Forest Investment Account (FIA) - Forest Science Program
FIA Project Y103264

    Modelling the development of Coastal BC stands: an individual tree model linked to a variable retention microclimate model.
Project lead: N.J. Smith (Island Timberlands Limited Partnership)
Contributing Authors: Smith, Nick J.; Rathbun, Leah
Subject: Forest Investment Account (FIA), British Columbia
Series: Forest Investment Account (FIA) - Forest Science Program
Plans for 2009-2010
No major deviations from the original project plan are envisaged. A PhD student is in place working on height, diameter, mortality and taper equations. We have made substantive progress modelling mortality (natural and managed) and height and diameter growth (natural stands) estimation functions. We have improved leaf area index estimates and are working on a new hemlock taper and branch data base. We have collected hemlock leaf area and taper data from approximately 40 trees at 3 sites and a range of densities. In 2009-2010 we plan to develop improved leaf area and taper models using ITLP data. The PSP and variable retention (VR) database are in place and the FORGE model (our modeling/simulation framework) has a mixture of new and existing parameters in place (see Hann et al., 2003) as well as improved microclimate equations. (In order to get the ITDI model functional we coded in equations presented in Hann et. al 2003 in 2008-2009 as a point of comparison: because these equations use crown ratio which is not generally measured on the ITLP PSP data the Hann equations cannot be used operationally). In 2009-2010 we will focus on final versions of dbh and height increment for managed stands (thinned, fertilized). We will continue to investigate the use of nonlinear mixed models on error structure in the modelling framework (see Weiskittel et al. 2007 for the general approach that we will use). This will improve the parameter estimates and reduce residual model variance. We will develop taper equations further using ITLP data and continue to add to the taper data base (an in-kind project). We will update all tree growth models in FORGE and continue model testing. The VR modifiers will also be further developed using new data collected in 2009-2010 (see links) and theoretical relationships. In 2007-2009 we developed some prototype natural and planted regeneration models (growing seedlings to 3m to pass onto the overstory model) these will continue to be improved on using new data (collected here and elsewhere) in 2009-2010. ITLP will directly fund the measurements of several VR edge and experimental sites and destructive taper samples (see below for a description of edge and experimental). These data are all important in ‘locally’ calibrating the model to BC Coastal condition. We request some funds to further develop our hemlock branch and leaf area modelling work in 2009-2010 using the approach outlined in Smith (1992) (see Methods) . Basically the goal is to have a functional FORGE model fit to updated dbh, height, volume and mortality equations that grows from bare ground or with cruise plot to final harvest.
General 3- year Project Description (unless noted)
Generally, the proposed model is designed to meet the following requirements for Coastal BC:
•take an existing inventory and grow each tree forward.
•take a given stand condition (for instance 900 fir, site index 30, age 30 years) and grow it forward.
•take a regeneration description (i.e. plant 1000 fir, natural regeneration of 300 hemlock, 10% group retention) and grow it forward.
•incorporate a mechanism for modelling the impacts of variable retention on the above
•output should be for any specified year (i.e. not just 5 year periods).The data sets includes:
•PSP database (~2500 PSPs): includes mainly trees greater than breast height, 1.3m.
•Regeneration data: collected from seedlings at planting to breast height in clearcut retention stands (~100 stands).
•A variable retention growth database of 11 experimental sites and 19 gradient analysis sites (Beese et al. 2005) that contributes regeneration data up to 8 years after planting. See also: for a description of the edge and experimental data
•Taper data: over 240 destructively sectioned trees, continued collection as an in-kind contribution.
•Leaf area index and branch data base and estimating equations for Douglas-fir previously developed. Existing models: no ITDI yield validated model exists for the BC Coast, existing models have weak regeneration components with rudimentary linkage to variable retention (i.e. they are largely data free).
The following model components will be developed over the course of the 3 year project:
1.Height growth;
2.diameter growth;
4.modifier effects of fertilizer and thinning, on 1, 2 and 3;
5.regeneration model: clearcut data and variable retention data;
6.taper equation;
7.modifier effects of variable retention on 1, 2, 3 and 5.

We are incorporating the ITDI model into an existing variable retention model called FORGE (Forest Growth Engine). See the following link for a description of FORGE: (contains: Smith, N.J. Variable retention, microclimate, experimental and modelling projects in TFL 39: Improvements to the Forge model). See Smith et. al. 1991 for some of the internal details of the model.
Forest management issues and application of results: a calibrated and validated ITDI model that can be used on the BC Coast; an inventory projection system; a regeneration component that enables the model to begin at bare ground; and incorporation into a spatially explicit model framework (FORGE) that allows explicit treatment of variable retention (complex stands). Finally the model provides a synthesis for numerous separate but linked data collection endeavors that will provide important information on various growth issues such as regeneration (planted and natural) and growth impacts of variable retention.(See links). The model will assist in management issues concerning levels of silvicultural investment, harvesting plans and short term tree and log profiles. The project will enhance the cooperation of industrial operational need and academic expertise. Thus the research undertaken here is directly concerned with modelling ‘complex’ variable retention stands using an extensive existing and newly collected database. The model provides a framework for synthesizing several initiatives and addressing a variety of management issues including forest growth and timber supply and silvicultural investment. We benefit immeasurably from the involvement of an industrial forest products company working in cooperation with UBC.
Literature cited: Beese, W.J., B.G. Dunsworth, and N.J. Smith. 2005. Variable retention adaptive management experiments: testing new approaches for managing British Columbia’s coastal forests. In: IUFRO: Balancing Ecosystem Values: innovative experiments for sustainable forestry, Portland, Oregon, August 2004. Hann, D.W., D.D. Marshall and M.L. Hanus. 2003. Equations for predicting height-to-crown-base, 5-year diameter growth rate, 5-year height growth rate, 5-year mortality rate and maximum size density trajectory for Douglas-fir and western hemlock in the Coastal region of the Pacific Northwest. Research Contribution 40. Forest Research Lab, Oregon State Univ., Corvallis. Mitchell, A.K. and W.J. Beese. 2005. Montane Alternative Silvicultural Systems (MASS) designing experiments for the future. Abstract In: IUFRO: Balancing Ecosystem Values Conference, Portland, Oregon, USA. Aug 16-20 2004. pg. 98. Smith, N.J. 1992. Estimating leaf area index and light extinction coefficients in stands of Douglas-fir. Can. J. For. Res. 23: 317-321. Smith, N.J. and K. Raynor. 2005. FORGE user’s manual. Available on request. Smith, N.J., L. Kremsater, J.M. Chen, F. Bunnell, T. A. Black, X. Lee and B. Sagar. 1991. Managed stands for deer winter range. Model Documentation. Weyerhaeuser BC Coastal Group. Stage, A.R. 1973. Prognosis model for stand development. USDA Forest Service. Res. Paper INT-137.
Related projects:  FSP_Y081264FSP_Y092264


Final technical report (1.3Mb)
Int Soc Ecol Model presentation (0.4Mb)
Western Mensurationists presentation (0.4Mb)
SAF poster: Modeling Diameter Growth in Response to Varying Silvicultural Treatments (0.6Mb)

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Updated August 16, 2010 

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