New York City’s Central Park might seem like an odd setting for scientists to study plant life. But this urban oasis is actually proving to be an interesting spot to examine the effects that rising heat levels and emissions have on plant growth—especially since all the news isn’t bad.
An article in The New York Times recently explained: “Cities produce high levels of atmospheric carbon dioxide, nitrogen oxides and ozone, all of which influence plant performance. The heat island effect arises because buildings, pavement and asphalt are better at absorbing and retaining solar energy than the fields and forests of the countryside.”
It’s thought that this urban cauldron, if you will, may provide some benefits for plant growth.
Professor Kevin Griffin, an ecophysiologist at Columbia University, participated in a study on the effect of New York City’s urban environment on northern red oak seedlings. Griffin told TakePart that the work done by he and his colleagues was influenced by Jillian Gregg, an ecologist. “She was the lead author on a terrific study that really caught my attention. In this paper she used cottonwood cuttings to show city trees were growing more quickly than rural trees, a response she attributed to ozone.”
Griffin goes on to explain that, “At the time I was working on the effect of nighttime temperatures on this same species and finding some interesting responses, so I wondered if the mechanism I was studying might also be contributing to the observed change in tree growth along the urban to rural gradient. Since I worked in the local forest I also knew that cottonwood is not very common in New York, but I thought that if similar effects were happening in oaks, the most common species locally, then it would be quite important.”
“One significant difference in oaks and cottonwood is that oak seedlings are known to be insensitive to ozone,” said Griffin. “When we found the same basic phenomenon—seedlings growing more quickly in the city—I knew a different mechanism had to be at work and ultimately found that the ratio of leaves to roots was being affected, leading to faster growth of city oaks.”
He adds that, “Globally, nighttime temperatures have been rising at nearly twice the rate of daytime temperatures. When we hear about global warming we hear mostly about the change in the average temperature. However, since plants do very different things in the day versus the night—photosynthesis requires light—the differences in the rate of temperature change can be very important for plant and ecosystem form and function.”
Dr. Lewis Ziska, a scientist and plant physiologist for the Department of Agriculture, has also been studying the effect of greenhouse gases and pollutants on plant growth. In an opinion piece published yesterday by The Scientist, he and Mark Howden (a Theme Leader in the Climate Adaptation Flagship of the Commonwealth Scientific and Industrial Research Organization, or CSIRO) advocate actively selecting crop varieties that are more efficient at converting additional atmospheric carbon dioxide into seed yield.
Ziska told TakePart that many studies have shown that CO2 increases wheat, oat, soybean, and cereals yields overall. His research focused on rice since he notes that “rice and wheat feed vast numbers of people.” He added that, “I think there have been a lot of papers that look at the effect of CO2 on rice, but what hasn’t been done is that there isn’t an effort by any university, federal agency, or private industry to select for a CO2 response for a given crop, yet this would be a really opportune moment to take advantage of that.”
Or to paraphrase The New York Times headline, let’s start the search for global warming’s silver lining.
Do you think more research should be done to determine how we can gain some benefit from climate change?