The effects of high plantation densities (espacement) on the growth and yield of lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) are reported over a 34-year period. Seven densities ranging from 2500 to 160 000 trees per hectare were established on plots in the Central Interior of British Columbia. This study was designed to investigate the height repression of lodgepole pine that has been observed with high densities established post-wildfire. A variety of statistical tests provided strong evidence of a general height reduction with increasing treatment density and stand density (post-mortality) compounded by age. Stand dominant height was described using top height (the height of the largest-diameter tree in a treatment plot) and site height (the height of the tallest 5% of the trees in a plot). Treatment-level top-height and site-height measures were found to be similar only when density was > 10 000 stems per hectare (sph). Site heights were greater than top heights when density was < 10 000 sph. Nonlinear segmented regression estimates suggested threshold repression densities of around 11 000 and 8000 sph, respectively, for top height and site height at age 15. Treatment density trajectories indicated that all plots were following known stand mortality dynamics. Total stand volumes were found to increase with increasing density with no indication of declining stand productivity at high treatment densities.
Harper, G.J., Astridge, K.; de Montigny, L.. 2018. Effects of High Plantation Densities on the Growth and Yield of Lodgepole Pine. 34-year Results at Barnes Creek (EP70.55). Ministry of Forests, Lands, Natural Resource Operations and Rural Development. Research Report (FLNRORD). TR115