Very few things are truly chaotic. E.g. the weather. It has chaotic elements, that make long range, hyper accurate predictions hard. We can still make larger scale predictions, like India's monsoons.

The same applies to ecosystems. We can make broad observations and predictions, without knowing the finer details. E.g. You will have a hierarchy of predators/prey. A lot of organisms on the bottom, with less as you move up. The other classic is colonisation of volcanic islands. Mosses etc come first, with progressively larger and more complex plants following, as soil develops. Animals follow the tiers of plants.