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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Maintaining a hill prairie ecosystem

Stoughton-Jackson, Courtney January 1997 (has links)
Fire has been an important influence on the structure and health of the North American grasslands for hundreds of years. In Jersey County Illinois, two natural loess hill prairies were studied to compare the effectiveness of varying management regimes. The purpose was to determine how a burn vs. a nonburn management regime enhances or hinders the establishment of the prairie grasses and forbs in a tallgrass hill prairie ecosystem. The variables studied included: the vegetational abundance, the frequency, and the biomass of the species that were present. In addition the soil's organic matter content and pH were measured. Overall, the Fire Road Prairie, or the unburned prairie, proved to be the community that was deteriorating and becoming unproductive. Whereas, the Osage Prairie contained a balance of grasses and forbs that were representative of a healthy and thriving community. The data supported the existing theory that a burn management plan does help the overall stability and productivity of a tallgrass ecosystem. / Department of Natural Resources and Environmental Management
82

Greenhouse gas emissions from irrigated crop production in the Canadian Prairies

2014 September 1900 (has links)
Irrigated agriculture in the Canadian Prairies is in a position to play a prominent role in addressing global food demands imposed by a growing world population. Particularly within Saskatchewan there is potential to see large increases in the number of irrigated hectares, due to the large irrigable land base and supply of freshwater resources. Yet, how this increase will influence the agricultural greenhouse gas (GHG) balance is not well understood. Through the quantification and comparison of GHG emissions from a typical irrigated and dryland cropping system in Saskatchewan, this research aimed to better understand the role of irrigated agriculture on GHG dynamics in this region. A field-scale analysis of irrigated soil conditions and resulting soil greenhouse gas emissions identified that soil N availability was likely the dominant factor influencing soil N2O emissions from irrigated systems. Soil moisture was also a key factor in soil GHG fluxes, governing seasonal CH4 uptake and episodic N2O and CO2 emissions. The development of system-specific GHG budgets—incorporating on-site GHG sources and sinks—identified electricity as irrigated cropping’s largest contributor of global warming potential (GWP). Emissions from soil and diesel-combustion sources were less intensive under irrigated production; yet overall greenhouse gas intensity (GHGI) was greater from irrigated cropping. This research provides a first look into GHG dynamics from irrigated agriculture in Saskatchewan and identifies areas for potential mitigation as irrigated crop production expands in the Province.
83

Voice Map Trekking

Klassen, Michael John 21 January 2008 (has links)
The site analysis and mapping methods in the design and planning professions follow a standardized quantitative and qualitative analyis of place that favors a design process which can limit creativity and render it difficult to do anything with the normative. This work is an exploration of the development of a design approach and method that uses voice mapping as a basis for design. The voice maps contain oral histories and personal accounts of landscape experiences. Voice mapping is employed not only as a method or for site analysis but also as a generator or ideas. Voice Map Trekking is explored through a trek in the Canadian Arctic and across the Canadian Prairies. Two specific landscapes were chosen as bases for testing concepts - one near St. Gertrude SK and the other near Morinville AB.
84

Producer stated preference for hypothetical new winter wheat varieties on the Canadian Prairies

Cole, Jesse 06 1900 (has links)
This research project gauges producer demand on the Canadian Prairies for the attributes of new hypothetical varieties of winter wheat. Data collected from a survey of producers in Western Canada is used to determine the values and attitudes of producers regarding new winter wheat variety traits with a focus on increased winter survival rates and increased waterfowl nesting habitat. Increased nesting habitat was found to have a small negative but significant impact on the decision to adopt hypothetical winter wheat varieties; however winter kill rates and gross profit had a large positive effect on its adoption and expansion. Other important drivers of the decision to adopt hypothetical winter wheat varieties are also analyzed. Policy implications include potential guidance of incentives for environmentally friendly farming practices, and the provision of information to winter wheat breeding programs about the needs of producers.
85

Passerine nest ecology in managed, mixed-grass prairie /

Kerns, Courtney K. January 2004 (has links)
Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references. Also available on the Internet.
86

Restoring blackland prairies in Mississippi remnant-restored prairie comparisons and techniques for augmenting forbs /

Dailey, Andrew Clifford, January 2008 (has links)
Thesis (M.S.)--Mississippi State University. Department of Wildlife and Fisheries. / Title from title screen. Includes bibliographical references.
87

Passerine nest ecology in managed, mixed-grass prairie

Kerns, Courtney K. January 2004 (has links)
Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references. Also available on the Internet.
88

Modélisation des bouquets de services écosystémiques et intensification écologique des pratiques d'élevage dans Vercors / Modeling ecosystem services for ecological intensification in grassland systems, Vercors

Gos, Pierre 16 December 2013 (has links)
La coïncidence des services écosystémiques ainsi que la coïncidence entre 'hotspots' de servicesécosystémiques et 'hotspots' de biodiversité ont suscité un intérêt croissant dans les évaluations desservices écosystémiques. Les seuils utilisés dans ces analyses pour déterminer la présence desservices écosystémiques varient de façon importante mais les effets consécutifs à leur choix n'ontpas été envisagés. Nous proposons ici une analyse de l'effet du choix de ces seuils sur lacoïncidence entre services écosystémiques ainsi que sur la distribution des 'hotspots'. A partir d'uneétude de prairies des Alpes Centrales françaises, nous avons fait varié des seuils appliqués à troisservices écosystémiques (agronomique, de régulation et de valeur esthétique) de façon continue,puis considéré des triplets de valeurs-seuils représentant trois points de vue contrastés associés à despoints de vue d'acteurs. Ces seuils sont interprétés comme une importance accordée par chaqueacteur à chaque service écosystémique.La coïncidence entre services écosystémiques dépend de la détermination de seuils de présence.L'étendue des 'hotspots' de services écosystémiques et leur coïncidence avec les 'hotspots' debiodiversité varient largement selon les points de vue. Les coldspots ne sont jamais superposés avecles zones d'intérêt pour la biodiversité dans cette étude, quel que soit le point de vue envisagé.L'analyse de superposition s'est révélée moins informative que le test de diagnostic de la capacitéindividuelle des services écosystémiques à capturer la distribution des autres services. La valeuragronomique capturait peu les autres services écosystémiques. La biodiversité était bien capturéepar les valeurs esthétiques et de régulation, mais faiblement par les ‘hotspots’ de services.Cette analyse souligne l'importance de considérer les attentes variables des teneurs d'enjeux dans lesévaluations de 'hotspots' de services écosystémiques. / The consequences of land use change and the impacts of agriculture on biodiversity and thefunctioning of ecosystems have received a growing attention since the end of the 20th century.Among other frameworks, some authors have called for an 'ecological intensification' of agriculture,defined as “all the processes of transformation of productive ecosystems towards higher yieldsproduced with reduced forcing of the agro-ecosytems”, with strong emphasis on the better uses ofecosystems functioning and services as inputs to production (Griffon 2009).This study aimed at disentangling the relations between ecosystem processes and ecosystemservices by quantifying the relative contributions of soil, management and plant communities to thevariations of seven relevant ecosystem properties associated with key grassland ecosystem services:above-ground biomass production at first harvest (ABM), fodder digestibility, plant speciesrichness, soil organic matter content (SOM), soil carbon content, total microbial biomass (TMB),and soil bacteria:fungi ratio (BFR), on a permanent grassland-dominated plateau in the French pre-Alps.Soil, management and plant communities showed complementary and confounded effects to thevariations of the set of ecosystem properties, and underpinned the bundling of ecosystem servicesand the tradeoffs among them. The bundling of ecosystem properties highlighted the trade-offbetween digestibility, the B:F ratio, and biomass production on the one hand, and species richnesson the other hand, associated with a gradient in LDMC confirming the relevance of the leafeconomics spectrum theory to analyses of ecosystem service trade-offs. The date of use showedsignificant effects on the variations of the set of ecosystem properties indicating the influence offine management factors on the provision of ecosystem services.
89

Economic Development of the Gulf Coastal Prairie

Lumpkin, George Enos January 1951 (has links)
The study of the economic development of the Gulf Coastal Prairie has been divided into the following seven chapters: (1) Physical Aspects, (2) Grazing, (3) Development of Farming, (4) Development of Transportation, (5) Development of Mineral Resources, (6) Development of Industry and (7) A Look to the Future.
90

Variabilité génétique et biologie de l'espèce Arnica montana dans un contexte de fragmentation des populations et de réchauffement climatique / Genetic variability and biology of Arnica montana in fragmented populations under climatic change

Maurice, Tiphaine 15 November 2011 (has links)
Le réchauffement climatique et la fragmentation des habitats sont les deux principales menaces pour les espèces rares et menacées telle qu’Arnica montana dont nous avons comparé les populations fragmentées de colline (500 m) de la région Ardennes-Eifel avec les populations montagnardes des Vosges (1200 m) où l’espèce est encore commune. Les communautés végétales des sites collinéens (Violion caninae) étaient différentes de celles des montagnes (Nardion strictae). Cependant, A. montana évolue dans la même niche aux deux altitudes. On a observé une modification de la reproduction d’A. montana d’un type sexué dans les collines vers un type clonal en altitude. Une étude des variations génétiques moléculaires (AFLP) a montré que ces populations avaient conservé une diversité génétique relativement grande. Nous avons établi qu’il y avait des différenciations génétiques entre les altitudes, avec une isolation par distance plus forte pour les populations fragmentées de colline, alors que les populations montagnardes constituent une métapopulation. Lors d’une expérience en jardins contrôlés à 200 et 1200 m d’altitude, il a été démontré qu’A. montana possédait une grande plasticité phénotypique et une variabilité génétique considérable qui pourraient s’avérer cruciales pour A. montana face aux changements climatiques. Une transplantation réciproque entre des populations de colline et de montagne a montré un fort effet site. La compétition pour la lumière et l’herbivorie pourraient être les causes principales de la sélection. La grande plasticité de l’espèce a montré que les plantules sont capables de survivre à une augmentation de températures annuelles d’au moins 2°C / Global warming and habitat fragmentation are two major threats to rare and endangered species as Arnica montana which we compared the fragmented colline populations (500 m) of the Ardennes-Eifel region with the montane populations of the Vosges crest (1200 m) where the species is still common. We recorded the vegetation and population structure of A. montana in the colline sites (Violion caninae) and the mountains sites (Nardion strictae). However, A. montana had the same niche at the two altitudes. The study of population structure revealed a shift from sexual to clonal reproduction with increasing altitude. A study of molecular genetic variation (AFLP) indicated that populations of A. montana have preserved a relatively high amount of genetic diversity. Populations were genetically differentiated between altitudes, with a stronger isolation by distance for the fragmented colline populations, while the montane populations may be considered as a meta-population. In a common garden experiment involving gardens at two altitudes (200 m and 1200 m), we showed that A. montana had a high phenotypic plasticity and a considerable genetic variability, which could be crucial for A. montana populations to respond to predicted climate changes. A reciprocal transplant experiment between colline and montane populations showed a strong effect of the transplantation sites. Competition for light and herbivory of seedlings may be the main causes of selection. The high plasticity of A. montana might permit the seedlings to survive an increase of at least 2°C in annual temperature

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