An imputation/copula-based stochastic individual tree growth model\xa0for mixed species Acadian forests: a case study using the Nova Scotia permanent sample plot network

John A Kershaw,Aaron R Weiskittel,Michael B Lavigne,Elizabeth Mcgarrigle

doi:10.1186/s40663-017-0102-2

John A Kershaw, Aaron R Weiskittel + Show 2 more

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https://doi.org/10.1186/s40663-017-0102-2

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Abstract

BackgroundA novel approach to modelling individual tree growth dynamics is proposed. The approach combines multiple imputation and copula sampling to produce a stochastic individual tree growth and yield projection system.Methods The Nova Scotia, Canada permanent sample plot network is used as a case study to develop and test the modelling approach. Predictions from this model are compared to predictions from the Acadian variant of the Forest Vegetation Simulator, a widely used statistical individual tree growth and yield model.ResultsDiameter and height growth rates were predicted with error rates consistent with those produced using statistical models. Mortality and ingrowth error rates were higher than those observed for diameter and height, but also were within the bounds produced by traditional approaches for predicting these rates. Ingrowth species composition was very poorly predicted. The model was capable of reproducing a wide range of stand dynamic trajectories and in some cases reproduced trajectories that the statistical model was incapable of reproducing. ConclusionsThe model has potential to be used as a benchmarking tool for evaluating statistical and process models and may provide a mechanism to separate signal from noise and improve our ability to analyze and learn from large regional datasets that often have underlying flaws in sample design.

Highlights

A novel approach to modelling individual tree growth dynamics is proposed
We propose an individual tree imputation/ copula model similar to the stand-level model developed by McGarrigle et al (2013)
We only used data from the Nova Scotia Permanent Sample Plot (NSPSP) system (Fig. 1) as it is comprehensive in terms of species and stand structure, has used a consistent measurement protocol, and has a long history of establishment

Summary

Introduction

A novel approach to modelling individual tree growth dynamics is proposed. The approach combines multiple imputation and copula sampling to produce a stochastic individual tree growth and yield projection system. In addition to providing forecasts of long-term resource flows, growth and yield models are used to design silviculture interventions (Maguire et al 1991; Barrett and Davis 1994), and to assess changes in factors such as fire risk (Keyes and O’Hara 2002) or wildlife habitat (MacLean et al 2010). Models differ primarily in terms of (1) what tree-level and stand-level information is required, and (2) how the underlying growth, survival, and ingrowth functions were derived (Flewelling et al 1986; Dixon et al 1991; Adlard 1995; Weiskittel et al 2011a)

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Discussion

Conclusion