Gardening for Health

A Diverse Ecosystem is a Stable Ecosystem

By Maria Price

We need biodiversity because it literally sustains us. Certain animal and plant species have been described as keystone species in an ecosystem. They are considered more important than other species in maintaining the sustainability of the ecosystem. According to Doug Tallamy’s book Bringing Nature Home, all species have the potential to sink or save the ecosystem, depending on the circumstances.

For example, in a diverse ecosystem, many species perform similar tasks. Penstemon flowers, for instance, might be visited by three species of bumblebees, five species of moths and one hummingbird. If one or two of these pollinators disappear, the plants will still be pollinated and make viable seeds. The rodents that eat the seeds will still have food, as will the screech owls that eat the rodents. Redundancy in pollinators will save the day.

But if the ecosystem loses some pollinator species, that loss might quickly lead to the local extinction of the penstemon population. This would not only hurt the rodents and the screech owls, but it would also lead to the extinction of all insects that eat only penstemon leaves. If the food reduction is large enough, insectivorous birds that breed in the area would not be able to feed their young and they too would be lost from the ecosystem.

We must preserve ecosystems with as many of their interacting species as possible. The ecosystem is an integrated functioning unit and it de-emphasizes the conservation of single species.

Biodiversity is essential to the stability of most ecosystems. If you are wondering what you can add to your landscape to have the most beneficial effect on pollinators, the following are native plants and the number of butterfly and moth species supported by each: Oak trees (534), black cherry trees (456), willow (455), birch trees (415), poplar (368), crab apple (311), blueberry (288), maple (285), elm (213), pine (203), hickory (200), hawthorn (159), spruce (156), beech (126), filbert (131).

Herbaceous plants that support butterfly and moth populations include goldenrod (115), asters (112), sunflowers (73), Joe Pye (42), morning glory (39), sedges (36), honeysuckle (36), violets (29), black-eyed Susans (17), evening primrose (16), milkweed (12), verbena (11), penstemon (8), phlox (8), bee balm (7).

With this much to choose from, everybody can help improve their immediate ecosystem. It’s all interrelated.