Eastern Red Cedar Trees Recovered After Clean Air Act

It turns out that the Clean Air Act may have had more benefits than expected. Scientists have discovered that this piece of legislation helped red cedars recover from decades of sulfur pollution and acid rain. The findings spell hope for the future and show just how effective certain policies can be when it comes to protecting the environment.

In order to see how red cedar trees were faring, the researchers collected and analyzed data from eastern red cedar trees ranging from 100 to 500 years old. By examining the rings on these trees, the researchers could see how they were impacted each year. More specifically, the scientists analyzed the stable carbon isotopes within each ring as a recorder of physiological changes through time.

"There is a clear shift in the growth, reflecting the impact of key environmental legislation," said Jesse Nippert, one of the researchers, in a news release. "There are two levels of significance in this research. One is in terms of how we interpret data from tree rings and how we interpret the physiology of trees. The other level of significance is that environmental legislation can have a tremendous impact on an entire ecosystem."

The findings revealed that despite increased carbon dioxide, which tends to increase plant growth, tree growth and physiology declined for the majority of the 20^th century when acidic pollution was high. This shifted around 1980, though. About 10 years after the Clean Air Act was enacted, trees began to recover once more.

"Our data clearly shows a break point in 1982, where the entire growth patterns of the trees in this forest started on a different trajectory," said Nippert in a news release. "It took 10 years for that landmark environmental legislation to reduce sulfur dioxide emissions, but it eventually did. When it did, we saw an entire ecosystem recover from years of acidic pollution."

The research shows exactly how effective legislation can be when it comes to protecting the environment. This shows promise for the future and reveals exactly how much policies can change the course of negative impacts.

The findings are published in the Proceedings of the National Academy of Sciences.