Which species are vital for safeguarding biodiversity?

Preserving biodiversity in a changing world is one of the greatest challenges that humans, as stewards of a sustainable globe, currently face, but we have allies already present within the plant and animal world. These species, called keystone species, are important allies in our attempts to preserve and rebuild global biodiversity--and in our ongoing efforts to understand the complex systems they inhabit.

PREDATORS

One of the simplest examples of keystone species are certain predators, which keep populations of prey animals from growing uncontrollably and stripping an area of resource.

When grey wolves were removed from Yellowstone National Park, the local deer populations flourished, and began to overgraze, stripping riparian areas of vital shelter and food for other species. The reintroduction of grey wolves to the park meant that the deer population was stabilized, which in turn stabilized the rest of the system.

Likewise, sea otters keep sea urchin populations under control, preventing the urchins from eating away the root systems of kelp forests. Without the presence of sea otters, whole kelp forests would simply drift away, leaving thousands of species without shelter or food.

MUTUALISTS

Other keystone species act as symbiotes, providing "services" for one another to ensure the survival of multiple species simultaneously. These mutualists are often pollinators or seed-carriers for local plant species. Bees are an excellent example of this effect.

The cassowary of New Guinea feeds on several different varieties of fruit. Seeds contained in the fruit diet of the cassowary are passed through the bird's system and redistributed over a wide area, allowing plant populations to stay diverse and spread over large territories. Some plants have developed shells that are tough enough to resist insect damage, but when scored by the cassowary's digestive systems, are able to grow normally. These seeds would never be able to germinate without the cassowary's assistance.

ENGINEERS

Engineer species fundamentally alter their environments and typically make them much more suitable to local plant and animal life. By building shelters, burrowing, or destroying old trees, these species keep the cycle of the ecosystem moving and allow for regular growth and renewal.

The familiar prairie dog of the American grassland tunnels extensively in its environment. Where grazing animals would tamp down and compress the soil, these tunnels provide aeration and soil turning for local plant life. They also channel water directly to the water table, reducing erosion and preserving the landscape.

Going even further, the beaver transforms a narrow stream into a broad swamp or marshland by construction its dam, creating whole new areas with broad appeal to a huge variety of species and greatly expanding available habitats. Beavers also clear older trees for their building projects, making way for younger trees to grow and renewing the ecosystem.

Preserving biodiversity remains a challenge, but by focusing on maintaining these key species, our efforts can have a wide-ranging effect. Keystone species like these are vital to the effort to restore global biodiversity and maintain the health of our planet's ecosystems.