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Jari Vauhkonen - One of the best experts on this subject based on the ideXlab platform.
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Effects of diameter distribution errors on Stand Management decisions according to a simulated individual tree detection
Annals of Forest Science, 2020Co-Authors: Jari VauhkonenAbstract:Key Message Tree-level forest inventory data are becoming increasingly available, which motivates the use of these data for decision-making. However, airborne inventories carried out tree-by-tree typically include systematic errors, which can propagate to objective function variables used to determine optimal forest Management. Effects of under-detection focused on the smallest trees on predicted immediate harvest profits and future expectation values were assessed assuming different sites and interest rates. Management decisions based on the erroneous information caused losses of 0–17% of the total immediate and future expected income of Scots pine Stands. Context Optimal decisions on how to manage forest Stands can depend on the absence or presence of intermediate and understory trees. Yet, these tree strata are likely prone to inventory errors. Aims The aim of this study is to examine implications of making Stand Management decisions based on data that include systematic errors resembling those typically observed in airborne inventories carried out tree-by-tree. Methods Stand Management instructions were developed based on theoretical diameter distribution functions simulated to have different shape, scale, and frequency parameters corresponding to various degrees of under-detection focused on the smallest trees. Immediate harvest income and future expectation value were derived based on various Management alternatives simulated. Results Errors in diameter distributions affected the predicted harvest profits and future expectation values differently between the simulated alternatives and depending on site type and interest rate assumptions. As a result, different alternatives were considered as optimal Management compared to the use of the error-free reference distributions. In particular, the use of no Management or most intensive Management alternatives became preferred over alternatives with intermediate harvesting intensities. Certain harvesting types such as thinning from below became preferred more often than what was optimal. The errors did not affect the selection of the Management alternative in 71% of the simulations, whereas in the remaining proportion, relying on the erroneous information would have caused losing 2%, on average, and 17% at maximum, of the total immediate and future expected income. Conclusion The effects above might not have been discovered, if the results were validated for inventory totals instead of separately considering the immediate and future income and losses produced by the erroneous decisions. It is recommended not to separate but to integrate the inventory and planning systems for well-informed decisions.
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Effects of diameter distribution errors on Stand Management decisions according to a simulated individual tree detection
Annals of Forest Science, 2020Co-Authors: Jari VauhkonenAbstract:Tree-level forest inventory data are becoming increasingly available, which motivates the use of these data for decision-making. However, airborne inventories carried out tree-by-tree typically include systematic errors, which can propagate to objective function variables used to determine optimal forest Management. Effects of under-detection focused on the smallest trees on predicted immediate harvest profits and future expectation values were assessed assuming different sites and interest rates. Management decisions based on the erroneous information caused losses of 0–17% of the total immediate and future expected income of Scots pine Stands. Optimal decisions on how to manage forest Stands can depend on the absence or presence of intermediate and understory trees. Yet, these tree strata are likely prone to inventory errors. The aim of this study is to examine implications of making Stand Management decisions based on data that include systematic errors resembling those typically observed in airborne inventories carried out tree-by-tree. Stand Management instructions were developed based on theoretical diameter distribution functions simulated to have different shape, scale, and frequency parameters corresponding to various degrees of under-detection focused on the smallest trees. Immediate harvest income and future expectation value were derived based on various Management alternatives simulated. Errors in diameter distributions affected the predicted harvest profits and future expectation values differently between the simulated alternatives and depending on site type and interest rate assumptions. As a result, different alternatives were considered as optimal Management compared to the use of the error-free reference distributions. In particular, the use of no Management or most intensive Management alternatives became preferred over alternatives with intermediate harvesting intensities. Certain harvesting types such as thinning from below became preferred more often than what was optimal. The errors did not affect the selection of the Management alternative in 71% of the simulations, whereas in the remaining proportion, relying on the erroneous information would have caused losing 2%, on average, and 17% at maximum, of the total immediate and future expected income. The effects above might not have been discovered, if the results were validated for inventory totals instead of separately considering the immediate and future income and losses produced by the erroneous decisions. It is recommended not to separate but to integrate the inventory and planning systems for well-informed decisions.
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Effects of diameter distribution errors on Stand Management decisions according to a simulated individual tree detection
Annals of Forest Science, 2020Co-Authors: Jari VauhkonenAbstract:Context: Optimal decisions on how to manage forest Stands can depend on the absence or presence of intermediate and understory trees. Yet, these tree strata are likely prone to inventory errors. Aims: The aim of this study is to examine implications of making Stand Management decisions based on data that include systematic errors resembling those typically observed in airborne inventories carried out tree-by-tree. Methods: Stand Management instructions were developed based on theoretical diameter distribution functions simulated to have different shape, scale, and frequency parameters corresponding to various degrees of under-detection focused on the smallest trees. Immediate harvest income and future expectation value were derived based on various Management alternatives simulated. Results: Errors in diameter distributions affected the predicted harvest profits and future expectation values differently between the simulated alternatives and depending on site type and interest rate assumptions. As a result, different alternatives were considered as optimal Management compared to the use of the error-free reference distributions. In particular, the use of no Management or most intensive Management alternatives became preferred over alternatives with intermediate harvesting intensities. Certain harvesting types such as thinning from below became preferred more often than what was optimal. The errors did not affect the selection of the Management alternative in 71% of the simulations, whereas in the remaining proportion, relying on the erroneous information would have caused losing 2%, on average, and 17% at maximum, of the total immediate and future expected income. Conclusion: The effects above might not have been discovered, if the results were validated for inventory totals instead of separately considering the immediate and future income and losses produced by the erroneous decisions. It is recommended not to separate but to integrate the inventory and planning systems for well-informed decisions.
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WHAT DATA ACCURACY SUFFICES FOR Stand Management DECISIONS? A SIMULATION STUDY CONSIDERING DIFFERENT SITES AND INTEREST RATES FOR SCOTS PINE
2018Co-Authors: Jari VauhkonenAbstract:The use of airborne inventory data to detect and delineate individual trees and to predict total tree diameter distribution (DD) has been studied a lot in recent years. However, it is unclear if the current methods produce a sufficient accuracy for forest Management decisions. Even if some studies in this field exist, these are limited to even-aged forestry. The aim here is to study the implications of varying accuracy of inventory data up to the next Management activity, depending on a wide set of alternatives also including thinning from above. The study is carried out by simulating DDs with varying shapes and scales, assuming the representation of the individual trees to be the main determinant of the related decisions (Vastaranta et al., 2011). The simulations were based on altogether 40 pure Scots pine Stands studied by Vauhkonen and Mehtatalo (2015). All DDs were described using the two-parameter form of the Weibull function. Reference DDs were obtained by fitting the Weibull function to the trees measured in the field plots. Varying accuracies for the DDs were obtained by applying three different airborne inventory approaches to the same plots (Vauhkonen and Mehtatalo, 2015): 1. Individual tree detection and estimation, in which tree crown segments were isolated using an adaptive filtering of local height maxima and watershed segmentation. Tree diameters were obtained using a locally fitted model with maximum height and radius of the segments as predictors. 2. Area-based approaches based on polynomial regression models to correct the censoring effect caused by overlapping tree crowns in the above data. Both the population-averaged and localized models of Vauhkonen and Mehtatalo (2015) were tested for this purpose. In addition, linear interpolation between the reference and predicted distribution parameters was used to generate a wider set of distributions that varied in terms of accuracy. In all alternatives, tree heights were predicted by the same, locally-fitted function. Using the diameter and height, the total stem and assortment volumes were estimated based on taper curves and a simple method mimicking stem bucking into logs for saw timber and pulp wood based on the same rules for allowable log lengths, their minimum diameters, and prices as used by Vauhkonen and Pukkala (2016), based on the specifications of roadside-transactions carried out in this area. Altogether seven different Management alternatives were simulated for each of the tree lists described above. The alternatives included no-Management, clear-cutting, thinning from below, and four different thinnings from above, based on different rules for tree selection (Pukkala et al., 2015; Vauhkonen and Pukkala, 2016) and therefore different distributions of the harvested and remaining trees. Except for simulating the Management alternatives for the different forest structures represented by the 40 plots, each plot was simulated as if it was located on three different sites (either on Myrtillus [mesic], Vaccinium [sub-xeric], or Calluna [xeric] site types) and using interest rates of 2–4%, which affected the productivity of the remaining tree stock and also tree selection rules in some harvesting alternatives. The results of the treatments for the different forest structures were evaluated in terms of two criteria: the present value of the harvested trees and the expectation value based on the bare land and the remaining trees. The present and future values were summed together and the Management alternative that produced the highest total value was considered as the most suitable for the plot. The dispersion of the selected alternatives was examined as a function of the accuracy of DD under different site types and interest rates. The present value of the harvested wood (€/ha) was obtained as price × quantity of the obtained timber assortments minus estimated costs of cut-to-length-logging and roadside-transportation of the trees marked to be harvested. The costs were estimated by modelling the time expenditure of these operations as a function of harvesting type (final felling vs. thinning) and the total removal. The time expenditure was multiplied by the unit cost assumed for operating a harvester and a forwarder in the relevant area. The SEV was the present value (€/ha) of the costs and revenues resulting from timber production in the remaining tree stock, when its Management rotations are expected to continue in perpetuity. The SEV was obtained as an average from a very high number of simulated rotations, in which the Stand treatments were optimized for timber production with the given site fertility, growing stock and operational environment (temperature, interest rates and prices) related parameters. Even if simulated on simple Weibull function forms, the different harvests resulted in different distributions of harvested and remaining trees, which differed depending on the quality of the DD predictions. However, complex interactions between site fertility, interest rate, and initial forest structure also affected the harvesting outcomes based on the reference and predicted distributions. The presentation will provide a detailed account of these effects that cannot be presented in this limited space. When pooled over all combinations of DDs, site fertilities, and interest rates, the predicted Management alternative matched precisely that of the reference distribution in altogether 77% of the plots or did not otherwise cause losses in terms of the total SEV. However, Management alternatives predicted on 5% of the plots would have caused losses corresponding to at least 6% of the total SEV and as much as 35% at maximum. The biggest losses did not occur with a specific inventory method or forest structure, but were related to the highest interest rates. Developing knowledge-based rules on Management alternatives selected on different site fertility – interest rate combinations based on the reference data allowed for preventing the simulation of infeasible alternatives. A set of simple rules halved the proportion of highest SEV losses presented above. The accuracy of forest inventory methods for selecting Management alternatives for Scots pine Stands was found adequate. However, because the decision of Stand Management is dependent on many other aspects than Stand structure, it is recommended not to separate but to integrate the inventory and planning systems for well-informed decisions.
Timo Pukkala - One of the best experts on this subject based on the ideXlab platform.
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Meta optimization of Stand Management with population-based methods
Canadian Journal of Forest Research, 2018Co-Authors: Xingji Jin, Timo PukkalaAbstract:The amount of different products and services obtained from forests depends on several Management decisions such as thinning years, thinning intensity, thinning type and rotation length. The relationships between Management actions and the various outputs obtained from forests are complicated. This makes Stand Management optimization challenging, especially if the number of simultaneously maximized outputs and the number of optimized variables are high. The direct search method of Hooke and Jeeves (HJ) has been used much in Stand Management optimization. In recent years, population-based methods have been proposed as an alternative to the HJ method. The performance of a population-based method depends on its parameters such as number iterations and population size (number of solution vectors used in the population-based method). This study used two-level meta optimization to simultaneously optimize the parameters of a population-based method and the Management schedule of a Stand. Four population-based me...
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Optimizing the joint production of timber and marketed mushrooms in Picea abies Stands in eastern Finland
Journal of Forest Economics, 2018Co-Authors: Veera Tahvanainen, Timo Pukkala, Jari Miina, Mikko KurttilaAbstract:Abstract There is a notable potential for utilizing marketed mushrooms in Finnish forests. The most marketed mushrooms in Finland are Boletus edulis and Lactarius spp. To improve preconditions for the use of this potential the Stand Management was optimized separately for joint production of (1) timber and B. edulis, (2) timber and Lactarius spp. and (3) timber and both B. edulis and Lactarius spp. in even-aged Picea abies Stands in eastern Finland. In optimizations soil expectation value (SEV) with a 3% discount rate was maximized and picking costs and mushroom prices were included in calculations. The optimal two-thinning Management schedule for timber only consisted of a rotation length of 96 years and heavy thinnings from above. The optimal Stand Management schedules for joint production were very similar to that of timber, because mushroom yields are at their highest just before the first commercial thinning. When Management was optimized for mushroom production only, the optimal rotation lengths were shorter, and for B. edulis the thinnings were lighter. Management optimal for Lactarius spp. did not include thinning treatments. The production of timber and marketed mushrooms were mostly in synergy, mushroom harvesting creating significant additional income to forest owners.
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Optimal crosscutting: any effect on optimal Stand Management?
European Journal of Forest Research, 2017Co-Authors: Timo PukkalaAbstract:Trees harvested in cuttings are usually partitioned into timber assortments, for instance, saw logs, poles and pulpwood logs. Since different assortments have different prices, the way in which harvested stems are crosscut affects the incomes of the forest landowner. Optimal crosscutting aims at maximizing the total value of the assortments obtained from the stems. Although forest research has developed several algorithms for optimal crosscutting, it has rarely been included in the optimization of Stand Management. Treatment prescriptions are often based on analyses in which the value of harvested trees is calculated without considering the whole set of timber price categories and without simulating the crosscutting of harvested trees. This may lead to biased conclusions about optimal Stand Management. This study proposed a fast and flexible method for optimizing the crosscutting of harvested trees in the context of Stand Management optimization. The method employs simulated annealing to find the optimal combination of log lengths, separately for each harvested tree. The results calculated for case study Stands suggest that optimal crosscutting leads to longer rotation lengths than obtained in analyses where the values of harvested trees are predicted with more simple methods. Optimal crosscutting increases the incomes of forest landowner and the proportions of the most valuable saw log assortments. The proportion of harvested pulpwood decreases.
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Adaptive Management rules for Pinus nigra Arnold ssp . salzmannii Stands under risk of fire
Annals of Forest Science, 2017Co-Authors: José Ramon Gonzalez-olabarria, Jordi Garcia-gonzalo, Blas Mola-yudego, Timo PukkalaAbstract:Key message We generate flexible Management rules for black pine Stands, adaptable to alternative Stand Management situations and entailing thinnings, final-felling, and salvage cuts, based on the results on 270 Stand level optimizations.
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Effects of climate change on optimised Stand Management in the boreal forests of central Finland
European Journal of Forest Research, 2014Co-Authors: Ane Zubizarreta-gerendiain, Timo Pukkala, Jordi Garcia-gonzalo, Seppo Kellomäki, Veli-pekka Ikonen, Heli PeltolaAbstract:In boreal conditions, climate change is expected to increase mean annual temperature and precipitation, increasing forest growth and productivity in managed forests. In this study, we aimed at finding out how climate change affects the optimal Management of Scots pine-, Norway spruce- and silver birch-dominated Stands on sites of varying fertility (high-herb, mesic and sub-xeric sites) in the boreal forests of central Finland. The objective function was to maximise net present value (NPV), considering the future incomes from timber sales and costs of forest operations. The results showed that under the gradually changing climate, the optimised Management schedules differed from those observed under the current climate. In Norway spruce- and birch-dominated Stands, cuttings were done earlier under the changing climate than under the current climate, while in Scots pine-dominated Stands they were delayed under the changing climate. The optimised Management schedules also varied, depending on tree species and site fertility types. Under the changing climate, both timber production and NPV increased compared to the current climate, regardless of species and site fertility type.
Atsushi Yoshimoto - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of carbon sequestration and thinning regimes within the optimization framework for forest Stand Management
European Journal of Forest Research, 2007Co-Authors: Atsushi Yoshimoto, Róbert MarušákAbstract:Due to the urgent demand for thinning in planted forests and the tend towards sustainable forest resource Management, the forest Stand age class eligible for the thinning subsidy in Japan was expanded during the period from 2000 to 2004. Currently, further expansion is under consideration in line with meeting the Kyoto Protocol target of carbon sequestration. In this paper, we conducted evaluation analyses of carbon sequestration and subsidy effects within the optimization framework for the forest Stand Management. The optimal forest Stand Management model called Dynamic Programming model for Kyushu Stand Simulator (DP-KYSS) was utilized for the analysis of the target sugi (Cryptomeria japonia) forest Stand in the Kyushu region, Japan. Our results showed that the thinning subsidy was effective to stimulate thinning activities at the eligible age class for the subsidy, and that 20% of the current or proposed payment was appropriate to give an incentive to forest owners for conducting the same optimal thinning regime. The amount of carbon sequestered in remaining trees at final harvest was not always shown to increase over time. Depending upon the subsidy condition, it could decrease. The average annual amount of carbon sequestered under no subsidy showed its maximum at age 35, while under the other subsidy conditions, it was shortened to age 25. The net present value of cost per unit carbon loss associated with subsidy became the highest for the rotation age of 35 years for all subsidy policies considered here.
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Stochastic control modeling for forest Stand Management under uncertain price dynamics through geometric brownian motion
Journal of Forest Research, 2002Co-Authors: Atsushi YoshimotoAbstract:In this paper, a stochastic control model is constructed by incorporating geometric Brownian motion to capture uncertain price dynamics into a one-stage and two-state stochastic dynamic programming model. The proposed model is designed to search for optimal harvest timing under price uncertainty without considering other forestry operations, e.g. , thinning. We consider the option of abandoning forest Management for an alternative use of forest land besides replantation. Our experimental analysis shows that the optimal harvest timing under stochastic log prices is delayed when a price level is crucially low for maintaining the Management. It is also shown that when the current log price is sufficiently high, the optimal harvest timing derived from both the stochastic and deterministic approach becomes the same. With a downward trend of stochastic price dynamics, the optimal harvest timing tends to be hastened overall. This is because of the depreciation effect on the future return, which stimulates harvesting in an earlier period.
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Risk Analysis in the Context of Timber Harvest Planning
Risk Analysis in Forest Management, 2001Co-Authors: Atsushi YoshimotoAbstract:Events related to forest Management are associated with uncertainty. This affects the Management decision for forest level planning as well as Stand level planning. In this paper, two stochastic models are introduced. The first model is a macro-type stochastic model for timber supply analysis by predicting harvesting events over the time horizon, while the second model is a micro-type stochastic model used to search for an optimal rotation for forest Stand Management under price uncertainty. A macro-type approach describes private forest owners’ harvesting behavior with the use of a stochastic process. The threshold method was assumed for the decision-making mechanism. In contrast, a micro-type approach was to search for an optimal rotation period for forest Stand Management under price uncertainty. Unlike the macro type approach, uncertainty was assumed for log price, which affects an optimal decision for the Stand Management. Stochastic differential equations are applied to capture stochasticity of price dynamics, and a stochastic dynamic programming approach is utilized for optimization. The continuous time stochastic process, i.e. the geometric Brownian motion, is used to model the log price process. The binomial option pricing approximation is then applied to discretize the price dynamics. Estimation of nonlinear models to stochastic phenomena is also elaborated.
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Searching for an optimal rotation age for forest Stand Management under stochastic log prices
European Journal of Operational Research, 1998Co-Authors: Atsushi Yoshimoto, Isao ShojiAbstract:Due to rapid change in timber prices in the Japanese market most likely affected by imported timber from countries such as the U.S., Canada, and the Nordic countries, the domestic forest managers have been facing a large degree of future price uncertainty. Because of this, it becomes necessary to take the future price uncertainty into account within the forest Management framework. In this paper, the continuous time stochastic process, i.e., the geometric Brownian motion, has been used to model the log price process. The binomial option pricing approximation was then applied to value the Sugi (Cryptomeria japonica) and Hinoki (Chamaecyparis obtusa) forested land under stochastic log prices in order to search for an optimal rotation age. Our experiments with the proposed two state stochastic dynamic programming model showed that when the current log price is high enough to cover all costs, an optimal rotation age from the stochastic price and deterministic price models coincides, although the total expected present net value from Management activities differs. Also it was shown that as the current log price decreases, an optimal rotation age derived from the stochastic price model becomes longer than that from the deterministic price model. If the current log price further decreases, then forest Management will be abandoned, and the forest Stand will be converted into alternative uses.
Seppo Kellomäki - One of the best experts on this subject based on the ideXlab platform.
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Effects of climate change on optimised Stand Management in the boreal forests of central Finland
European Journal of Forest Research, 2014Co-Authors: Ane Zubizarreta-gerendiain, Timo Pukkala, Jordi Garcia-gonzalo, Seppo Kellomäki, Veli-pekka Ikonen, Heli PeltolaAbstract:In boreal conditions, climate change is expected to increase mean annual temperature and precipitation, increasing forest growth and productivity in managed forests. In this study, we aimed at finding out how climate change affects the optimal Management of Scots pine-, Norway spruce- and silver birch-dominated Stands on sites of varying fertility (high-herb, mesic and sub-xeric sites) in the boreal forests of central Finland. The objective function was to maximise net present value (NPV), considering the future incomes from timber sales and costs of forest operations. The results showed that under the gradually changing climate, the optimised Management schedules differed from those observed under the current climate. In Norway spruce- and birch-dominated Stands, cuttings were done earlier under the changing climate than under the current climate, while in Scots pine-dominated Stands they were delayed under the changing climate. The optimised Management schedules also varied, depending on tree species and site fertility types. Under the changing climate, both timber production and NPV increased compared to the current climate, regardless of species and site fertility type.
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Anticipatory vs adaptive optimization of Stand Management when tree growth and timber prices are stochastic
Forestry, 2012Co-Authors: Timo Pukkala, Seppo KellomäkiAbstract:Summary Forest Management involves considerable amounts of uncertainty related to future timber prices and tree growth. A new element in forest-Management planning is climate-induced change in tree growth. This study used stochastic adaptive optimization to derive optimal adaptive rules for the Management of a mixed Stand of Norway spruce, Scots pine and birch, when (1) both price and growth were stochastic and (2) there was a climate-induced growth trend. Optimized reservation-price function was used as the adaptive rule for final felling. The optimal times of thinning treatments were described by rules that related the thinning year to the growth rate of the Stand. The results suggest that an improving growth trend slightly shortens optimal rotation lengths. On the other hand, risk related to timber price and growth tended to increase the rotation length. Increasing timber-price volatility increased the reservation price and rotation length. When risk and risk-aversion increased, maintaining a more diverse Stand structure was profitable.
C. H. Michler - One of the best experts on this subject based on the ideXlab platform.
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Managing fine hardwoods after a half century of research: Proceedings of the Seventh Walnut Council Research Symposium
2013Co-Authors: J. Van Sambeek, Mark V. Coggeshall, Elizabeth A. Jackson, Andrew L. Thomas, C. H. MichlerAbstract:This report presents information from the Seventh Walnut Council Research Symposium, held August 1-3, 2011. This report includes 14 papers and abstracts relating to economics and utilization, pest Management, nursery production, plantation establishment, tree improvement, Stand Management, agroforestry, and nut production of black walnut, related Juglans species, and other high value hardwoods.
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Black walnut in a new century, proceedings of the 6th Walnut Council research symposium; 2004 July 25-28; Lafayette, IN.
2004Co-Authors: C. H. Michler, P.m. Pijut, J. Van Sambeek, Mark V. Coggeshall, J. Seifert, Keith E. Woeste, R. Overton, Felix PonderAbstract:Presents papers and abstracts relating to genetic improvement, nursery production, plantation establishment, natural Stand Management, pest Management, agroforestry and economics of black walnut and related Juglans species.
