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Modelling the development of Coastal BC stands: an individual tree model linked to a variable retention microclimate model.
Smith, Nick J.
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 f ...
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Final technical report
Int Soc Ecol Model presentation
Western Mensurationists presentation
SAF poster: Modeling Diameter Growth in Response to Varying Silvicultural Treatments

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