Evaluating soil health using bioindicator organisms has been suggested as a method of analyzing the long-term sustainability of agricultural management practices. The main objective of this study was to determine the effects of vineyard management strategies on soil food web structure and function, using nematodes as bioindicators by calculating established nematode ecological indices. Three field trials were conducted in a commercial Pinot Noir vineyard in San Luis Obispo, California; the effects of (i) fertilizer type (organic and inorganic), (ii) weed management (herbicide and tillage), and (iii) cover crops (high or low water requirements) on nematode community structure, soil nutrient content, and crop quality and yield were analyzed. Overall, although nematode ecological indices indicated that all plots had disturbed soil food webs, the indices proved to be less useful for measuring subtle differences in soil management over the short-term than anticipated. They showed few differences treatments. In general, the most pronounced differences were seen by sample location (under the vine or in the tractor row) and sample date, rather than treatment. None of the evaluated strategies affected crop quality, although fertilizer had a slight effect on yield. However, several indices were correlated with soil chemical parameters, including pH, nitrogen, carbon, and, to a lesser extent, EC. These results indicate that while nematode indices can be useful for comparing the state of the soil food web under long-term soil conditions, they may not be a robust measure of how agricultural management practices change soil health over a single growing season.

The hydrography of Utah may be thought of as being roughly divided into two large general drainage areas--, the Colorado River draining the eastern halt and southern portion ot the state and the Bonneville Drainage encompassing the remaining part of it. Earlier workers have listed eight genera and fourteen species of minnows occuring in Utah. Of these this report includes seven genera and ten species found within the borders of our state.

No description available.

Thesis (M.S.)--Simon Fraser University, 1999. / Includes bibliographical references (leaf 69).

Four 286m2 plots on alternate sides of the spur ridges on Brush Mt. were established and their plant communities characterized. Agaric and Bolete basidiomycetes were sampled for two years. Fifty species were recorded on the plots. Phenologically, decomposer species were highly dependent upon rainfall events, whereas mycorrhizal species were more seasonal. Two species emerged as dominant litter decomposers. Marasmiellus praeacutus (Ellis) Halling is dominant on southwest facing slopes and occurs on a wide variety of coniferous and hardwood detritus. Collybia subnuda (Ellis ex. Peck) Gilliam is dominant on northeast facing slopes, and occurs on hardwood leaves and small woody detritus. The population structure of both of these species was investigated using tests of somatic incompatibility. Genets of both species are able to persist for more than one year. The observed minimum population density is 0.071 - 0.121 genets/m² for M. praeacutus and 0.039 - 0.093 genets/m² for g. subnuda. Mating tests indicate that M. praeacutus is heterothallic and tetrapolar, and that C. subnuda is heterothallic and bipolar. Preliminary crosses between monokaryotic tester sets indicate a surprisingly low number of mating alleles in both species. Decomposition studies suggest that while the restricted distribution of ~. subnuda to the northeast slopes may be affected by substrate specificity, the restriction of M. praeacutus to the southwest slopes is due to other factors. / Master of Science

No description available.

published_or_final_version / Ecology and Biodiversity / Master / Master of Philosophy

Landscape management has altered the population dynamics of many species residing in old growth ecosystems. As a result, fragmentations in residual old oak habitats in Sweden have led to the decline of endangered and long-lived polypores including the bright orange Hapalopilus croceus. Since little is known about this species, the aim was to investigate its growth, mating, and population biology using molecular and ecological methods. Specifically, what its growth patterns are, what its mating type is, and whether there is genetic variation among sampled populations in Sweden and the Baltic area. Fruiting body samples were collected from 34 localities in Sweden and 6 localities in neighboring Baltic States. Heterokaryotic mycelia were then cultivated from these samples and the genomes sequenced. 42 single-spore isolates from SLU's culture bank were also revived and cultured. These homokaryons were then crossed to determine mating type. Mating type was examined using morphological observations and calculated via mating matrix. To examine growth rate and establishment, H. croceus mycelia were grown in comparison to Fomitopsis pinicola mycelia. To explore the population biology, the potential for gene flow was analyzed among Swedish and Baltic isolates. As a result, H. croceus was found to be slow growing, exhibit a tetra polar mating type, and with limited genetic variation in the Baltic Sea area. Its slow growth could provide a possible insight into colonization strategy, whereas its multiallelic mating system could possibly increase outcrossing in the future. Minimal genetic variation could result from previous connectivity between oaks, where the fungus may have outbred readily and colonized more hosts, maintaining a more uniform genetic structure. However, recent habitat alteration has not been analyzed for this species, nor has community interaction among other fungi and fruiting dynamics. Thus, further examination of these factors would help expand this study and possibly provide conservation and management guidelines for future projects.

Methane hydrates are frozen deposits of methane and water found in high pressure or low temperature sediments. When these deposits destabilize, large quantities of methane can be emitted into the atmosphere. This is significant to climate change because methane has 25 times more greenhouse gas potential than Carbon Dioxide. Worldwide, it is estimated there are between 2500 and 10000 gigatons of methane stored in hydrate deposits. This represents more carbon than all fossil fuels on Earth. It is estimated that between 200 and 2000 gigatons of methane are stored in hydrates in Arctic waters acutely vulnerable to greenhouse warming. Over the last decade, researchers have identified instances of hydrate destabilization that have already begun. To gain insight into the potential climatic effects widespread hydrate dissociation would have, researchers have examined hydrate dissociation during the Paleocene Eocene Thermal Maximum 55 million years ago as a geologic precedent. In this period, large-scale hydrate dissociation contributed to 5-8 degree Celsius warming worldwide. If such a climatic shift were to transpire today, impacts on society would be enormous. There is currently a debate in the scientific community as to whether the risk of methane hydrate dissociation is relevant to the present generation. One side argues that not enough methane could be emitted into the atmosphere from today’s hydrate sources to have a meaningful impact on climate warming, where the other side contends that more than enough methane could be emitted from present day hydrate deposits to cause significant impacts to the global greenhouse effect. Given the information currently known about hydrates, it is reasonable to conclude there is a moderate risk of widespread destabilization that could impact global climate change in the coming decades. Significant acceleration of the conversion to alternative energies and implementation of geoengineering strategies should be considered.

The present study sets out to assess patterns of evolutionary diversification in central African duikers (subfamily Cephalophinae). The sampling strategy consisted of collecting geo-referenced duiker feces across 43 sites and seven countries. However, several challenges related to the use of non-invasive samples needed to be addressed prior to large scale DNA amplification. First, the best storage method for obtaining DNA from fecal samples needed to be established. Our study revealed that while silica is best for nuclear microsatellite analyses, RNAlater is the best storage medium for maximal mitochondrial amplification. Moreover, extracting DNA as early as possible always provided the best results. Second, since it is impossible to determine the species identity of duiker feces solely based on their morphology, a simple and reliable molecular method was needed. A tree-based approach based on ~650 base pairs of the control region amplified from reference samples was found to be the most reliable method to recover the identity of unknown samples. Third, for fine scale analyses of population genetic structure, a set of twelve nuclear microsatellites were assembled from existing bovid data. These microsatellites markers were chosen because they are very polymorphic, cross amplify among targeted taxa, co-amplify with combined markers of the same multiplex, and are powerful enough for individual identification. Patterns of mitochondrial and nuclear microsatellite variation were used to test two important hypotheses of diversification in the tropics: the Pleistocene refugia and the riverine barrier hypotheses. Analyses of historical and contemporary population genetic structure were carried out on the three most abundant species in our sampling area: the bay duiker (C. dorsalis), the Peter’s duiker (C. callipygus), and the blue duiker (P. monticola) using mitochondrial and nuclear markers described above. These data show that (1) southwest Nigeria and southwest Cameroon comprise genetically distinct populations in C. callipygus and P. monticola species, (2) signatures of demographic expansion for all three taxa are broadly coincident with the location of hypothesized upland refugia in Gabon and Equatorial Guinea and (3) the Sanaga, Ogooué, and Sangha rivers may constitute a partial riverine barrier and/or act as fluvial refugia for duikers.