2017 ESA Annual Meeting (August 6 -- 11)

COS 166-4 - Spatial patterns of tree yield explained by endogenous forces: The Ising model and ecology

Thursday, August 10, 2017: 2:30 PM
D138, Oregon Convention Center
Alan Hastings, Department of Environmental Science and Policy, University of California, Davis, Davis, CA, Andrew E. Noble, Environmental Science and Policy, University of California, Davis, CA, Patrick H. Brown, Department of Plant Sciences, University of California Davis, Davis, CA, Todd S. Rosenstock, Land Health Decisions, World Agroforestry (ICRAF), Kinshasa, Congo (The Democratic Republic of the) and Jonathon Machta, Physics, Unviersity of Massachusetts, Amherst, MA
Background/Question/Methods

Synchrony of periodic dynamics across space is a dramatic ecological phenomenon. A central question in ecology is the degree to which the spatial synchrony of oscillating populations is explained by endogenous forcing, related to coupling and local dynamics, versus exogenous forcing, known as the Moran effect. Explaining spatially synchronous dynamics in ecology is a fundamental challenge. By applying ideas from statistical physics originally used to explain the behavior of magnets to a data set on yield from pistachio trees, we work towards a robust description and potential explanation for the generation of spatial synchrony in ecology.

Results/Conclusions

We show, using 5 years of data on over 6,500 trees in a pistachio orchard, that annual nut production, in different years, exhibits either large-scale synchrony or self-similar, power-law decaying correlations corresponding to the Ising model near criticality. Our approach suggests looking for novel mechanistic underpinnings that lead to synchrony and a surprising correspondence between the description of a physical phenomena, magnetization, and ecological dynamics. The results demonstrate a novel interplay of both exogenous and endogenous forces in producing observed patterns of ecological dynamics. More specifically, this provides new evidence that long range synchrony can be explained by short range interactions even in the presence of noise.