No description available.

No description available.

No description available.

Upper Respiratory Tract Disease (URTD), caused by the pathogens Mycoplasma agassizii and M. testudineum, has been documented in the desert tortoise (Gopherus agassizii). Although URTD was identified as a putative agent that led to federal listing of the Mojave population of the desert tortoise, little is known about this disease in the Sonoran population of the desert tortoise. The purpose of this study was to determine: 1) the prevalence of URTD across an urban gradient in Greater Tucson, Arizona, 2) the relationship between URTD and captive and free-ranging tortoises in Mohave, Maricopa, and Pima counties in Arizona, and 3) the effects of URTD on desert tortoise home range size and winter temperature selection.

About 1,600,000 ha of desert mule deer range in Mexico are currently altered with vegetation clear-cutting and establishment of buffelgrass pastures. Consequently, the availability of resources as cover and forage from scrub vegetation has been reduced for mule deer. No previous research has been conducted to investigate how desert mule deer respond to those alterations. Therefore, the purpose of this research was to examine movements of mule deer, evaluate their home range sizes and determine habitat use, and analyze their diets in areas of central and western Sonora, Mexico. The approach involved the use of radiotelemetry techniques and GIS programs to calculate home range sizes, examine selection of vegetation associations, and identify the specific components of habitat that distinguished the characteristics of selected sites by desert mule deer. I used the microhistological technique to determine botanical components of desert mule deer diets, and compare diets of desert mule deer and cattle in habitat with buffelgrass pastures. Diet analyses included spatial and temporal comparisons of diversity and similarity indices. Sizes of home ranges were larger in the more arid environments of western Sonora (27.3 km2) than in central Sonora (14.5 km2). Desert mule deer used altered habitat differently than use areas without buffelgrass, however, there was no difference in the size of home ranges of mule deer from inside buffelgrass areas and the size of home ranges of deer in native scrub vegetation. Thermal cover, ground cover, and percent of gravel in the ground were the variables that distinguished locations selected by desert mule deer. Desert mule deer selected xeroriparian vegetation and sites closer to water sources. Water sources may have influenced mule deer to stay in buffelgrass areas despite the lack of cover and forage from shrubs and trees. For diets of mule deer, I identified 96 plant species, 69 of which have not previously been reported as forage for this herbivore. Desert mule deer and cattle shared 45 forage species from central Sonora. However, biological overlap of diets occurred only for spring. Results from these studies provide information to understand ecological relationships of desert mule deer on altered habitats.

Bibliography: p. 191-200. / 200 p. : ill. (chiefly col.), map (fold.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Persistence mechanisms of Erodiophyllum elderi are investigated in terms of life history strategies and patchy population theory. / Thesis (Ph.D.)--University of Adelaide, Dept. of Botany, 1999

[Truncated abstract] Establishment of vegetation and ecosystem functioning is central to the mitigation of environmental impacts associated with mining operations. This study investigated the ecophysiological functioning of mature plants in natural vegetation and applied this knowledge to diagnose problems affecting plant health and causes of poor plant cover at a mine-rehabilitation site. Ecophysiological parameters, including plant water relations and mineral nutrition, were studied in conjunction with soil physical, hydraulic and chemical properties. The natural ecosystem at the study location in the Great Sandy Desert is characterised by sand dunes and interdunes with distinct plant communities on each. One of the most notable features of the vegetation is the presence of large Corymbia chippendalei trees high on the dunes and relatively small scattered shrubs in the interdunes. Triodia grasses (spinifex), dominate the vegetation in both habitats but different species occur in each; T. schinzii is restricted entirely to the dunes, and T. basedowii occurs only in the interdunes. It was hypothesised that the deep sandy dunes afford greater water availability but lower nutrient supply to plants in this habitat compared with those occurring in the lower landscape position of the interdunes. Water-relations parameters (leaf water potentials, stomatal conductance, d13C) revealed that dune plants, particularly woody species, displayed higher water status and water use than closely related and often congeneric plants in the interdunes. Nutrient concentrations in soils were significantly higher in the interdunes, but concentrations in foliage were similar for related species between habitats. It is concluded that the dunes provide a greater store of accessible water than the soil profile in the interdunes. ... Following an experimental wetting pulse equivalent to a summer cyclone event, A. ancistrocarpa plants displayed significant increases in stomatal conductance, leaf water potential and sap velocity in lateral roots within three days of irrigation at the natural site and two days at the rehabilitation site. Secondary sinker roots originating from distal sections of lateral roots were evidently supplying water to maintain hydraulic function in laterals, thus enabling a fast pulse response. This was accentuated at the rehabilitation site where roots were confined closer to the surface. These results indicate that plants at the rehabilitation site are more dependent on small pulses of water and have less access to deep reserves than plants at the natural site. It is concluded that high runoff losses and insufficient soil depth are major factors contributing to plant water stress, and combined with the direct impacts of erosion, are largely responsible for plant death and ultimately poor plant cover. These issues can be alleviated if cover soil depth is increased to more than 0.5 m and slope angles are reduced to <12o. This study demonstrates the value of an ecophysiological approach for diagnosing problems affecting plant establishment at mine-rehabilitation sites. Furthermore, it has provided recommendations that will improve the rehabilitation strategy and lead to the development of a well vegetated, resilient ecosystem on a stable and non-polluting land form.

The central event in this thesis is the Little Desert dispute, a 1969 controversy about whether land in western Victoria should be developed for agriculture or retained as natural bushland. The Little Desert dispute has lived on in the minds of protagonists and later environmentalists as a cultural icon and a ‘win’ for conservation. This pivotal event provides a framework within which the politics of nature conservation, ecology and land management can be examined. The thesis explores the role of ‘public science’ – science in government, bureaucracy and the community – in this context, as well as tracing the history of the science of ecology in post-war Australia. / The second focus of this thesis is ‘the rise of ecological consciousness’ – the rise of the political relevance of the natural world and emerging concerns about the place of people in nature. This is a multifaceted concept, and includes ‘ecological’ in both its scientific and philosophical guises. ‘Consciousness’ is studied I the individual, collective and political senses. / The Little Desert dispute occurred just as ecological consciousness was beginning to rise in Australia and throughout the western world. The resolution of the dispute through the establishment of the Conservation Council of Victoria and the Land Conservation Council, in 1969 and 1970 respectively, was played out against a backdrop of changing environmental values and systems. The dispute had antecedents in diverse utilitarian, scientific, aesthetic and romantic conservation traditions. It was these values that motivated the leading protagonists, who were conservationists but not environmentalists. However, many environmentalists today look back on the Little Desert dispute as the beginning of the new ‘ecologically conscious’ era. The contribution of earlier conservationists to the environmental movement is often overlooked in environmentalist literature. Through examining closely the role of science and scientists in land management, this thesis explores some of the continuities as well as the discontinuities of the ‘environmental revolution’ in Australia.

More than two-thirds of Australia is classified as arid or semi arid and receives less than 500 mm of rain annually. Throughout these arid areas, rivers and drainage lines (which often have their catchments in higher rainfall areas) act as arteries for vast amounts of water to flow into these dry landscapes. Many inland rivers, including the Paroo, Bulloo and Cooper Creeks, have highly variable flow rates and can go many years with very little or no flow. As a result of the hydrology of these areas, they contain different soil characteristics and vegetation communities from the surrounding arid landscapes. For example, soil nutrients are thought to be higher along drainage lines and on floodplains due to sediment deposition and decomposition of organic material. Also, vegetation in these areas needs to not only survive drought conditions (as a plant or propogule), but also periodic inundation and flood events. These characteristics are thought to make these areas more productive than the surrounding arid lanscapes and are thought to be important habitats for flora and fauna. There has been much debate over the importance of riparian corridors to vertebrate species. Several studies internationally in mesic areas have suggested that riparian corridors contain higher levels of biodiversity than the surrounding habitats, although this pattern is not replicated in all areas or for all taxonomic groups. Many of these studies suggest that the difference in biodiversity between riparian areas and adjacent habitats should be greater in xeric areas where the habitat differences between these areas are greatest. Other studies have suggested that diversity is not necessarily greater but riparian areas are important habitats for different species and may act as a refuge for some species. In Australia, very few studies have been conducted on the importance of riparian corridors to vertebrates in arid areas, despite these habitats being under threat from grazing, flow alteration and flow diversion. In this study I examined the role of the Field River in the Simpson Desert as a potential refuge for vertebrate species and compared diversity and population dynamics of vertebrates at dune and riverine sites. Specifically this study aimed to: 1) determine if species richness of vertebrates along the Field River was greater in riverine ecosystems than the surrounding dune habitats; 2) quantify how the riverine habitats differed in terms of floristics, vegetation complexity, soils and water availability from the surrounding landscapes; 3) determine the dynamics of terrestrial vertebrate populations along the Field River; and 4) determine if the abundance, diversity and demographics of small vertebrate populations along the Field River was different from populations in the sand dune fields on a broader landscape scale. These questions were examined on Ethabuka Station in the Simpson Desert, Queensland, from 2006 to 2008. The riparian corridor along the Field River was found to have a range of characteristics that make it unique from the surrounding dune habitats. Soils along the riverine corridor were found to be characterised by more than 20% clay while soils on the dune crest were characterised by no more than 5% clay. Further, soil carbon and nitrogen was significantly higher in the riverine corridor than in the dune habitats and decreased with distance from the catchment. Spinifex (Triodia basedowii) cover was low in the corridor but dominated the dune swale. Number of trees and cover by trees and non-spinifex grasses were also significantly higher in the riverine corridor when compared to the surrounding dunes. Following the rainfall, annual cover was also significantly greater and they persisted much longer than in the dunes. There was very little difference in the diversity or number of invertebrates between the different habitat types. Species richness was estimated to be highest (48 species) in the riverine centre and lowest in the floodplain (30 species). The riverine habitats had different species pools when compared to the dune habitats. Several species including Amphibolurus longirostris and Litoria rubella exclusively inhabited the riverine habitats while others such as the skinks Ctenotus ariadnae and Ctenotus dux were captured only in the dune habitats. Results from a Canonical Correspondence Analysis suggest that the distribution of some species in arid areas, such as the introduced House Mouse (Mus musculus), may be correlated with habitat characteristics associated with the riverine corridor, e.g. soil moisture or high annual cover. Abundance, body condition and reproduction of mammals along the Field River was generally driven by time. On a local scale, habitat had little effect on the abundance of the Sandy Inland Mouse (Pseudomys hermannsburgensis) and Lesser Hairy-footed Dunnart (Sminthopsis youngsoni), although M. musculus showed some preference for the riverine corridor. Abundance and reproduction of both rodent species increased following rainfall while S. youngsoni abundance was strongly seasonal with increases in abundance in autumn and winter. More than 45% of all captures were reptiles and this group was the most diverse and conspicuous fauna group along the riverine corridor. Abundance of the two most common lizard species, the Military Dragon (Ctenophorus isolepis) and Central-netted Dragons (Ctenophorus nuchalis), was significantly affected by time, with the abundance of both species decreasing dramatically 12 months after rainfall, possibly due to increased predation. Abundance of the Beaked Gecko, Rhynchoedura ornata, began to decrease prior to rainfall, suggesting a factor other than habitat structure or food availability causing the decline. The skink, Lerista labialis, showed strong seasonal trends in abundance and body condition, which suggested that within the desert riverine corridor the species was not reliant on rain-induced changes in food availability. To compare the effect of habitat on species richness, composition and population dynamics at a regional scale, sites along the riparian corridor were compared with dune sites located 500 m to 45 km from the Field River. On this scale, species species richness varied spatially with only one of the riverine sites having higher estimated species richness than the dune sites. Species turnover was greater in riverine sites despite the habitat data suggesting that primary production in these sites was more stable. Some species were able to persist at riverine sites at all times of the year but were only present in the community at dune sites following rainfall, suggesting that the riverine sites may be a more stable habitat for some species. Composition analysis revealed that dune and riverine habitats contain different communities, and some species, particularly Amphibolurus longirostris and Litoria rubella, probably rely on the river for their habitat requirements. Population dynamics including abundance, reproduction and body condition of seven species were compared between dune and riverine habitats. Only four, M. musculus, L. labialis, C. nuchalis and S. youngsoni, showed any significant affect of habitat on abundance. Abundance of C. nuchalis, S. youngsoni and L. labialis were generally more abundant in the dune habitats although the affect was only significant for some sampling sessions. The only species that was significantly more abundant in the riverine habitats than dune habitats was the introduced M. musculus. This species appears to be reliant on the riverine corridor, only appearing commonly in the dune habitats following rainfall. For most species, the number of juveniles captured increased following the rainfall in January 2007 but only in C. nuchalis and P. hermannsburgensis was there any significant difference between habitat types. For both species, generally more juveniles were captured in the dune habitats than in the riverine habitats. This study provided information on the role of the Field River to vertebrate fauna on Ethabuka Station. Although, the study focused only on one ephemeral desert river, it could be considered representative of similar desert rivers such as the Hay, Plenty and Hale rivers further west in central Australia. The riverine corridor did represent a different habitat to the surrounding sand dunes, and some characteristics, such as greater soil moisture, soil nutrients and annual cover, suggest that it may have greater and more stable primary production. Although the species studied did not generally have greater abundance and body condition, or reproduce more in the riverine corridor, many species including the Long-nosed Dragon (Amphibolurus longirostris), Desert Tree Frog (Litoria rubella) and Pygmy Mulga Monitor (Varanus gilleni) are likely to rely on the habitat that the riverine corridor provides. With expanding human populations placing greater pressure on rivers around the world, particularly in arid areas, it is imperative that we understand the ecology of these riparian systems so that effective management and conservation strategies can be developed.

More than two-thirds of Australia is classified as arid or semi arid and receives less than 500 mm of rain annually. Throughout these arid areas, rivers and drainage lines (which often have their catchments in higher rainfall areas) act as arteries for vast amounts of water to flow into these dry landscapes. Many inland rivers, including the Paroo, Bulloo and Cooper Creeks, have highly variable flow rates and can go many years with very little or no flow. As a result of the hydrology of these areas, they contain different soil characteristics and vegetation communities from the surrounding arid landscapes. For example, soil nutrients are thought to be higher along drainage lines and on floodplains due to sediment deposition and decomposition of organic material. Also, vegetation in these areas needs to not only survive drought conditions (as a plant or propogule), but also periodic inundation and flood events. These characteristics are thought to make these areas more productive than the surrounding arid lanscapes and are thought to be important habitats for flora and fauna. There has been much debate over the importance of riparian corridors to vertebrate species. Several studies internationally in mesic areas have suggested that riparian corridors contain higher levels of biodiversity than the surrounding habitats, although this pattern is not replicated in all areas or for all taxonomic groups. Many of these studies suggest that the difference in biodiversity between riparian areas and adjacent habitats should be greater in xeric areas where the habitat differences between these areas are greatest. Other studies have suggested that diversity is not necessarily greater but riparian areas are important habitats for different species and may act as a refuge for some species. In Australia, very few studies have been conducted on the importance of riparian corridors to vertebrates in arid areas, despite these habitats being under threat from grazing, flow alteration and flow diversion. In this study I examined the role of the Field River in the Simpson Desert as a potential refuge for vertebrate species and compared diversity and population dynamics of vertebrates at dune and riverine sites. Specifically this study aimed to: 1) determine if species richness of vertebrates along the Field River was greater in riverine ecosystems than the surrounding dune habitats; 2) quantify how the riverine habitats differed in terms of floristics, vegetation complexity, soils and water availability from the surrounding landscapes; 3) determine the dynamics of terrestrial vertebrate populations along the Field River; and 4) determine if the abundance, diversity and demographics of small vertebrate populations along the Field River was different from populations in the sand dune fields on a broader landscape scale. These questions were examined on Ethabuka Station in the Simpson Desert, Queensland, from 2006 to 2008. The riparian corridor along the Field River was found to have a range of characteristics that make it unique from the surrounding dune habitats. Soils along the riverine corridor were found to be characterised by more than 20% clay while soils on the dune crest were characterised by no more than 5% clay. Further, soil carbon and nitrogen was significantly higher in the riverine corridor than in the dune habitats and decreased with distance from the catchment. Spinifex (Triodia basedowii) cover was low in the corridor but dominated the dune swale. Number of trees and cover by trees and non-spinifex grasses were also significantly higher in the riverine corridor when compared to the surrounding dunes. Following the rainfall, annual cover was also significantly greater and they persisted much longer than in the dunes. There was very little difference in the diversity or number of invertebrates between the different habitat types. Species richness was estimated to be highest (48 species) in the riverine centre and lowest in the floodplain (30 species). The riverine habitats had different species pools when compared to the dune habitats. Several species including Amphibolurus longirostris and Litoria rubella exclusively inhabited the riverine habitats while others such as the skinks Ctenotus ariadnae and Ctenotus dux were captured only in the dune habitats. Results from a Canonical Correspondence Analysis suggest that the distribution of some species in arid areas, such as the introduced House Mouse (Mus musculus), may be correlated with habitat characteristics associated with the riverine corridor, e.g. soil moisture or high annual cover. Abundance, body condition and reproduction of mammals along the Field River was generally driven by time. On a local scale, habitat had little effect on the abundance of the Sandy Inland Mouse (Pseudomys hermannsburgensis) and Lesser Hairy-footed Dunnart (Sminthopsis youngsoni), although M. musculus showed some preference for the riverine corridor. Abundance and reproduction of both rodent species increased following rainfall while S. youngsoni abundance was strongly seasonal with increases in abundance in autumn and winter. More than 45% of all captures were reptiles and this group was the most diverse and conspicuous fauna group along the riverine corridor. Abundance of the two most common lizard species, the Military Dragon (Ctenophorus isolepis) and Central-netted Dragons (Ctenophorus nuchalis), was significantly affected by time, with the abundance of both species decreasing dramatically 12 months after rainfall, possibly due to increased predation. Abundance of the Beaked Gecko, Rhynchoedura ornata, began to decrease prior to rainfall, suggesting a factor other than habitat structure or food availability causing the decline. The skink, Lerista labialis, showed strong seasonal trends in abundance and body condition, which suggested that within the desert riverine corridor the species was not reliant on rain-induced changes in food availability. To compare the effect of habitat on species richness, composition and population dynamics at a regional scale, sites along the riparian corridor were compared with dune sites located 500 m to 45 km from the Field River. On this scale, species species richness varied spatially with only one of the riverine sites having higher estimated species richness than the dune sites. Species turnover was greater in riverine sites despite the habitat data suggesting that primary production in these sites was more stable. Some species were able to persist at riverine sites at all times of the year but were only present in the community at dune sites following rainfall, suggesting that the riverine sites may be a more stable habitat for some species. Composition analysis revealed that dune and riverine habitats contain different communities, and some species, particularly Amphibolurus longirostris and Litoria rubella, probably rely on the river for their habitat requirements. Population dynamics including abundance, reproduction and body condition of seven species were compared between dune and riverine habitats. Only four, M. musculus, L. labialis, C. nuchalis and S. youngsoni, showed any significant affect of habitat on abundance. Abundance of C. nuchalis, S. youngsoni and L. labialis were generally more abundant in the dune habitats although the affect was only significant for some sampling sessions. The only species that was significantly more abundant in the riverine habitats than dune habitats was the introduced M. musculus. This species appears to be reliant on the riverine corridor, only appearing commonly in the dune habitats following rainfall. For most species, the number of juveniles captured increased following the rainfall in January 2007 but only in C. nuchalis and P. hermannsburgensis was there any significant difference between habitat types. For both species, generally more juveniles were captured in the dune habitats than in the riverine habitats. This study provided information on the role of the Field River to vertebrate fauna on Ethabuka Station. Although, the study focused only on one ephemeral desert river, it could be considered representative of similar desert rivers such as the Hay, Plenty and Hale rivers further west in central Australia. The riverine corridor did represent a different habitat to the surrounding sand dunes, and some characteristics, such as greater soil moisture, soil nutrients and annual cover, suggest that it may have greater and more stable primary production. Although the species studied did not generally have greater abundance and body condition, or reproduce more in the riverine corridor, many species including the Long-nosed Dragon (Amphibolurus longirostris), Desert Tree Frog (Litoria rubella) and Pygmy Mulga Monitor (Varanus gilleni) are likely to rely on the habitat that the riverine corridor provides. With expanding human populations placing greater pressure on rivers around the world, particularly in arid areas, it is imperative that we understand the ecology of these riparian systems so that effective management and conservation strategies can be developed.