A new study published recently in PNAS documents the epidemic of non-native pests that are threatening US forests. According to the study, which concentrated on the 15 most damaging non-native forest pests, approximately 40% of all US forest biomass is under siege from these pests – a fact that has substantial consequences not only on the nation’s ecosystems and habitats but also on the climate.
You only skim back into the US’s history to know that foreign pests have not been friendly for American forests. With the American chestnut extinguished by a foreign fungus and elms drastically affected by Dutch elm disease, the fear of migrating pests is a valid one – especially since roughly 450 non-native forest pests to date have been introduced to US forests.
Songlin Fei, a forestry expert and author of the study from Purdue University, commented that the dying-off of so many trees in US forests is having devastating effects. “It is turning forests from storers of carbon to a carbon source,” Fei says. Fei and colleagues reported that around 6 million tons of carbon are emitted annually from the dying plants.
The problem is exacerbated by other climate change factors such as increasing temperatures and unpredictable precipitation, as well as more frequent wildfires. In total, experts estimate there are over 6 billion standing dead trees just in the western United States, adding to the already very present concern of brush that could spark wildfires.
From wood borers to bark beetles to European gypsy moths, these pests are eating away at trees not only in forests, which are a valuable climate resource because of their ability to capture carbon dioxide from the atmosphere, but also in urban cities.
So, what should we do? Fei says, “The best way to control these pests it through inspections and quarantine – once they are in the system it’s hard to stop them. For many trees it’s too late.” We can also plant more trees, to replace the ones that have been killed. In fact, according to the Guardian, a recent study found that planting more than a trillion trees around the world could remove two-thirds of all the emissions that humans have pumped into the atmosphere.