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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

Hurricane-caused defoliation and post-hurricane refoliation at elevated CO2 in a scrub-oak ecosystem.

LI, J.H.1, SEILER, T.J 1, POWELL, T.L. 1, ANDERSON, H.P. 1, HINKLE, C.R. 2, DRAKE, B.G. 1, 1 Smithsonian Environmental Research Center, Edgewater, MD 21037, USA2 Dynamac Corp., Kennedy Space Center, FL 32899, USA

ABSTRACT- Defoliation is the most common damage to ecosystems by hurricane. Hurricane Frances passed central Florida in September 2004 and damaged the Florida scrub-oak ecosystem which has been exposed in situ to elevated atmospheric carbon dioxide concentration (Ca) (twice ambient Ca) in large open-top chambers since May 1996. We measured the reduction of leaf area index (LAI), the number of completely defoliated shoots and the new growth after hurricane. The absolute reduction of LAI was 69 % higher at elevated Ca than at ambient Ca and the number of defoliated shoots per ground area was 58% higher at elevated Ca. The reduction of LAI was linearly correlated to the number of defoliated shoots. The higher absolute defoliation at elevated Ca was due to larger plant size since the relative Ca effect on the reduction of LAI and the number of completely defoliated shoots was not significant. New shoots started to emerge within a month after the hurricane and matured after two months. The refoliation from new growth was not significantly affected by Ca. At the mature stage, new leaves compensated only 19% of the loss of LAI from hurricane damage. So the net absolute defoliation was 74% higher at elevated than at ambient Ca. These results indicate that ecosystem defoliation caused by hurricanes would significantly increase with the rising in Ca.

Key words: Hurricane, Defoliation, Refoliation, Elevated CO2

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