Amenity trees provide physical, social and economic benefits to people sharing their environment. To maintain the benefits that many people have come to expect of trees in their urban landscapes, a viable and dynamic tree population is required. To this end it is necessary to plant new trees or replace existing trees when they require removal. The challenge when replacing mature trees is not simply the process of planting a tree when one is removed, but of the continual replacement of the entire tree population in a planned and managed fashion. In urban landscapes this is not a natural process, and human intervention is required.

Thesis (M.S.)--Oregon State University, 1984. / Typescript (photocopy). Includes bibliographical references (leaves 59-61). Also available on the World Wide Web.

The purpose of this study was to examine whether an inventory of the vegetation overgrowth could be used to indicate a locally nutritional impact. The study was conducted at Märstaån where the water runs through a number of agricultural lands that could lead to an increased amount of diffuse emissions of nutrients. The vegetation overgrowth in the water was also studied in relation to shade, meandering and water flow effects on the vegetation. With this method, no definitive conclusions could be drawn. Where the water was shaded, no vegetation overgrowth could be found. Therefor trees should be planted to prevent any future overgrowths. The majority of Märstaån is straightened and should get an increased meandering to lower the water flow. The water pond in Steningedalen could also be more effective by lowering the water flow. In the future, more extensive studies should be conducted in the purpose to find other substances in the water that comes from point sources in the area.

It is commonly known that coastal vegetation dissipates energy and aids in shoreline protection by damping incoming waves and depositing sediment in vegetated regions. However, this critical role of vegetation to dampen wave forces is not fully understood at present. A series of laboratory experiments were conducted in the Haynes Coastal Laboratory and 2-D flume at Texas A&M University to examine different vegetative scenarios and analyze the wave damping effects of incident wave height, stem density, wave period, plant type, and water depth with respect to stem length. In wetland regions vegetation is one of the main factors influencing hydraulic roughness. Traditional open-channel flow equations, including the Manning and Darcy- Weisbach friction factor approach, have been successfully applied to determine bottom friction coefficients for flows in the presence of vegetation. There have been numerous relationships derived relating the friction factor to different flow regime boundary layers to try and derive a wave friction factor for estimating energy dissipation due to bottom bed roughness. The boundary layer problem is fairly complex, and studies relating the wave friction factor to vegetation roughness elements are sparse. In this thesis the friction factor is being applied to estimate the energy dissipation under waves due to artificial vegetation. The friction factor is tuned to the laboratory experiments through the use of the numerical model COULWAVE so that the pipe flow formulation can be reasonably applied to wave problems. A numerical friction factor is found for each case through an iterative process and empirical relationships are derived relating the friction factor for submerged and emergent plant conditions to the Ursell number. These relationships can be used to reasonably estimate a wave friction factor for practical engineering purposes. This thesis quantitatively analyzes wave damping due to the effects of wave period, incident wave height, horizontal stem density, water depth relative to stem length, and plant type for a 6 m plant bed length. A friction factor is then determined numerically for each of the laboratory experiments, and a set of equations is derived for predicting a roughness coefficient for vegetation densities ranging between 97 stems/m2 and 162 stems/m2.

A mapping study using remote sensing software called ENVI was conducted utilizing four software algorithms to investigate whether these techniques could accurately classify habitat types and vegetation communities along West Bay of the Galveston Bay Ecosystem from color infra-red (CIR) imagery. The algorithms were used in a small-scale study to investigate which of these techniques could most accurately distinguish habitat types and vegetation communities from the imagery at a site specific location. The most accurate algorithm of the four was used in a large-scale classification study in which entire images were classified utilizing the same data from the small-scale study. Regions of interest (ROIs) were used within ENVI to specify areas of interest within each image that was classified. The locations of ROIs were recorded using a GPS prior to classification, then each was added into ENVI as data points, and each ROI polygon was digitized according to its respective pixel color. Once all of the ROI polygons were completed, each software algorithm was employed. After classification, each habitat type and vegetation community was ground-truthed in order to verify the accuracy of the algorithms. The position points were added as ground truth points within ENVI and an accuracy matrix was assessed. The technique with the greatest averaged accuracy within the smallscale study was selected for the large-scale study. The ROIs and ground truth points used in the smallscale study were used again in the large-scale study. The small-scale study concluded that the Parallelepiped algorithm produced significantly less accurate classifications than the other three. Although the Mahalanobis algorithm was not significantly different from the other two algorithms, it yielded the highest overall average accuracy and was used in the large-scale study. In both the small-scale and large-scale studies there was no significant difference in the two different years of aerial imagery and there were no significant differences in accuracy for locations. None of the software algorithms were accurate at classifying habitat types and vegetation communities using the imagery. The accuracy for the Mahalanobis algorithm was less than 60%. Inaccuracies were largely due to overlapping spectral signatures among habitat types and vegetation communities.

Thesis (doctoral)--Universität Marburg, 2001. / Also available in PDF format. Includes bibliographical references (p. 89-102).

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This research presents a new multivariate statistical approach to downscale hydroclimatic variables associated with global climate signals, from low-resolution Global Climate Models (GCMs) to high-resolution grids that are appropriate for regional and local hydrologic analysis. The approach uses Principal Component Analysis (PCA) and Multichannel Singular Spectrum Analysis (MSSA) to: 1) evaluate significant variation modes among global climate signals and spatially distributed hydroclimatic variables within certain spatial domain; 2) downscale the GCMs' projections of the hydroclimatic variables using these significant modes of variation and 3) extend the results to other correlated variables in the space domain. The approach is applied to the Colorado River Basin to determine common oscillations among observed precipitation and temperature patterns in the basin and the global climate signals El Nino Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO). These common oscillations serve as a basis to perform the downscaling of ENSO-related precipitation and temperature projections from GCMs, using a new gap-filling algorithm based on MSSA. The analysis of spatial and temporal correlations between observed precipitation, temperature and vegetation activity (represented by the Normalized Difference Vegetation Index, NDVI) is used to extend the downscaling of precipitation to vegetation responses in ten ecoregions within the basin. Results show significant common oscillations of five and 15-year between ENSO, PDO and annual precipitation in the basin, with wetter years during common ENSO and PDO positive phases and dryer years during common negative phases. Precipitation also shows an increase in variability in the last 20 years of record. Highly correlated responses between seasonally detrended NDVI and precipitation were also identified in each ecoregion, with distinctive delays in vegetation response ranging from one month in the southern deserts (in the fringe of the monsoon precipitation regime), to two months in the mid latitudes and three months to the north, affected by seasonal precipitation. These results were used to downscale precipitation and temperature from two GCMs that perform well in the basin and have a distinctive ENSO-like signal (MPI-ECHAM5 and UKMO-HADCM3) and to extend the downscaling to estimate vegetation responses based on their significant correlations with precipitation.

The response of vegetation to climate change and permafrost disturbance was studied at the Cape Bounty Arctic Watershed Observatory (CBAWO) on Melville Island, Nunavut. Climate change is expected to alter the terrestrial ecosystem of this area and cause non-linear responses. This study focussed on two predicted outcomes of climate change in the western Canadian High Arctic: the occurrence of a permafrost disturbance termed active layer detachments (ALDs), and increased air temperature and precipitation. To study the effects of ALD formation twenty 1 m2 plots were established within two ALDs. One ALD (ALD05) was formed in July 2007 and represented the initial impact of slope failure caused by an exceptionally warm year. The other (ALD04) was formed at least sixty years ago and represented the long-term impact of slope failure. Physical soil measurements and vegetation surveys were completed in both disturbances. ALD formation creates depressions on the landscape that increase snow accumulation. Snow accumulation was greater in the more recent ALD than in the older one and this resulted in greater changes to the physical environment. Vegetation was not significantly impacted by disturbance, although phenology was delayed due to snowcover retention. To study the effects of increased air temperature and precipitation an International Tundra Experiment (ITEX) site was established at CBAWO in July 2008. Snow fences and open-top chambers (OTC) were erected to increase snow accumulation and air temperature. Physical soil measurements and vegetation surveys were completed through the summer of 2009. Soil temperature and active layer depth were affected by snow and phenology was delayed in plots with snow enhancement. Experimental warming also had some effects on the parameters measured but only in conjunction with snow enhancement. This study found that in the first year of experimentation snow enhancement has a greater effect than increased air temperature. These studies represent the beginning of two long-term projects at CBAWO and the results from this study represent baseline data for future research. Continued monitoring will show the evolution of vegetation in the ALDs and the potential long-term effects of temperature and snow manipulation. / Thesis (Master, Geography) -- Queen's University, 2011-01-04 20:53:31.689

Natriumklorid sprids i ca. 20 skidbackar inom Åres skidsystem. Natriumklorid sänker vattens fryspunkt och gör att snön kan hållas hård under tävlingar, vilket ger de tävlande så lika förutsättningar som möjligt. Studiens främsta syfte var att undersöka om spridning av natriumklorid i Åres skidbackar är skadlig för vegetation i dess område och Indalsälvens vattenmiljö. Huvudsakligen utfördes detta genom en kartläggning av natriumkloridets väg via mark och vatten. Men hjälp av kartläggningen beräknades mängden kloridjoner som når Indalsälven från spridningen samt bidraget till koncentrationen av kloridjoner i Indalsälven. Genom en litteraturundersökning och fältstudie har natriumkloridets påverkan på vegetation och mark undersökts. Resultaten visar att de flesta kloridjoner från saltning med natriumklorid i skidbackarna når Indalsälven genom ytavrinning och att kloridjonernas uppehållstid i backarna är mindre än ett år. På grund av utspädningseffekten bedöms bidraget till koncentrationen av kloridjoner i Indalsälven vara försumbar. Ingen påverkan på markvegetation i eller nedanför backarna kunde identifieras. Markens fysikaliska egenskaper och struktur inom de saltade områdena och 25 m nedanför bedöms kunna försämras, vilket kan skapa ökad erosion. Det är däremot inte fastställt att så är fallet. Sammanfattningsvis indikerar resultaten i studien en begränsad påverkan på miljön av saltanvändningen i Åres skidbackar. Det fordras ytterligare undersökningar för att kunna få en djupare förståelse av saltningens miljöpåverkan på kort och lång sikt. / Sodium chloride is spread in approx. 20 ski slopes within the ski system of Åre. Sodium chloride lowers the waters freezing point and can keep the snow stable during ski competitions, which gives the contestants as similar conditions as possible. The primary purpose of the study were to examine if the distribution of sodium chloride in ski slopes is harmful to vegetation in the area and in the aquatic environment of Indalsälven. Mainly, this was done through a mapping of the sodium chloride transport through the soil and water. By using the mapping, calculations were done to know which amount of chloride ions that reaches Indalsälven from the spreading and the contribution to the concentration of chloride ions in Indalsälven. Through a literature- and field study, the sodium chloride impact on vegetation and soil were investigated. The results shows that the most of the chloride ions from the salting of sodium chloride in ski slopes reaches Indalsälven through surface runoff and the chloride ions residence time in the slopes is less than a year. Because of the dilution effect, the contribution to the concentration of chloride ions in Indalsälven deemed negligible. No impact on ground vegetation in or below the slopes were identified. The soil physical properties and structure within the salted area and 25 m below, is expected to deteriorate which can cause increased erosion. However, it is not established that this is the case. Summarize, the results of the study shows limited impact on the environment by the use of salt in the ski system of Åre. It requires further investigation in order to gain deeper understanding of the environmental impacts in short and long term of salt use.