954 resultados para Elm Grove


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Esta tesis doctoral pretende profundizar en el conocimiento de la ecología de Ulmus laevis Pallas, especie autóctona en peligro de extinción en la Península Ibérica, con el fin de proponer medidas adecuadas para su conservación. Se ha estudiado la distribución natural de la especie atendiendo a aspectos edáficos. Los resultados muestran que U. laevis presenta menor capacidad de acidificación de la rizosfera, menor actividad de la reductasa férrica y menor homeostasis que U. minor Mill. cuando crecen en sustratos con una disponibilidad de hierro limitada. Estas diferencias ayudan a comprender la distribución de ambas especies en la Península Ibérica: U. laevis se ve restringido a suelos ácidos o moderadamente ácidos, mientras que U. minor es capaz de habitar tanto suelos ácidos como básicos. Se han analizado las propiedades hidráulicas y anatómicas de U. laevis, constatando que sus características son favorables en ambientes con gran disponibilidad hídrica y que se trata del olmo ibérico más vulnerable a la cavitación por estrés hídrico, por lo que la aridificación del clima y la pérdida de los freáticos supone un riesgo para sus poblaciones. Para evaluar la capacidad de recuperación de la especie se han estudiado la diversidad y estructura genética espacial de las dos mayores poblaciones españolas. Los resultados evidencian que estas poblaciones mantienen niveles de diversidad equiparables o ligeramente superiores a los europeos, pese a haber sufrido un cuello de botella prolongado durante las glaciaciones y a las reducciones poblacionales recientes. En la actualidad la endogamia no representa un riesgo para estas poblaciones. También se ha analizado la producción, dispersión y predación de semillas en Valdelatas (Madrid). Los resultados han mostrado que el viento dispersa las sámaras a corta distancia (<30 m) y que los años no veceros las probabilidades de establecimiento de regenerado son bajas. Además, la producción de sámaras vanas puede tratarse de un carácter adaptativo que aumenta la eficiencia biológica de la especie, ya que favorece la supervivencia de las semillas embrionadas disminuyendo sus tasas de predación pre- y post-dispersión. La modificación del hábitat de esta especie como consecuencia de las actividades humanas afecta de manera negativa al establecimiento del regenerado. La conservación de esta especie a largo plazo requiere la recuperación de los niveles freáticos y de regímenes hidrológicos que permitan avenidas, ya que estas crean las condiciones adecuadas para el establecimiento de regenerado al eliminar la vegetación preexistente y depositar barro. ABSTRACT Ulmus laevis Pallas is an endangered species in the Iberian Peninsula. Therefore, in order to be able to propose adequate management guidelines for its conservation, this PhD Thesis intends to advance the knowledge on the species ecology in the region. Firstly, the species natural distribution was studied in relation to soil nature. Results show that U. minor Mill. had a higher root ferric reductase activity and proton extrusion capability than U. laevis, and maintained a better nutrient homeostasis when grown under iron limiting conditions. These differences in root Fe acquisition efficiencies proved helpful to understand the distribution of these species in the Iberian Peninsula, where U. laevis is restricted to acid or moderately acid soils, whereas U. minor can grow both in acid and basic soils. Secondly, we studied Ulmus laevis’ xylem anatomy and hydraulic traits. These proved favourable for growing under high water availability, but highly susceptible to drought-stress cavitation. Therefore, this species is vulnerable to the Iberian Peninsula’s aridification. Spatial genetic structure and diversity were evaluated in two of the biggest U. laevis populations in Spain in order to evaluate their recovery capabilities. These populations maintain similar or slightly higher diversity levels than European populations, despite having undergone an ancestral genetic bottleneck and having suffered recent population size reductions. No inbreeding problems have been detected in these populations. Seed production, dispersal and predation were assessed in Valdelatas’ elm grove (Madrid). Despite U. laevis samaras being winged nuts, wind dispersed them short distances from the mother tree (<30 m). The seed shadow models show that non-mast years provide very few chances for the stand to regenerate due to their low full seed flux. Empty samaras deceive pre- and post-dispersal predators increasing full seed survival probabilities. Therefore, empty fruit production might be an adaptive trait that increases plant fitness. Finally, human-induced changes in water-table levels and river regulation may affect U. laevis seed dispersal and regeneration establishment negatively. The long-term conservation and expansion of this species in the Iberian Peninsula requires the recovery of water-tables and of natural hydrological regimes, as flooding eliminates vegetation, creating open microhabitats and deposits mud, creating the ideal conditions for seedling establishment.

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This layer is a georeferenced raster image of the historic, topographic paper map entitled: Milwaukee and vicinity, Wisconsin, 1959, mapped, edited and published by the Geological Survey. It was published by U.S. Dept. of the Interior, Geological Survey in 1962. Scale 1:24,000. Compiled from 1:24,000-scale maps of Thiensville, Menomonee Falls, Wauwatosa, Milwaukee, South Milwaukee, Greendale 1958, and Hales Corners 1959 7.5 minute quadrangles. Selected hydrographic data compiled from U.S. Lake Survey Charts 74 and 743 (1957). This layer is image 1 of 4 total images of the four sheet source map representing the northwest portion of the map. The image inside the map neatline is georeferenced to the surface of the earth and fit to the Wisconsin South State Plane NAD 1927 coordinate system (Fipszone 4803). All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This is a typical topographic map portraying both natural and manmade features. It shows and names works of nature, such as mountains, valleys, lakes, rivers, vegetation, etc. It also identify the principal works of humans, such as roads, railroads, boundaries, transmission lines, major buildings, etc. Relief shown by contours (interval 10 feet) and spot heights. Depths shown by contours and soundings. This layer is part of a selection of digitally scanned and georeferenced historic maps from The Harvard Map Collection as part of the Imaging the Urban Environment project. Maps selected for this project represent major urban areas and cities of the world, at various time periods. These maps typically portray both natural and manmade features at a large scale. The selection represents a range of regions, originators, ground condition dates, scales, and purposes.

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This layer is a georeferenced raster image of the historic, topographic paper map entitled: Milwaukee and vicinity, Wisconsin, 1959, mapped, edited and published by the Geological Survey. It was published by U.S. Dept. of the Interior, Geological Survey in 1962. Scale 1:24,000. Compiled from 1:24,000-scale maps of Thiensville, Menomonee Falls, Wauwatosa, Milwaukee, South Milwaukee, Greendale 1958, and Hales Corners 1959 7.5 minute quadrangles. Selected hydrographic data compiled from U.S. Lake Survey Charts 74 and 743 (1957). This layer is image 3 of 4 total images of the four sheet source map representing the southwest portion of the map. The image inside the map neatline is georeferenced to the surface of the earth and fit to the Wisconsin South State Plane NAD 1927 coordinate system (Fipszone 4803). All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This is a typical topographic map portraying both natural and manmade features. It shows and names works of nature, such as mountains, valleys, lakes, rivers, vegetation, etc. It also identify the principal works of humans, such as roads, railroads, boundaries, transmission lines, major buildings, etc. Relief shown by contours (interval 10 feet) and spot heights. Depths shown by contours and soundings. This layer is part of a selection of digitally scanned and georeferenced historic maps from The Harvard Map Collection as part of the Imaging the Urban Environment project. Maps selected for this project represent major urban areas and cities of the world, at various time periods. These maps typically portray both natural and manmade features at a large scale. The selection represents a range of regions, originators, ground condition dates, scales, and purposes.

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Opinnäytetyöni käsittelee Yleisradion edesmenneen radiokanavan uuden YleQ:n taivalta sen perustamisesta huhtikuussa 2004 kanavan päättymiseen syyskuussa 2006. Ensisijaisina pohdinnan kohteinani ovat kanavan työntekijöiden ajatukset YleQ:n merkityksestä sekä sen päättymisen syistä. YleQ poikkesi muista Yleisradion kanavista sisältönsä puolesta, ollen populaarikulttuuria painottanut, nuorelle aikuisyleisölle suunnattu radiokanava. Erityisesti YleQ:n musiikkitarjonta täydensi laajuutensa ja monipuolisuutensa ansiosta Yleisradion kokonaistarjontaa. Opinnäytetyöni on toteutettu henkilöstöhaastattelujen avulla. Haastattelin 21 entistä YleQ:n työntekijää muutamaa kuukautta kanavan päättymisen jälkeen. Työn edetessä tuli tarpeelliseksi myös selvittää kuuden muun haastattelun avulla mm. kysymyksiä Yleisradion uudesta strategiasta sekä populaarikulttuurin asemasta Yleisradiossa. Oman työni taustalla on autenttinen kaksivuotinen osallistuminen tutkittavaan työyhteisöön. Lähtökohtana haastatteluille ovat ne käsitykset, joita minulle oli syntynyt työskennellessäni YleQ:ssa. Tutkimuksellisesti vahvat ennakkokäsitykseni voivat olla ongelmallisia, mutta toisaalta hiljainen tieto osoittautui tarpeelliseksi haastatteluita analysoidessani. YleQ:n entiset työntekijät kokivat tulleensa pompotelluiksi ja hyväksikäytetyiksi kokeiluun, johon Yleisradiossa ei kunnolla edes panostettu. Moni haastatelluistani koki, että YleQ:n hyvä idea epäonnistui huonon toteutuksensa vuoksi. Yleisesti kuitenkin ymmärrettiin kanavan lakkauttamisen johtuneen priorisoinnista yhtiön uusiin palveluihin. Tästä huolimatta moni haastatelluistani on huolissaan populaarikulttuurin tarjonnasta Yleisradiossa YleQ:n päättymisen jälkeen.

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Referat: Skräddaren Emil Peltonens liv

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