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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.
51

Effects of Grazing of Reed Canarygrass (Phalaris arundinacea) in Restored Wet Meadows in the Northern Tall Grass Prairie

Cleys, Jake Robert January 2019 (has links)
Reed canarygrass (Phalaris arundinacea) is a grass species that can dominate wet meadow plant communities. This study investigated if grazing by cattle on restored wet meadows suppresses reed canarygrass, thereby promoting the restored plant community. This study was conducted at two locations in northwest Minnesota. Management practices used were a patch-burn grazing treatment and a four-pasture high intensity-short duration grazing rotation. A pretreatment survey was conducted before grazing followed by annual surveys every five years after grazing. Both treatments reduced reed canarygrass canopy cover by 49 percent compared to non-grazed control sites. Grazed patches were moving towards a Carex dominated community. The community not invaded with reed canarygrass had similar native species richness at the end of the experiment in the rotational grazing treatment, and improved plant richness in the patch-burn grazing treatment. This study demonstrates grazing reduces cover of reed canarygrass, while maintaining or increasing native plant species richness.
52

Investigating catchwork water-meadows as a social-ecological conservation opportunity with focus on Jämtland

Lind, John January 2021 (has links)
Wetlands are crucial for respecting the planetary boundaries and reaching the United Nations Sustainable Development Goals, but wetland areas in Sweden has decreased significantly. The need for restoration, stronger protection, and land-sharing opportunities requires exploration of the subsistence practices involving wetlands in the past. This thesis investigates the sustainability potential of catchwork water-meadows. An integrated landscape analysis method (ILA) using spatial targeting was designed and tested in QGIS with a range of supporting data aiming to locate previously unknown and unprotected catchwork water-meadows in Jämtland County, that could be potential restoration targets. A literature search was conducted to gather general information on catchwork water-meadows impact on climate change, biogeochemical flows, threatened species, to re-imagine social aspects, and to find morphological characteristics that could be compared to remote sensing data. The literature search revealed varieties in construction, development of theories on nutrient sources over time, a species composition with 19 species and genera present on the Red List of threatened species. It is found that novel construction of catchwork water-meadows likely increase GHG release, but restoration projects on already modified land could possibly decrease GHG output depending on the no-action scenario and use of the produced biomass. There are indications that nutrient removal is possible but experimentation and more scientific measurements are needed. Social benefits include: resilience from economic diversification and being organised as a common, production of plant biomass for various uses, community building, and knowledge production. The ILA consisted of three stages, 1. spatial targeting, 2. site interpretation, and 3. evaluation. Three potential sites were located. Indications for and against identifying these as catchwork water-meadow are presented, and refinement of the ILA to reach definite verdicts are suggested.
53

A Comparison of Antlions, Bees, Darkling Beetles and Velvet Ants Across Sand Dune and Non-Sand Dune Habitats at Ash Meadows National Wildlife Refuge

Boehme, Nicole F. 01 May 2014 (has links)
Insects fulfill important roles within all ecosystems, including deserts, and interact directly and indirectly with the endemic and endangered species at the Ash Meadows National Wildlife Refuge (AMNWR). Here I investigate the variability of species richness, diversity, abundance and community composition of four insect groups between stabilized sand dune habitats, unstabilized sand dune habitats and non-sand dune habitats. The insects examined in this thesis include antlions (Myrmeleontidae), bees (Apiformes), darkling beetles (Tenebrionidae) and velvet ants (Mutillidae). As the impact and interactions of two of the insect groups, antlions and velvet ants, are largely unknown within any ecosystem, this thesis also includes a faunal study of velvet ants at AMNWR and their spatial and temporal variation at the refuge. Generalized linear mixed models were used to identify significant differences in richness, diversity and abundance for each insect group between the stabilized sand dune, unstabilized sand dune and non-sand dune habitats. Species richness differed between habitats for antlions, beetles and velvet ants over the study period. Diversity differed between habitats for antlions and beetles, and abundance differed between habitats for all groups over the study period. Nearly every habitat supported some unique species. The faunal survey of velvet ants revealed minor variation in flight times between species and a unique pattern of temporal niche partitioning in one species. Habitat preferences were observed for seven of 42 velvet ant species at AMNWR. In a comparison of the diversity of velvet ants between AMNWR and the Nevada Test Site (NTS), six velvet ant species that occurred at the NTS were not found at AMNWR. Diagnoses and a key are provided for the velvet ants of AMNWR. This thesis increases the number of known terrestrial invertebrates at the refuge and provides a comparison of terrestrial insect distribution and habitat use at AMNWR. These investigations contribute to the goals and objectives of the U. S. Fish and Wildlife Service to obtain basic inventories and understand the terrestrial habitat use of invertebrates at AMNWR.
54

Bird and Small Mammal Communities of Sagebrush-Dominated Mountain Meadows: An Examination of Meadow Characteristics as Part of a Hierarchical, Multi-Level Study of the Wasatch-Cache National Forest

Johnson, Elizabeth 01 May 2005 (has links)
Sagebrush shrubsteppe ecosystems have increasingly garnered attention as an endangered ecosystem. Ninety nine percent of all sagebrush ecosystems are thought to have been impacted by humans, and over 50% of grassland and shrubsteppe species are believed to be in decline. Most of the research on sagebrush ecosystems has been conducted at lower elevations and in large expanses of sagebrush. A considerable amount of sagebrush is found at higher elevations, often in meadows found within a forest matrix. The role of this high-elevation habitat is poorly understood. We conducted bird, small mammal, vegetation, and soil surveys in sagebrush-dominated mountain meadows within the Wasatch-Cache National Forest in northeastern Utah. Meadows ranged from 0.6 to 782 hectares in size and included an impressive list of associated plant species. We detected two sagebrush-obligate species and numerous shrubsteppe-associated species. Each species appears to respond to different habitat characteristics, but all species that showed a significant relationship with meadow size were more likely to occur in larger meadows. Many species showed no relationship with size, suggesting that while larger meadows were preferred by some species, small meadows could also play an important role as habitat. While sagebrush-dominated mountain meadows were important for some species, we also failed to detect a number of species of interest. In particular, Sage Thrasher, Sage Sparrow, and pygmy rabbit were not found within the study area. North American Breeding Bird data suggests that Sage Thrashers can be found nearby. It is likely that these birds are only found in large expanses, and none of our meadows were large enough to support them. Sagebrush-dominated mountain meadows appear to be an important supplement to large expanses of sagebrush shrubsteppe habitat, but are not substitutable for all species.
55

Dépôt des nitrates atmosphériques sur les prairies subalpines du Lautaret / Atmospheric nitrate deposition on subalpine meadows of the Lautaret pass

Bourgeois, Ilann 08 December 2017 (has links)
L’accroissement des dépôts de nitrate atmosphérique (NO3-atm) sur les bassins versants d’altitude, limités en ressources, entraîne des changements nets de disponibilité d’azote. Ces apports modifient la diversité biologique (végétation, plantes), les processus des sols liés à l’azote et conduisent à l’eutrophisation des cours d’eau. A terme, l’impact sur les populations humaines se traduira par la perte d’importants services fournis par ces écosystèmes (alimentation en eau, qualité du fourrage, contrôle de l’érosion, biodiversité). Si les effets des dépôts de NO3-atm sur les bassins versants pauvres en azote sont maintenant bien documentés, il n’en reste pas moins à comprendre les processus régissant la rétention de NO3-atm dans les écosystèmes de montagne. Pour ce faire, la variabilité spatio-temporelle de la répartition du NO3-atm dans tous les compartiments subalpins est ici étudiée en utilisant un traceur multi-isotopique (17O, 18O, 15N) du NO3-. L’importante proportion de NO3-atm dans les cours d’eau de montagne, tout au long de l’année et plus particulièrement à la fonte des neiges, laisse à penser que les bassins versants sont cinétiquement saturés en azote. La composition isotopique du NO3- dans les eaux de surface illustre la transformation rapide de l’ammonium de la neige et confirme que la fonte des neiges est une période cruciale du cycle de l’azote dans les montagnes enneigées. La proportion de NO3-atm dans les sols varie, quant à elle, en fonction du type d’occupation des sols et des propriétés biotiques et abiotiques afférentes. Le suivi de la végétation a montré une forte teneur en NO3-atm dans les tissus, par assimilation racinaire et foliaire. Ces avancées scientifiques permettront, à terme, de mieux comprendre comment les dépôts de NO3-atm affectent l’environnement. / Increasing rates of atmospheric nitrate (NO3-atm) deposition in nutrients poor mountainous regions have led to critical changes in nitrogen (N) availability, with consequences on biodiversity (plants, microbes), soils N turnover, and water nutrients status. This will ultimately affect human populations through the loss of critical ecosystem services (e.g., provision of clean freshwater, erosion control, biodiversity). If the impacts of NO3-atm deposition to N-limited basins are now well documented, little is known about the processes driving NO3-atm retention in subalpine ecosystems. In this context, new tools are necessary to better understand the fate of NO3-atm in mountains and to predict the mid and long-term ecological consequences of increasing NO3-atm deposition. This work uses a high-resolution multi-isotopic technique combining 17O, 18O and 15N signatures of NO3- in the different subalpine compartments to understand the temporal and spatial evolution of NO3-atm partitioning in a subalpine watershed of the French Alps. Subalpine streams elevated year-round exports of NO3-atm suggest that the watersheds are kinetically N saturated, especially after snowmelt. The isotopic composition of NO3- in freshwaters also points at the rapid processing of snow ammonium, confirming that snowmelt is “hot moment” for the N cycle in seasonally snow-covered catchments. The monitoring of soils reveals varying NO3-atm proportions depending on the land management treatments and implied biotic and abiotic characteristics. Two dominant subalpine plants showed high proportions of NO3-atm in organs acquired by both root and foliar uptake. These scientific breakthroughs will ultimately lead to a better understanding of how NO3-atm deposition affects the environment.
56

How ant communities are shaped by vacant land management strategies, landscape context, and a legacy of industrialization

Tyrpak, Alex Marcus January 2020 (has links)
No description available.
57

Hydrological control of plant species composition and distribution in Dal River alluvial meadows

Jimel, Matouš January 2023 (has links)
Northern boreal alluvial meadows are ecologically significant semi-natural ecosystems within the riparian zone. The effects of disturbance like flooding, grazing, and mowing have historically maintained high nutrient turnover and succession disruption that led to high biodiversity, leading to their inclusion in the Natura 2000 network. Today, alluvial meadows are threatened by human abandonment and river flow regulations, both of which provided necessary disturbances. This leads to encroachment by woody plants and a significant reduction in biodiversity. The purpose of this project was to investigate the hydrological conditions required for the long-term maintenance of floodplains of the regulated lower Dal River and how varying water levels affect the species distribution and various vegetation characteristics. This was done by examining plant data from 3 sites in an alluvial meadow in Bredforsen and datalogger water level data to calculate the duration of flooding of plots in a transect study. The effects of altitude, flooding durations, and frequencies on species richness, proportion of woody plants, and vegetation cover were examined. Flooding times showed the most significant effects on vegetation characteristics, while altitude and flooding frequencies differed greatly between sites, with variability explained being low for all explanatory variables. On one hand, this shows that that a lack of seasonal flooding has a negative effect on the alluvial meadow ecosystem and an increase in water flow would be beneficial. On the other hand, the low degree of explained variability implies that flooding solely is not the determining factor and other management methods are necessary to maintain the alluvial meadows.
58

Žabovřeské louky / Žabovřesky Meadows

Šárka, Jan January 2010 (has links)
In my master’s thesis I focus on some of the challenges we will face in this century. I would like to investigate whether new lanscape, new building typology (vertical farm) and new methods of agriculture (permaculture, hydroponic, aeroponic and aquaponic systems, meat in vitro, and NASA research) could be the answer to questions concerning sustainable development, urban population increase, cities food supply, consumption habits of people, climate changes, CO2 emissions, ecological footprint and biocapacity.
59

Sportovní vybavenost v kontextu místa / Sports facilities in the context of the site

Bužek, Jiří January 2011 (has links)
The essay is based on urban development of Komin meadows and proposal of football academy. In the proposal is centre line, which is connecting two entrances to the area and is splitting the area in two parts.The first part by the river is for relaxation, pick-nicks etc. It behaves as a city park. In the proposal you'll find inorganic river basin for swimming, ice skating, renting pedals. Created islands behaves as a forest parks with insistence to protect original biotopes of the river. Other entrances connect tram stops No.1. From these entrances conduct paths to the centre line and split the area into primary flow lines. Next splitting of the area into secondary structure is by paths erected to the centre line. Size of the paths is in the measure of football ground and are located in important points of the area. Individual flow lines could be flowed by water. Those flow lines which can be flowed by water most frequently behaves as gardens, sample agriculture, sports areas with absolute access. Other flow lines are for building and setting up sport grounds with supervised access. Football academy is located at crossing of the centre line and path from the tram stop.
60

VODA + MĚSTO AQUADOMOS příběh řeky / WATER+TOWN AQUADOMOS river story

Smirnov, Anton January 2012 (has links)
The proposal is to create an architecturally interesting and unique, comprehensive, research-modern complex information and visitor center "WATER TOWN AQUADOMOS". The project addresses the urban design concept of the complex and its individual elements - visitor center with aquariums, museums and galleries with the history of the river Svratka outdoor recreation area with a water surface, the input element and an underground car park for visitors. The design of all elements are reflected themes of inspiration vody.Navržený house responds to the urban context in the area and complements the present block of buildings on the waterfront. The main entrance is placed on the most exposed part of the plot, the entrance to the underground garage and restaurant supply is oriented to the street Pisárecká, near křižovatky.Budova is fashioned in the shape of two prisms, which are linked through a central part. The shape of the building is influenced by communication and development plan.

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