Forest Investment Account (FIA) - Forest Science Program
FIA Project Y071255

    Regeneration Recruitment and Early Stand Growth in Partially Cut and Burned IDFww Stands
Project lead: Negrave, Roderick
Author: Negrave, Roderick W.
Imprint: [BC] : Ministry of Forests and Range, 2007
Subject: Forest Investment Account (FIA), Pseudotsuga Menziesii, British Columbia
Series: Forest Investment Account (FIA) - Forest Science Program
The combined treatment of partial cutting with prescribed under burning is a promising treatment regime for restoration of dense Douglas-fir stands to more typical, pre-contact ecological conditions. This regime allows economic activity to occur, while also recruiting stand conditions suitable for other non-timber values, including northern spotted owl habitat, and reduction of hazardous fuel conditions. These treatments also allow for increased stand value, though the production of large stems of valuable species (Douglas-fir and yellow pine). It is thought that this regime may also defray silvicultural costs, because it creates conditions conducive to the recruitment of natural regeneration. This treatment regime has been operationally applied in the Darcy area (Squamish Forest District) and was involuntarily achieved at the Boston Bar silvicultural systems trial (Chilliwack Forest District) when a wild fire burned through this partial cutting trial. This study will document the occurrence of natural regeneration and investigate factors affecting the growth of planted regeneration under this combined treatment regime. The first phase of the project will measure the recruitment of Douglas-fir and yellow pine natural regeneration and document associated site features. Existing silviculture survey data for the treatment areas will be pooled and the occurrence of natural regeneration summarized by site factor (i.e. slope class; aspect; canopy cover). Ingress of natural regeneration since last survey will be determined on older areas (portions of Darcy and all of Boston Bar). Standard 3.99 m radius regeneration survey plots will be used to tally species, estimated age and height of natural regeneration and record site factors for each plot. Frequency and growth of natural regeneration will be compared over time and by retention level and site factor using Chi-squared and non-parametric statistics. The second phase of this study will examine factors affecting the growth of planted regeneration in detail. Approximately 100 200 sample trees (seedlings and small saplings) will be randomly located for each species. For each species, these samples will be stratified by site series and, if significant variation occurs, also by aspect. Samples will be placed into two site series groups (i.e. mesic and likely subhygric) and, possibly, two aspect groups (i.e. southerly and northerly). Separate analyses will be conducted for each site series-aspect combination. The larger number of sample trees will be used if the aspect classification is used. Age, height, calliper and three-year height increment will be measured for each sample tree. Hemispheric photography will be used to quantify canopy openness for each sample tree. This method has been show go give a comparatively accurate and biologically meaningful estimate of light conditions under tree canopies (Comeau et al. 1998, Frazer et al. 2000). Slope and dominant texture of the top 10 cm of soil will also be recorded. The neighbourhood environment around each sample tree will be quantified. Within each plot the following will be measured: stem number and height of all shrub species; aggregate herbaceous species cover; height of other tree regeneration and distance to the target tree. The relationship between tree growth variables and competition will be examined using multivariate regression methods that include neighbourhood and environmental data as independent variables (Wagner and Radosevich 1991). This analysis will be conducted for each site series. Significance of regression coefficients for competition and environmental variables will be compared for different species. Where the two species occur on the same site series, growth of each species will be compared using covariate analysis, in order to identify the better growing species. Path analysis (Shipley 2000) will be used to examine the direct and indirect effects and interactions of environmental and neighbourhood variables on tree growth and to test hypotheses that suggest themselves from the data. Use of path analysis will allow a separation of competitive effects due to shading from other competitive effects, such as limitation of soil resources, on the growth of planted regeneration. Separate analyses will be conducted for each species using these procedures.
Contact: Negrave, R.W., (250) 751-7160,


Executive Summary (17Kb)

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Updated August 16, 2010 

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