Thesis (M.A.)--University of Wisconsin--Madison, 1937. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf 41).

Thèse (D. Sc)--Genève.

Thesis (Ph.D.). / Written for the Dept. of Plant Science. Title from title page of PDF (viewed 200/01/11). Includes bibliographical references.

To better understand the maintenance of diversity within the genus Carex in the forest understory, I investigated the effects of micro-environmental factors and regeneration patterns on the distribution of four Carex species in an old-growth temperate deciduous forest. Detailed characterization of the micro-environments within 1 m2 plots centered around established individuals of Carex backii, C. communis, C. plantaginea, and C. platyphylla revealed significant differences among species. Carex plantaginea was found at the wet end of a moisture gradient, with C. backii and C. platyphylla at the dry end. Carex backii occurred in plots with higher phosphorus availability and in earlier successional stands than C. platyphylla. Carex communis occurred in the broadest range of micro-environments, often co-occurring with C. backii and C. platyphylla. Both equilibrium and non-equilibrium factors act to maintain diversity within the genus Carex in the forest understory. (Abstract shortened by UMI.)

No description available.

Congeneric species occupying different habitats might be expected to have different seed dormancy strategies and germination requirements while those growing in the same habitats may be more similar. I tested this hypothesis with a broad survey of the germination of 51 Carex species from mesic deciduous forests, wet deciduous forests, and wetland or seasonally flooded areas in response to different controlled environmental conditions. A canonical discriminant analysis based on the responses of 29 species to various treatments showed clear differences among seeds from each habitat with respect to germination behaviour. Germination of seeds from mesic deciduous forest species was generally faster after moist stratification than after either submersion or dry storage. In seeds from most wet areas of deciduous forest, wetland, or seasonally flooded habitats, germination was similar or greater after submerged as compared to moist stratification. Total germination was significantly increased by light in all species except Carex pedunculata , an ant-dispersed species. Germination was not significantly different on a poorly drained peat soil than on a well-drained sandy loam. Seeds of most species were at least physiologically dormant at maturity and germination of fresh seeds was generally low. Spring germination was similar among species from all habitats and generally began in late May or early June, at fairly high temperatures (min 7°C, max 17°C), which is unusual for forest species but consistent among Carex species.

No description available.

Enzyme electrophoresis, chromosome counts and self-incompatibility trials were used to compare genetic and clonal diversity in Carex lasiocarpa and C. lanuginosa, two closely-related wetland sedge species of north-temperate distribution. Genetic variation was similar in the two species, but C. lanuginosa was somewhat less diverse and had a higher coefficient of genetic differentiation among populations than C. lasiocarpa. Wright's fixation index indicated that both species are primarily outcrossing, although crossing experiments suggested that C. lanuginosa may be self-fertile. The haploid chromosome numbers were n = 38 for C. lasiocarpa and n = 40 or 41 for C. lanuginosa. Cluster analysis using genetic identities and principal components analysis of allele frequencies clearly grouped the two species, but the separation was less clear for morphological data. Clonal diversity was higher and clone size smaller in C. lasiocarpa than in C. lanuginosa, but C. lasiocarpa showed less clonal and genetic diversity at dry than at wet sites.

No description available.

The succession process of interest in this study, the succession of fens and bogs, is driven to a large extent by the lowering of the water-table level as Sphagnum moss and vascular plants invade the habitat. I used a plasticity experiment to compare the phenotypic responses of two groups of sedges (Carex; Cyperaceae) to a water-table gradient: a group of pioneer species, C. aquatilis, C. oligosperma and C. rostrata, that also persist throughout the succession sequence and a group of late-invading species, C. michauxiana, C. paupercula and C. vaginata. The genotypes in the study exhibited largely uniform, adaptive responses on seven functional response variables, but were stable for total biomass, an estimator of fitness. The percentage of significant environment main effects per species and the magnitudes of genotypic coefficients of variation suggested greater plasticity in the late-invading species while reaction norms indicated no difference in pattern of plasticity between the groups. A second experiment made an intra-specific comparison of morphological response between early and late successional populations of both C. aquatilis and C. rostrata to a continuous water-table gradient. (Abstract shortened by UMI.)