Alternatives to broadcast burning in the northern interior of British Columbia: Short-term tree results

We compared the growth and foliar nutrients of lodgepole pine and hybrid white spruce following mechanical site preparation treatments and broadcast burning in a high-elevation plantation in north-central British Columbia. After five years, the largest trees were found on the broadcast burn (44% increase over raw planting), followed by disc-trenching (26% increase), and then windrow piling (9% increase). Height increment was similarly significantly different between treatments after seven years. Equal increases in nitrogen, phosphorus, and sulphur foliar concentrations were found across all site preparation treatments compared to controls. Foliar nutrients alone, however, did not further explain the differences in tree productivity between site preparation treatments. The results demonstrated how some sites can benefit from site preparation, in the short-term at least, and also emphasized the positive role fire can have on forest productivity. Key words: mechanical site preparation, broadcast burning, Picea gluaca, Pinus contorta