EFFECTS OF NITROGEN-FERTILIZATION ON SEVERAL WOODY AND NONWOODY BOREAL FOREST SPECIES

The effects of three levels of fertilizer were tested on the growth of several woody and nonwoody plants from a boreal forest community in southwestern Yukon. The effects of fertilization were assessed by clipping ground layer vegetation and measuring twig growth at the end of the second summer. Over the 2 years of fertilization there were significant increases in growth over control levels for perennial grasses (Festuca altaica and Calamagrostis lapponica), two herbs (Epilobium angustifolium and Achillea millefolium), and two deciduous shrubs (Salix glauca and Betula glandulosa). However, the growth of white spruce trees (Picea glauca) increased only slightly in response to increasing nitrogen levels, and the evergreen dwarf shrub Arctostaphylos uva-ursi showed no response.