Department of Statistics Seminar
North Carolina State University

presents

Dr. Akiko Satake

Kyushu University

"Pollen coupling of forest trees: forming synchronized and periodic reproduction out of chaos"

ABSTRACT

Many trees in mature forests show masting; their reproductive activity has a large variance between years and is often synchronized between different individuals. We study coupled map models of masting assuming that trees accumulate photosynthate every year, produce flowers when the energy reserve level exceeds a threshold, and set seeds and fruits at a rate limited by pollen availability. When fruit production is limited by the availability of outcross pollen, trees become synchronized in seed reproduction, otherwise the trees show independent chaotic fluctuation. The whole forest shows diverse dynamical behavior determined by two essential parameters; the energetic cost for reproduction and the coupling strength. We find annual reproduction, coherent periodic reproduction, coherent chaotic reproduction, clustering reproduction, and desynchronized reproduction. We also investigate the effect of common environmental fluctuation. The reactive changes in annual productivity and the reproductive threshold are accounted for by an additional term in the energy reserve dynamics. In the absence of pollen limitation, strongly correlated environmental fluctuations (Moran effect) failed to produce a high positive correlation in seed production across the forest. A significantly large correlation was maintained when both pollen limitation and correlated environmental fluctuation occurred. The work will be illustrated with spatio-temporal data of the amount of seeds produced by Surbus aucuparia L.

Friday, October, 18, 2002

3:35 - 4:35 pm

206 Cox Hall

Refreshments will be served on the second floor of Dabney Hall (left of Room 222) at 3:00 pm.