Many physically-based models of surface and groundwater hydrology are constructed without the possibility of multiple stable states. For such a conceptualisation, at the cessation of a transient hydrological disturbance of any magnitude, the model will return to the original stable state and therefore will have an infinite resilience. Ecosystem resilience science propose a very different dynamic where, if the system has a positive feedback, disturbances may shift the system over a threshold where, upon cessation of the disturbance, the system will move to a different steady state. This dissertation brings together concepts from hydrology and ecosystem resilience science to highlight this often implicit assumption within hydrology. It tests the assumption that dry land water-limited catchments always have only one steady state (henceforth referred to as 'attractor'). Following a discussion of this implicit assumption within hydrology, approaches for rigorous testing that could result in its falsification are considered and that of numerical modelling is adopted. The aims of the research were to test this assumption by proposing a biophysically plausible hydrological model; utilise it to investigate the catchment attributes likely to result in multiple attractors; and to assess the model's validity by way of implementation and calibration. (For complete abstract open document.)

In much of Australia and the United States, the almost universal right to have a house on rural allotments has resulted in rural living settlement in areas intended, by land use planning policy, to be used for agriculture. Such ‘unplanned’ rural living has a range of potential adverse impacts, including, among other things, loss of agricultural production, land use conflicts with agriculture, land value constraints on farm restructuring, and changes to the rural landscape character. Given the strongly held community perception of a house as a development right, this research was motivated by the need to understand the effects of that right, in order to assess the potential value of any change in policy. An integral consideration was the influence of the size of allotments with any such right. The research was also driven by an interest in explaining the pattern of unplanned rural living settlement, i.e. why are particular allotments converted and others not? Largely in the absence of previous studies of unplanned rural living as a distinct phenomenon, there was scope for this thesis to make a contribution to knowledge in these respects. The research involved three stages of empirical analysis. Firstly, a Queensland-wide survey of land use conversion from sugarcane production supported the choice of the Bundaberg region as the study area. Contingency table analyses were then conducted into the current land use and other attributes of land in the study area that, in 1980, was used for sugarcane. Those analyses identified distinguishing attributes of the different land use sub-sets of allotments, and informed the selection of observation units for the third stage. The third stage provided the principal basis for fulfilling the research objectives. It focused on logit models of the choice, at the time of sale, between using a particular allotment for unplanned rural living or sugarcane production. Those analyses provided an indication of the role of individual land attributes while controlling for the effects of other attributes. It was found there had been limited conversion of suitable, productive sugarcane land to unplanned rural living. Compared to those allotments that remained in sugarcane production, allotments converted to rural living were, on average, much smaller, of less value, had lower agricultural production potential, and were situated in more undulating and forested landscapes further from Bundaberg. These clear distinctions between rural living and sugarcane allotments contributed to logit models with high explanatory power. The expected productive income of allotments had overwhelming weight and was highly statistically significant in explaining the land use choice between unplanned rural living and sugarcane. This is a notable finding, because some other studies have not shown such a strong relationship between land use and measures such as soil productivity. There was a degree of natural coincidence between more undulating and forested landscapes and lower productive potential. Notably, landscape attributes appeared to be of secondary importance in determining land use. The presence of a house at the time of sale was not a statistically significant explanatory factor for land use. This finding, together with that of limited conversion of suitable, productive land to unplanned rural living, meant there was a lack of evidence to support a change to the right to have a house on rural allotments. The findings did indicate that the allotment area required to avoid conversion to unplanned rural living was different to the area required for agricultural viability. In the circumstances of this study area and period, 20 ha would have been an acceptable minimum to retain suitable cropping land in productive use. This is compared to the 60 ha suggested as necessary for farm viability. However, the potential for changed economic conditions to reduce the productive value of agricultural land, and increase demand for rural living, makes it appropriate to be cautious about permitted allotment sizes. A detailed conceptual framework informed the selection of observation units and variables for the third stage of analyses. The framework helped to confirm allotment sales as the observation units, and provided the rationale for excluding the difficult to measure influences of a landowner’s attachment to the land, and inertia, as explanatory variables. The high explanatory power of the logit models provides support for the approach, which may be useful in future studies.

In much of Australia and the United States, the almost universal right to have a house on rural allotments has resulted in rural living settlement in areas intended, by land use planning policy, to be used for agriculture. Such ‘unplanned’ rural living has a range of potential adverse impacts, including, among other things, loss of agricultural production, land use conflicts with agriculture, land value constraints on farm restructuring, and changes to the rural landscape character. Given the strongly held community perception of a house as a development right, this research was motivated by the need to understand the effects of that right, in order to assess the potential value of any change in policy. An integral consideration was the influence of the size of allotments with any such right. The research was also driven by an interest in explaining the pattern of unplanned rural living settlement, i.e. why are particular allotments converted and others not? Largely in the absence of previous studies of unplanned rural living as a distinct phenomenon, there was scope for this thesis to make a contribution to knowledge in these respects. The research involved three stages of empirical analysis. Firstly, a Queensland-wide survey of land use conversion from sugarcane production supported the choice of the Bundaberg region as the study area. Contingency table analyses were then conducted into the current land use and other attributes of land in the study area that, in 1980, was used for sugarcane. Those analyses identified distinguishing attributes of the different land use sub-sets of allotments, and informed the selection of observation units for the third stage. The third stage provided the principal basis for fulfilling the research objectives. It focused on logit models of the choice, at the time of sale, between using a particular allotment for unplanned rural living or sugarcane production. Those analyses provided an indication of the role of individual land attributes while controlling for the effects of other attributes. It was found there had been limited conversion of suitable, productive sugarcane land to unplanned rural living. Compared to those allotments that remained in sugarcane production, allotments converted to rural living were, on average, much smaller, of less value, had lower agricultural production potential, and were situated in more undulating and forested landscapes further from Bundaberg. These clear distinctions between rural living and sugarcane allotments contributed to logit models with high explanatory power. The expected productive income of allotments had overwhelming weight and was highly statistically significant in explaining the land use choice between unplanned rural living and sugarcane. This is a notable finding, because some other studies have not shown such a strong relationship between land use and measures such as soil productivity. There was a degree of natural coincidence between more undulating and forested landscapes and lower productive potential. Notably, landscape attributes appeared to be of secondary importance in determining land use. The presence of a house at the time of sale was not a statistically significant explanatory factor for land use. This finding, together with that of limited conversion of suitable, productive land to unplanned rural living, meant there was a lack of evidence to support a change to the right to have a house on rural allotments. The findings did indicate that the allotment area required to avoid conversion to unplanned rural living was different to the area required for agricultural viability. In the circumstances of this study area and period, 20 ha would have been an acceptable minimum to retain suitable cropping land in productive use. This is compared to the 60 ha suggested as necessary for farm viability. However, the potential for changed economic conditions to reduce the productive value of agricultural land, and increase demand for rural living, makes it appropriate to be cautious about permitted allotment sizes. A detailed conceptual framework informed the selection of observation units and variables for the third stage of analyses. The framework helped to confirm allotment sales as the observation units, and provided the rationale for excluding the difficult to measure influences of a landowner’s attachment to the land, and inertia, as explanatory variables. The high explanatory power of the logit models provides support for the approach, which may be useful in future studies.

In much of Australia and the United States, the almost universal right to have a house on rural allotments has resulted in rural living settlement in areas intended, by land use planning policy, to be used for agriculture. Such ‘unplanned’ rural living has a range of potential adverse impacts, including, among other things, loss of agricultural production, land use conflicts with agriculture, land value constraints on farm restructuring, and changes to the rural landscape character. Given the strongly held community perception of a house as a development right, this research was motivated by the need to understand the effects of that right, in order to assess the potential value of any change in policy. An integral consideration was the influence of the size of allotments with any such right. The research was also driven by an interest in explaining the pattern of unplanned rural living settlement, i.e. why are particular allotments converted and others not? Largely in the absence of previous studies of unplanned rural living as a distinct phenomenon, there was scope for this thesis to make a contribution to knowledge in these respects. The research involved three stages of empirical analysis. Firstly, a Queensland-wide survey of land use conversion from sugarcane production supported the choice of the Bundaberg region as the study area. Contingency table analyses were then conducted into the current land use and other attributes of land in the study area that, in 1980, was used for sugarcane. Those analyses identified distinguishing attributes of the different land use sub-sets of allotments, and informed the selection of observation units for the third stage. The third stage provided the principal basis for fulfilling the research objectives. It focused on logit models of the choice, at the time of sale, between using a particular allotment for unplanned rural living or sugarcane production. Those analyses provided an indication of the role of individual land attributes while controlling for the effects of other attributes. It was found there had been limited conversion of suitable, productive sugarcane land to unplanned rural living. Compared to those allotments that remained in sugarcane production, allotments converted to rural living were, on average, much smaller, of less value, had lower agricultural production potential, and were situated in more undulating and forested landscapes further from Bundaberg. These clear distinctions between rural living and sugarcane allotments contributed to logit models with high explanatory power. The expected productive income of allotments had overwhelming weight and was highly statistically significant in explaining the land use choice between unplanned rural living and sugarcane. This is a notable finding, because some other studies have not shown such a strong relationship between land use and measures such as soil productivity. There was a degree of natural coincidence between more undulating and forested landscapes and lower productive potential. Notably, landscape attributes appeared to be of secondary importance in determining land use. The presence of a house at the time of sale was not a statistically significant explanatory factor for land use. This finding, together with that of limited conversion of suitable, productive land to unplanned rural living, meant there was a lack of evidence to support a change to the right to have a house on rural allotments. The findings did indicate that the allotment area required to avoid conversion to unplanned rural living was different to the area required for agricultural viability. In the circumstances of this study area and period, 20 ha would have been an acceptable minimum to retain suitable cropping land in productive use. This is compared to the 60 ha suggested as necessary for farm viability. However, the potential for changed economic conditions to reduce the productive value of agricultural land, and increase demand for rural living, makes it appropriate to be cautious about permitted allotment sizes. A detailed conceptual framework informed the selection of observation units and variables for the third stage of analyses. The framework helped to confirm allotment sales as the observation units, and provided the rationale for excluding the difficult to measure influences of a landowner’s attachment to the land, and inertia, as explanatory variables. The high explanatory power of the logit models provides support for the approach, which may be useful in future studies.

Marine ecosystems are increasingly being subject to human impact from diverse recreational and commercial activities, not necessarily restricted to those of a marine nature. This has significant implications for biodiversity. The large dog cockle, Tucetona laticostata, once occurred live in Rangitoto Channel, Hauraki Gulf, although this species no longer appears to occur there, most likely as a consequence of repeated dredging and channel excavation and continued siltation. Tucetona laticostata still occurs in a few isolated pockets of sea bed throughout Hauraki Gulf, particularly off Otata Island, part of the Noises complex of islands, where it resides partially buried in shell and rock gravels in shallow water (to 15 metres depth). The shells of T. laticostata collect in large post-mortem deposits in an area ramping from the sea bed off southwestern Otata Island. These mounds differ significantly in structural complexity from those of adjacent, extensively fragmented shell and rock gravels. Using the mounds of T. laticostata shell as a proxy for structural complexity, in order to appraise the effect of complexity on benthic-invertebrate diversity, the sea bed off southwestern Otata Island was sampled quarterly at two depths and in both T. laticostata shell mounds and adjacent extensively fragmented shell and rock gravels. These data were complemented with those from additional surveys around Otata Island, and off eastern Motutapu Island to determine the distribution and composition of benthic-invertebrate community assemblages throughout the region, and from concurrent surveys throughout the Waitemata Harbour and inner Hauraki Gulf to determine the current distribution of T. laticostata in this region. The number of benthic invertebrate species and individuals within T. laticostata habitat almost always was higher than that occurring within extensively fragmented shell- and rock gravel habitat, with densities to 142,385 individuals m-2 encountered. Temporal and spatial variations in benthic community structure also are reported for the two habitats, T. laticostata-based shells and extensively fragmented shell- and rock gravels. The numbers of species were higher amongst samples collected off the southwestern and eastern sides of Otata Island than elsewhere around this island, or of eastern Motutapu Island. Of the 351 species reported from all Otata and Motutapu Island samples combined, 73% of them occurred off southwestern Otata Island, 30% of which were found exclusively within T. laticostata shell habitat, and 10.5% within extensively fragmented shell and rock gravel habitat. The sea bed off southwestern Otata Island is regularly, seasonally dredged by recreational scallop fishers, in addition to being a popular small-vessel anchorage site. Both of these activities, dredging and anchorage, stand to reduce substratum complexity by fragmentation and dispersal of the valves of T. laticostata. Given the unique benthic invertebrates reported from T. laticostata shell deposits reported from southwestern Otata Island, any activity that damages the shells of this species, regardless of whether they are live or dead, is likely to result in loss of biodiversity. Admittedly, many of species identified as major contributors to differences in benthic invertebrate assemblages between T. laticostata shell-based habitats and those of extensively fragmented shell and rock gravels are not particularly charismatic or large, but each likely plays a role in local food webs and/or sediment and water column chemistry. It was not the intention of this research to determine the effects of anthropogenic disturbances like dredging or vessel anchorage on benthic-invertebrate communities off southwestern Otata Island. However, given the reported differences in species diversity within the structurally complex substratum provided by T. laticostata, conservation of biogenic reef-forming species like it might be a prudent, precautionary measure to take.

New Zealand is an isolated island nation and more than 95% of its commodities are imported by ship, making New Zealand particularly vulnerable to marine bioinvasion. Its marine biota and ecosystem are unique with numerous endemic organisms, and it is a biodiversity hotspot of global significance. The objective of this study was to integrate invasive theory with phylogeographic studies on a native ascidian. This study was motivated by the introduction of an invasive ascidian, Styela clava to New Zealand. To date, S. clava’s cytochrome oxidase I (COI) data indicate limited sharing of haplotypes between the ports of Lyttelton and Auckland, and areas within Hauraki Gulf. The connectivity between these disparate sites may be a consequence either of common overseas origins via international shipping or local vectoring within New Zealand by coastal shipping. In this thesis I have examined the phylogeographic relationships among populations of an endemic ascidian, Cnemidocarpa nisiotis, to attempt to gauge the likely role that local vectoring plays in the movement of ascidians and other species among New Zealand ports. This study also provides the first population genetic information on a native New Zealand ascidian An endemic New Zealand ascidian was chosen as the study species because the use of an endemic species excludes or at least reduces the possibility of external input from overseas sites con-founding any patterns observed in the data. Furthermore, by excluding external input, the pattern of genetic diversity observed in this species might enable us to determine if local shipping pathways are homogenising C. nisiotis populations. C. nisiotis individuals were collected inside and outside of ports and marinas around Haruaki Gulf, Wellington, Lyttelton, and Dunedin harbours. Each individual were dissected and morphologically identified. Morphological identification of C. nisiotis matched type specimen (Chapter 2). However, preliminary results with COI haplotype network revealed three lineages (A, B and C) and such was the level of differences among these lineages raised the question of the possibility of a cryptic species. This 3 hypothesis was further investigated with phylogenetic analysis using both COI and 18S ribosomal DNA sequence data. Phylogeographic analysis of C. nisiotis COI molecular data demonstrated no significant population genetic structure, with a single common haplotype shared between the North and South islands (Chapter 4). Sharing of haplotypes was also evident between harbours in the South Island and within sites where population samples from inside ports, marinas, and natural habitats were not significantly different from each other. The lack of difference between the North and South Island for this species was surprising given that it was believed to have limited dispersal ability in the absence of anthropogenic movement. However, C. nisiotis displays a star-like phylogeny indicative of a selective sweep, population bottleneck or founder event followed by a population range expansion, thus the lack of difference between islands may be a consequence of too little evolutionary time having passed since the populations shared a common origin for differentiation to have occurred.

In much of Australia and the United States, the almost universal right to have a house on rural allotments has resulted in rural living settlement in areas intended, by land use planning policy, to be used for agriculture. Such ‘unplanned’ rural living has a range of potential adverse impacts, including, among other things, loss of agricultural production, land use conflicts with agriculture, land value constraints on farm restructuring, and changes to the rural landscape character. Given the strongly held community perception of a house as a development right, this research was motivated by the need to understand the effects of that right, in order to assess the potential value of any change in policy. An integral consideration was the influence of the size of allotments with any such right. The research was also driven by an interest in explaining the pattern of unplanned rural living settlement, i.e. why are particular allotments converted and others not? Largely in the absence of previous studies of unplanned rural living as a distinct phenomenon, there was scope for this thesis to make a contribution to knowledge in these respects. The research involved three stages of empirical analysis. Firstly, a Queensland-wide survey of land use conversion from sugarcane production supported the choice of the Bundaberg region as the study area. Contingency table analyses were then conducted into the current land use and other attributes of land in the study area that, in 1980, was used for sugarcane. Those analyses identified distinguishing attributes of the different land use sub-sets of allotments, and informed the selection of observation units for the third stage. The third stage provided the principal basis for fulfilling the research objectives. It focused on logit models of the choice, at the time of sale, between using a particular allotment for unplanned rural living or sugarcane production. Those analyses provided an indication of the role of individual land attributes while controlling for the effects of other attributes. It was found there had been limited conversion of suitable, productive sugarcane land to unplanned rural living. Compared to those allotments that remained in sugarcane production, allotments converted to rural living were, on average, much smaller, of less value, had lower agricultural production potential, and were situated in more undulating and forested landscapes further from Bundaberg. These clear distinctions between rural living and sugarcane allotments contributed to logit models with high explanatory power. The expected productive income of allotments had overwhelming weight and was highly statistically significant in explaining the land use choice between unplanned rural living and sugarcane. This is a notable finding, because some other studies have not shown such a strong relationship between land use and measures such as soil productivity. There was a degree of natural coincidence between more undulating and forested landscapes and lower productive potential. Notably, landscape attributes appeared to be of secondary importance in determining land use. The presence of a house at the time of sale was not a statistically significant explanatory factor for land use. This finding, together with that of limited conversion of suitable, productive land to unplanned rural living, meant there was a lack of evidence to support a change to the right to have a house on rural allotments. The findings did indicate that the allotment area required to avoid conversion to unplanned rural living was different to the area required for agricultural viability. In the circumstances of this study area and period, 20 ha would have been an acceptable minimum to retain suitable cropping land in productive use. This is compared to the 60 ha suggested as necessary for farm viability. However, the potential for changed economic conditions to reduce the productive value of agricultural land, and increase demand for rural living, makes it appropriate to be cautious about permitted allotment sizes. A detailed conceptual framework informed the selection of observation units and variables for the third stage of analyses. The framework helped to confirm allotment sales as the observation units, and provided the rationale for excluding the difficult to measure influences of a landowner’s attachment to the land, and inertia, as explanatory variables. The high explanatory power of the logit models provides support for the approach, which may be useful in future studies.

Diss. (sammanfattning) Uppsala : Univ., 2004. / Härtill 6 uppsatser.

Thesis (M.S.)--University of Nevada, Reno, 2005. / "May, 2005." Includes bibliographical references. Online version available on the World Wide Web.

Thesis (Ph. D.)--Washington State University, August 2008. / Includes bibliographical references.