Growth loss and economic consequences following two years defoliation of pinus sylvestris by the pine sawfly neodiprion sertifer in West‐Norway

Abstract

Two years of heavy defoliation of Pinus sylvestris by Neodiprion sertifer caused a volume loss of 33 % during a 9‐year period after the defoliation of 90–120 years old pine forests. This loss corresponds to 3 normal annual increments. The increment losses in height, diameter and basal area are calculated both for the old stands and a young one (40 years of age). The economic consequences of the growth loss are also calculated and discussed.