Colonization potential of seven arctic plant species as determined under controlled environmental conditions

Revegetation of disturbed arctic tundra areas has been considered essential for maintenance of soil stability, aesthetic quality and preservation of a natural system for dependant species. Seven species associated with early stages of tundra succession were studied to determine their qualities as potential colonizers of man disturbed sites.Chemical and non-chemical methods for detection of seed viability in the field were suggested. Seed viability was found to be dependant on locality and collection data. Germination capacity varied with soil type, planting depth, intermittent soil freezing and the moisture regime. The threshold emergence temperature and range were interpreted under constant and alternating temperatures. Germination did not occur until a 11 day induction period at 8°C /5 C had been given. Eriophorum angustifolium and Arctophila fulva only emerged under higher temperatures.Linear and biomass measurements of above and below ground production were determined after a cool growth season simulation. A leaf area index (L.A.I.) to standing crop for quantitative intraspecies measurements or  relative interspecies measurements was suggested for rapid field computation. Under similar growth conditions, Eriophorum angustifolium produced the greatest L.A.I, of the sedges (31,399 mm2 per 100 plants); and Calamagrostis canadensis, the greatest L.A.I, of the grasses, (24,858 mm2 per 100 plants). Rhizome patterns were mathematically analyzed. Comparative species growth rates are presented for the simulated growth season.Potential frost hardiness levels were determined for four seedling growth stages. Frost resistance was found to vary according to the developmental stage and the individual plant part. Rhizomes were considered the  determinant of total plant survival for grasses, sedges and Epilobium angustifolium. Senecio congestus, withstanding -2 3°C , produced hardier foliage and exhibited greater total plant freeze survival than rhizomatous species. Extended conditioning at a constant 2°C promoted greater hardiness in all species. The hardiness threshold was found to be interspecific with some degree of hardening occurring under a diurnal alternation of 14°C /6°C for Epilobium angustifolium, Arctophila fulva, Calamagrostis canadensis and Carex aquatilis. A basic or 'spontaneous' hardiness level was considered to be interspecific and independent of conditioning. Increased  resistance resulting from conditioning was superimposed on the 'spontaneous' level of hardiness so that the potential level could be approximated. Extended freeze duration was found to increase injury in similarly  conditioned seedlings. All species were found capable of hardening under continuous illumination.A scale was designed to predict species potential hardiness in C° throughout a seedlings initial growth season. Examples of meteorological data for disturbed sites of the Inuvik region, N.W.T. were provided for  comparison with the scale to determine if species hardiness levels were adequate for recolonization of exposed areas. A colonizing potential scale from 1 to 10 was compiled by assessing a species ability to respond to a disturbed area with respect to germination, establishment, production and frost hardiness. Senecio congestus attained a rating of 8 which predicted a high performance and suitability for the colonizing of sub-arctic tundra areas.