Abstract

Ocular appraisal on occurrence of decay in living trees in natural stands in the State employing external decay indicators revealed an average incidence of 20.7. Highest percent incidence of decay of 23.6 was recorded in the evergreen forest at Aramba (Achenkoil Forest Divn.) and lowest in the semi-evergreen forest at Kottiyoor (Kannur Forest Divn.), while in wet-evergreen forest at Panthanthodu (Silent Valley National Park), it was 18.71 . Altogether 44 polypores belonging to 18 genera were found associated with decay in living trees. Detection and estimation of decay in standing trees in natural stands at Aramba (SFC III) were made by non-destructive as well as destructive methods. Direct probing into the wood of V. indica, P. ellipticum, persea macrantha and B. javanica for measuring the electrical resistance of the wood using pulsed electric current (Shigometer) proved less reliable in detecting the decay in living trees.In ocular appraisal, a total of 794 external decay indicators belonging to seven categories were recorded on 139 trees and in destructive sampling 495 indicators belonging to all the seven categories were found associated with decay, entailing a total loss of 129.63 m3 of timber. Regression analysis revealed sporophore, canker and open wound, tree dbh, hollow in the bole and swollen bole as the most reliable variables in predicting the decay volume in mixed stand, whereas hollow in the bole, tree dbh and swollen bole were the reliable variables in natural stands of V. indica. Decay prediction equations were generated separately for V. indica and mixed natural stand