THE MODERN AND LATE-QUATERNARY VEGETATION OF THE DOLL CREEK AREA, NORTH YUKON, CANADA.

The modern vegetation of the mountainous Doll Creek region consists of tundra on surfaces above roughly 700 m elevation and spruce woodlands on lower slopes and valleys. Ordination of quadrat cover data by &trended correspondence analysis displays the characteristics and relationships of the vegetation. Tundra on non-calcareous parent materials is distinctive, dominated by Betula glandulosa, Arctostaphylos alpina, Ledum decumbens and Salix arctica. Limestone ridge surfaces, by contrast, support a tundra dominated by Dryas integrifolia, Carex scirpoidea and Cetraria species; lower slopes on limestone are dominated by a Dryas-Cassiope Tomenthypnum cover which also characterizes the ground vegetation of Picea glauca woodlands on lower surfaces. Bottomland mires are dominated by Picea mariana-Sphagnum woodlands and moraines support a Picea mariana-Betula glandulosa-ericad community. Larix laricina shares dominance with Picea glauca at treeline on northwest-facing gulley surfaces where deep and persistent snow appears to be important. A detailed pollen analysis of one site, using percentage and influx diagrams, running means of influx of the main taxa, and a pollen influx-vegetation representation calibration method, reveals that immediately following the maximum of the latest glacial cycle (18000 B.P.) the area supported a sparse, unproductive herb tundra on the lower montane slopes and a sedge-grass marsh complex in poorly drained sites. Between 16000 and 12500 ¹⁴C years rapid changes in the plant populations occurred, particularly involving species of willow, grass, sedge and herbs. By 12 500 the entire area was occupied by a mosaic of treeless communities in response to a slow amelioration of the climate. [ABSTRACT FROM AUTHOR]