Speaking to the Middle and Upper School students, faculty, and staff on Wednesday morning, Mr. Tallamy brought a topic to our attention that might not normally be considered: are the plants in our yards helpful to our ecosystem?

“I’d like to help you change the world, and we only have thirty minutes to do it,” he began. “We thought we could develop anywhere,” and nature would still be there, but it turns out that there are now very few places where “nature is working.” Mr. Tallamy tossed out the question, “Why do we need biodiversity?” Without a supported ecosystem of plants and animals, extinction is always a threat, which ultimately means negative consequences for humans as well.

Mr. Tallamy led the audience through a demonstration of why native plants matter. By focusing on one type of bird in a nest in his own yard, he was able to deduce the specific types of plants the bird used to produce the insects it fed its babies. Noting which types of caterpillars feed on certain plants, Mr. Tallamy theorized that native plants are more productive for the insect world, and thus, birds do not have to work as hard to survive.

Interestingly, many plants in today’s landscaping industry are brought to America from other countries, which would be acceptable if they could replicate the eco-benefits of the native plants. “Plants don’t want to be eaten,” Mr. Tallamy said, adding that plants defend their tissues with distasteful chemicals. Insects can adapt to imported plants, but a long evolutionary process is involved. When insects can only eat one type of plant, they begin to specialize; the insect populations that depend on the native plants die down, and as a result, the animal populations begin to trend toward endangerment.

Mr. Tallamy conducts research throughout Delaware, Pennsylvania, and Maryland in an effort to determine how he can promote “good land stewardship.” Instead of planting numerous Bradford pear trees, for example, he wants landscaping to include more native plants that will benefit wider variety of insects, and thus keep our biodiversity in good health. He told the students, “You don’t own any homes right now, but you will shortly,” with the hope that they will make a difference in their own backyards.

In addition to his morning talk with the students, Mr. Tallamy presented an evening lecture for members of the community. He also spent time with several classes throughout the day, including a wildlife walk with the second grade to look for insects, and a first-grade activity in the newly named Reynolds Family Studios.