Keystone Species
The health and resilience of ecosystems depends on the presence of keystone species.
In the scientific world, "keystone species" are species of animals and plants that play a disproportionately large role compared to other species in sustaining biodiversity and ecosystem function. Though managed European honey bees are vital for U.S. crop pollination, they actually have minimal ecological importance in North America.
Our native pollinating insects, on the other hand, (bumble bees in particular, but also beetles, butterflies, moths, flies, wasps and other pollinating animals) have "keystone status" because they are able to pollinate a diverse range of wild plant communities.
Biodiversity is lost when keystone species begin to disappear.
A stone arch derives its strength and stability from a central keystone that locks all other stones into place. Remove the keystone, and the arch crumbles.
Similarly, remove "keystone species" from an ecosystem and food webs begin to fail, biodiversity is lost, alien species invade, and the ecological function and resiliency of that natural landscape is severely if not entirely diminished.
The ecologist Dr. Robert Paine coined the term "keystone species" in his 1966 groundbreaking study of species interactions in the rocky tidal pools of Washington state.
The presence of keystone species in a landscape has cascading positive effects on species abundance, diversity, and ecosystem function.
The Importance of Bumble Bees
The special physiological characteristics of diverse wild bumble bee species make them vital pollinators for a wide variety of native plants. For example, long-tongued bumble bee species, are able to extract floral resources deep within tubular plants that other bee species, including honey bees, are unable to access.
The large size of bumble bees gives them the physical strength that smaller bees lack to pry open more complex flower forms. Native white turtlehead (Chelone glabra) is just one example of such a flower.
Photo credit: Nicole Mordecai
The orange patch along the hind leg of this common bumble bee is called the CORBICULA, (a "pollen basket"), which female bumble bees use to collect and hold pollen in place while foraging.
Additionally, the unique ability of bumble bees to remove large amounts of pollen through buzz-pollination (or sonication), is something that honey bees cannot do and makes bumble bees vitally important for wild flowering plants that rely on buzz pollination to successfully reproduce. (e.g. apples, cherries, plums, pepper, tomatoes, eggplants, blueberries, and cranberries.)
Photo Credit: Barbara Fullerton
A pollination system is a subset of plant and animal species that have co-evolved to "exploit" one another in order to survive and reproduce. These co-dependent relationships between native plants and wild pollinating animals is what drives biodiversity and runs the food webs in local ecosystems.
Though honey bees perform most of the crop pollination services required to put food on our tables (nearly 75% of the food we eat is pollinated by introduced, managed honey bee livestock), they are but a single introduced species out of nearly 4,000 native insects who help pollinate the majority of diverse wild flowering plants in North America, estimated to be around 32,000 species!
Healthy and resilient ecosystems depend on a diversity of ecological interactions, both specialized and general, between native plants and wild pollinators who share an evolutionary history.
These interactions ensure a diversity of native plant communities which sustain the foraging and habitat needs of wildlife up and down food chains.
Most birds rely on the nutrient-rich foods produced by native plants (seeds, nuts, and berries), and the insect herbivores, particularly caterpillars, that eat these plants.
Native plants also provide birds with shelter from predators and weather, and nest sites for rearing offspring. So when you create more space in your yard for diverse native plant and wild pollinator communities, know that you are also helping to sustain a diversity of birds and other wildlife.
A diversity of herbivores and insectivores that utilize the resources of pollinated native plant species (flowers, foliage, grasses, berries, nuts, and seeds), in turn furnish the food that sustain predatory populations.
Food webs in nature are built from specialized interactions.
And these interactions always start with networks of thriving native plant-pollinator communities.
A diversity of native flowering plants and pollinating species = greater biodiversity, stable food webs, and productive, resilient ecosystems.
