A comparison of three methods for predicting wind speeds in complex forested terrain

Abstract

Wind is one of the most important limiting factors for forestry in Britain. Most forestry plantations in this country have been established in upland areas on land marginal for agricultural use. These locations are commonly affected by high winds and poor soil conditions which make windthrow the most serious abiotic hazard in forestry (Miller, 1985). The effect of the wind is directly responsible for important losses of timber every year in Great Britain (NAO, 1993). Forest management options to improve the final crop quality are limited by windiness because it constrains the number of thinning regimes and shortens rotations. In addition, the quality of the timber is also affected by an increase in the proportion of compressed wood, poor stem straightness, repeated loss of leaders, which may developed crooked stems, and important alteration in the relation height‐diameter. Therefore sites affected by high levels of windiness tend to produce timber less suitable for higher value markets. Consequently, the determination of site vulnerability is important in order to minimise the risk of damage. Aspects influenced by site vulnerability include the choice of species for planting, the selection of silvicultural treatments (thinning and rotation length) and the estimation of the economic return on the investment in plantations (Miller, 1985).