It is remarkable that the inner heartwood of old trees remains as sound as it usually does, since in many cases it is hundreds, and in a few instances thousands, of years old. Every broken limb or root, or deep wound from fire, insects, or falling timber, may afford an entrance for decay, which, once started, may penetrate to all parts of the trunk. The larvae of many insects bore into the trees and their tunnels remain indefinitely as sources of weakness. Whatever advantages, however, that sapwood may have in this connection are due solely to its relative age and position. COUNT 5
QSN1 What do broken limbs and deep wounds open a door for in a tree? ANS1 decay QSN2 Decay can spread to all of what part of a tree? ANS2 the trunk QSN3 What growth stage of insects bore holes into trees? ANS3 larvae QSN4 What part of a tree often stays impressively sound even when hundreds or thousands of years old? ANS4 inner heartwood QSN5 What evidence do some insect larvae leave in a tree forever? ANS5 tunnels