Ecosystems Are Chaotic: Small Changes Have Huge Consequences

Ecosystems provide a model for complex causality. They also explain human interactions, since within our species we create something similar to ecosystems. New research suggests that, like complex chaotic systems tend to be, ecosystems involve a fragile balance of many equal parts contributing to one another, and even small disruptions can have vast consequences for ecosystems:

New research from Binghamton University, State University of New York reveals that interactions between relatively small organisms are crucial to mutualistic relationships in an ecosystem dominated by much larger organisms, including trees and elephants.

Binghamton University Assistant Professor of Biological Sciences Kirsten Prior, along with Todd Palmer from the University of Florida, studied the symbiotic interaction between the whistling thorn acacia tree (the dominant tree in the East African savanna) and the ants that inhabit them. The ants benefit from the tree by getting housing and sugar-rich nectar, and the tree benefits because the ants protect it from large herbivores such as elephants. Using observational studies and experiments, the researchers discovered that a third partner, scale insects, are the most important resource affecting ant colony size and activity, as well as their effective defense against predators. The honeydew produced by the insects is a consistent source of sugar for the ants, providing them with a source of nutrients during prolonged dry seasons when nectar from the tree is scarce.

This suggests that human effects on the environment will be vastly amplified, even if they target only a small part of the ecosystem. The ants depend on the scales, the trees depend on the ants, and the elephants depend on the trees; instead of being linearly causal, this forms a pattern, where is any element is missing, the pattern breaks.

Human ecosystems take on a similar role. A real estate developer owns a shopping center; lawyers, accountants, and staff depend on that; store owners rent, and pay employees, but also depend on customers, and also other businesses across town for competition. Distributors bring products. Poor people get given old products, paychecks buy new products, and taxes pay for services.

When we look at human ecosystems in this light, we see how centralization makes them fragile despite reducing the number of elements. A natural ecosystem can fail gracefully if interrupted; a centralized system will march on like a zombie, causing externalized damage instead of rebalancing itself.