Forest Investment Account

Abstract of FIA Project Y051220

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Harvesting and site preparation treatments to develop and maintain open canopy conditions in dry-belt Douglas-fir forests: the Isobel project

Author(s): Regimbald, Darrell
Imprint: Victoria, B.C. : B.C. Ministry of Forests, 2005
Subject: Forest Investment Account (FIA), Understory Plants, Trees, Growth
Series: Forest Investment Account (FIA) - Forest Science Program


. There were six key objectives for the Isobel project in 2004-05. (1) assess and complete a report on the short-term effects of harvesting on understory vegetation composition and biomass, (2) assess factors that contribute to the post-harvest vigor of pinegrass, (3) upgrade a selection of vegetation permanent sample plots to provincial growth and yield standards, and provide regeneration data for the provincial PrognosisBC calibration process, (4) complete stand structure modelling of the Isobel treatments using TASS and prepare a manuscript on the modelling work, (5) collect pre-treatment data on understory vegetation, conifer regeneration and fuel loads on the 72 site preparation-livestock exclosure plots, and (6) begin the process of building a project metadata archive including field truthing of plots where data conflicts are identified, a project mapbase consisting of project GPS information and spatially accurate (GIS) maps, and a long-term, secure data archive. Objectives 2 (pinegrass), 3 (growth and yield), 5 (site-preparation pre-treatment data) and 6 (project metadata) were completed successfully and are on or ahead of schedule. Project 1 was restricted to the collection of data and a preliminary analysis of the data following an assessment of variability of the data collected in 2004, and the decision to collect data in 2005 because of the of highly variable annual weather and the relationship between vegetation cover/biomass and precipitation. A complete analysis of the data will be conducted following sampling in 2005. Project 4 was delayed to correct a TASS calibration issue relating to the use of narrow (standard IDF version of TASS) vs. wide crowns (reflected in data from Isobel-Opax area). Model recalibration was completed and the role of regeneration density substituted for insect mortality as a stand structure factor as preliminary runs indicated regeneration density is a key factor driving the log-term maintenance of open canopy conditions.

For further information, please contact Walt Klenner, BC Ministry of Forests (

Updated September 08, 2005 

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