TYPHOON DISTURBANCE AND STAND-LEVEL DAMAGE PATTERNS AT A SUBTROPICAL FOREST IN TAIWAN

We examined the typhoon wind disturbance regime of the Fu-Shan Experim ental Forest in northeastern Taiwan. Mean number of typhoons passing w ithin 200 kilometers of Taipei (40 kilometers from the site) was 1.4 p er year. Category 4 and 5 typhoons, which are intense enough to uproot large numbers of trees, occurred every 8.3 and 12.5 years respectivel y, although it is likely that some category 4 and 5 typhoons did not p roduce extensive blowdowns at Fu-Shan because the area of maximum wind s missed the study site. Uprooting was more common than snapped boles; the most common damage to trees, however, was probably defoliation, a lthough this damage was not quantified in the current study Thirty-liv e percent of wind-damaged trees were associated with a gap. Six percen t of the land area was in gaps. Canopy turnover time was calculated at 175 years when all gaps less than or equal to 9 years old were includ ed in the calculation, but the time decreased when older gaps were exc luded from the calculation. Turnover time was somewhat higher than cal culated for other tropical forests. Because turnover time increases as the percent of land in gaps decreases, the short life span of gaps at Fu-Shan probably contributed to our higher calculated time. Probabili ty of being damaged was not related to tree species identity, and only a few species of trees were found regenerating in gaps. Principal Com ponents Analysis indicated that damaged trees varied largely in treefa ll orientation and aspect; gaps varied primarily in aspect and in gap size.