Forest Investment Account

Abstract of FIA Project Y051025

" ALT="See below to download" WIDTH="100" HEIGHT="129" BORDER="0" bordercolor="#000000">

Old-growth attributes in managed forests: integrating stand productivity with mammal diversity

Author(s): Sullivan, Thomas P.
Imprint: Vancouver, B.C. : University of British Columbia, 2005
Subject: Forest Investment Account (FIA), Pinus Contorta, Growth, Forest Thinning, British Columbia
Series: Forest Investment Account (FIA) - Forest Science Program


Enhanced growth of crop trees and development of late-seral structural characteristics in second-growth stands in temperate and boreal forest zones could be achieved by silvicultural practices such as pre-commercial thinning (PCT). This study was designed to test the hypotheses that large-scale stand thinning at a 15-year period after PCT, would enhance: (i) productivity and structural features (crown volume, diameter, and height growth of lodgepole pine (Pinus contorta) crop trees; and (ii) coniferous stand structure (abundance, species diversity, and structural diversity of coniferous tree layers). Replicate study areas were located near Penticton, Kamloops, and Prince George in south-central British Columbia, Canada. Each study area had three stands thinned to densities of ~500 (low), ~1000 (medium), and ~2000 (high) stems/ha, with an unthinned young pine and old-growth pine stand for comparison. An overall analysis of tree growth across these regional replicates indicated that lodgepole pine grew significantly faster in mean diameter in the low- than either of the medium- or high-density stands. There was no difference in mean height growth among stand densities over the 15-year period since PCT. Mean crown volume of crop trees was significantly greater in the low- (52.8 m3) and medium- (42.9 m3) stands than in the high-density (27.8 m3), unthinned (11.7 m3), or old-growth stands (30.9 m3 pine only). This measure of crown size was similar between pine trees in the low-density, medium-density, and all conifers (43.2 m3) in the old-growth stands. Other measurements of crown architecture followed this same pattern. Mean species diversity and structural diversity of coniferous tree layers were highest in the low- and medium-density stands than in other treatment stands. Our results support the hypotheses that PCT enhances 3 productivity and structural features of young lodgepole pine, as well as diversity of coniferous tree layers. This conclusion is certainly the case when comparing thinned and unthinned stands of pine at 15 years after PCT, but not necessarily for height growth among the thinned stands. Some aspects of structural features of late-seral forest appeared in our young managed stands.

For further information, please contact Thomas P. Sullivan, University of British Columbia (

Updated September 08, 2005 

Search for other  FIA reports or other Ministry of Forests publications.

Please direct questions or comments regarding publications to