INFLUENCE OF ECOLOGICAL CONDITIONS ON ENGELMANN SPRUCE (PICEA-ENGELMANNII) AND SUB-ALPINE FIR (ABIES-LASIOCARPA) GERMINANT SURVIVAL AND INITIAL SEEDLING GROWTH IN SOUTH-CENTRAL BRITISH-COLUMBIA

The influence of seedbed (undisturbed forest floor, burned forest floo r, and mineral soil), light (closed forest: open forest, and clearcut) , and competing vegetation (present, not present) on germination and i nitial seedling survival and growth of subalpine fir( Abies lasiocarpa ) and Engelmann spruce (Picea eagelmannii) was investigated after appl ying seeds to small (1 m(2)) plots established in each of the two majo r site types present in the wet cold Engelmann spruce-subalpine fir bi ogeoclimatic subzone (ESSFwc) of south-central British Columbia. Seedl ing survival and growth generally did not differ between site types an d were little influenced by competing vegetation. After three growing seasons, the number of living seedlings of both species increased as t he degree of forest floor disturbance increased. The number of living fir seedlings increased as the amount of light increased whereas parti al shade benefitted spruce seedling survival. After two growing season s, surviving fir seedlings had grown larger, (height, basal diameter, and crown volume) and were generally less influenced by seedbed, light , and competition, than spruce seedlings. Spruce seedling growth was g reatest on undisturbed forest floor seedbeds in clearcut areas. If ESS Fwc forests are to be naturally regenerated with Engelmann spruce and subalpine fir, clearcutting with exposure of mineral soil would be the optimum treatment for promoting fir seed germination and initial seed ling growth as long as a seed source is present and sufficient seed su rvives predation. If spruce is to be promoted, provision of partial sh ade initially, for up to 2 yrs, and provision of small patches of mine ral soil should assist seedling survival and minimize potential growth losses. (C) 1998 Elsevier Science B.V.