What is a Keystone Species?

The term keystone species has been around for decades and refers to species with significant influence in their natural environment – so much so that they are critical to maintaining the diversity and stability of an ecosystem. Keystones are not always the most abundant species in the ecosystem, but their existence has a big impact on the local food web.

Very often keystone species are apex predators, but that is not always the case. Animals or insects, plants, fungi or microorganisms can all be keystone species. Bumble bees are keystone species in most terrestrial ecosystems. They are responsible not only for the reproduction of countless plants, but they’re also instrumental in creating the seeds and fruits that feed wildlife – from songbirds to grizzly bears. When bees disappear, the ecological impacts are catastrophic. The removal of a keystone species can trigger a cascade of negative changes. The effects differ, depending upon the particular habitat, but generally speaking the disappearance of a keystone species creates a habitat out of balance.

Keystone plants provide a critical source of food and/or shelter for a large number of other species. One study found that 90% of all caterpillar diversity is centered around just 14% of plant species. While the main contributors are tree species, shrubs and wildflowers can also play an important role with their sheer numbers and variety. The five heavy-lifters among trees are the oaks, willows, cherries (and other prunus species), pines, and poplars.  In the midwest and midatlantic, goldenrods and wild sunflowers are important keystone plants that together support the caterpillars of over well over 100 different species of butterflies and moths.

Dominant Species

Dominant species are those that are most abundant in a community, or have the highest biomass. Keystone species exert a strong influence on a community by their ecological roles, or niches. In contrast to dominant species, they are not necessarily the most abundant.

Which Native Plants are Keystone Species?

Keystone species are defined by "ecoregion." The keystone plants listed on our website are members of the Eastern Temperate Forest ecoregion, and some also inhabit the Great Plains, or Northern Forest ecoregions. Explore the National Wildlife Fedederation website for complete list of Keystone plants by ecoregion.