Abstract
Lightning damage was studied on predominant trees growing at two experimental forests whose area were 3 ha of level land and 1 ha of a gentle slope. Though external lightning scars of cracks and black colored on bark were noted on 114 trees of the two forests, the damaged trees did not die but continued to grow. In the forest situated on flat land, 18% of 593 surveyed trees had external lightning scars, and the tree species with the highest percentage of external scars was Pinus densiflora (52%). In the forest situated on a gentle slope, 33 trees were cut and a cross section of each was examined. Internal lightning scars of rings damaged were counted on 62% of surveyed trees of P. densiflora, as well as on 10% of surveyed trees of Quercus serrata and on 0% of surveyed trees of Chamaecyparis obtusa. Internal and external lightning scars parallel with inner bark fibers were formed, and most of these scars were observed at stems under tree crowns. Thirteen external scars remained on bark just above internal ones, but one scar disappeared due to covering over with callus tissue. Average and range of thirteen internal scars in P. densiflora were 2.2 (1∼4.5) m in length and 8 (4∼18) cm in maximum width, while the callus width on sites above internal scars was from 0.1 cm to 1.3 cm/year. Rot was formed around scars in one Q. serrata tree.
