An Economic Evaluation of Alternative Stand Treatments in Relation to the Development of Understorey Vegetation and Subsequent Regeneration Costs

A study on the development of understorey vegetation and itseconomic implications in managed stands of Sitka spruce in GwydyrForest, North Wales, is described. The relationships betweenstand age, relative light intensity, thinning regime, and Yieldor Quality Class are used to predict the possible developmentof understorey vegetation. This prediction mechanism is thenused, together with economic analysis techniques, to determinewhether the money economically available for weeding is adequatefor this purpose. Four combinations of current and future thinningregimes and five Yield Classes are considered. It is shown thatin the higher Yield Classes light thinning is advisable butheavier thinning appears more profitable in the lower YieldClasses. It is emphasized that these conclusions are applicableonly where the assumptions used are valid but that the techniqueis of universal application.