Ten ideas from ecology that help explain the world

I've spent more than twenty years studying ecology. My world view has been shaped by my quest to understand how the natural world works.

But ecology isn’t just about plants, animals, and the environment. It’s also about understanding complex systems. It has shaped how I think about risk, recovery, history, and time.

Here are ten ideas from ecology that have changed how I see the world. While they emerged from studying nature, these ideas can help us understand organisations, economies, institutions, societies, and our increasingly uncertain future.

Ecosystems remember their past. The fish and invertebrates living in your local river today reflect how the land was managed decades ago. Ecologists call this legacy of past disturbances ecological memory.

Yet, humans often forget. Shifting baselines syndrome has taught us that each generation tends to accept the world it has inherited as normal, losing sight of what came before.

The paradox is that societies and institutions carry the legacy of past decisions long after they’ve been forgotten. Many of today’s social, economic, and political challenges were set in motion long before they became visible to us.

Diversity is a hedge against the unknown. It’s a key way in which nature manages risk.

Alaska salmon returns were less variable over five decades because hundreds of discrete populations were maintained rather than one single population. This reduced volatility of the aggregate system compared to its component parts is what we call the portfolio effect. Just like investing in a diverse portfolio of stocks and shares buffers investors from unexpected shocks, the same thing applies in ecology.

Nature also builds in backup systems. We call this functional redundancy: multiple species performing similar ecological roles. That redundancy may look inefficient, but it acts as insurance when conditions change or species are lost. Monocultures are efficient until conditions change.

And, we’ve seen the risks of optimisation at all costs in society. Resilience often comes from diversity and redundancy, not optimisation.

Ecosystems can tip into new states abruptly. A shallow lake that looks healthy can cross a threshold into a turbid state almost overnight. But the path to recovery can take decades and is not the same as the path to degradation. This hysteresis — where the path forward is different to the path backwards — is a reminder that restoring a system requires more effort than was needed to degrade it.

In short, breaking things is often easier than putting them back together.

Reintroducing wolves to Yellowstone changed the behaviour of elk, which altered where vegetation grew. Changes at one level of a food web having cascading impacts on lower levels of the web is what we call a trophic cascade. In Yellowstone, those effects extended beyond the food web itself, eventually changing the shape of rivers.

The connected nature of ecosystems reminds us that consequences can show up far away from where they started. The same applies to human ecosystems. If we ignore this connectivity and focus just on the observed changes, we can miss where the change actually began.

Organisms have evolved to synchronise with seasonal cues like temperature, day length, and river flow. When the snow melts earlier, the arctic fox still changes its coat colour because it uses day length as its cue to do so. Timing that took millennia to evolve is beginning to fall out of sync. A brown fox in a white landscape isn’t an effective predator.

We call these phenological mismatches, which also occur between predators and prey, plants and pollinators, and many other interactions.

Organisms can adapt to these changes. The challenge is when parts of an interconnected system adapt at different speeds. There are lessons for society in that.

Average years do not define the future. Extremes do. Floods, wildfires, once-in-a-generation droughts — these can restructure ecosystems and set them on new courses. We plan around averages because they’re easier to measure but the future is shaped by surprises.

In short, what happens most often is not always what is most important.

Who arrives first can matter just as much as who is best adapted. Early arrivers can change their environment in ways that can favour some species and disfavour others. As a result, the trajectory ecological communities follow can be very different depending on the arrival order of species despite experiencing the same conditions — what we call priority effects.

History matters because the options available today are a product of the choices and events that came before.

Organisms have evolved to choose habitats following cues like water temperature or vegetation structure. But because we’ve modified the environment so dramatically, they can be lured into habitats that are suboptimal — what we call ecological traps. An attractive habitat can be a death sentence (e.g. headwater streams in California that attract juvenile Coho salmon then dry up).

Rules that worked in the past can become traps as the world changes.

For most of human history, the safest assumption in environmental management was that the future would roughly resemble the past. That assumption is now wrong.

Many models, policies, restoration targets built on that assumption need to be rethought from scratch. We’re facing new problems — new kinds of problems — and we need to start treating them that way.

Some populations exist only because they are supplemented by individuals arriving from more productive habitats elsewhere — what we call source-sink metapopulation dynamics. Remove the source and the sink population collapses even though the local conditions remain the same. What matters is the network of populations across a landscape, not just one.

Success of one system depends on the success of the system as a whole — and the connections between the parts.

Ecosystems are more than just charismatic animals — they’re complex systems that hold lessons for us all. These ideas are about how complex systems work, why history shapes the future in ways we overlook, and why we need to update our ways of handling risk, recovery, and change.

The longer I spend studying ecology, the more I realise it’s about more than just biology. It’s a way of understanding how complex systems work and change through time.

In a world that is changing dramatically — one that’s filled with uncertainty — that’s a perspective we could use more of.

What do you think? Which one resonates the most?

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