Control function optimization for stochastic continuous cover forest management

Lohmander, Peter

doi:10.15406/iratj.2019.05.00178

Cited by 4 publications

(15 citation statements)

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“…The most obvious example is to define separate target diameters per roundwood grading class (set by the butt log quality) and tree species (Knoke 2012). Other influential and useful criteria for target diameter adjustment, are local competition indices (Lohmander 2019b), subject tree vitality (indirectly estimated as a crown status index, Abetz 1974, Pretzsch 2009 and relative market price level (Haight andMonserud 1990, Pukkala 2015).…”

Section: Individual-tree-selection In Practicementioning

confidence: 99%

“…The selected scale of the optimized system is, by tradition, the forest stand, normally requiring simulation of the stand development over a defined period of time. The criterion for comparing alternatives would typically be expected net present value of the investigated time period (Lohmander 2019b).…”

Section: Useful Concepts For Optimization Of Tree Selectionmentioning

confidence: 99%

“…This format is adequate for all forestry simulations since harvesting operations always occur as concentrated interventions with long periods in between (Lohmander 2007). With these basic components, complete stochastic stand simulation models with discrete time are possible to define (Lohmander 2019a).…”

Section: Useful Concepts For Optimization Of Tree Selectionmentioning

confidence: 99%

“…target diameter) as a function of relevant state variables (Lohmander 2007). When this control function is optimized with relevant techniques, including formulation of an objective function with variable data from management simulations, the outcome will be an optimized control function that is adaptive to changes in the stand state variables (Lohmander 2019a(Lohmander , 2019b).…”

Section: Useful Concepts For Optimization Of Tree Selectionmentioning

confidence: 99%

“…However, the challenge of ITS is further linked to the fact that individual tree growth and tree-group internal growth competition are dynamic processes that change over time. Furthermore, market price fluctuations will always have an impact on any predictions of future value growth (Pukkala 2015, Lohmander 2019b. Risk aversion to wind damage is another influential factor Kallio 2006, Díaz-Yáñez et al 2017).…”

Section: Introductionmentioning

confidence: 99%

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Individual-tree-selection in uneven-sized Norway spruce stands in southern Sweden: Developments of tools for simulation and optimization

Fagerberg¹

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Individual-tree-selection (ITS) is a continuous cover forestry method thataims to utilize the uneven-sized stand structure through optimized individualtree selections. ITS is an interesting management alternative to rotationforestry in terms of production of multiple benefits and forest ownerprofitability. With regard to Fennoscandia, ITS is currently only practiced to alimited extent, partly because of a scarcity in knowledge and skills among allstakeholders, but also due to the shortage of scientific guidelines for howoptimized tree selections are performed in practice. Thus, the aim of thethesis is to develop tools for optimizing practical ITS recommendations forNorway spruce.Tree position data for model fitting were collected from five trial sites insouthern Sweden, one of which was documented with terrestrial laser scanningto get crown shape data for knot size modelling. A method that optimizes thetarget diameter dependent on the discount rate and the degree of thelocal competition exposed to the subject tree, was developed. Technically, adefined adaptive control function was optimized with full system stochasticsimulation and with expected present value as the objective functionvariable. Since the quality of the optimization is dependent on the qualityof the models in the simulation, priority was given to the evaluation anddevelopment of the central models. Available individual tree growth modelswere tested and evaluated with tree data from long term uneven-sizedtrial plots. Furthermore, new individual-tree distance-dependent growthmodels were developed for uneven-sized Norway spruce. A modellingframework, for prediction of the largest knot size per stem height section,was developed to provide means of simulating log quality depending on theimpact from local tree competitors.The results indicated that the thinning intensity in uneven-sized standstructures may be used to actively control the transition point where smallerdiameter classes are subjected to suppressed growth. The evaluation ofthe Swedish individual-tree growth models which are included in theHEUREKA forest simulator, showed underestimation of large trees andoverestimation of small trees. The underestimation is smaller or absent indenser forests for diameter classes above 40 cm. The new distance-dependentgrowth models are presented in two versions, one with and one without crownratio as a predictor. The new growth models facilitate the testing of spatialdecision criteria in ITS optimization. From the results of the ITSoptimization, field operators can choose either a fixed level target diameteror a flexible target diameter that is adaptive to the degree of localcompetition surrounding the subject tree. Optimal fixed target diametersat breast height range from 33 cm to 23 cm depending on discount rate(1–3 %). A decision support structure for ITS is proposed.

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Section: Individual-tree-selection In Practicementioning

confidence: 99%

Section: Useful Concepts For Optimization Of Tree Selectionmentioning

confidence: 99%

Section: Useful Concepts For Optimization Of Tree Selectionmentioning

confidence: 99%

Section: Useful Concepts For Optimization Of Tree Selectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Individual-tree-selection in uneven-sized Norway spruce stands in southern Sweden: Developments of tools for simulation and optimization

Fagerberg¹

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Climate-related subsidies for CO2 absorption and fuel substitution: Effects on optimal forest management decisions

Mohammadi

Lohmander

Kašpar

et al. 2023

Journal of Environmental Management

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Optimization of continuous cover forestry expansion under the influence of Global warming

Lohmander¹

2020

IRATJ

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Planet Earth faces the problem of global warming. Recent research on the dynamics of the CO 2 concentration in the atmosphere has shown how reductions of global industrial emissions of CO 2 can solve a large part of the global warming problem. However, there are more control options available. Our world is covered by large areas of primary (natural) forests that are almost not managed at all. They do not contribute very much to the net absorption of CO 2 . Parts of these natural forests may be transformed to continuous cover forests, which mean that the absorption of CO 2 increases so that the CO 2 level in the atmosphere can be further reduced. This transformation can be made without severely damaging the environmental conditions. The analysis in this paper shows how to define an optimization problem with two objectives with different weights in the objective function. These objectives are the economic present value of profits and the utility of the climate. The analysis shows how the optimal transformation of natural forests to managed continuous cover forests is affected by the relative weights of the utility of the climate and of the present value of the profits. If the relative weight of the utility of the climate increases, the optimal area of natural forests that should be transformed to managed continuous cover forests increases. If 600 M hectares are transformed during 60 years, from 2020 until 2080, then the concentration of CO 2 in the atmosphere can be reduced by 8 ppm until the year 2100.

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Control function optimization for stochastic continuous cover forest management

Cited by 4 publications

References 9 publications

Individual-tree-selection in uneven-sized Norway spruce stands in southern Sweden: Developments of tools for simulation and optimization

Individual-tree-selection in uneven-sized Norway spruce stands in southern Sweden: Developments of tools for simulation and optimization

Climate-related subsidies for CO2 absorption and fuel substitution: Effects on optimal forest management decisions

Optimization of continuous cover forestry expansion under the influence of Global warming

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