Forestry Advance Access originally published online on October 24, 2007
Forestry 2007 80(5):587-611; doi:10.1093/forestry/cpm039
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Growth response of young lodgepole pine to thinning and repeated fertilization treatments: 10-year results
1 Applied Mammal Research Institute, 11010 Mitchell Avenue, Summerland, British Columbia, Canada V0H 1Z8
2 Faculty of Forestry, Department of Forest Sciences, 2424 Main Mall, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
3 Kalamalka Research Station, Ministry of Forests and Range, 3401 Reservoir Road, Vernon, British Columbia, Canada V1B 2C7
4 Forest Practices Branch, Ministry of Forests and Range, 727 Fisgard Street, Victoria, British Columbia, Canada V8W 9C2
* Corresponding author. E-mail: tom.sullivan{at}ubc.ca
| Abstract |
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This study was designed to test the hypothesis that large-scale pre-commercial thinning (PCT) to various stand densities, at ages 12–14 years, combined with repeated fertilization, would, over a 10-year treatment period, enhance productivity of lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) crop trees. Study areas were located near Summerland, Kelowna and Williams Lake in south-central British Columbia, Canada. Each study area had nine treatments: four pairs of stands thinned to densities of
250 (very low),
500 (low),
1000 (medium) and
2000 (high) stems ha–1, with one stand of each pair fertilized five times at 2-year intervals, and an unthinned stand. The very low, low- and medium-density stands were also pruned to a 3-m lift 5 years after thinning. At the tree level, fertilization treatments significantly increased diameter at breast height (DBH), basal area (BA) and volume growth and heavy PCT significantly increased DBH and BA growth. Pruning may mitigate some of the negative stem form and wood quality attributes associated with fast-growing trees without adversely affecting stem growth. At the stand level, PCT to very low and low densities significantly decreased the volume growth compared with high-density stands. The potential beneficial impacts that PCT and repeated fertilization treatments have for mitigating timber supply shortfalls, as well as potentially minimizing crop tree losses due to mountain pine beetle (Dendroctonus ponderosae Hopk.), are also discussed.
Received 26 March 2007.