NEWS QUARTER, Pen., August 13, 2019 – In addition to cleaning air and water, forests hold a huge amount of separate carbon. When trees die and then decompose on the forest floor, this carbon is released into the atmosphere, a phenomenon that is one of the drivers of climate change. A first-of-its-kind study by a team that included scientists from the Department of Forestry and the Purdue University Office found that non-invasive invasive insects and diseases reduce the amount of carbon stored in trees in the United States.
A study by Forest Service scientists Randall Maureen, Chris Oswalt and Andrew Liebold, with lead author Songlin Fay of Purdue University, uses data from 92,978 field plots taken from the FIA in the first attempt at comprehensive cumulative assessment tree losses due to the invasion of all types of non-native insects and diseases nationwide.
The study, "Biomass Losses from US Forest Insect and Disease Invasions," is available at: https: /
In North America, forests account for 76 percent of carbon sequestration or atmospheric removal and global storage. "The key impact of extraterrestrial insects and tree-killing diseases is that they significantly increase the rate at which trees die on average," Libhold said. "This transfers carbon stored in living trees to dead material and much of that carbon is likely to return to the atmosphere."
Scientists emphasize that the study does not suggest that the trees killed by insects become immediate sources of carbon emissions. "The transfer of carbon from living trees and plants to dead organic matter, and the evolution of carbon is progressive with the decomposition of organic matter," Fay said. "However, the total amount of carbon in these dead materials is significant, comparable to the carbon footprint of 4.4 million vehicles, or nearly one fifth of all fires in the US annually."
More than 430 non-native insects and diseases have found their way to forests in the United States. Most of these species have little known effects on forests, but 83 have caused noticeable damage. In their study, scientists from Fei and Forest Service investigated the effects of these 83 known native forest insects and disease-causing species and calculated the rate at which live wood biomass was killed by the 15 species that had the greatest impact on the forests. Insects such as emerald ash, gypsy moth and woolly wool adelide and diseases, including Dutch elm disease, beech bark disease and laurel wilt, are among the 15 most harmful non-native species.
As these insects and diseases continue to spread and tree mortality increases, the charge on afforested landscapes and the associated carbon conservation will continue; the survey suggests that 41 percent of all living forest biomass left in the neighboring US is endangered.
For more than 80 years, the FIA has been collecting data to inform forest management. The historically large data set has been used by states and private groups to monitor forest area, health and conditions. Recent collaborations have demonstrated new, interdisciplinary applications. "This study demonstrates the power of FIA data to quantify the impact that foreign forest pests have on the United States," Morin said.
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