News

Study of Dogwood Growth Invites Local Residents to Assist as "Citizen Scientists"

by Bill Giduz
Mark Stanback
Prof. Mark Stanback and student assistant David Reagan ’15 examine a tree near campus.

To the casual observer, the Flowering Dogwood (Cornus florida), is notable for producing beautiful four-petal blossoms in the spring and shiny red fruits in the fall.

But Mark Stanback knows there's more going on with this official state flower of North Carolina than meets the eye! The Davidson College biology professor explained, "Unlike most trees, the Flowering Dogwood produces its next year's flower buds at the same time that it's ripening this year's fruits. That means the tree must ‘decide' how much of its energy to invest in producing the red fruits now, versus producing the buds that turn into flower blossoms the next spring."

To assist in his study of the phenomenon, Stanback has been recruiting "citizen scientists" who live in town to help him gather data on dogwoods in their yards. He began last spring when the trees were in bloom. He visited all the trees that residents volunteered for the study, placed a small tag on two small branches and recorded the number of flowers on each. He instructed the citizen scientists to follow up on that initial count with a fruit count this summer, and to continue the two annual counts for several years. Stanback noted that the count requires just a few minutes.

Stanback's student research assistant David Reagan '15 said the number of fruit and buds to be counted ranges from under 10 to a couple of dozen. Reagan and Stanback have so far tagged and inventoried about 80 dogwood trees on the college campus, and about 100 in town.

Stanback, who specializes in ornithology and usually conducts studies of birds, said that the Davidson Dogwood Project is the same manifestation of the "life history theory" as one of his bird experiments.

That theory, applicable across a wide swath of the animal and plant kingdoms, considers how organisms deal with necessary trade-offs such as size versus number of offspring, current versus future reproductive effort, and reproductive lifespan and ageing. Stanback's bird experiments involve manipulating the number of chicks in nest boxes to see what effect that has on the female bird's future egg laying.

Stanback said, "Every organism has to walk a fine line between current growth and future reproduction, and those that can walk it best dominate the population."

In other words, available resources for any given individual are finite. Time, effort and energy used for one purpose automatically diminishes the time, effort and energy available for another. Stanback explained that dogwoods are excellent for studying life history trade-offs because they have to commit to next year's flowers while they are ripening this year's fruits.

Davidson residents interested in serving as citizen scientists with the Davidson Dogwood Project should contact Stanback at mastanback@davidson.edu.