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
Impact of annual typhoon disturbance on forest dynamics on a subtropical.
Lin, Teng-Chiu *,1, Hamburg, Steven 2, Wang, Lih-Jih3, King, Hen-Biau4, Hsia, Yue-Joe5, Lin, Kuo-Chuan4, 1 National Changhua University of Education, Changhua, Taiwan2 Brown University, Providence, Rhode Island, USA3 National Taiwan University, Taipei, Taiwan4 Taiwan Forestry Research Institute, Taipei, Taiwan5 National Donghwa University, Shou-Feng, Hualien, Taiwan
ABSTRACT- Approximately 1.4 typhoons/y with hurricane level intensities impact Fushan Experimental forest (FEF) on average over the past 100 y. Typhoons result in limited stand damage at FEF, even the six typhoons of 1994 caused only 1.4% of canopy trees to fall. The most common and important type of typhoon damage is defoliation. Frequent canopy defoliation maintains high understory light levels, allowing for the establishment of pioneer and late successional species, thereby maintaining species diversity in the absence of large canopy gaps, in contrast to that seen in the New World. At FEF typhoons contribute 20% of the flux of ions in precipitation, and depleted in anthropogenically enriched ions such as sulfate and nitrate, as typhoons do not pass over any industrialized land masses prior to arriving in Taiwan. The contribution of typhoon to the output of seawater constituents was approximately 20% but the contribution to sulfate (16%) and nitrate (36%) was greatly increased. Although typhoons contribute very little to P input (below detection limits) the stream export of total P during typhoon storms could reach 50% of total outputs in typhoon years. The P limitations of the FEF forest suggest that the high levels of P lost during typhoons may impact overall net ecosystem productivity. Stream water concentrations of total P, nitrate and ammonium increase dramatically during typhoon disturbance and lasted for several days in contrast to the one to several years observed in Puerto Rico following hurricane Hugo. Our results indicate that tropical cyclone effects on forest dynamics differ significantly between the New Word and the FEF. Assumptions of the similarity of forest responses to cyclonic events in the new and old world are suspect.
Key words: typhoon, defoliation, streamwater chemistry, regeneration