Forest Investment Account

Abstract of FIA Project R2003-250

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Growth & Yield Attributes of Three Lodgepole Pine Provenances in the BC Tree Improvement Program

Author(s): Thrower, J.S., G. Gulyas, G. Therien, E. McWilliams, D. Turner
Imprint: B.C. Growth & Yield Program, 2003
Subject: Forest Science Program
Series: Forest Investment Account (FIA) - Forest Science Program


Tree and branch attributes were measured in four lodgepole pine (Pl) progeny test sites planted with 30 families (10 from each of three provenances) selected for the BC Ministry of Forests Pl breeding program. The 1,697 measured trees were planted in 1986 at 4,444/ha and thinned to 2,222/ha at age 10-11 years. The analysis compared attributes among test sites, provenances, and families after 17 years of growth. The goal was to detect differences in key growth and yield attributes and model the potential impact on lumber grade recovery and value at rotation. The growth and yield of Pl planted at 1200, 1600, and 2000/ha at site indices of 16, 19, and 22 m was modeled using TASS . Branch size, log grade, lumber grade, and value were predicted using methods we developed for Weyerhaeuser in other projects. The results were compared using financial analysis to evaluate the differences in branch size and growth rate. The major results from these measurements and simulations are:

These results suggest there are potentially meaningful differences in tree and branch characteristics that should be included in Pl growth and yield models. The site index differences should be maintained to rotation; however, differences in other attributes such as tree form (taper), crown width, and rate of crown lift may not persist. Therefore, these trials should be periodically remeasured to compare differences and detect changes in these trends. These results show the trade-off between volume and value gains as many Pl families with higher growth rates also have larger branches. For example, an increase of 1.0 m in site index can be accompanied by an increase of about 0.3-0.4 cm in average branch diameter without reducing financial Site Value (assuming average costs and 6% discount rate). Conversely, slower growing stands with smaller knots and higher lumber values can give higher financial Site Values than faster growing stands with larger knots.

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Updated August 02, 2006 

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