Using JABOWA-3 for forest growth and yield predictions under diverse forest conditions of Nova Scotia, Canada

Abstract

Empirical growth and yield models developed from historical data are commonly used in developing long-term strategic forest management plans. Use of these models rests on an assumption that there will be no future change in the tree growing environment. However, major impacts on forest growing conditions are expected to occur with climate change. As a result, there is a pressing need for tools capable of incorporating outcomes of climate change in their predictions of forest growth and yield. Process-based models have this capability and may, therefore, help to satisfy this requirement. In this paper, we evaluate the suitability of an ecological, individual-tree-based model (JABOWA-3) in generating forest growth and yield projections for diverse forest conditions across Nova Scotia, Canada. Model prediction accuracy was analyzed statistically by comparing modelled with observed basal area and merchantable volume changes for 35 permanent sample plots (PSPs) measured over periods of at least 25 years. Generally, modelled basal area and merchantable volume agreed fairly well with observed data, yielding coefficients of determination (r 2 ) of 0.97 and 0.94 and model efficiencies (ME) of 0.96 and 0.93, respectively. A Chi-square test was performed to assess model accuracy with respect to changes in species composition. We found that 83% of species-growth trajectories based on measured basal area were adequately modelled with JABOWA-3 (P > 0.9). Model-prediction accuracy, however, was substantially reduced for those PSPs altered by some level of disturbance. In general, JABOWA-3 is much better at providing forest yield predictions, subject to the availability of suitable climatic and soil information.Key words: forest model, growth and yield predictions, individual-tree-based model, model-accuracy assessment, statistical-performance indicators RÉSUMÉOn se sert couramment de modèles empiriques de croissance élaborés à partir de données historiques pour faire des plans stratégiques d'aménagement forestier à long terme. L'utilisation de ces modèles repose sur l'hypothèse que le milieu de croissance ne changera pas dans le futur. Or, on s'attend à ce que les changements climatiques modifient considérablement les conditions de croissance en forêt. Il y a donc un besoin urgent de mettre au point des outils capable de tenir compte les effets dus aux changements climatiques dans la prévision de la croissance et du rendement en forêt. Les modèles de procédés ont cette capacité et peuvent donc être d'une aide précieuse à cette fin. Dans cet article, nous évaluons la pertinence d'un modèle écologique par pied d'arbre (JABOWA-3) pour effectuer des prévisions de croissance et de rendement en forêt dans diverses conditions forestières de la Nouvelle-Écosse, au Canada. On a évalué de façon statistique la préci-sion des prévisions obtenues avec ce modèle en comparant les changements de surface terrière et de volume marchand à partir de 35 placettes permanentes (PEP) mesurées sur des périodes d'au moins 25 ans. De façon génér...

A Novel Modelling Approach for Predicting Forest Growth and Yield under Climate Change

“…Tree growth projections were developed for 34 PSP locations across NS, selected to represent nine eco-regions and capture the diverse climatic and site growing conditions of NS. The model was first calibrated using historical weather records and observed PSP data from NS [ 41 ]. JABOWA-3 was initiated with existing stand conditions using relevant projected future climates.…”

Mathematical Models Arising in the Fractal Forest Gap via Local Fractional Calculus

“…where is the diameter at breast height, 0 is the scaling coefficient, and is the fractal dimension. Making use of the fractional complex transform [29] and (20), the growth equation in the JABOWA model with local fractional derivative (LFJABOWA) is suggested by…”

“…Forest gap model (JABOWA) developed by Botkin et al [14][15][16] was the first simulation model for gap-phase replacement. It was applied to describe a forest as a mosaic of closed canopies and simulate forest dynamics based upon the establishment, growth, and death of individual trees [17][18][19][20]. The JABOWA model in the form of the FORET model (called JABOWA-FORET) was further developed in [21][22][23][24].…”

Mixed Regional Shifts in Conifer Productivity under 21st-Century Climate Projections in Canada’s Northeastern Boreal Forest

“…Although the formulation of the physiological functions driving PBM are often rooted in empirical studies or otherwise in contemporary understandings of ecophysiologic response, a departure from the statistical relationships and parameters that form empirical-type models is often thought to absolve the PBM from any underlying assumption of static growing conditions [24,38]. As such, PBM are often considered to be more suitable in accounting for climate change [35,39]. Despite their advantages, all PBM reflect a contemporary understanding of the complex processes that influence tree growth, which are of course based on historical quantitative records.…”

“…In this paper, we provide an evaluation of the impact of climate change on the boreal forests of Newfoundland and Labrador (NL), Canada, using the JABOWA-3 forest gap model. Although there have been recent applications of PBM in the New England-Acadian transitional forests of Canada's maritime provinces [14,39], there have been no such applications in the northeastern boreal forests of NL. We used JABOWA to explore the impacts of climate change on the composition and growth of the northeastern boreal forest by inferring regional-level trends simulated through the use of a detailed forest gap model by leveraging a large number of forest sample plots across the regions of interest.…”