Environmental Monitoring and Assessment

, Volume 74, Issue 3, pp 295-309

First online:

The Accuracy of Forest Damage Assessments – Experiences from Sweden

  • Sören WulffAffiliated withDepartment of Forest Resource Management and Geomatics, Swedish University of Agricultural Sciences Email author 

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access


In this article the consistency of forest damageassessments on conifer trees is analysed, by usingdifferent methods in estimating the accuracy inassessments of defoliation and discolouration. The dataoriginate from control surveys in the Swedish nationalforest damage survey, as well as from national andinternational training courses. Standard deviation ofdifferences in the assessment of defoliation on singletrees is found to be about 10% units for Norway spruceand 8.5% for Scots pine. Problems in correctly assessingdamaged Scots pine trees and discoloured Norway sprucetrees are revealed by measures of agreement (Kappastatistic). Results from several years of nationaltraining courses indicate that, on an average, theobserver teams do not significantly differ from a nationalstandard, but significant differences between observerteams are found. The presented estimates indicate asubstantial within observer error compared to the betweenobserver error. The results indicate that the long-termdevelopment of forest damage, rather than short-termfluctuations, is the most important information fromthese kinds of inventories.

defoliation discolouration forestdamage kappa statistic observer error