Hot temperatures accelerating the spread of invasive species |

Hot temperatures accelerating the spread of invasive species

Justin Liles
Updated: July 19, 2021 10:37 PM
Created: July 19, 2021 06:25 PM

The hot weather we've been having in the Northland, may not be as unusual as it used to be. Scientists say the extreme heat can accelerate the spread of invasive species by altering their life cycles and their ability to spread into new areas.  Our current drought and warmer summer are creating favorable conditions that could one day, change the Northland landscape as we know it. 

Lee Frelich the Director of Forest Ecology at the University of Minnesota says he is worried about the future, “What if the weather we’ve had so far this year or the weather we had in 2012, becomes the norm?"

Records show the Northland is getting warmer.  

"In the last one to two decades, we've seen our temperatures kind of being above our long term normal both in our summers and our winters," Warning Coordination Meteorologist Joe Moore said. Moore works for the National Weather Service in Duluth.

The increase in warmth is accelerating the introduction and spread of invasive species. Laura Van Ripert is the Invasive Species coordinator with the Minnesota Department of Natural Resources. Van Ripert says as of 2019, they have evaluated 604 species, of which 333 have been found in Minnesota. 

"Something like the emerald ash borer that kills ash trees,"  Van Ripert says, "is going to have a big economic impact to forest industry and ecological impacts to species that depend on those trees." 

However, there are other non-native species like earth worms and jumping worms that are also hitting the timber industry hard.

"The problem with the earthworms is they strip the leaf litter layer on the forest floor and that makes the forest floor more droughty," Frelich says. "Stripping the natural mulch layer so the floor gets warmer and drier at the same time as a warmer climate.”

It's a process already taking place along the North Shore. 

"I'm sure you've seen all the dead birch up the North Shore that died during the droughts we had during 2000 and 2012," said Frelich. He says it could impact our beloved Boundary Waters. 

"If we were to have weather like we had in 2012, or like we've had so far this year the forests in the boundary waters would die and it would become a big brush land and settle into some sort of Savannah ecosystem with scattered trees and grassland," Frelich said.

Our forest could change from a boreal forest such as spruce and jackpine to more of temperate forest of maple and oak leading to deeper troubles down the road. According to Frelich, the forest industry would be in bad shape and there would be a lot of dead trees, much more than could be salvaged.  It would be hard to grow new trees and the forest industry would have to change.

A change to our current ecosystem would invite more non-native animals to move north, such as the red belly woodpecker once dominant in Iowa, possums and more wild turkeys among others.

Jon Erb who is a Wildlife Research Biologist with the Minnesota Department of Natural Resources says, "Species like foxes, raccoons will do well in that. Fishers and martins are forest dependent, and would likely recede."

Human health could be more at risk too. Things like wild parsnip would flourish.  According to Van Ripert, if you get wild parsnip sap on your skin and become exposed to sunlight, you can get a chemical burn.

One of the main things that can help stop the spread of invasive species is the one thing everyone loves to hate.

 "Their population can be lowered if we had an extremely cold winter but we don't always have very cold winters anymore,” says Lee Frelich.  

Frelich says that if our warmer winters and summers continue, nearly all of Minnesota would have a prairie climate by 2070.

 "And just a little woodland of oak and maple in the tip of the arrowhead," Frelich said. "If we are on that trajectory, that's pretty concerning. You won't recognize Minnesota several decades from now if we follow that trajectory."

333 invaders are helping to change the landscape, a landscape we love to live and play in.


Justin Liles

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