The Evaluation of a National Forest Harvest Scheduling System for Ireland - Two Case Studies

摘要

Coillte Teoranta (the Irish Forestry Board) harvested approximately 2.0 million m3 in 1994. By the year 2000 this annual harvest is projected to increase to approximately 2.8 million m3 and to 3.7 million m3 by the year 2011. To facilitate the management of these increased timber flows more efficiently and effectively, the Harvest Scheduling System (HSS) was developed. In order to evaluate the HSS's solutions, five case studies were carried out, two of which are presented in this paper. Initially, the HSS model was solved without any management constraints, resulting in a theoretical maximum net present value (NPV) (case study 1). Subsequently, the effect of imposing national and regional level volume fluctuation constraints was examined (case study 2). The investigations in the "no constraints" study resulted in a theoretical optimal harvest schedule for Coillte over the period 1998 to 2002. The solution showed great volume fluctuations from year to year, in terms of total volume, species, harvest type and product. It would be impossible to implement such a schedule, due to management, harvesting resources and industry requirements. However, the NPV achieved was used as a base to estimate the cost of applying management constraints in the second case study. This second study also showed that Coillte's production smoothing process results in harvest schedules that are not feasible, as no adjustments for volume are included.