PARENT SESSION
Oral Session # 13: Statistical Ecology.
Presiding: R Stevens
Monday, August 4. 8:00 AM to 11:30 AM, SITCC Meeting Room 205.

Masting, variance and the mean.

Ballantyne, Ford ^*,, Kerkhoff, Andrew,

ABSTRACT- Masting, or synchronized reproduction in forests may occur as a result of "communication" between trees in the form of pollen output. Satake and Iwasa have formulated an energy based tree reproduction model that takes coupling of trees, through pollen production, into consideration. Depending on parameter values of their model, simulated forests exhibit synchronized reproduction or masting as well as completely desynchronized reproduction. We use this model to test predictions about the degree of correlation among individuals and the slope of the variance to mean scaling relationship known as Taylor's power law. We show that populations of independent individuals yield a slope of one for Taylor's power law whereas completely dependent individuals yield a slope of two. Desynchronized reproduction in the forest model corresponds to a population of independent individuals and synchronized reproduction corresponds to a population of dependent individuals. Our theory predicts a slope of one for regions of forest model parameter space that result in desynchronized reproduction and a slope of two for regions that result in masting. Taylor power laws calculated from the forest model output confirm our theoretical predictions. This indicates that Taylor's power law reflects the degree of correlation among individuals in a population.

Key words: masting, Taylor power law, scaling