PARENT SESSION
Oral Session #5: Plant Demography and Reproductive Ecology.
Presiding: R. Kobe
Monday, August 5. 8:00 AM to 11:30 AM. Coconino Meeting Room, TCC.
Pollen-coupling of forest trees, as a factor for synchronized and intermittent reproduction.
SATAKE, AKIKO*,1, IWASA, YOH1, 1 Kyushu University, Fukuoka, Japan
ABSTRACT- We study coupled map models for synchronized and intermittent reproduction of forest trees (mast seeding), widely observed in mature forests. We assume 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 reproduction. Without pollen limitation, the trees show independent chaotic fluctuation. Two different types of pollen dispersal, global pollen coupling and local pollen coupling, are examined. With global pollen coupling, trees show various reproductive patterns, 1) annual reproduction, 2) coherent periodic reproduction, 3) coherent chaotic reproduction, 4) clustering reproduction, and 5) desynchronized reproduction. When pollen dispersal range is limited only to the neighbors (local pollen coupling), a strong synchrony in seed production over a long distance was restricted to the parameter range that generate mostly a period-2 year cycle reproduction. We then investigate the effect of common environmental fluctuation either in annual productivity or the reproductive energy level. In the absence of pollen limitation, environmental fluctuation correlated strongly between individuals failed to produce a high positive correlation in seed production between individuals. In contrast, a significantly large correlation was maintained if both pollen limitation and correlated environmental fluctuation are at work. For the case of local pollen coupling, we derived a regression formula for the degree of synchronization. The correlation coefficient of seed crops between distantly located individuals decreases with the resource depletion coefficient, but it increases with the strength of pollen limitation, the standard deviation of environmental noise, and the correlation of environmental noises between different trees.
KEY WORDS: masting, synchronized reproduction, pollen coupling