Models for the optimal management of Pinus radiata D. Don in Galicia (north-western Spain) under risk of fire

摘要

This study presents regression models for the optimal management of even-aged Pinus radiata D. Don stands in Galicia under the risk of forest fires. P. radiata is an economically important species in the region but lacks management instructions basedon systematic analyses. The study employed a growth and yield model and optimisation to produce data for regression analysis. The objective variable of optimisation was soil expectation value. Optimisations were done for nine initial stands that represent the existing range of variation in site productivity and planting density of P. radiata in Galicia. Several prices for three different timber assortments were used in the optimisations, as well us different discounting rates. To characterise the risk of fire, two variables were varied, probability of fire and salvage percentage. Based on the results of the optimisations, regression models for the optimal rotation length and optimal timing and type of the thinnings were developed. The results show thathigh probability of fire and high discounting rate lead to short rotations (21 to 32 years) and heavy thinnings. When the risk of fire and the discounting rate are low, much longer rotations (53 to 64 years) are needed to maximise profitability. As logical, increasing salvage percentage decreases the effect of the probability of fire. Higher site index and increased price of medium-sized timber shorten optimal rotations while increasing planting density and price of large timber lead to longer rotationlengths.