Chaos in ecology is more common than you think

We find evidence for chaos in over 30% of time series in an ecological database using updated, flexible, and rigorously tested algorithms. Lack of evidence for chaos in prior meta-analyses is likely the result of methodological and data limitations, rather than inherent stability.

Systems that are 'chaotic' are sensitive to small changes in initial conditions, and are predictable in the short term, but not in the long term. The weather is an example of a chaotic system - it is completely governed by the rules of physics, but difficult to predict accurately beyond several days. This is in contrast to 'stable' dynamics, which are predictable over long periods, or 'random' fluctuations, which are not predictable over any time horizon. Populations in nature fluctuate a great deal, and knowing whether these fluctuations are regular, chaotic, or random has major implications for how well (and how far into the future) we can predict population sizes, and how they will respond to management interventions.  

Chaos was first introduced to ecology in the 1970s, and there was great interest in whether the seemingly erratic population fluctuations we see in nature could be explained by relatively simple (single species) chaotic population models. However, by the late 1990s, it had become increasingly clear that this wasn’t the case. Chaos detection studies based on these simple models found little evidence for chaos in field data, and the idea that chaos is rare in ecology became increasingly widespread. 

Source: https://go.nature.com/3bwHoGe

Research paper:

Chaos is not rare in natural ecosystems  

Chaotic dynamics are thought to be rare in natural populations but this may be due to methodological and data limitations, rather than the inherent stability of ecosystems. Following extensive simulation testing, we applied multiple chaos detection methods to a global database of 172 population time series and found evidence for chaos in >30%. In contrast, fitting traditional one-dimensional models identified <10% as chaotic. Chaos was most prevalent among plankton and insects and least among birds and mammals. Lyapunov exponents declined with generation time and scaled as the −1/6 power of body mass among chaotic populations. These results demonstrate that chaos is not rare in natural populations, indicating that there may be intrinsic limits to ecological forecasting and cautioning against the use of steady-state approaches to conservation and management.

Rogers et al., 2022. https://www.nature.com/articles/s41559-022-01787-y

.