Preliminary results from this project indicate that the repeated fertilization of young, managed forests may offer a potentially viable strategy for addressing timber supply challenges in the B.C. interior. Young spruce plantations may be particularly well suited to intensive forest management. Four of five lodgepole pine 'maximum productivity' installations have produced solid growth gains following periodic (every 6 years) and yearly fertilization, representing relative stand volume increases up to 120% over unfertilized treatments after 6 years. However, lodgepole pine growth responses have been more variable and consistently smaller than those obtained at the spruce study sites. Foliar nutrient imbalances and growth disruptions at some lodgepole pine study sites were apparently induced by large, and frequent, nutrient additions. Conversely, the largest spruce growth responses have been obtained with the most intensive fertilization treatments. Annual fertilization of spruce has produced up to 45 m3/ha of extra wood over 9 years, representing a relative increase of 290% over the unfertilized treatment. It?s too early to reliably predict the potential impact of intensive fertilization on harvest yield and/or rotation length of managed interior spruce and lodgepole pine in north-central B.C. However, preliminary responses from 'maximum productivity' installations appear to be tracking along similar pathways as Scots pine and Norway spruce 'optimum nutrition' studies in Sweden. The Swedish results suggest that the volume yield of spruce plantations can potentially be doubled in southern Sweden, and more than trebled in the north, by frequent application of balanced fertilizers. Growth projection models estimate that the rotation length for Norway spruce can be shortened by 20 to 30 years in the south and by 40 to 60 years in the north. In B.C., potential productivity gains of this magnitude would be of huge benefit in addressing timber supply challenges such as the amount, and timing, of future harvests from interior managed forests.
Robert P. Brockley et al.
Brockley, Robert P., Simpson, David G.; Amponsah, Isaac G.; Lieffers, Victor J.; Comeau, Philip G.; VanAkker, Lara; Alfaro, René I.. 2004. Effects of intensive fertilization on the foliar nutrition and growth of young lodgepole pine and spruce forests in the interior of British Columbia (E.P. 886.13)/: establishment and progress report. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report