Forests hold sequestered carbon, which is released into the atmosphere when trees die, and this phenomenon is one of the drivers of climate change.
A new study has revealed that non-native invasive insects and diseases help reduce the amount of carbon stored in forests across the United States.
Researchers made this conclusion after looking at data from nearly 93,000 field plots that were sampled to comprehensively quantify the cumulative losses of trees following the invasion by species of non-native insects and diseases.
Forests in North America account for about 76 percent of carbon sequestration, the removal of carbon dioxide from the atmosphere and held in solid of liquid form.
Study researcher Songlin Fei of Purdue University and colleagues said tree-killing invasive insects and diseases greatly increase the rate at which trees die on average.
As a result, carbon stored in trees are transferred to dead material and much of this planet-warming carbon are more likely to return to the atmosphere.
Fei said the carbon transfers from the living plants and trees to dead matters, and the release of carbon happens gradually during the decomposition of the organic matter.
The total amount of carbon in the dead materials, however, is substantial. Fei said the total amount of carbon is comparable to carbon emissions from 4.4. million cars, or almost a fifth of the wildfires that occur in the United States per year.
More than 430 alien insects and diseases are now in the U.S forests. While most of these species have little known effects on the forests, 83 percent have caused noticeable damage.
As alien insects and diseases continue to spread and mortality of the trees increases, they will have substantial impact on forested landscapes and associated carbon storage.
The study suggests these invasive insects and diseases could threaten up to 41 percent of the total live forest biomass that remain in the conterminous United States.
“We quantified pest-induced biomass loss across the conterminous United States for the first time,” the researchers wrote in their study.
“We show that invasive pests are causing significant shifts in carbon dynamics in US forests. In addition, >40% of the total live biomass in US forests is at risk for invasion by currently established pest species. “