The relationship of vegetation and disturbance factors to the distribution, abundance and diversity of small mammals in the eastern Otway region, Victoria were investigated. Antechinus stuartii, Rattus fuscipes and Rattus lutreolus were widely distributed and occurred in the majority of the eleven floristic vegetation groups identified. Antechinus minimus, Antechinus swainsonnii and Pseudomys novaehollandiae had restricted distributions and were recorded in only two or three vegetation groups. New information on the distribution of the rare species P. novaehollandiae, was obtained and two floristically rich vegetation groups that it preferred were identified. Species-rich small mammal communities occurred in vegetation communities with high numbers of sclerophyll plant species and high structural diversity. Maximum food resources were considered to be provided in these communities. Local habitat diversity was also correlated with species-richness. Small mammal abundance was maximum in non-sclerophyllous canmunities, where high plant productivity was considered to be important. For the first time, the presence of the plant pathogen Phytophthora cinnamomi was shown to affect small mammals. It was associated with small mammal communities of low species richness and abundance, Recovery of small mammal populations after wildfire was slow until the fourth year. Mus musculus reached peak abundance from 2-3 years and then declined rapidly. P. novaehollandiae was the only native species that achieved maximum abundance early in the succession. A. stuartii, R. fuscipes and R. lutreolus approached maximum abundance in mid-succession, while Isoodon obesulus was a mid- to late-successional species. A. minimus survived the fire, but did not persist after one year. The pattern of succession was influenced by attributes of species, such as survival after fire, their ability to disperse and reproduce.

Thesis (M.S.) in Forestry--University of Maine, 2004. / Includes vita. Includes bibliographical references (leaves 104-115).

Graduation date: 1999

Thesis (Ph. D.)--University of Oregon, 2002. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 170-178). Also available for download via the World Wide Web; free to University of Oregon users.

published_or_final_version / Botany / Doctoral / Doctor of Philosophy

In mountains throughout western North America, large, mixed-severity fires produce a mosaic of low and high tree mortality. Following wildfire, plant communities may recover to their pre-fire state, or may remain altered in composition and structure. In this study I quantified the extent to which fire severity influenced post-fire vegetation composition and structure in comparison to pre-fire states in the Santa Catalina Mountains, Arizona, USA. I used a stratified random design that sampled plots across ecological units and fire severity classes. Tree diameter at breast height (DBH), shrub cover, and seedling and sapling density was recorded by species in five plant communities: oak/pinyon/juniper woodland on hills landscapes of mixed lithology; Madrean pine-oak forest/woodland on granite, gneiss, or metasedimentary rock; Madrean oak/conifer/manzanita on rock outcrops; ponderosa pine forest on granite, gneiss, and similar rocks; and mixed conifer forest on metasedimentary landscapes. Subsets of these data were then used to reconstruct overstory vegetation present when the Bullock (2002) and Aspen (2003) fires occurred. Data from a 1984 pre-fire study was used to substantiate the overstory reconstruction and to determine shrub understory components. I tested the hypothesis that tree mortality was a determinant of post-fire shrub cover, and calculated post-fire importance values (IVs) of tree and shrub components. Ordination and non-metric multidimensional scaling (NMS) of IVs confirmed that overstory reconstruction aligned with 1984 field surveys. Tree mortality was a predictor of post-fire shrub cover, but only with certain species in specific ecological units. Ordinations indicated that tree composition in post-fire plots has diverged from that in pre-fire plots in all but the oak/ pinyon/juniper community. Ordination of shrub components indicated novel configurations of post-fire communities, including association of pre-fire mixed conifer elements with oak woodland elements. The intermixing of tree species in mid- and higher-elevation communities with those historically confined to lower elevation community types suggests that recent fires has disrupted vegetation inertia and initiated novel ecological change. The re-structuring observed within these community types are in agreement with projections that disturbance and climate change will interact to facilitate the spread of lower elevation species to higher elevation zones. Fire x climate interactions may therefore trigger long-lasting changes to ecosystem structure in ways not predicted by models of fire-effects or climate-effects occurring in isolation from each other.

This thesis documents a research study of High Voltage transmission line faults induced by fire. Conductor to conductor and conductor to ground flashovers have been experienced by electricity utilities around the world under conditions of veld and sugar cane fires. These types of faults are unpredictable and negatively impact line reliability and quality of supply. This is a crucial problem when the revenue of the industry is sensitive to voltage dips. Electricity utilities have taken a preventative approach, like clearing vegetation from the line servitude in order to decrease the frequency of line faults. There has also been a drive to collaborate with sugarcane farmers in order to have harvesting fires planned with utilities. Some success has been achieved with these initiatives however there still remains a large number of faults. The focus of this study is on the mechanism of fire-induced flashover. Previou s work has displayed the existence of two theories. The first theory suggests that flashover is due to the reduction in air insulation strength caused by a reduced air density that results from the thermal effect of the fire. The second theory suggests that small particles present in the fire cause electric field distortions that induce flashover. This study is focused on a theory , which indicates that flashover is induced due to an enhanced electric field which is a result of the conductive properties of the flames present in the air gap (the flame conductivity theory). The effects of particles and a reduced air density is said to support this mechanism that is the primary reason for flashover. This thesis present s a summary of the literature where firstly an understanding of air insulation behavior is displayed. Thereafter specific interest is given to the effect of fire and flames wherein the physics of flames are discussed. This then leads to the description of the flame conductivity theory. Chapter 4 deals with a simulative investigation into the effect a conducting flame has on the electric field distribution. This is looked at with a varying flame conductivity and gap length in mind. The simulations specifically cover the 275 kV and 400 kV line configurations. The simulative investigation results in a mapping of electric field enhancement against conductivity values and gap sizes. Thus a flashover probability is assessed by using the two factor flashover criteria when analyzing the electric field stresses. The objective of the experimental work in this study is to obtain insight on how the flame geometry and orientation affects flashover and the dependence of flashover on gap size. Tests involving a fire beneath a conductor were carried out for different gap sizes . Experimentation with particles above a flame was also conducted. It was concluded that flame structure does have an impact on flashover since a flame with sharp edges is more likely to cause flashover. Particles have a reducing effect on air insulation strength. This is mainly due to the fact that the particle reduces the effective air-gap size. No significant effect over and above this is noticed . For gaps spanned by clean Liquid Petroleum Gas (LPG) flames flashover voltage increases as gap-length increases with some degree of nonlinearity. Flame resistances and conductivity were approximated from measured currents and voltages. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2005.

No description available.

Thesis (M.S.)--University of Toledo, 2007. / Typescript. "Submitted as partial fulfillment of the requirements for The Master of Science in Biology, Ecology-track." Bibliography: leaves 68-78.

Thesis (M.S.)--University of Nevada, Reno, 2007. / "August, 2007." Includes bibliographical references. Online version available on the World Wide Web.