investigate the sorption mechanism of key hydrophobic pesticides and model compounds to cuticular plant materials; (3) To examine the sorption mechanisms at the molecular level using spectroscopic techniques; (4) To investigate the sorption of key hydrophobic pesticides to synthetic polymers; (5) To evaluate the content of cuticular materials in agricultural soils; and (6) To study the effect of incubation of plant cuticular materials in soils on their sorptive capabilities. This project demonstrates the markedly high sorption capacity of various plant cuticular fractions for hydrophobic organic compounds (HOCs) and polar organic pollutants. Both cutin (the main polymer of the cuticle) and cutan biopolymers exhibit high sorption capability even though both sorbents are highly aliphatic in nature. Sorption by plant cuticular matter occurs via hydrophobic interactions and H-bonding interactions with polar sorbates. The cutin biopolymer seems to facilitate reversible and noncompetitive sorption, probably due to its rubbery nature. On the other hand, the epicuticular waxes facilitate enhance desorption in a bi-solute system. These processes are possibly related to phase transition (melting) of the waxes that occur in the presence of high solute loading. Moreover, our data highlight the significance of polarity and accessibility of organic matter in the uptake of nonpolar and polar organic pollutants by regulating the compatibility of sorbate to sorbent. In summary, our data collected in the BARD project suggest that both cutin and cutan play important roles in the sorption of HOCs in soils; however, with decomposition the more condensed structure of the cutin and mainly the cutan biopolymer dominated sorption to the cuticle residues. Since cutin and cutan have been identified as part of SOM and humic substances, it is suggested that retention of HOCs in soils is also controlled by these aliphatic domains and not only by the aromaticrich fractions of SOM.
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Douglas, Thomas A., Christopher A. Hiemstra, Stephanie P. Saari, Kevin L. Bjella, Seth W. Campbell, M. Torre Jorgenson, Dana R. N. Brown et Anna K. Liljedahl. Degrading Permafrost Mapped with Electrical Resistivity Tomography, Airborne Imagery and LiDAR, and Seasonal Thaw Measurements. U.S. Army Engineer Research and Development Center, juillet 2021. http://dx.doi.org/10.21079/11681/41185.

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Accurate identification of the relationships between permafrost extent and landscape patterns helps develop airborne geophysical or remote sensing tools to map permafrost in remote locations or across large areas. These tools are particularly applicable in discontinuous permafrost where climate warming or disturbances such as human development or fire can lead to rapid permafrost degradation. We linked field-based geophysical, point-scale, and imagery surveying measurements to map permafrost at five fire scars on the Tanana Flats in central Alaska. Ground-based elevation surveys, seasonal thaw-depth profiles, and electrical resistivity tomography (ERT) measurements were combined with airborne imagery and light detection and ranging (LiDAR) to identify relationships between permafrost geomorphology and elapsed time since fire disturbance. ERT was a robust technique for mapping the presence or absence of permafrost because of the marked difference in resistivity values for frozen versus unfrozen material. There was no clear relationship between elapsed time since fire and permafrost extent at our sites. The transition zone boundaries between permafrost soils and unfrozen soils in the collapse-scar bogs at our sites had complex and unpredictable morphologies, suggesting attempts to quantify the presence or absence of permafrost using aerial measurements alone could lead to incomplete results. The results from our study indicated limitations in being able to apply airborne surveying measurements at the landscape scale toward accurately estimating permafrost extent.
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Miller, Julianne, Vic Etyemezian, Mary E. Cablk, Rose Shillito et David Shafer. Monitoring Soil Erosion on a Burned Site in the Mojave-Great Basin Transition Zone : Final Report for the Jacob Fire Site. Office of Scientific and Technical Information (OSTI), juin 2013. http://dx.doi.org/10.2172/1096173.

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Walsh, Alex. The Contentious Politics of Tunisia’s Natural Resource Management and the Prospects of the Renewable Energy Transition. Institute of Development Studies (IDS), février 2021. http://dx.doi.org/10.19088/k4d.2021.048.

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For many decades in Tunisia, there has been a robust link between natural resource management and contentious national and local politics. These disputes manifest in the form of protests, sit-ins, the disruption of production and distribution and legal suits on the one hand, and corporate and government response using coercive and concessionary measures on the other. Residents of resource-rich areas and their allies protest the inequitable distribution of their local natural wealth and the degradation of their health, land, water, soil and air. They contest a dynamic that tends to bring greater benefit to Tunisia’s coastal metropolitan areas. Natural resource exploitation is also a source of livelihoods and the contentious politics around them have, at times, led to somewhat more equitable relationships. The most important actors in these contentious politics include citizens, activists, local NGOs, local and national government, international commercial interests, international NGOs and multilateral organisations. These politics fit into wider and very longstanding patterns of wealth distribution in Tunisia and were part of the popular alienation that drove the uprising of 2011. In many ways, the dynamic of the contentious politics is fundamentally unchanged since prior to the uprising and protests have taken place within the same month of writing of this paper. Looking onto this scene, commentators use the frame of margins versus centre (‘marginalization’), and also apply the lens of labour versus capital. If this latter lens is applied, not only is there continuity from prior to 2011, there is continuity with the colonial era when natural resource extraction was first industrialised and internationalised. In these ways, the management of Tunisia’s natural wealth is a significant part of the country’s serious political and economic challenges, making it a major factor in the street politics unfolding at the time of writing.
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Wyndham, Amber, Emile Elias, Joel Brown, Michael Wilson et Albert Rango. Drought Vulnerability Assessment to Inform Grazing Practices on Rangelands of Southeastern Colorado’s Major Land Resource Area 69. USDA Southwest Climate Hub, juillet 2018. http://dx.doi.org/10.32747/2018.6947062.ch.

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Increased climate variability, including more frequent and intense drought, is projected for the southwestern region of the United States. Increased temperatures and reduced precipitation lower soil water availability, resulting in decreased plant productivity and altering species composition, which may affect forage quality and quantity. Reduced forage quality and increased heat stress attributable to warmer temperatures could lead to decreased livestock performance in this system, which is extensively used for livestock grazing. Mitigating the effects of increasing drought is critical to social and ecological stability in the region. Reduced stocking rates, change in livestock breeds and/or grazing practices are general recommendations that could be implemented to cope with increased climatic stress. Ecological Sites and their associated state–and-transition models (STMs) are tools to help land managers implement and evaluate responses to disturbances. The projected change in climate will vary depending upon geographic location. Vulnerability assessments and adaptation strategies are needed at the local level to inform local management decisions and help ameliorate the effects of climate change on rangelands. The United States Department of Agriculture (USDA) Southwest Climate Hub and Natural Resources Conservation Service (NRCS) worked together to produce this drought vulnerability assessment at the Major Land Resource Area (MLRA) level, based on ecological sites and state-and-transition models that will help landowners and government agencies to identify and develop adaptation options for drought on rangelands. The assessment illustrates how site-specific information can be used to help minimize the effects of drought on rangelands and support informed decision-making for the selection of management adaptations within MLRA 69.
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Phuong, Vu Tan, Nguyen Van Truong, Do Trong Hoan, Hoang Nguyen Viet Hoa et Nguyen Duy Khanh. Understanding tree-cover transitions, drivers and stakeholders’ perspectives for effective landscape governance : a case study of Chieng Yen Commune, Son La Province, Viet Nam. World Agroforestry, 2021. http://dx.doi.org/10.5716/wp21023.pdf.

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Integrated landscape management for sustainable livelihoods and positive environmental outcomes has been desired by many developing countries, especially for mountainous areas where agricultural activities, if not well managed, will likely degrade vulnerable landscapes. This research was an attempt to characterize the landscape in Chieng Yen Commune, Son La Province in Northwest Viet Nam to generate knowledge and understanding of local conditions and to propose a workable governance mechanism to sustainably manage the landscape. ICRAF, together with national partners — Vietnamese Academy of Forest Sciences, Soil and Fertilizer Research Institute — and local partners — Son La Department of Agriculture and Rural Development, Son La Department of Natural Resources and Environment, Chieng Yen Commune People’s Committee — conducted rapid assessments in the landscape, including land-use mapping, land-use characterization, a household survey and participatory landscape assessment using an ecosystem services framework. We found that the landscape and peoples’ livelihoods are at risk from the continuous degradation of forest and agricultural land, and declining productivity, ecosystem conditions and services. Half of households live below the poverty line with insufficient agricultural production for subsistence. Unsustainable agricultural practices and other livelihood activities are causing more damage to the forest. Meanwhile, existing forest and landscape governance mechanisms are generally not inclusive of local community engagement. Initial recommendations are provided, including further assessment to address current knowledge gaps.
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Wyndham, Amber, Emile Elias, Joel R. Brown, Michael A. Wilson et Albert Rango. Drought Vulnerability Assessment to Inform Grazing Practices on Rangelands in Southeast Arizona and Southwest New Mexico’s Major Land Resource Area 41. United States. Department of Agriculture. Southwest Climate Hub, août 2018. http://dx.doi.org/10.32747/2018.6818230.ch.

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Increased climate variability, including more frequent and intense drought, is projected for the southwestern region of the United States. Increased temperatures and reduced precipitation lower soil water availability, resulting in decreased plant productivity and altered species composition, which may affect forage quality and quantity. Reduced forage quality and increased heat stress attributable to warmer temperatures could lead to decreased livestock performance in this system, which is extensively used for livestock grazing. Mitigating the effects of increasing drought is critical to social and ecological stability in the region. Reduced stocking rates and/or a change in livestock breeds and/or grazing practices are general recommendations that could be implemented to cope with increased climatic stress. Ecological Sites (ESs) and their associated state-and-transition models (STMs) are tools to help land managers implement and evaluate responses to disturbances. The projected change in climate will vary depending upon geographic location. Vulnerability assessments and adaptation strategies are necessary at the local level to inform local management decisions and help to ameliorate the effects of climate change on rangelands. The USDA Southwest Climate Hub and the Natural Resources Conservation Service (NRCS) worked together to produce this drought vulnerability assessment at the Major Land Resource Area (MLRA) level: it is based on ESs/STMs that will help landowners and government agencies to identify and develop adaptation options for drought on rangelands. The assessment illustrates how site-specific information can be used to help minimize the effects of drought on rangelands and to support informed decision-making for selecting management adaptations within MLRA 41.
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Wyndham, Amber, Emile Elias, Joel R. Brown, Michael A. Wilson et Albert Rango. Drought Vulnerability Assessment to Inform Grazing Practices on Rangelands of Southeastern Colorado’s Major Land Resource Area 69. United States. Department of Agriculture. Southwest Climate Hub, janvier 2018. http://dx.doi.org/10.32747/2018.6876399.ch.

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Increased climate variability, including more frequent and intense drought, is projected for the southwestern region of the United States. Increased temperatures and reduced precipitation lower soil water availability resulting in decreased plant productivity and altering species composition which may affect forage quality and quantity. Reduced forage quality and increased heat stress attributable to warmer temperatures could lead to decreased livestock performance in this system, which is extensively used for livestock grazing. Mitigating the effects of increasing drought is critical to social and ecological stability in the region. Reduced stocking rates, change in livestock breeds and/or grazing practices are general recommendations that could be implemented to cope with increased climatic stress. Ecological Sites (ESs) and their associated state and transition models (STMs) are tools to help land managers implement and evaluate responses to disturbances. The projected change in climate will vary depending on geographic location. Vulnerability assessments and adaptation strategies are needed at the local level to inform local management decisions and help ameliorate the effects of climate change on rangelands. The USDA Southwest Climate Hub and Natural Resources Conservation Service (NRCS) worked together to produce this drought vulnerability assessment at the Major Land Resource Area (MLRA) level based on ESs/STMs that will help landowners and government agencies identify and develop adaptation options for drought on rangelands. The assessment illustrates how site-specific information can be used to help minimize the effects of drought on rangelands and support informed decision-making for selecting management adaptations within MLRA 69.
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Wyndham, Amber, Emile Elias, Joel Brown, Michael Wilson et Albert Rango Rango. Drought Vulnerability Assessment to Inform Grazing Practices on Rangelands in Southeast Arizona and Southwest New Mexico’s Major Land Resource Area 41. USDA Southwest Climate Hub, août 2018. http://dx.doi.org/10.32747/2018.6947060.ch.

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Résumé :
Increased climate variability, including more frequent and intense drought, is projected for the southwestern region of the United States. Increased temperatures and reduced precipitation lower soil water availability, resulting in decreased plant productivity and altered species composition, which may affect forage quality and quantity. Reduced forage quality and increased heat stress attributable to warmer temperatures could lead to decreased livestock performance in this system, which is extensively used for livestock grazing. Mitigating the effects of increasing drought is critical to social and ecological stability in the region. Reduced stocking rates and/or a change in livestock breeds and/or grazing practices are general recommendations that could be implemented to cope with increased climatic stress. Ecological Sites (ESs) and their associated state-and-transition models (STMs) are tools to help land managers implement and evaluate responses to disturbances. The projected change in climate will vary depending upon geographic location. Vulnerability assessments and adaptation strategies are necessary at the local level to inform local management decisions and help to ameliorate the effects of climate change on rangelands. The USDA Southwest Climate Hub and the Natural Resources Conservation Service (NRCS) worked together to produce this drought vulnerability assessment at the Major Land Resource Area (MLRA) level: it is based on ESs/STMs that will help landowners and government agencies to identify and develop adaptation options for drought on rangelands. The assessment illustrates how site-specific information can be used to help minimize the effects of drought on rangelands and to support informed decision-making for selecting management adaptations within MLRA 41.
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