Keystones

Without Keystone Species, Ecosystems would Collapse

 Keystone species are species that ecosystems depend on in order to be stable. They are species that "exert an impact on its community that is both strong and disproportionate to its abundance." Keystones can be as small as a honey bee, to as large as an elephant, but all share some very important traits in common. They are critical for the long-term success, and health of the environment they are in. The term keystone comes from the stone at the top of an arch that the arch depends on.

Alligator Tracks

Keystone is an umbrella term and encompasses three different types of important characteristics that certain species exhibit. First there are habitat engineers. It's easy to imagine how beavers, woodpeckers, prairie dogs, and earthworms make homes for themselves and others to live in, but how about an elephant or an alligator? Elephants constantly eat, and as they do they keep tree growth in the tropical grasslands down. This allows countless species to use the savanna as their home that normally wouldn't have been able to. Alligators crawl through mud and leave little pools of water behind that fill with aquatic life. Habitat engineers can also include plants, such as sphagnum moss in bogs that allow water to become a type of organic compost based soil and fill with all sorts of terrestrial plants.

Bears Love Sal

Predators are another very important keystone. Gray wolves help control vast animal populations. Sea otters help keep the ocean floor from becoming overgrown with sea urchins, and sea stars control mussel populations in intertidal zones. One very important predator, the grizzly bear, could be looked at as a jack-of-all trades. Not only does he eat salmon and help bring nutrients far into the woods, but by not finishing the fish it helps feed many other organisms. Bears are also omnivorous, and help spread seeds from fruit through their waste. Bats, a favorite of mine, are great at keeping insect populations down, one bat can eat 3000 insects in one night.

Busy as a Bee

Mutualists are kind of a catch-all category to finish out keystone species. Especially important are pollinators and seed-spreaders, but they can also include prey or plant matter that plays a critical role in food webs. Without bees, for example, 30% of our crops, and 90% of wild plants couldn't reproduce. That's 15 billion dollars a year in the U.S. alone. Decomposers are also placed here, as they play critical roles in the nutrient cycle and the food web.