Thesis (Ph. D.)--Washington State University, December 2007. / Includes bibliographical references.

No description available.

No description available.

Although pollinator-driven selection is known to generate pigmentation variation in plants, the contribution of abiotic factors in the evolution of pigmentation is still poorly understood. This is largely due to a lack of research on pigmentation variation in wind-pollinated (anemophilous) plants, where the confounding effect of pollinators can be excluded. Here, I study pigmentation variation in Carex, the world’s largest anemophilous genus. Using 456 North American species, I use phylogenetic comparative methods to test (1) whether darker inflorescence parts are correlated with short growing seasons and (2) whether inflorescence pigmentation has affected the diversification dynamics of Carex throughout time. I also examine UV irradiance and precipitation at both the interspecific and intraspecific (four wide-ranging species, >100 accessions each) levels, factors previously associated with floral darkness at high altitude and latitude. At the inter- and intraspecific level, darker inflorescence parts are associated with short growing seasons, as seen in arctic and alpine regions. Additionally, dark pigmentation is associated with stronger UV irradiance and higher precipitation in the intraspecific dataset. Finally, despite the adaptive importance of pigmentation in arctic and alpine regions, it has not contributed to the diversification dynamics of Carex. The results suggest that climatic conditions can promote pigmentation variation in anemophilous plants, and are most consistent with the hypothesis that dark inflorescence parts accelerate reproductive development by absorbing solar energy. Finally, despite the adaptive importance of pigmentation in arctic and alpine regions, it has not contributed to the diversification dynamics of Carex.

No description available.

The Stress-gradient hypothesis predicates a change of interspecies relations from negative to positive according to the stress gradient. The basic assumption is that the presence of one species (the facilitator) makes the growth of other species easier. In this study was determined based on the 5years experiment, whether the interspecies interactions (i.e. the importance of facilitation and competition) changes according to the hydrological conditions. Three wetland species (Calamagrostis canescens, Carex elongata and Deschampsia cespitosa) were planted in experimental pots with the presence and absence of the dominant species (Carex elata). The hydrological gradient (= the stress gradient) was simulated by three types of hydrological conditions: dry, fluctuating and wet. The success of the species within the specific conditions was correlated with the fitness-related characteristics of the plants including the biomass, the number of ramets and the height of the plants. Following hypotheses were tested: i) at a low intensity of stress (with the wet treatment), the C. elata represents a competitor for other species. On the other hand, at a high intensity of stress (with the dry treatment), the C. elata represents a facilitator, making it easier to the other coexisting species to grow. This presumption was confirmed only with the D. cespitosa, which was more successful under dry treatment with the presence of a dominant species, which facilitated it. With the other two species the change of interspecific relations was not observed and the relationships remained negative. Furthermore the results showed, that in the dry treatment with the presence of a dominant species, there was a lower intensity of competition among the coexisting species. The experiment showed, that the interactions of particular species with dominant species can vary according to the stress gradient. The hydrological gradient also influences the character and intensity of interactions among the species.

It has been the purpose of the author in this study to determine, as far as possible in the available tim.e, the number and kinds of Carex which occur in Utah County; their distribution in relation to region, soil, moisture and other factors, and to provide keys to the species and a description of each one that occurs in this natural area.

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Field studies were used to characterize habitat and evaluate morphological characters of Carex glaucescens, C. joorii and C. verrucosa. Morphometric analysis of herbarium specimens along with field studies, Environmental Scanning Electron Microscopy (ESEM), pollen viability and phenology show C. glaucescens, C. joorii and C. verrucosa to be taxonomically distinguishable at the species level. The taxonomy of Carex section Glaucescentes is presented in an artificial dichotomous key to the taxa and in species descriptions.

Exploration and extraction activities in the Alberta Oil Sands region have degraded thousands of hectares of land, about 40 % of which were once covered by peatlands. To date, there is very little information regarding the reclamation of peatlands, and even less related to their reclamation after oil sands disturbances. The results of this study will be used to develop protocols for the reclamation of peatlands after disturbance due to oil sands exploration and extraction operations in the Alberta Oil Sands region. Carex aquatilis is considered to be an ideal candidate species for initiating reclamation because it is a common pioneer species of disturbed landscapes, and has been shown to have a wide range of tolerances for several environmental factors in other areas of its overall distribution. The results of this study showed even wider ranges of tolerance than previous studies have reported, and did so using an ecological field study, a greenhouse propagation study, and a greenhouse Na+ tolerance study. A field study used vegetation surveys and environmental data to determine that Carex aquatilis is abundant in several wetland types and is not strongly associated with any of the species with which it was commonly found. In addition, C. aquatilis also was present across wide ranges of environmental variables including pH, conductivity, shade, water depth, Na+ concentration of surface water and percent organic carbon content of the substrate. These wide ranges of tolerance should allow C. aquatilis to establish after many types of disturbance. A greenhouse propagation study tested for population differences in percent germination after four stratification treatments, three stratification durations and four germination treatments. The overall best stratification treatment was to store seeds moist at 4°C for 30 days. The most effective germination treatment across all treatments was to plant seeds just below the surface of the substrate with the water level maintained at 1cm below the substrate surface. Only 9% of all sown seeds germinated. There were differences in germination rates between populations, although it is unknown whether these differences were due to differences in viability, timing of seed maturation, stratification requirements or germination requirements. A greenhouse Na+ tolerance experiment tested for differences in Na+ tolerance between four populations and two age classes to assess the efficacy of C. aquatilis as a pioneer species after oil sands surface mining disturbance. Five Na+ concentrations ranging from 5 to 2000 mg L-1 were tested. Plants showed no differences in Na+ tolerance between populations, but younger plants were more susceptible to damage from Na+ stress than older plants so it is recommended that older plants are used to initiate reclamation. It is also recommended that Na+ be managed on surface mine reclamations so that it is below 500 mg L-1.