(ORDO NEWS) — A horrifying ecological disaster is looming, researchers warn: Invasive insects will destroy about 1.4 million trees across the US over the next three decades.
The main driver of this devastation is the emerald ash beetle (Agrilus planipennis), which is predicted to be responsible for 90 percent of those 1.4 million dead trees. This beetle can destroy ash trees in more than 6,000 urban areas, according to a new study.
The cost of tree replacement and associated damage can reach an average of US$30 million per year. If more invasive species settle in the US, then by 2050 this figure could be in the billions of dollars.
“These results can hopefully serve as a cautionary tale against planting a single tree species in all cities, as has been done with ash trees in North America,” says computational ecologist Emma Hudgins of McGill University in Canada.
The sobering estimates were based on data collected from approximately 30,000 US metropolitan areas. The tree population models were then combined with distribution projections for 57 different invasive species.
The hotspots – including New York, Chicago and Milwaukee – were identified in the report due to the large number of ash trees and also because they are in the path of the emerald ash petrel recently or in the near future. According to the study, less than a quarter of US communities will bear 95 percent of the impact of invasive species on trees.
Part of the problem is the lack of diversity in tree species in urban areas, as evidenced by the concentration of ash trees. More species means more resistance to threats like the emerald ash petrel insect.
“Many urban areas are dominated by a single species or genus of trees, which means that a newly arrived insect that hosts these trees can easily spread,” says environmentalist Frank Koch of the USDA Forest Service South Research Station.
“In addition, there are generally fewer natural predators and warmer temperatures compared to nearby natural forests, which may favor the development of invasive insects.”
The researchers also considered the potential impact of insect species that have not yet arrived in the US, including the citrus longhorn (Anoplophora chinensis), which is known to kill many species of hardwoods.
Despite the dire warning, the study’s team hopes it will help urban tree care managers plan ahead and prevent the same costly damage elsewhere.
We know that urban trees play an important role in keeping cities cool, enhancing biodiversity, and even increasing people‘s happiness. With this in mind, it is vital that these corners of nature in our cities thrive and stay healthy.
“With a number of European countries already facing the problem of ash dieback, preventing further spread of the emerald ash petrel in Europe is critical,” says Koch. “I hope the lessons learned in North America will be useful in Europe.”
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