Wild Things | Science News

ADVERTISEMENT

MISSION CRITICAL

Support credible science journalism.

Subscribe to Science News today.

Wild Things

The weird and wonderful in the natural world

Sarah Zielinski

Wild Things


Wild Things

Invasive earthworms may be taking a toll on sugar maples

earthworm

Earthworms are good for soil — when the ecosystem has evolved with the worms. Where worms are newcomers, though, such as in Upper Great Lakes groves of sugar maples, the invaders can cause problems.

Sponsor Message

Earthworms are great for soil, right? Well, not always. In places where there have been no earthworms for thousands of years, foreign worms can wreak havoc on soils. And that can cause a cascade of problems throughout an area’s food web. Now comes evidence that invader worms in the Upper Great Lakes may be stressing the region’s sugar maples.

There are native earthworms in North America, but not in regions that had been covered in glaciers during the Ice Age. Once the ice melted, living things returned. Earthworms don’t move that quickly, though, and even after 10,000 years, they’ve only made small inroads into the north on their own.

But people have inadvertently intervened. Sometimes they’ve dumped their leftover bait in worm-free zones. Or they’ve accidentally brought worms or eggs in the soil stuck to cars or trucks. And the worms took up residence as far north as Alberta’s boreal forests.

Earthworms “are not really supposed to be in some of these areas,” says Tara Bal, a forest health scientist at Michigan Technological University in Houghton. “In a garden, they’re good,” she notes. They help to mix soil. But that isn’t a good thing in a northern forest where soil is naturally stratified and nutrients tend to be found only in the uppermost layer near the leaf litter. “That’s what the trees have been used to,” Bal says. Those trees include sugar maples, which have shallow roots to get those nutrients. But worms mix up the soils and take away that nutrient-rich layer.

stressed sugar maple Bal didn’t start out studying worms in northern regions. She and her colleagues were brought in to address a problem that sugar maple growers were experiencing. Some of the trees appeared to be stressed out. They were experiencing what’s called dieback, when whole branches die, fall off and regrow. This is worrisome because if enough of the tree dies off, “it’s a slow spiral from there,” Bal says — the whole tree eventually dies.

To investigate, the researchers collected data on trees and anything that could be affecting them, from soil type to slope to insects. They looked at trees in 120 plots in Michigan, Wisconsin and Minnesota. And they compared trees that were on growers’ land with those on public land, thinking that how the trees were managed might have some effect.

When the researchers analyzed the data, “the same thing that kept coming up over and over again was the forest floor condition,” Bal says. “That is directly related to the presence of earthworms.” They didn’t go out to look for the worms, but they could see signs of them in the amount of carbon in the soil and in changes in the ground cover. Wildflowers, for instance, were replaced by grasses and sedges, the researchers report July 26 in Biological Invasions.

Bal and her team can’t say what this means for maple syrup production. It might not mean anything at all. But “worms are ecosystem engineers,” she notes. “They’re changing the food chain.” Everything from insects to birds to salamanders could be affected by the arrival of worms.

Even if the sugar maples take a hit, though, there could be an upside, Bal says. These trees are often grown with few other types of trees around. Such a grove is naturally less resilient to climate change and extreme weather. So replacing some of those sugar maples with other trees could result in a healthier, more resilient forest in the future, Bal says.

Animals

With climate change, grizzly bears may hibernate less

By Sarah Zielinski 1:00pm, October 25, 2016
New research shows that food availability and weather are driving when grizzly bears enter and exit their dens for hibernation.
Animals

Painted lady butterflies’ migration may take them across the Sahara

By Sarah Zielinski 11:32am, October 12, 2016
The migratory patterns of painted lady butterflies are largely unknown. Now scientists have found evidence that some may migrate across the Sahara.
Animals,, Conservation

Nature has a dog problem

By Sarah Zielinski 11:00am, September 30, 2016
Free-roaming dogs spread disease, kill wildlife by the thousands and have even caused extinctions. But their full effect on the environment has been little studied.
Animals,, Evolution,, Conservation

Kauai’s native forest birds are headed toward extinction

By Sarah Zielinski 3:00pm, September 13, 2016
Kauai’s honeycreepers are losing their last refuges from mosquito-borne diseases that are spreading due to climate change. Some could become extinct within a decade.
Animals,, Conservation

As IUCN votes on ivory trade, elephants’ future looks bleak

By Sarah Zielinski 9:34am, September 9, 2016
As the IUCN prepares to debate an end to the ivory trade, two new reports show just how poorly Africa’s elephant species are faring.
Animals,, Evolution

Tail vibrations may have preceded evolution of rattlesnake rattle

By Sarah Zielinski 7:00am, August 31, 2016
The rattle on a rattlesnake evolved just once. A new study contends it may have come out of a common behavior — tail vibration — that snakes use to deter predators.
Animals,, Evolution

The weird mating habits of daddy longlegs

By Sarah Zielinski 11:00am, August 22, 2016
Scientists studying the sex lives of daddy longlegs are finding there’s a lot of diversity among this group of arachnids.
Animals

Lizard mom’s microbiome may protect her eggs

By Sarah Zielinski 5:19pm, August 16, 2016
Striped plateau lizard moms don’t do any parenting beyond laying eggs. But they may convey protection from pathogens with help from their microbiome.
Animals,, Ecology

Capybaras may be poised to be Florida’s next invasive rodent

By Sarah Zielinski 11:30am, August 12, 2016
Some capybaras have escaped their owners in Florida. Others have been set loose. Now there are fears the giant rodents could become established in the state.
Animals

Bird-friendly yards have a major downside — for birds

By Sarah Zielinski 7:00am, August 3, 2016
Vegetation and feeders bring birds into our yards. But those lures also bring more birds to collide with the windows in our homes.
Subscribe to RSS - Wild Things