Pollution Squeezing Out Rare Plants

ByABC News
April 26, 2005, 11:13 AM

April 27, 2005 — -- Nitrogen, that miracle cure for ailing plants in our gardens, may actually be pushing a lot of rare and endangered plants closer to extinction, according to an exhaustive new study.

Although nitrogen is already the most common element in the atmosphere, its abundance is rising -- largely through the burning of fossil fuel -- and the study indicates that the change is upsetting the natural balance across the North American continent. That makes it harder for many plants to compete.

"Nitrogen changes a lot of things in the system, and those things are probably what's making a lot of plants endangered," says Katharine Suding, assistant professor of ecology and evolutionary biology at the University of California, Irvine. She is the lead author of a report on the research in a recent edition of the Proceedings of the National Academy of Sciences.

"It's an indirect cascade," she says, because when the level of nitrogen goes up, some plants do better than others, thus smothering, or starving, plants that may already be in a life-or-death struggle.

The study was carried out by scientists from eight institutions across the country, and it consisted of 34 experiments in areas ranging from the desert of the Southwest to the Arctic tundra, and from coast to coast. It is part of a long-range study of environmental changes, sponsored by the National Science Foundation, and while the findings do not suggest that we should stop dumping nitrogen on the plants in our gardens, they underscore the wide-ranging effect of human activities.

In most areas of the country, nitrogen availability, through such things as acid rain, has more than doubled since the 1940s, the researchers say. Factories and automobiles in one area of the country can release nitrogen that is carried by the wind to far-flung places, even the tundra of the far north and the alpine meadows of the high mountains.

So if we think we are protecting some of our parks and other resources from human contamination, we better think again.