Ask the Conservationist

Why Does Biodiversity Matter?

Read our scientist's explanation for why it's important to preserve biodiversity.

The link between species, ecosystems and the benefits of both to people can sometimes be subtle. But our scientist explains it all—by way of Mongolian gazelle, sea otters and airplane rivet analogy.

Get a quick lesson in conservation science—when you're done reading, you'll be able to impress your friends with an explanation of "foundation species" versus "keystone species" when they ask why you support the work of The Nature Conservancy!

Sara Sol, of Lewiston, Maine, writes:

Why is it important to preserve biodiversity, and how do you reconcile this when people in need use the resources that are being protected for their own livelihood?

Rob McDonald, lead scientist for the Global Cities program of The Nature Conservancy, replies:

Why protect biodiversity? This is the central question that conservation biologists and natural resource planners seek to answer with our work.

On a personal level, I'm motivated to protect biodiversity because I love hiking in intact natural areas, where the full diversity of life remains, and I want my young son to also have this opportunity when he grows up. This kind of direct love for the land motivates much protection of biodiversity, including the many acts of important conservation done by American fisherman and hunters—they want to protect the landscapes they love spending time in.

I also believe that the diversity of life on Earth has an innate right to exist that must not be impinged upon lightly. I feel it is immoral for humanity to drive any species to extinction unnecessarily. Moreover, I and millions of other people get some pleasure in protecting a spectacular species like the Mongolian gazelle even if we ourselves will never see it, simply because we are proud that we will pass this natural heritage on to the next generation.

More broadly, we are all dependent on the benefits that nature provides us. To take just one example, if you want clean water to drink, then in many cases you are dependent on healthy forests and wetlands upstream that filter water before it reaches reservoirs. Millions of people in Latin American drink water that the Conservancy helps purify through our water funds, where urban water users help protect and restore natural areas upstream. These benefits from nature fundamentally rely on biodiversity, and if critical species are lost then these benefits will disappear.

The links between biodiversity and the benefits we receive from nature are often subtle, and conservationists cannot pretend to understand all of them. For instance, sea otters were almost driven to extinction on California's coast by traders wanting to sell their fur. This was an unintended boon for sea urchins—sea otters like eating urchins, and without the otters the population of urchins boomed. Sea urchins feed on kelp, and eventually all the sea urchins ate most of the kelp forests. Without kelp forests, many other species were lost or dramatically decreased in abundance, including some that people liked to fish for.

Conservation biologists have rules of thumb for which species are most important. That kelp forest is called a "foundation species" because its biomass forms the primary structure of the ecosystem that so many other species depend on. The sea otter is called a "keystone species" because without them the ecosystem will fall apart and take on a radically different structure. In general, losing a foundation or keystone species will cause a greater change in an ecosystem and hence a greater change in the benefits we receive from nature.

However, conservation biologists are generally not able to predict in advance what will happen when any particular species is removed from an ecosystem. This has been famously described with the rivet analogy. Suppose you are sitting in a plane flying through the air, and you look out the window and see rivets starting to fall out of the wing. Plane wings have massive redundancy, so you can likely lose a fair number of rivets before the wing falls off. Interestingly, engineers would have a hard time telling you exactly how many rivets you could lose before the wing falls off, but they could be certain that if rivets kept falling out at some point the wing would fall out.

The situation is much the same for biodiversity and the benefits we receive from nature: if you keep removing species from an ecosystem, at some point you will lose most of the natural benefits from that site, but we don't know exactly which species will prove critical.

How do you reconcile biodiversity protection and human wellbeing?
There is no necessary conflict between protecting the diversity of life and safeguarding people's long-term livelihoods. The Conservancy often does projects in "working landscapes," seeking to reconcile human needs and the natural environment. We work with timber companies to find sustainable ways to harvest timber while protecting land from developing, as in our Southern Forests Conservation Project. Similarly, we work with ranchers to maintain range health while avoiding suburban sprawl, as in our work with the Malpai Borderland Group. Good stewardship is often compatible with preserving people's livelihoods.

There are cases, however, where the short-term personal gain of some individuals is inconsistent with the long-term health of the landscape. In these cases, the Conservancy intervenes to try to find a durable solution. We are a voice for the voiceless biodiversity of the Earth, seeking to preserve it for future generations.

Originally posted in January 2011.



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