A team of researchers at Purdue University and the U.S. Department of Agriculture have found that trees in the United States face harmful threats from invasive species. In its document published in Protocol of the National Academy of Sciences, the group describes an analysis of thousands of U.S. forest parcels and mortality due to 15 major tree pest infestations and what they have found.
The United States has long been associated with large forest areas, but large-scale deforestation has reduced forests over the last century. Now the forest trees are facing a new threat – an invasion by invasive pests introduced involuntarily into the country. Some infections have already made headlines, such as the widespread loss of trees due to Dutch elm disease, the loss of most American chestnuts due to fungal disease; In addition, fly ash has decapitated ash populations in the Chicago area. In addition to providing wood-based products and beautiful parkland, forests are part of the carbon cycle – every tree releases a lot of carbon – when they die, they release that carbon into the atmosphere, contributing to global warming. Previous research shows that there are now approximately 450 invasive tree pests in the United States that damage or kill trees. Most are thought to have been transported to the country through international trade and travel. In this new endeavor, researchers have set themselves the goal of learning the scale of the threat American forests face.
To gain some perspective on the threats to forests in the United States, researchers analyzed 92,978 forest parcels across the country. They note the types of trees in each plot and the degree of contamination of 15 major tree pests.
Researchers have found that approximately 40 percent of all forested land in the United States is endangered by invasive species. They also found that such pests are already killing so many trees that 6 million tonnes of carbon are released into the atmosphere each year. They note that not much can be done for already infected trees, but that quarantine programs can be implemented to prevent the spread of pests.
Commercial seeds of forest trees pose a high risk of introducing harmful pests
Songlin Fei et al. Biomass loss as a result of insect infestation and disease in American forests, Proceedings of the National Academy of Sciences (2019). Doi: 10.1073 / pnas.1820601116
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Trees in the US face harmful threats due to invasive species (2019, August 13)
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