PARENT SESSION
Organized Oral Session 4: Tropical cyclone disturbance and forest dynamics at multiple temporal scales: results from long-term studies in the new and old worlds
Organizer(s): T Lin, H King, and SP Hamburg
Monday, August 8, 8:00 AM - 11:30 AM, Meeting Room 511 B, Level 5, Palais des congrès de Montréal
Comparison of litterfall dynamics resulting from severe typhoon disturbances in lucidophyllous forests, southwestern Japan.
SATO, Tamotsu1, SAITO, Satoshi2, KOMINAMI, Yohsuke3, NIIYAMA, Kaoru1, TANOUCHI, Hiroyuki1, NAGAMATSU, Dai4, 1 Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, JAPAN2 Kyushu Research Institute, Forestry and Forest Products Research Institute, Kumamoto, Kumamoto, JAPAN3 Shizuoka University, Shizuoka, Shizuoka, JAPAN4 Tottori University, Tottori, Tottori, JAPAN
ABSTRACT- We explored how major typhoon disturbances could alter fine litterfall dynamics in lucidophyllous forests (warm-temperate evergreen broad-leaved forests) in southwestern Japan. In the early 1990s, two strong typhoons, Typhoon Mireille and Typhoon Yancy, struck and caused disturbances at our study sites. Both typhoons had gusts that exceeded 50 m s-1. Their return intervals are more than 100 years around the study area. We compared the subsequent pattern of litterfall after typhoon disturbances between two different forests: a 50-year-old secondary forest site disturbed by Typhoon Mireille (recorded on 27 September 1991) and an old-growth forest site disturbed by Typhoon Yancy (recorded on 3 September 1993). Over the observation period, mean annual litterfall input was 6.00 Mg ha-1, averaged over eight years (1991-1998) in the secondary forest and 6.10 Mg ha-1, averaged over nine years (1992-2000) in the old-growth forest. After the massive input caused by typhoon disturbances, annual litterfall input in the following year drastically fell at both sites owing to defoliation. Although mean annual input was almost the same for both sites, annual fluctuation in the secondary forest was higher than in the old-growth forest. The canopy structure derived from sprouting (single stratum, uniform canopy height) may result in greater annual litterfall fluctuations being seen in secondary forests than in old-growth forests, which have multilayered and irregular canopy height. Over the 7 years following the disturbances, annual input had recovered to 94% of the pre-disturbance value in the secondary forest and 91% in the old-growth forest. Re-leafing from typhoon survivors may play an important role in the recovery of litterfall input in these forests.
Key words: Litterfall fluctuations, Recovery from disturbance, Temperate evergreen broad-leaved forest, Typhoon