If you find yourself in the South this spring, you’ll have a chance to witness a predictable plague.

A species of Magicicada emerges after 17 years underground in swarms so vast they overwhelm their predators. Nearly each year sees an emergence of a given subpopulation in the U.S. Numbers vary by region; this year, Brood VI will rise in the mountains of Georgia and South and North Carolina (and elsewhere in patches) as it last did in the year 2000.

Despite extraordinary variation in brood size and distribution, boundaries between them remain sharp and steadfast, according to more than a century of records.

Meanwhile, pistachio farmers in California are keen to find ways to disrupt their crop’s synchrony for economic reasons, explains External Professor Jon Machta, a statistical physicist at University of Massachusetts, Amherst. The trees’ two-year pattern of high and low yields often fall into phase across orchards, frustrating growers who prefer a more uniform production and income.

How and why these ecological systems synchronize is what the “Origins of Large-Scale Spatial Synchrony in Ecology” working group will explore April 18-20. This third-annual meeting builds on their earlier work that considered variations, measures, and indicators of synchrony — that is, spatially extended populations all behaving in the same way in time — and “extends it to more realistic situations,” says Machta, by developing models based on those in statistical physics and nonlinear dynamics.

The group has a couple of robust datasets (by ecology standards) to work with, thanks to the longstanding interest in cicada behavior and “precision agriculture”methods applied to thousands of pistachio trees.

Among the more intriguing phenomena up for inquiry are local drivers like root grafting or soil temperature and global drivers like major weather events, what happens when both kinds of effects are at play, and how to go about disentangling them.

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