A system with many parts is generally more resilient that a system with few parts. Diversity is key to health. If you have lots of different parts of a system that can do the same job, if one fails, you have a back-up. In the case of food, having a wide range of food sources means that if one source fails, you have others you can go to.

We can think of a football team. When you have one star player the whole team becomes very reliant on that person. If that player gets injured or leaves, the team is in trouble. Or maybe the whole team is made of excellent players. But the substitutes are not as good. When a player has to come off during a game the whole system becomes a lot weaker. But if you invest not just in strengthening the first-choice players, but the substitutes as well, then whole team will be stronger. If you lose a player, you have one just as good to come in. The system has an insurance policy and so is more resilient.

This idea is called functional redundancy. It means that different parts of the system can perform the same function and so the system is not reliant on any one of them.

Now if each of these parts react differently to change or disturbance then the system has even greater resilience. This we call response diversity. This means that different parts operate at different sizes and scales. As a result, they have different strengths and weaknesses. If they have different strengths and weaknesses, the same disturbance is not likely to present the same risk to the different parts.

As an example of this we can look at seed dispersal in Ugandan forests. Different sized mammals are involved in this process from mice to chimpanzees. While the smaller mammals might be affected by a local change, the larger mammals that roam across larger territories won’t be. They can continue to spread the seed.

This is why biodiversity is so important. Our ecosystem becomes fragile when there is less diversity. We need it for pollination, control of pests and getting rid of waste. In every other area of life diversity is important because it brings in other perspectives that we can learn from. The same goes for a human system like a community. More perspectives means more creativity because many minds can come up with more ideas than one mind.