Roadside vegetation provides numerous environmental and psychological benefits to drivers. Previous studies have shown that natural landscapes can effectively lower crash rates and cause less stress and frustration to the driver. However, run-off-the-road crashes resulting in a collision with a tree are twice as likely to result in a fatality, thus reinforcing the need to examine the placement of vegetation within the clear zone. This study explores the relationship between the size of the clear zone and the presence of roadside vegetation on selected driver attributes, including both driver speed and lateral positioning. To evaluate the effect on the driver speed selection process, a static evaluation was employed. Completed by more than 100 drivers, the static evaluation was utilized to gather speed selections on both real and virtual roads containing four combinations of clear zone size and roadside vegetation density. Additionally, field data was collected to validate the findings of the static evaluation and to determine the extent to which roadside vegetation impacts driving attributes. When presented with a large clear zone, drivers positioned the vehicle further from the edge of the road as the vegetation density increased. Furthermore, the speeds observed in the field correlated with the speeds that participants selected when watching a video of the same road. Finally, the UMassSafe Traffic Safety Data Warehouse was utilized to link crash and roadway data, allowing for an in-depth analysis of run-off-the-road (ROR) crash severity. The results of this study further demonstrate the nature of the relationship between clear zone design and driver behavior.

Fuel reduction treatments are management activities implemented to reduce the quantity of hazardous fuels in forests to decrease the probability of severe and intense wildfires. As nonindustrial private forest (NIPF) landowners own most forests (77%) in Mississippi, their involvement is essential for effective and coordinated fuel reduction treatments to achieve a large-scale wildfire hazard reduction. However, NIPF landowner attitudes towards wildfire risk and mitigation activities implemented to reduce wildfire risk are not well understood. This study determined attitudes of NIPF landowners towards wildfires, current trends in implementation of fuel reduction treatments, socioeconomic and geospatial factors affecting treatment implementation, and landowner willingness to pay (WTP) for prescribed burning. Data were collected via a mail survey of NIPF landowners and public sources including Mississippi Forestry Commission and National Land Cover Database. The contingent valuation method (CVM) was used to quantify the WTP for prescribed burning. Data were analyzed using seemingly unrelated and binary probit, and binary logit models. Approximately 68% of landowners were concerned about wildfires, but only 45% implemented hazardous fuel reduction treatments. Prescribed burning was the most commonly implemented and the least costly treatment. Furthermore, only 30% of landowners were likely to implement fuel reduction treatments in the next five years. Past implementation of treatments, concern about property damages due to wildfires, familiarity with wildfire prevention and mitigation programs, size of forest land owned, ecological services ownership objectives, past experience with wildfires, and motivation from neighbors’ implementation of treatments were positively associated with the likelihood of implementing fuel reduction treatments in the next five years. Landowners were willing to pay from $14.70 to $66.86 per acre, with an average of $41.39 per acre, for implementing prescribed burning on their forest land. The payment amount was negatively related to WTP, whereas education level, tolerance of smoke from prescribed burns, concern about property damages due to wildfires, and consideration of liability issues as an important factor were positively related. Results will help better understand NIPF landowner wildfire mitigation activities and associated social and geospatial factors, and aid in the development of more effective strategies and resource allocation for wildfire prevention and mitigation.

No description available.

In order to understand vegetational gradients which develop in response to environmental gradients, the physiological capabilities of each species must be examined in relation to the observed environmental gradient. The distributions of three temperate zone shrub species which occupy different positions on the spur ridges of Brush Mountain may be influenced by their tolerances to light and moisture. Greenhouse studies indicate that <i>R. maximum</i> has a 60 % reduction in photosynthesis at water potentials below -1.0 MPa. <i>R. nudiflorum</i> has only a 30 % reduction and <i>K. latifolia</i> has less than 10 % reduction. Seasonal pressure volume curve determinations, conductance measurements, and water potential measurements of plants in the natural environment indicated that photosynthesis is not affected by water potential in <i>K. latifolia</i>. <i>R. maximum</i> has a significant reduction in conductance during drought which may limit photosynthesis. R. nudiflorum appears to begin senescence prior to severe drought in this area. Greenhouse experiments of adaptability to increasing light intensity show that <i>K. latifolia</i> and <i>R. nudiflorum</i> can significantly increase their light saturation point and maximum rate of photosynthesis in high light environments. <i>R. maximum</i> does not increase its photosynthesis rate in high light environments and appears to undergo chloroplast degradation when grown in high irradiance. Gradient analysis of vegetation on Brush Mountain shows that <i>R. maximum</i> reaches its highest importance in low light, high moisture sites. <i>K. latifolia</i> is most important in low moisture, high irradiance sites. <i>R. nudiflorum</i> is infrequent in the study area but occurs mostly in moderate moisture and irradiance sites. The distributions of <i>R. maximum</i> and <i>K. latifolia</i> appear to match their experimentally determined physiological tolerances. The results for <i>R. nudiflorum</i> are inconclusive. / Master of Science

Forests have the ability to sequester carbon from our atmosphere. Soil respiration (Rs) plays a role in a forest's ability to do so as it is a significant source of carbon dioxide back to the atmosphere. Therefore, understanding the process of Rs under varying conditions is gaining more attention. As of now we have a relatively good understanding of Rs under managed forest ecosystems such as pine plantations. This particular study examined Rs under different overstories and understories in a high elevation Southern Appalachian forest in order to get a better understanding of Rs under a natural hardwood system. The four vegetation types under consideration were an eastern hemlock (Tsuga canadensis L. Carriere) dominated overstory, a hardwood overstory with little to no understory, a mountain laurel (Kalmia latifolia L.) dominated understory, and a cinnamon fern (Osmundastrum cinnamomeum (L.) C.Presl) dominated understory. Differing temporal variations of Rs were observed under the vegetation types. We found monthly differences in rates among vegetation type however, an overall annual difference in Rs rates between vegetation types was not observed. This simply indicates the importance of observing Rs under different time scales to get a better understanding of its variation. We also calculated vegetation indices from remotely-sensed data to explore any relationships to Rs as well as if the indices themselves could improve out model. A vegetation index is a number that is calculated for every pixel in a remotely sensed image and represents plant vigor or abundance. Few significant relationships were found between the indices and Rs. Future work may want to better understand vegetation indices' spatial extent and accuracy in order to find whether they may be beneficial in Rs estimation. Understanding the influence of varying vegetation type and soil temperature and moisture on Rs will ultimately improve our ability to predict what drives changes in carbon fluxes. / Master of Science / Forests have the ability to sequester carbon from our atmosphere. Soil respiration (Rs) plays a role in a forest’s ability to do so as it is a significant source of carbon dioxide back to the atmosphere. Therefore, understanding the process of Rs under varying conditions is gaining more attention. As of now we have a relatively good understanding of Rs under managed forest ecosystems such as pine plantations. This particular study examined Rs under different overstories and understories in a high elevation Southern Appalachian forest in order to get a better understanding of Rs under a natural hardwood system. The four vegetation types under consideration were an eastern hemlock (Tsuga canadensis L. Carriere) dominated overstory, a hardwood overstory with little to no understory, a mountain laurel (Kalmia latifolia L.) dominated understory, and a cinnamon fern (Osmundastrum cinnamomeum (L.) C.Presl) dominated understory. Differing temporal variations of Rs were observed under the vegetation types. We found monthly differences in rates among vegetation type however, an overall annual difference in Rs rates between vegetation types was not observed. This simply indicates the importance of observing Rs under different time scales to get a better understanding of its variation. We also calculated vegetation indices from remotely-sensed data to explore any relationships to Rs as well as if the indices themselves could improve out model. A vegetation index is a number that is calculated for every pixel in a remotely sensed image and represents plant vigor or abundance. Few significant relationships were found between the indices and Rs. Future work may want to better understand vegetation indices’ spatial extent and accuracy in order to find whether they may be beneficial in Rs estimation. Understanding the influence of varying vegetation type and soil temperature and moisture on Rs will ultimately improve our ability to predict what drives changes in carbon fluxes.

Peatlands are important and common wetland ecosystems where the wet conditions result in formation and accumulation of peat, i.e., not fully decomposed organic matter. Many peatlands have been negatively affected by drainage (i.e., ditches) and restoration is conducted, although the effects on vegetation are not fully understood. This study aimed to investigate the differences in vegetation composition between natural and restored parts of peatlands and the effect of local conditions on vegetation composition. Data was collected on vegetation composition and local environmental conditions (pH, electrical conductivity and water table depth) of natural and restored parts of seven peatlands across Sweden. Statistically significant differences in the species composition between natural and restored parts were detected and natural parts were dominated by Sphagnum species while restored parts were characterised by shrubs and sedges. The environmental variables had a similar impact on the vegetation composition of both northern and southern sites and were in line with the microhabitat preferences of different species. Although restored parts still have a lower cover of Sphagnum, the vegetation community appears to develop towards compositions similar to those of natural peatlands as most plots are dominated by species found in both natural and restored parts. However, this study is based on vegetation data collected in one year and the results only show the current vegetation community composition and should be interpreted cautiously when evaluating the long-term development of vegetation composition after peatland restoration. As peatlands form during long periods of time, differences in vegetation composition after this relatively short time were expected and in line with previous research. Further studies and long-term follow-up surveys are needed to better understand the vegetation development after peatland restoration.

Yes / The three-dimensional (3D) numerical modelling in an open channel flow field of a group of submerged vegetations using computational fluid dynamics (CFD) platform of FLOW-3D HYDRO was performed in this study. A set of acoustic Doppler velocimetry (ADV) measurements have been conducted as benchmark to validate the numerical model. A quantitative comparison was performed on several hydrodynamic variables that impacted the vegetated open channel flow, such as flow depth, streamwise water velocity, turbulent intensity, and Reynolds shear stress. In the numerical analysis, the flow turbulence was treated using the RANS approach (within RNG k-ε); while the Volume Of Fluid (VOF) method was used to track the air-water interface. Structured meshes with hexahedral elements were used to discretize the channel geometry. In the findings, the numerical model reasonably reproduced the flow field and presented corresponding agreement with the experimental turbulent structures. This study showed that the differences in results between various analyses were all less than 10% and concludes that the presented numerical approach can be utilised as an efficient tool for simulations of the flow field within a vegetation patch (i.e. by using the simplified RANS approach).

As part of a vegetation survey program for the newly acquired farms incorporated into the Loskop Dam Nature Reserve, the vegetation of the Hondekraal Section was investigated. The study provides an ecological basis for establishing an efficient wildlife management plan for the Reserve. From a TWINSPAN classification, refined by Braun-Blanquet procedures, 12 plant communities, which can be grouped into eight major plant communities, were identified. A classification and description of the major plant communities are presented as well as a management plan. Descriptions of the plant communities include characteristic species as well as prominent and less conspicuous species of the tree, shrub, herb and grass strata. This study proves that the extended land incorporated into the Reserve contributes to the biological diversity of the Reserve. / Environmental Sciences / M. Tech. (Nature Conservation)

Den här studien undersöker hur vegetationen förändras mellan 1979 och 2010 i området som idag är Hornborgasjöns naturreservat. Sjösänkningar i området ledde till att ett igenväxt träskområde ersatte en viktig vattenreservoar och närsaltfälla. Restaureringsarbetet under 80-talet var banbrytande och antagligen ett av vår tids mest omfattande naturvårdsarbete. Studien svarar också på om restaureringen uppnådde sitt mål och om resultatet blev som man tänkt sig. I arbetet skapades en aktuell vegetationskarta för 2010, denna jämfördes med en i arbetet digitaliserad vegetationskarta från 1979. Kartbilder skapades och justerades i ArcGIS och vegetationsytornas area framtogs för att möjliggöra en vegetationsanalys mellan kartorna. Vegetationsförändringarna i området visade sig vara omfattande mellan 1979 och 2010, där tydlig igenväxtningsmark med stora monokulturer ersattes med öppnare marker där vegetationstyperna var spridda över hela området i mindre ytor. Mångfalden i området ökade liksom vattenytan. Vattenytans stora utbredning efter restaureringen blev den stora överraskningen tillsammans med att sävvegetationen helt försvann. Undervattensvegetationens stora spridning räddade dock restaureringens syfte att gynna fågellivet trots sävruggarnas frånvaro. En ny viktig naturtyp framkom i vegetationskartan 2010, öppet vatten med död vegetation, där stora delar av vegetationstypen består av den för många hotade arter vitala biotopen död sumplövskog. / This study investigates vegetation changes in the nature reserve of Lake Hornborga between 1979 and 2010. Lowering of the surface of the lake had changed an important water reserve and nutritive salt trap into an overgrown fen and during the 80's a total pioneering restoration, perhaps the most important work of nature conservation of our time, was made. This study claims to answer if the restoration was successful and if its goals were reached. A current vegetation map for 2010 was created and adjusted in ArcGIS and this map was compared with a vegetation map of 1979. Vegetation areas were calculated to facilitate analyses between the maps. Large-scale vegetation changes have occurred between 1979 and 2010. Overgrown fenland with monoculture vegetation has been replaced by a more open landscape with a diversified growth and an open surface of water. The large extension of open surface and the disappearance of rush vegetation are two great surprises of the restoration. Thanks to a large-scale spread of underwater vegetation the aim of furthering birdlife could be reached despite the loss of rush vegetation. A new type of vegetation area has also been created, where  open water submerges dead vegetation, one of which is a biotope of dead marsh broadleaf trees, vital to many threatened species. / Vid kontakt med Lantmäteriet har muntlig bekräftelse getts gällande tillstånd av publicering av deras upphovsrätts skyddade material, där alla högskolearbeten ges sådant tillstånd vid alla Sveriges lärosäten. I mitt arbete gäller detta figur 1.

[Truncated abstract] Native vegetation (bushland) in urban areas remains in small, isolated patches embedded within a matrix of human-dominated land uses. Bushlands in urban areas have high biodiversity conservation and social values, and there has been a local-level movement towards protecting and managing urban bushlands in Australia. This thesis aims to test principles, theories and concepts relating to the ecology and management of bushland fragments in Australian cities ... A commonly used qualitative scale was compared with an ecologically based, quantitative technique developed in the research. The qualitative scale was found to be a reliable proxy for assessing vegetation condition, while also being more user-friendly for community groups and other bushland managers. The human-caused disturbances and weed cover in urban bushlands indicate a need for management intervention. Local government has an important role in local biodiversity management, yet there has been little research on this topic ... Positive partnerships developed where local governments have taken a ‘contract model’ approach to volunteer coordination, have a number of expectations of volunteer groups, and provide the groups with relatively high level of assistance. Also important is a local government that supports, respects, trusts and communicates with the community group, and recognises volunteers’ skills, knowledge and contributions. With increased resources allocated to local government bushland management and conservation, and coordination with community groups, the full potential of local bushland management would be realised.