Jerry G. Chmielewski

Testate Amoebae (Protozoa) as Indicators of Drainage in a Forested Mire, Northern Ontario, Canada

Summary Testate amoebae (Protozoa) were examined in a Picea mariana forested mire in northern Ontario, Canada to assess the use of testate amoebae as environmental bioindicators of drainage. Habitat types included Picea mariana trees, Ericaceae shrubs, and Sphagnum mosses. Several of the species or species groups recorded in the study area, emerged as showing significant differences in abundance between control and drained microsites. Significant differences were recorded between control and drained microsites for Cyclopyxis arcelloides-type Assulina muscorum and Centropyxis aerophila-type in certain site types. In other site types Cyclopyxis arcelloides, Trinema lineare, and Centropyxis aerophila-type, decreased in abundance with drainage whereas Assulina muscorum and Corythion dubium increased in abundance with drainage. This study demonstrates for the first time that alterations in the soil microenvironment from drainage are reflected almost immediately by the abundance of certain species of testate amoebae, some of which increase in number, whereas other decrease in number. Testate amoebae may, therefore, be used to monitor environmental effects of drainage in peatland forestry.

The biology of Canadian weeds. 113. Symphyotrichum lanceolatum (Willd.) Nesom [Aster lanceolatus Willd.] and S. lateriflorum (L.) Löve & Löve [Aster lateriflorus (L.) Britt.]

Symphyotrichum lanceolatum, the tall white aster, is a morphologically variable, native North American, polyploid (tetraploid, pentaploid, hexaploid, heptaploid, and octoploid cytotypes) species with a transcontinental distribution. Commonly found along fence rows, ditches, road and rail right-of-ways, and field, pond, and wood lot margins, the species is not a serious agricultural weed but may become problematic in neglected fields, poorly managed pastures, and cultivated fields on recently plowed land. For this review of the biology of the species, we recognize two subspecies, the eastern subsp. lanceolatum and western subsp. hesperium. The former is further divided into varieties lanceolatum, hirsuticaule, interior, and latifolium. Symphyotrichum lateriflorum, the one-sided aster, is also morphologically variable. The distribution of this native, polyploid (diploid, tetraploid, hexaploid, and octoploid cytotypes) extends from the Magdalen Islands and Prince Edward Island in the north, south to Florida,...

The biology of Canadian weeds. 114. Symphyotrichum pilosum (Willd.) Nesom (Aster pilosus Willd.)

Symphyotrichum pilosum (Willd.) Nesom, the white heath aster, is a robust, native North American, polyploid, herbaceous perennial. Until recently the species was treated as part of Aster. Its placement in the segregate genus Symphyotrichum follows the revised generic combinations proposed for North American asters. Occurring throughout eastern North America from Nova Scotia and Maine in the northeast, southward to Georgia, west ward through southern Quebec and Ontario to Wisconsin, Iowa, Kansas, and Arkansas in disturbed areas such as fallow land, roadsides, dumps, quarries, arable fields, railroad beds, and embankments, the species is troublesome in the United States but a weed of minor importance in Canada. Two varieties, var. pilosum and var. pringlei are recognized. The former, the hairy variety, is weedier than the latter, the hairless variety. The species commonly occurs in fields following the first year of abandonment and may dominate in the second, or subsequent years. Control may be achieved thr...