Thesis--Dorpat.

Thesis (M.S.)--University of Wyoming, 2008. / Title from PDF title page (viewed on Jan. 19, 2010). Includes bibliographical references.

No description available.

Thesis (BSci. Hons.) -- University of Technology, Sydney, 2008.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2000. / Restricted until November 2001. Bibliography: leaves 97-104.

The Sphagnum bogs of the Tofino-Ucluelet area of the western coast of Vancouver Island were studied from vegetational, edaphic, and historical aspects. An integrated approach to these three aspects was attempted in order to give in a relatively limited time as complete a picture as possible of the bog ecosystem. The bog vegetation was studied on 110 sample plots using analytical and synthetic methods of the Zurich-Montpellier school of phytosociology. Ten different vegetation types were described and characterized, nine belonging to the bog ecosystem and one to the surrounding scrub forest. The nine bog vegetation types consist of five distinct associations and one association composed of five variants. The vegetation types studied are summarized below, in order of increasing floristic complexity. Low moor bog associations: 1. Caricetura pluriflorae (Carex plurlflora association) 2. Scirpeto-Sphagnetum mendoclnl (Sclrpus caespitosus - Sphagnum mendocinum association) 3. Oxycocceto-Sphagnetum papillosi (Oxycoccus quadripetalus - Sphagnum papillosum association) High moor bog association: 4. Ledeto-Sphagnetum caplllacei (Ledum groenlandicum - Sphagnum capillaceum association) Peripheral bog associations: (Bog-forest transition) 5. Pineto-Sphagnetum capillacei (Pinus contorta - Sphagnum capillaceum association) a. Pineto-Sphagnetum capillacei sphagnosum papillosi (Pinus contorta hummock variant) b. Pineto-Sphagnetum capillacei myricosum galis (Myrica gale variant) c. Pineto-Sphagnetum capillacei chamaecyparosum nootkatensis (Chamaecyparis nootkatensis variant) Secondary succession variants established after fire: d. Pineto-Sphagnetum capillacei vacciniosum vitis-idaeae (Vaccinium vltis-idaea variant) e. Pineto-Sphagnetum capillacei vacciniosum parvifolii (Vaccinium parvifollum variant) Scrub forest association surrounding bogs: 6. Pineto-Chamaecypareto-Sphagnetum recurvi (Pinus contorta - Chamaecyparis nootkatensis - Sphagnum fecurvum association) (Bog forest) Edaphic considerations were limited to the analysis of soils from representative sample plots of each association and variant. Soils were analyzed for available cations, including Ca⁺⁺, Mg⁺⁺, Na⁺, K⁺, adsorbed phosphate, total nitrogen, cation exchange capacity, percent base saturation pH, and soil moisture. The results of the soil analyses were wherever possible correlated with trends in the development of plant associations. Climatic factors were regarded as constant over so limited an area as the one under study. Historical considerations included a pollen analysis from a representative core in the center of the major study bog, and a radiocarbon dating to determine the age of a representative bog. The results of the pollen analysis appeared to confirm previous ideas that the bog did not develop from a lake, but rather it developed from a wet seepage forest habitat. The radiocarbon dating indicated the age of the bog at only 390± 90 years B.P., thus explaining partially the apparent very juvenile phase of the bogs of the area. The general hypothesis is suggested that the distribution of the bog plant associations is primarily dependent upon a complex of environmental factors that are dependent upon topography. / Science, Faculty of / Botany, Department of / Graduate

No description available.

The presence of mosses in black spruce forests is known to have an important impact on the availability and abundance of nutrients in this ecosystem. Mosses contribute to long-term accumulation of organic matter and storage of nutrients as well as to short-term nutrient release. In the boreal forest of northwestern Quebec, the effect of mosses on nutrient cycling was examined within the framework of a chronosequence ranging from 25 to 300 years of age. Laboratory and buried bag incubations, total nutrient digests, respirometric and root abundance measurements as well as moisture and temperature measurements were done to characterize the nutritional status of the organic matter profiles. In general, no change in moss accumulation, or nutrient storage or availability across the chronosequence could be detected. There were, however, differences between feather mosses and Sphagnum mosses, the latter having significantly lower levels of nutrients than the former in terms of mineralizable nitrogen and total carbon, nitrogen, phosphorus, magnesium and potassium content. The nutritional profile of moss cores showed different horizons, reflecting differences in organic matter quality down the organic layer. More specifically, nitrogen availability on a concentration basis as well as root abundance decreased with depth. Forest floor temperature seemed to confine the most biologically active horizon, referred to as the active layer, to a shallow depth, however neither temperature nor moisture seemed to explain the nutritional differences between feather mosses and Sphagnum mosses. These results may lead to practical consequences in that they show a clear distinction between the effects of feather mosses and Sphagnum mosses in nutrient cycling, suggesting that moss cover, might be useful as an indicator of site nutritional status. The results also show that accumulation of nutrients in organic surface horizons, as has been observed elsewhere, does not appear to occur in blac

Decomposition and MeHg concentration were measured for Sphagnum fuscum, Sphagnum angustifolium and Chamaedaphne calyculata in a poor fen in the low boreal forest zone of the Canadian Shield. Litter bags were transplanted reciprocally into hummocks, hollows and lawns and retrieved after 1, 2, 3,11 and 15 months. / Mass losses follow the trend: Chamaedaphne calyculata >> S. angustifolium > S. fuscum. Between species differences were far more significant than differences between locations or depths, indicating that litter quality is the major control on decomposition. / McHg concentrations generally increased during decomposition, particularly near the water table: for C. calyculata up to 13000%, for the two Sphagnum mosses up to 500%, suggesting that decomposition stimulates mercury methylation or McHg scavenging. / The discovery of a high McHg substance on C. calyculata leaf surfaces (25 ng g-1) suggests that much plant MeHg data may by skewed by the presence of a biologically active 'film'.

No description available.