The influence of simulated erosion on crop growth and the value of topsoil in soil productivity

Non-Peer ReviewedWind erosion is a major soil degradation phenomenon on the Canadian prairies but its effects on soil productivity are not well quantified. In the spring of 1990, incremental depths of soil (0, 5, 10, 15 and 20 cm) were removed with an excavator, to simulate wind erosion at four sites (three dryland and one irrigated) in southern Alberta. Highly significant non-linear relationships were found between the depth of de-surfacing and subsequent spring wheat grain yields showing that simulated erosion drastically reduced soil productivity. Treatment effects at the irrigated site followed the same trend as the dryland site illustrating that topsoil loss cannot be compensated by adequate soil moisture. The 0-1 cm increment of topsoil was worth more (in terms of magnitude of yield loss when it was removed) on the irrigated site followed by the Black, Dark Brown, and Brown dryland soils

Residual impact of topsoil removal and soil amendments on crop productivity over sixteen years

Non-Peer ReviewedSoil erosion remains a threat to our global soil resource. This study was conducted to ascertain the effects of simulated erosion on soil productivity and methods for its amendment. Incremental depths (0, 5, 10, 15 and 20 cm) of surface soil or cuts were mechanically removed to simulate erosion at two sites (one dryland, one irrigated) in southern Alberta in 1990. Three amendment treatments (nitrogen + phosphorus fertilizer, 5 cm of topsoil, or 75 Mg ha-1 of feedlot manure) and a check were superimposed on each of the cuts. The sites were cropped annually until 2006. On average, sixteen year yield reductions were 10.0 % for 5 cm, 19.5 % for 10 cm, 29.0 % for 15 cm and 38.5 % for 20 cm of topsoil removal. Average grain yield loss was 50 kg ha-1 cm-1 yr-1 at the Dryland site and 59 kg ha-1 cm-1 yr-1 at the Irrigated site. Amendments ranked manure > topsoil > fertilizer in terms of restoring productivity to the desurfaced soils. The study reinforces the need to prevent erosion and indicates that application of livestock manure is an option for restoring soil productivity in the short term

Practising social justice: Community organisations, what matters and what counts

This thesis investigates the situated knowing-in-practice of locally-based community organisations, and studies how this practice knowledge is translated and contested in inter-organisational relations in the community services field of practices. Despite participation in government-led consultation processes, community organisations express frustration that the resulting policies and plans inadequately take account of the contributions from their practice knowledge. The funding of locally-based community organisations is gradually diminishing in real terms and in the competitive tendering environment, large nationally-based organisations often attract the new funding sources. The concern of locally-based community organisations is that the apparent lack of understanding of their distinctive practice knowing is threatening their capacity to improve the well-being of local people and their communities. In this study, I work with practitioners, service participants and management committee members to present an account of their knowing-in-practice, its character and conditions of efficacy; and then investigate what happens when this local practice knowledge is translated into results-based accountability (RBA) planning with diverse organisations and institutions. This thesis analyses three points of observation: knowing in a community of practitioners; knowing in a community organisation and knowing in the community services field of practices. In choosing these points of observation, the inquiry explores some of the relations and intra-actions from the single organisation to the institutional at a time when state government bureaucracy has mandated that community organisations implement RBA to articulate outcomes that can be measured by performance indicators. A feminist, performative, relational practice-based approach employs participatory action research to achieve an enabling research experience for the participants. It aims to intervene strategically to enhance recognition of the distinctive contributions of community organisations’ practice knowledge. This thesis reconfigures understandings of the roles, contributions and accountabilities of locally-based community organisations. Observations of situated practices together with the accounts of workers and service participants demonstrate how community organisations facilitate service participants’ struggles over social justice. A new topology for rethinking social justice as processual and practice-based is developed. It demonstrates how these struggles are a dynamic complex of iteratively-enfolded practices of respect and recognition, redistribution and distributive justice, representation and participation, belonging and inclusion. The focus on the practising of social justice in this thesis offers an alternative to the neo-liberal discourse that positions community organisations as sub-contractors accountable to government for delivering measurable outputs, outcomes and efficiencies in specified service provision contracts. The study shows how knowing-in-practice in locally-based community organisations contests the representational conception of knowledge inextricably entangled with accountability and performance measurement apparatus such as RBA. Further, it suggests that practitioner and service participant contributions are marginalised and diminished in RBA through the privileging of knowledge that takes an ‘expert’, quantifiable and calculative form. Thus crucially, harnessing local practice knowing requires re-imagining and enacting knowledge spaces that assemble and take seriously all relevant stakeholder perspectives, diverse knowledges and methods

Secondary metabolite profiling, growth profiles and other tools for species recognition and important Aspergillus mycotoxins

Species in the genus Aspergillus have been classified primarily based on morphological features. Sequencing of house-hold genes has also been used in Aspergillus taxonomy and phylogeny, while extrolites and physiological features have been used less frequently. Three independent ways of classifying and identifying aspergilli appear to be applicable: Morphology combined with physiology and nutritional features, secondary metabolite profiling and DNA sequencing. These three ways of identifying Aspergillus species often point to the same species. This consensus approach can be used initially, but if consensus is achieved it is recommended to combine at least two of these independent ways of characterising aspergilli in a polyphasic taxonomy. The chemical combination of secondary metabolites and DNA sequence features has not been explored in taxonomy yet, however. Examples of these different taxonomic approaches will be given for Aspergillus section Nigri

Terrestrial habitat requirements of nesting freshwater turtles

Because particular life history traits affect species vulnerability to development pressures, cross-species summaries of life history traits are useful for generating management guidelines. Conservation of aquatic turtles, many members of which are regionally or globally imperiled, requires knowing the extent of upland habitat used for nesting. Therefore, we compiled distances that nests and gravid females had been observed from wetlands. Based on records of \u3e 8000 nests and gravid female records compiled for 31 species in the United States and Canada, the distances that encompass 95% of nests vary dramatically among genera and populations, from just 8 m for Malaclemys to nearly 1400 m for Trachemys. Widths of core areas to encompass varying fractions of nesting populations (based on mean maxima across all genera) were estimated as: 50% coverage = 93 m, 75% = 154 m, 90% = 198 m, 95% = 232 m, 100% = 942 m. Approximately 6–98 m is required to encompass each consecutive 10% segment of a nesting population up to 90% coverage; thereafter, ca. 424 m is required to encompass the remaining 10%. Many genera require modest terrestrial areas (\u3c200 m zones) for 95% nest coverage (Actinemys, Apalone, Chelydra, Chrysemys, Clemmys, Glyptemys, Graptemys, Macrochelys, Malaclemys, Pseudemys, Sternotherus), whereas other genera require larger zones (Deirochelys, Emydoidea, Kinosternon, Trachemys). Our results represent planning targets for conserving sufficient areas of uplands around wetlands to ensure protection of turtle nesting sites, migrating adult female turtles, and dispersing turtle hatchlings

The western painted turtle genome, a model for the evolution of extreme physiological adaptations in a slowly evolving lineage

Background: We describe the genome of the western painted turtle, Chrysemys picta bellii, one of the most widespread, abundant, and well-studied turtles. We place the genome into a comparative evolutionary context, and focus on genomic features associated with tooth loss, immune function, longevity, sex differentiation and determination, and the species' physiological capacities to withstand extreme anoxia and tissue freezing.Results: Our phylogenetic analyses confirm that turtles are the sister group to living archosaurs, and demonstrate an extraordinarily slow rate of sequence evolution in the painted turtle. The ability of the painted turtle to withstand complete anoxia and partial freezing appears to be associated with common vertebrate gene networks, and we identify candidate genes for future functional analyses. Tooth loss shares a common pattern of pseudogenization and degradation of tooth-specific genes with birds, although the rate of accumulation of mutations is much slower in the painted turtle. Genes associated with sex differentiation generally reflect phylogeny rather than convergence in sex determination functionality. Among gene families that demonstrate exceptional expansions or show signatures of strong natural selection, immune function and musculoskeletal patterning genes are consistently over-represented.Conclusions: Our comparative genomic analyses indicate that common vertebrate regulatory networks, some of which have analogs in human diseases, are often involved in the western painted turtle's extraordinary physiological capacities. As these regulatory pathways are analyzed at the functional level, the painted turtle may offer important insights into the management of a number of human health disorders

Diverse aging rates in ectothermic tetrapods provide insights for the evolution of aging and longevity

Comparative studies of mortality in the wild are necessary to understand the evolution of aging; yet, ectothermic tetrapods are underrepresented in this comparative landscape, despite their suitability for testing evolutionary hypotheses. We present a study of aging rates and longevity across wild tetrapod ectotherms, using data from 107 populations (77 species) of nonavian reptiles and amphibians. We test hypotheses of how thermoregulatory mode, environmental temperature, protective phenotypes, and pace of life history contribute to demographic aging. Controlling for phylogeny and body size, ectotherms display a higher diversity of aging rates compared with endotherms and include phylogenetically widespread evidence of negligible aging. Protective phenotypes and life-history strategies further explain macroevolutionary patterns of aging. Analyzing ectothermic tetrapods in a comparative context enhances our understanding of the evolution of aging.Animal science