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NIVMA?S new models of regenerated forest stands
Smith, Stephen M.
The Northern Interior Vegetation Management Association (NIVMA) is a forest industry co-operative initiated by major forest products companies in northern BC and Alberta, the BC Ministry of Forests, the Canadian Forest Service, the University of British Columbia and the University of Alberta. NIVMA uses a common monitoring protocol to track plantation and managed stand development and performance. Since 1996, over 800 installations have been established across BC and Alberta using the Treatment Regime Evaluation Numerical Support (TRENDS) protocol. The data from the BC installations have been used to build a series of early stand simulation models which can be used to project the growth of very young stands to expected stand structures 10-15 years after harvest. The output from these models can then be used as the initial stand conditions for long term stand models like TIPSY or PROGNOSISBC. In this way, stands regenerated under various operational conditions can be linked to realistic long-term growth and yield predictions. This model simulates the early growth of conifer stands in the stand initiation stage of stand development. This is the phase of stand establishment before crowns close and before competitive mortality begins. During the initiation stage, some plants die and others increase in size, while others continue invading. Oliver and Larson (1996) state that a stand?s development pattern is largely determined during this stage. The NIVMA model includes eight submodels that represent growth in different ecosystems, levels of site productivity and growing space. After the stand initiation stage, a stand enters the stem exclusion stage. The NIVMA model produces stand structures that represent the later stages of the stand initiation phase. These stand structures will define future development and can be input to computer models that simulate stand development starting at the stem exclusion stage. TASS, TIPSY and PROGNOSIS are examples of these models. The NIVMA model uses transition matrices to simulate stand dynamics during the stand initiation stage. Transition matrices assume the presence of a Markov process. The basis of a Markov process is that the regenerated stand can be classified into a finite number of different states. Then the probability of trees moving from one state to another over a fixed time period is estimated. Stephen M. Smith.
Report Number
Final Report V.2
NIVMA's Workbook
NIVMA Model Data

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