Market Adaptive Control Function Optimization in Continuous Cover Forest Management

Document Type: Research Paper

Author

Optimal Solutions in Cooperation with Linnaeus University, Umea, Sweden

Abstract

Economically optimal management of a continuous cover forest is considered here. Initially, there is a large number of trees of different sizes and the forest may contain several species. We want to optimize the harvest decisions over time, using continuous cover forestry, which is denoted by CCF. We maximize our objective function, the expected present value, with consideration of stochastic prices, timber quality variations and dynamically changing spatial competition. The problem is solved using an adaptive control function. The parameters of the control function are optimized via the first order optimum conditions based on a multivariate polynomial approximation of the objective function. The second order maximum conditions are investigated and used to determine relevant parameter ranges. The procedure is described and optimal results are derived for a general function multi-species CCF forest. Concrete examples from Germany, with beech, and from Sweden, with Norwegian spruce, are used to illustrate the methodology and typical numerical results. It is important to make market adapted harvest decisions. If the stochastic price variations are not considered when the harvest decisions are taken, the expected present value is reduced by 23%.

Keywords

Main Subjects


Article Title [Persian]

بهینه سازی مدیریت بازار – وابسته جنگلهایی با پوشش پیوسته

Author [Persian]

  • پیتر لُهماندر
گروه مدیریت و بهینه سازی اقتصادی، دانشگاه اومئو، امئو، سوئد
Abstract [Persian]

در این پژوهش مدیریت بهینه اقتصادی در یک جنگل با پوشش پیوسته که دارای گونه­های متفاوت و ابعاد متفاوت است،  مورد نظر است. ما درچارچوب مفهوم جنگلداری با پوشش پیوسته به دنبال بهینه­سازی میزان برداشت در طی زمان بودیم. تابع هدف  براساس پارامترهای قیمت­های تصادفی، تغییرات کیفیت چوب و پویایی تغییرات مکانی رقابت، به دنبال به حداکثر رساندن ارزش فعلی موردانتظار است. چالش اصلی با لحاظ کردن و اعمال مدل کنترل تطبیقی مورد بررسی قرار گرفت. بهینه سازی پارامترهای تابع کنترل با استفاده از شرایط بهینه درجه اول (شرط لازم) و براساس تخمین چندجمله­ای چنذمتغیره تابع هدف انجام گرفت. شرایط بهینه درجه دوم (شرط کافی) برای تعیین دامنه پارامترهای موثر نیز استفاده گردید. در این مقاله مراحل انجام پژوهش بیان و نتایج بهینه برای یک مدل عمومی جنگل پیوسته به صورت مختلط (چند گونه) آورده شده است. روش  تحقیق پیشنهاد شده به صورت عملی در یک جنگلی با گونه غالب راش در آلمان و جنگلی دیگر در سوئد با گونه غالب نوئل مورد آزمون قرارگرفت و نتایج کمی و عددی آن در این مقاله آمده است. نکته اساسی که باید در نظر گرفته شود تعیین سن بهره­برداری براساس قیمت بازار است. اگر در اینچنین پژوهش­هایی تغییرات تصادفی قیمت در تعیین سن بهره برداری لحاظ نگردد ارزش فعلی مورد انتظار تا حدود 23 درصد کاهش خواهد یافت.

Keywords [Persian]

  • بهینه سازی اقتصادی
  • جنگل چند گونه ای
  • مدیریت جنگل
  • فرآیند تصادفی
  • مدل بهینه تطبیقی
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