Speed is not a word typically associated with trees; they can take centuries to grow. However, a new study to be published the week of Feb. 1 in the Proceedings of the National Academy of Sciences has found evidence that forests in the Eastern United States are growing faster than they have in the past 225 years. The study offers a rare look at how an ecosystem is responding to climate change.
For more than 20 years forest ecologist Geoffrey Parker has tracked the growth of 55 stands of mixed hardwood forest plots in Maryland. The plots range in size, and some are as large as 2 acres. Parker's research is based at the Smithsonian Environmental Research Center, 26 miles east of the nation's capital.
Parker's tree censuses have revealed that the forest is packing on weight at a much faster rate than expected. He and Smithsonian Tropical Research Institute postdoctoral fellow Sean McMahon discovered that, on average, the forest is growing an additional 2 tons per acre annually. That is the equivalent of a tree with a diameter of 2 feet sprouting up over a year.
Forests and their soils store the majority of the Earth's terrestrial carbon stock. Small changes in their growth rate can have significant ramifications in weather patterns, nutrient cycles, climate change and biodiversity. Exactly how these systems will be affected remains to be studied.
Parker and McMahon's paper focuses on the drivers of the accelerated tree growth. The chief culprit appears to be climate change, more specifically, the rising levels of atmospheric CO2, higher temperatures and longer growing seasons.
Assessing how a forest is changing is no easy task. Forest ecologists know that the trees they study will most likely outlive them. One way they compensate for this is by creating a "chronosequence"a series of forests plots of the same type that are at different developmental stages. At SERC, Parker meticulously tracks the growth of t
|Contact: Tina Tennessen|