Evaluating forest growth models

Vanclay, Jerome K.; Skovsgaard, J.P.

doi:10.1016/s0304-3800(96)01932-1

Cited by 350 publications

(200 citation statements)

References 38 publications

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“…Optimization often reveals weaknesses (Vanclay and Skovsgaard, 1997), and in the present case, was quick to reveal that equation 2 can overestimate for extremes including low (e.g., <100 stems/ha) and high stocking (>10,000 stems/ha) and for heavy thinning (e.g., removing >50% of the stand).…”

Section: Testing the Equationsmentioning

confidence: 58%

“…Figures 2, 3 and 4 reveal that although imprecise, the equations have relatively little bias in well-stocked stands typically encountered in production forestry. Under these circumstances, many of the usual model evaluation procedures (Vanclay and Skovsgaard, 1997) have limited utility, and the most useful test may be examine the implications of the interaction of these equations in complex situations, such as the optimization of thinning prescriptions.…”

Section: Testing the Equationsmentioning

confidence: 99%

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Robust relationships for simple plantation growth models based on sparse data

Vanclay

2010

Forest Ecology and Management

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Section: Testing the Equationsmentioning

confidence: 58%

Section: Testing the Equationsmentioning

confidence: 99%

Robust relationships for simple plantation growth models based on sparse data

Vanclay

2010

Forest Ecology and Management

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“…Ideally, a newlycollected data set will be available for validation [9,34,41,60]. Due to the scarcity of such data, several methods have been proposed (e.g.…”

Section: Model Comparison and Model Selectionmentioning

confidence: 99%

Un modèle pour l’estimation du volume commercialisable de chêne pédonculé dans le Nord-Ouest de l’Espagne

et al. 2007

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-A model is required for accurate estimation of the merchantable volume of pedunculate oak (Quercus robur L.) trees in Galicia, northwestern Spain. Accordingly, the purpose of the present study was to obtain equations for predicting merchantable volumes and stem profiles of individual trees. For this reason, two compatible and four non-compatible volume systems were initially evaluated and fitted to data from 251 destructively sampled trees which were collected in stands located throughout the area of distribution of the species in Galicia. The outliers were removed to provide a data set of measurements from 3 090 sections, which was then available for fitting. A second-order continuous autoregressive error structure was used to account for autocorrelation. Comparison of the models was carried out using overall goodness-of-fit statistics and box plots of residuals against relative height or diameter class. The compatible volume system of Fang et al. [22] provided the best compromise in describing the stem profile and estimating merchantable height, merchantable volume and total volume and is therefore recommended for pedunculate oak stands in Galicia.taper function / volume ratio / Galicia / Quercus robur Résumé -Un modèle pour l'estimation du volume commercialisable de chêne pédonculé dans le Nord-Ouest de l'Espagne. Un modèle d'estimation précise du volume marchand du chêne pédonculé (Quercus robur L.) à l'échelle des individus en Galice au Nord-Ouest de l'Espagne était indispensable. En conséquence, cette étude a été réalisée pour obtenir des équations de prédiction du volume marchand et du profil de tronc d'arbres individuels. Pour cela, deux modèles compatibles et quatre modèles non compatibles de volume ont été analysés et comparés à un échantillon de 251 arbres récoltés dans des peuplements de la zone de distribution de l'espèce en Galice. Les données extrêmes ont été éliminées pour fournir un ensemble de 3 090 sections disponibles pour l'étude. Une structure d'erreur auto-régressive continue a été utilisée pour prendre en compte l'autocorré-lation. La comparaison des modèles a été réalisée en utilisant les statistiques de meilleur ajustement et les nuages de points des résidus comparés aux classes de hauteur relative ou de diamètre. Le système de volume compatible de Fang et al. [22] a fourni le meilleur compromis pour la description du profil de tronc et l'estimation de la hauteur marchande, du volume marchand et du volume total et son usage est donc recommandé pour les peuplements de chêne pédonculé en Galice. fonction profil / rapport de volume / Galice / Quercus robur

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“…Yet, while necessary, this may be insufficient to achieve credibility with decision makers and other stakeholders. Possibly, a real test of model value is whether stakeholders have sufficient confidence in the model to use it as the basis for making management decisions (Vanclay and Skovsgaard 1997). Figure 2 is representative of the role that science-stakeholders dialogue may play in a comprehensive model evaluation.…”

Section: Deliberative Processes For Comprehensive Model Evaluationmentioning

confidence: 99%

Deliberative processes for comprehensive evaluation of agroecological models. A review

Bellocchi

Rivington

Matthews

et al. 2014

Agron. Sustain. Dev.

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The use of biophysical models in agroecology has increased in the last few decades for two main reasons: the need to formalize empirical knowledge and the need to disseminate model-based decision support for decision makers (such as farmers, advisors, and policy makers). The first has encouraged the development and use of mathematical models to enhance the efficiency of field research through extrapolation beyond the limits of site, season, and management. The second reflects the increasing need (by scientists, managers, and the public) for simulation experimentation to explore options and consequences, for example, future resource use efficiency (i.e., management in sustainable intensification), impacts of and adaptation to climate change, understanding market and policy responses to shocks initiated at a biophysical level under increasing demand, and limited supply capacity. Production concerns thus dominate most model applications, but there is a notable growing emphasis on environmental, economic, and policy dimensions. Identifying effective methods of assessing model quality and performance has become a challenging but vital imperative, considering the variety of factors influencing model outputs. Understanding the requirements of stakeholders, in respect of model use, logically implies the need for their inclusion in model evaluation methods. We reviewed the use of metrics of model evaluation, with a particular emphasis on the involvement of stakeholders to expand horizons beyond conventional structured, numeric analyses. Two major topics are discussed: (1) the importance of deliberative processes for model evaluation, and (2) the role computer-aided techniques may play to integrate deliberative processes into the evaluation of agroecological models. We point out that (i) the evaluation of agroecological models can be improved through stakeholder follow-up, which is a key for the acceptability of model realizations in practice, (ii) model credibility depends not only on the outcomes of well-structured, numerically based evaluation, but also on less tangible factors that may need to be addressed using complementary deliberative processes, (iii) comprehensive evaluation of simulation models can be achieved by integrating the expectations of stakeholders via a weighting system of preferences and perception, (iv) questionnaire-based surveys can help understand the challenges posed by the deliberative process, and (v) a benefit can be obtained if model evaluation is conceived in a decisional perspective and evaluation techniques are developed at the same pace with which the models themselves are created and improved. Scientific knowledge hubs are also recognized as critical pillars to advance good modeling practice in relation to model evaluation (including access to dedicated software tools), an activity which is frequently neglected in the context of time-limited framework programs.

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Evaluating forest growth models

Cited by 350 publications

References 38 publications

Robust relationships for simple plantation growth models based on sparse data

Robust relationships for simple plantation growth models based on sparse data

Un modèle pour l’estimation du volume commercialisable de chêne pédonculé dans le Nord-Ouest de l’Espagne

Deliberative processes for comprehensive evaluation of agroecological models. A review

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