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The ecology of genus Typha in wetland communities of the eastern Ontario-western Quebec region of Canada Bayly, Isabel

Abstract

The study was designed to determine the nature of Typha communities in the area and correlate the characteristics of these communities with differences in climatic, edaphic and aquatic environment. A seasonal comparison of plant - soil - water relationships was made between Typha glauca and Phragmites communis, the two major competitors for marsh habitats. Phragmites is seen to make high demands on the substrate for calcium, magnesium and phosphorus, requirements which may limit its colonization of nutrient-poor habitats. Except for potassium, Typha is shown to make only moderate demands on the substrate, and also shows the ability to accumulate high concentrations of sodium without toxic effects. Pattern of uptake and recycling of macronutrients is similar in both species, but the graphs of seasonal uptake differ in shape. Onset of seasonal senescence in Typha coincides with achievement of maximum growth, but in Phragmites, a plant of indeterminate seasonal growth, seasonal senescence is not correlated with maximum height. Pattern of uptake and utilization of ions differs, and the ions may be classified into three categories. First are those ions which are utilized early in the growing season, and are then cycled between plant and substrate, e.g., calcium and magnesium. Second are the ions which are utilized early in the growing season and are then cycled to the rhizome for overwinter storage, e.g., potassium and phosphorus. Third are ions which fluctuate passively in response to external concentrations, e.g., sodium and iron. Seasonal studies of uptake and growth of floating mat communities of Typha confirm that (a) the pattern of uptake, and amount of uptake of ions is similar in floating mats, despite lower concentrations of nutrients in the mat matrix, (b) the floating mat matrix contributes to the growth of Typha in the same manner that normal soil contributes to growth in soil rooted communities. Introgressive hybridization in Typha in eastern Canada has been investigated. With hybridization and introgression, T. angustifolia and T. latifolia produce variable series of character recombinations, including T. glauca. Such introgression makes positive identifications to species difficult. Within the study, variability is found to be greater on new habitats, particularly those bordering bodies of shallow water. Older more stable communities are represented by fewer variants, the environment apparently selecting particular genotypes. Sample material was taken both from Typha stands and from stands dominated by other major species, including the following: Acorus calamus, Alisma plantago-aquatica, Calamagrostis canadensis, Agrostis stolonifera, Butomus umbellatus, Decodon verticillatus, Dulichium arundinaceum, Epilobium hirsutum, Eupatorium maculatum, Glyceria canadensis, Impatiens biflora, Juncus effusus, Nuphar advena, Onoclea sensibilis, Phalaris arundinacea, Phragmites communis, Sagittaria latif olia, ,S. rigida, Scirpus americanus, cyperinus, S. fluviatilis, S. rubrotinctus , S. validus, Sparganium androcladum, S. eurycarpum, Spiraea alba and Zizania aquatica. Three distinct community types were recognized and described: (a) Typha communities of the deeper waters of open marshes, where nutrients are low in the substrate, but water circulates freely presenting a constant if dilute supply of nutrients; (b) Typha-Sagittaria communities of open marshes, in the shallower water, they are two-layered, with the lower story composed of Sagittaria latifolia or Pontederia cordata; nutrient levels are higher, as the result of accumulation of organic matter in the substrate; (c) Typha- Galium communities, found in the shallow and moist portions of open marshes as well as in closed marshes where water may subside to ground level in the late summer months. Here the mature soils are high in organic matter and nutrients. Typical species in addition to Typha, are Galium palustre, Cicuta bulbifera, Lysimachia terrestris and Glyceria canadensis. Floating mat communities of Typha, derived from land-based communities are also described. They consist of buoyant, leached organic mats. Mature marsh soils are found to be modified by the particular dominant so that unique soils emerge. Typical marsh soil as a colonizing substrate of Typha communities is the Rego Gleysol. Recycling and accumulation of organic matter develops the soils into Humisols. Floating mat soils have been classified as Hydric Fibrisols, according to the Canadian classification. Competition from other marsh species is limited. Most species, regardless of nutrient requirements, can be overtopped by Typha. Scirpus validus can occupy deeper waters. Phragmites communis, possibly the strongest competitor, is probably eliminated from colonization of low nutrient soils because of its high requirement for calcium and magnesium.

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