The herbivory experienced by non-native invasive plants may depend on their local environments, such as herbivore abundance. In this study, I performed a common garden experiment with plants sampled from 11 populations of Arctium minus, from southern Ontario to near its northern range limit. I also compared performance and herbivory of burdock in open and understory habitats. Finally, I conducted freezing tolerance experiments with the lepidopteran seed predator Metzneria lapella, and palatability tests with plants from different populations. Results suggested that the previously described latitudinal trends in herbivore damage among populations are due to environmental differences rather than genotypic differences among populations. At a local scale, plants of open habitat were less damaged and had better performance than understory plants. Burdock has not escaped damage by herbivores in its invaded range; instead variation among sites in herbivore populations and impacts may significantly affect the invasiveness of this species.

The herbivory experienced by non-native invasive plants may depend on their local environments, such as herbivore abundance. In this study, I performed a common garden experiment with plants sampled from 11 populations of Arctium minus, from southern Ontario to near its northern range limit. I also compared performance and herbivory of burdock in open and understory habitats. Finally, I conducted freezing tolerance experiments with the lepidopteran seed predator Metzneria lapella, and palatability tests with plants from different populations. Results suggested that the previously described latitudinal trends in herbivore damage among populations are due to environmental differences rather than genotypic differences among populations. At a local scale, plants of open habitat were less damaged and had better performance than understory plants. Burdock has not escaped damage by herbivores in its invaded range; instead variation among sites in herbivore populations and impacts may significantly affect the invasiveness of this species.

Copy of author's previously published work inserted. / Bibliography: leaves 261-306. / xxix, 308 leaves : ill. (some col.), maps ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The objectives of the project were: i. to determine whether there are competitive interactions between Aporrectodea trapezoides and A. caliginosa and A. rosea.--ii. to investigate compeditive interactions between A. calignosa, Microscolex dubius and A. trapezoides.--iii . to determine the likely impact of A. longa on soil fauna, especially the native earthworm, Gemascolex lateralis, in native ecosystems. / Thesis (Ph.D.)--University of Adelaide, Dept. of Soil Science, 1996

4 fold. maps in end pocket of v.2 / 2 v. : ill., photos., maps, diags. (some fold) ; 26 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Geology and Mineralogy, 1975

Thesis(M.S.)--Auburn University, 2006. / Abstract. Includes bibliographic references.

Thesis (M.S.)--Oregon State University, 2000. / Typescript (photocopy). Includes bibliographical references (leaves 62-65). Also available on the World Wide Web.

The range sheep industry , economically important to Utah and to the United States , produces needed food and fiber from much of the less productive land. Improved management will depend on more knowledge of the range ecosystem . Research to determine the time spent by sheep in activities of differing energy demands and to determine what factors affect sheep activity was completed on Utah ranges. The research was conducted in central Utah on foothill range near Eureka and on mountain range near Scofield. Rambouillet sheep were loosely herded on the s agebrush-aspen areas on mountain range and were unherded on foothill range where they were assigned to 14 pastures. Activities on foothill range were studied in May and June at two grazing intensities on three species of seeded wheatgrasses and on native sagebrush-juniper range. Feeding , standing ruminating, standing idle, lying ruminating, lying idle , and traveling were recorded as all-inclusive activities by observing the behavior of four randomly selected sheep from among marked ewes at 90 instantaneous scans at 10-minute intervals from 0500 to 1950 hours on each of 28 days at each location . Hourly readings were made on the degree of cloudiness , wind movement, ambient temperature, and relative humidity. Data we re analyzed to determine components of varian c e and to evaluate effect s of month, grazing intensity, and kind of forage. Each activity was regressed on environment l factors in a stepwise-deletion multiple regression procedure. Sheep daily repeated a bimodal routine of early morning feeding followed by midday ruminating and resting which lasted until late afternoon, followed by feeding again before bedding down at nightfall on high ground. On mountain range the morning and afternoon feeding periods were of similar length, but on foothill range the sheep began feeding ear lier in the afternoon and thus fed longer in the afternoon than during the morning hours. Sheep were highly synchronous in their choice of activity. Sheep spent more time feeding on seeded foo thill range than on either native foothill or mountain range . Conversely , they spent more time lying ruminating and standing idle during the daylight hours studied on mountain and on native foothill range . Traveling time was greater on mountain than on foothill range , but the horizontal distances traveled were the same at both locations. Sheep spent more time lying idle on native foothill range than on seeded pastures . At the spring foothill location the sheep also spent more time standing idle and traveling in May than in June. No differences were noted in any activities between intensities of grazing. The daily feeding time of sheep responded positively to average daily temperature. Both lying ruminating and lying idle showed positive regressions on relative humidity . Traveling and standing idle were negatively related to mean daily temperature , which varied only within a narrow temperate range and averaged 20 C during the two periods of study. Sheep activities necessary to the animal on a daily basis were little affected by small changes in the range environment. Feeding time was proportional to the estimated energy expenditure for maintenance, activity, and production at each location.

No description available.

This study investigates the ecology of one of the best known Australian marsupials, the Common Brushtail Possum Trichosurus vulpecula, in central Australia. Trichosurus vulpecula is one of few medium-sized mammal species that persist in arid Australia today. Its distribution within the arid zone has declined markedly since European settlement. Two populations, one within the East MacDonnell Ranges along the Hale River and the other on Irving Creek, a River Red Gum creek in the Petermann Ranges, were studied in the southern Northern Territory. Others locations in the region were visited opportunistically. Trie central Australian Trichosurus is not distinct genetically from populations elsewhere in Australia. The diet of T. vulpecula consisted of a range of leaves, flowers and fruits of perennial dicotyledonous species as well as some ephemeral herbs. Grasses were absent from the diet. Variation in the diet reflected seasonal availability in flowers and fruits. The species preferentially consumed at each site had significantly higher moisture content and dry matter digestibility than species not consumed. Preferred species included Amyema maidenii leaves (a mistletoe), Acacia spp. flowers and fruits, Santalum lanceolatum leaves (a shrub), Marsdenia australis leaves (a vine), Solarium quadriloculatum fruit (shrub) and Euphorbia spp. leaves (herb). Small amounts of invertebrate material were consumed throughout the year. Other non-plant material consumed included honeycomb and unfledged birds eg. Budgerigars. There were no significant differences in the diet between the sexes. Trichosurus vulpecula were found in six main habitats: Acacia aneura/Callitris glaucophylla on rocky hills; E. camaldulensis sandy creek-lines; mixed Acacia rocky hills, Rocky Eucalyptus creek-lines; Degraded drainage lines; and Wet gullies. Logistic regression modelling revealed a significant correlation between mistletoe species richness, higher levels of soil nitrogen and the presence of T. vulpecula. In habitats occupied by T. vulpecula species richness of mistletoes was associated with the absence of fire and the presence of reliable ground water supplies. Trichosurus vulpecula were highly mobile with mean home ranges at Hale River of 44.21 � 22.76 ha and considerably higher than those recorded in previous studies in Australia. Mean home ranges at Irving Creek were much smaller, at 4.99 � 1.46 ha and VII similar to that recorded in other studies in Australia. At both sites, males had larger home ranges and there was a high degree of overlap with other males and females. At the Hale River study site, T. vulpecula predominantly denned in caves or cavities in rocks, whereas at Irving Creek all den sites were in large Eucalyptus camaldulensis on the drainage line. Adult and pouch young sex ratios were at parity. During this study, T. vulpecula was found to breed continuously, with births recorded in almost all months. Growth of the young were more rapid than previously recorded for Trichosurus in Australia. This is interpreted as an adaptation for living in an arid environment, enabling the young to achieve independence before quality food supplies diminish. No single exotic predator or competitor was solely responsible for the decline of T. vulpecula in arid Australia, implying an interactive impact. Prey switching by dingoes from rabbits to T. vulpecula, macropods and echidnas followed the crash of rabbit populations at Hale River. Predation by dingoes on T. vulpecula was only recorded once, at the Irving Creek study site, where numbers of rabbits remained stable throughout the study. The impact of exotic herbivores occurred through habitat degradation rather than competition. Evaluation of the ecological data collected during this study generally supports current models of decline and extinction in medium-sized mammals in arid Australia, integrating the effects of predators, competitors, drought and fire. However, the importance of each factor on populations of T. vulpecula was found to vary depending on their location in the landscape. This study suggests two separate models to explain the decline of T. vulpecula in arid Australia after the arrival of Europeans. The first operates in the riparian lowlands and the second on the rocky ranges. In both models, prior to European settlement, T. vulpecula occupied refuge habitats characterised by readily available moisture for plant growth (run on areas and/or shallow water tables) and soils with higher soil nutrient concentrations. The impact of fires on these refugia was minimal, as Aboriginal burning practices protected them with mosaic burning generally preventing large-scale fires from developing. Following European settlement, the forces impacting on populations were different in the riparian lowlands from those affecting rocky ranges. In the riparian lowlands, the effects of rabbits and livestock together with predation were found to have the major impact on T. vulpecula populations. Fire was not a significant factor in these areas. In the rocky ranges, fire was the most significant factor affecting T. vulpecula populations. Introduced herbivores did not degrade these habitats as they did in the riparian lowlands because the rugged and steep nature of the ranges acted as a physical barrier. Similarly, predator numbers were lower because of the relative difficulty in moving over rough ground and the generally lower relative abundance of preferred prey such as rabbits. An adaptive management strategy needs to be implemented to determine the effects of different management regimes on T. vulpecula population viability. The key elements of a management strategy in the riparian lowlands involves the manipulation and monitoring of predators, rabbits and livestock numbers. In the rocky ranges, the key management strategy involves the implementation of a patch burning to prevent fires entering habitats occupied by T. vulpecula. Importantly, any management strategies should involve Aboriginal people. Trichosurus vulpecula is an important part of Aboriginal culture. Its decline is of great concern to many people and several of the remaining populations and potential reintroduction locations are on Aboriginal land. Because of their relationship with the land and the animals, people have both the knowledge of the animal and the skills (such as patch burning) to provide information to managers which will assist with management. To achieve these management directions a coordinated national education programme is required to inform and convince the Australian community that conservation of T. vulpecula is deserving of attention in arid and semi-arid Australia. This is particularly important given the perception that T. vulpecula is a common species throughout Australia, despite its massive decline in arid Australia since European settlement.

"February, 2005" / Bibliography: leaves 259-272. / ix, 272 leaves : ill. (some col.), maps (col.), plates (col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / "The Mount Lofty Ranges and flanking St Vincent and Western Murray Basins preserve a rich record of Australian intraplate neotectonic movements and their effects of landscape evolution and sedimentary basin development in this region of South Australia." "The major goal of this study is to develop a new tectonic model that contributes to our fundamental understanding of how neotectonic motions and deformations operate within this sector of the southern Australian Earth crust. The other main aim of this thesis is to provide a better understanding of the effects those neotectonic movements imposed on landscape evolution and sedimentation." --Introd. / Thesis (Ph.D.)--University of Adelaide, Faculty of Science, School of Earth and Environmental Sciences, Discipline of Geology and Geophysics, 2005