AMELIORATION OF WOOD ASH TOXICITY AND JACK PINE ESTABLISHMENT

Fresh wood ash inhibits the germination and early survival of some con ifers but this ameliorates with leaching. It was unknown, however, how much precipitation and time it takes for wood ash to become a favoura ble seedbed. Laboratory and field studies showed that the rate of leac hing of conifer and aspen ash was dependant on the amount of water, bu t a break between watering periods allowed the ionic content of ash to recover and rise. Field trials on a wildfire site and experimental pl ots in the Northwest Territories and Alberta indicated that 600-700 mm of water could leach 2-3 cm of ash sufficiently to allow some establi shment of jack pine (Pinus banksiana Lamb.), equivalent to that on und isturbed and vegetated duff. Precipitation in excess of 1000 mm appear ed necessary for substantial jack pine establishment. With normal prec ipitation levels these levels of establishment would take 1-2 years (6 00-700 mm) and 2-3 years (1000 mm). After 1 year, jack pine seedfall f rom serotinous cones is complete and the opportunity for seedling esta blishment on ash has been lost. Wildfire sites with deep wood ash tend to be dominated by Betula and Salix species.