Joannes A. Janssens

The chemistry of streams in southwestern and central Nova Scotia, with particular reference to catchment vegetation and the influence of dissolved organic carbon primarily from wetlands

The percentage of wetlands in a catchment accounted for about half of the variance in transformed data for concentrations of dissolved organic carbon (DOC) in 42 Nova Scotian streams draining catchments with 11 different kinds of vegetation. Color increased with DOC, as did total dissolved nitrogen (TDN). Thecolor/DOC andDOC/TDN quotients also rose with increasing DOC, indicating a change in the quality of dissolved organic matter with increasing wetland influence. Dissolved Fe, and to a much lesser extent dissolved Al, showed a strong positive correlation with DOC. Stream pH showed a strong negative correlation with DOC, largely from wetlands, and a strong positive correlation with non- marine Ca2+ weathered from mineral soils. Non-marine SO42− from acid deposition had no apparent influence on stream pH and decreased with increasing streamwater DOC in summer, presumably owing to reduction processes in wetlands that mitigated the effects of acid deposition. Apparently, these reduction processes also produced small amounts of dissolved, non-ionic organic sulfur. Non-marine Ca2+ was related strongly to the percentage of upland hardwood forests in the catchments. Wetlands exert a profound influence on the chemistry of streams, principally through their export of DOC but also because of reduction reactions in their anerobic peats.

The Natural and Anthropogenic Acidification of Peatlands

Peatlands are ubiquitous in northern landscapes, and decomposition of their plant remains produces complex, coloured organic acids that acidify their waters and those of the streams and lakes into which they drain. Fens with weakly acid surface waters (pH about 6) and low alkalinity (about 40 μeq.L−1) are vulnerable to rapid change, and may be acidified by invasion of carpet-forming Sphagnum mosses that bring about major alterations in their biotic communities. The plant communities of such fens include a mixture of species characteristic of both minerotrophic and ombrotrophic peatlands.

Contributions to the flora of the Red Lake Peatland, northern Minnesota, with special attention to Carex

The Red Lake Peatland, situated in N-central Minnesota, is the largest continuous mire in the northern portion of the contiguous United States. It consists of a mixture of ombrotrophic bogs and minerotrophic fens organized into a complex of highly distinctive landforms, including open bogs, wooded bogs, Sphagnum lawns, strings, flarks, fen-pools and wooded islands. The bogs are poor in species and occupy acid sites with water poor in mineral salts; the minerotrophic areas are floristically richer and can be divided into poorand rich-fen sites. Ditching and roadbuilding in certain portions of the peatland have produced drastic changes in the vegetation and landscape as a result of obstructed water tracks flooding upstream and drying out downstream. The peatland, which occupies a large area of gentle slope and poor drainage, has a flora that is relatively impoverished. In all, 331 plant taxa were recorded from the mire, including 195 vascular plants, 67 bryophytes and 69 lichen taxa. Members of the Cyperaceae account for 23 % of the vascular flora, and the largest genus in the mire is Carex with 29 species. Each landform feature is distinctive in its floristic composition, and the vascular and nonvascular taxa associated with the different physiographic features are discussed. This paper provides an account of Carex in the peatland and discusses the differential response by members of the genus to gradients of nutrition, shading and hydrology. Some carices grow best under acid conditions, thus frequenting ombrotrophic and poor-fen sites, whereas other species grow best in rich-fen sites. Carex species useful in separating areas of ombrotrophy from those of poor fen are indicated, as are those carices that serve as obligate rich-fen indicators. The floristic similarities between the Red Lake Peatland and 14 other peatlands in North America and northern Europe are discussed, and the ombrotrophic bog flora of the Red Lake Peatland is compared to the bog floras of the Hudson Bay lowlands and northern Fennoscandia.

The distribution and accumulation of chemical elements in five peat cores from the mid-continent to the eastern coast of North America

Analysis of 38 chemical elements in five peat cores from the mid-continent to the eastern coast of North America shows that the concentrations and rates of accumulation of chemical elements supplied by atmospheric deposition toSphagnum bog peats vary greatly with geographic location, which determines the relative importance of emissions to the atmosphere from the soil (e.g., Al, La, Th) and the sea (e.g., I., Br, Cl, Na). Biological uptake also has a considerable effect upon certain elements (e.g., C, N, K, P). The concentration/depth profiles of several lithophilic and biophilic elements reveal greater concentrations in fen than in bog peats, and in surficial than in deeper bog peats, but only in some sites. Some mobile elements are lost to a marked degree from the peat column (Na, K) or are influenced by upward migration from fen peat into the bog peat above it (Ca, Fe, Mn). No single chemical element, or elemental quotient (e.g., Ca/ Mg, C/N), clearly distinguishes the transition from fen to bog peat in all sites.