Impacts of climate change

You don’t need to drive far in northern Minnesota to see the devastating impacts of the Eastern larch beetle on tamarack forests. The swaths of dead and dying trees are a sight Adam Munstenteiger sees every day as the DNR Regional Forestry Manager in the Roseau and Warroad areas. The destruction has grown more pronounced during the past couple of decades, as warmer, less severe winters have allowed the beetle population to increase faster than it did in the past. Larch beetles create feeding galleries in trees that eventually cut off the trees’ nutrient and water supply, which kills them.

“You can look at old photos of these big expanses of green lowland conifers and within a few years the same photo is just brown – you can just see the mortality,” Munstenteiger said. “It’s tough to watch. You almost feel like you are watching time in fast forward as fast as those infestations can move.”

More than 440,000 acres of tamarack forest have been affected by Eastern larch beetle. In areas without infestations, foresters wait until tamarack reaches a certain age before harvesting it. But when it starts to show signs of infestation – and it’s of a size that it’s commercially marketable – they’ll harvest it earlier in hopes that live trees in the area will naturally seed the ground from where the infested trees were cut. Additionally, crews aerially seed about 200 acres of tamarack each year.

“Tamarack is a survivor and regenerates and reoccupies sites pretty well,” Munstenteiger said. “So we do have a lot of cases where we are having good success regenerating tamarack.”

Adam Munstenteiger
^{DNR Regional Forestry Manager - Roseau, MN}

Bryan started deer hunting during the muzzleloader season – which runs from late November through about mid-December – for a number of reasons, including the fact there are fewer hunters out and about. The later season also provided more time for ditches, small lakes and wetlands to freeze, affording him the opportunity to hunt parts of state wildlife management areas (WMAs) that weren’t accessible to hunters earlier in November.

But in recent years, thanks to delayed freeze-up, that hasn’t been the case as much on the WMAs he likes to hunt in east-central Minnesota. Studies have shown that lakes are freezing later and thawing earlier in the Upper Midwest, and that the frozen soil season has shortened in recent decades.

“It’s prevented me from hunting some of the traditional areas that require frozen wetlands and ditches for access, which has reduced my hunting options,” he said. “As a result, I’ve had to hunt ‘drier’ WMAs that are also accessible during the regular firearms seasons. These units tend to be smaller, and are not suitable for the larger groups of hunters we sometimes like to organize.”

Bryan Lueth
^{Deer hunter, DNR Wildlife Habitat Manager - North Branch, MN}

Chris Heeter has been guiding wilderness trips into the wilds of northern Minnesota, including the Boundary Waters Canoe Area, and Ontario for 34 years now. Such sojourns require lots of work and plenty of planning but afford people the opportunity to see landscapes and animals they’ve seen only in books or magazines. As time has passed, though, Heeter began to see fewer of one animal that once was an iconic part of Minnesota’s wilderness.

In fact, it’s been a decade since she’s seen a moose in the wild. Minnesota’s moose population has fallen during the past decade or so, and researchers say there isn’t a silver bullet that neatly and simply explains the decline. However, Heeter believes warmer weather has made northern Minnesota more hospitable to deer, to the detriment of moose. Additionally, warmer winters allow winter ticks to flourish. At high enough levels, the ticks can kill moose.

“We never plan to see wildlife because hopefully there’s enough space out there for them to stay away from humans,” Heeter said. “Moose are really special to see. They’re remarkable – they’re so big and so cool. For me personally, the length of time since I’ve seen one is disheartening. It tells me a bigger story about the impact of climate change on all inhabitants with whom we share this planet.”

Chris Heeter
^{Nature guide - Bloomington, MN}

Walleyes are synonymous with fishing in Minnesota, but in many lakes throughout the state they wouldn’t exist without a little help from humans. Every spring, DNR Fisheries staff collect eggs from wild walleyes, and then hatch and raise them in hatcheries. Some of the newly hatched fish go directly to lakes, while others go to rearing ponds where they grow to larger sizes before being stocked later in the year.

Crews try to remove as many walleyes as possible from the ponds, but invariably some remain, which can be problematic because bigger walleyes will eat smaller walleyes.

“Our base production challenge now is overwinter survival of fish in the wetlands – we get little winterkill,” said Dean Beck, the area fisheries manager in Glenwood. “It is impossible to trap out all fingerlings raised in rearing ponds. In the absence of winterkill, those surviving walleyes remain in the waters as yearlings or older fish. Those overwinter survivors compete with and prey on young walleyes stocked back into the rearing ponds.”

Beck and other fisheries managers have adapted by searching out new, smaller and shallower rearing ponds that are more susceptible to winterkill.

Dean Beck
^{DNR Area Fisheries Supervisor - Glenwood, MN}

For decades, Doug Smith and his friends have hunted the grouse opener near communities throughout northern Minnesota, including Cromwell, Duluth, Grand Rapids, Tofte and Rutledge. Even though the presence of leaves on trees and shrubs in mid-September often made hunting difficult, the opener was a treasured tradition that included reuniting with friends and sitting around a campfire at night with tired dogs.

But warmer falls – opening weekend temperatures in the Grand Rapids area in 2017 and 2018 were in the 70s and 80s – have caused them to alter their tradition. Scientists say that this is indicative of things to come – average annual temperatures have risen by 2°F since the beginning of the 20th century, and are projected to climb as much as 6°F more by 2050. Now, the crew heads north in October, hoping for cooler weather, fewer leaves and fewer active Lyme disease-carrying deer ticks.

“That’s just too warm for our hunting dogs to work through heavy cover and, frankly, it’s no fun for us, either,” Smith said. “Eventually, the cold weather comes and we make the most of the season. My favorite part of grouse hunting is simply walking in the woods with my dog, inhaling the scent of decaying leaves and being startled by the flush of a ruffed grouse exploding from cover. Bagging a bird is a bonus.”

Doug Smith
^{Grouse hunter - Lakeville, MN}

Jeff Broberg isn’t particularly picky about when he fishes the trout streams of southeastern Minnesota. With gorgeous scenery, generally healthy fish populations and the quiet allure of the water, any day spent casting for trout is a good one. He’ll fish wherever his whims take him, but Winona County’s Rush Creek remains a favorite, which made what happened during the winters of 2013 and 2014 such a bummer.

The ground was frozen, as is usual in the winter. What wasn’t normal was the heavy rain events during February. The rain couldn’t penetrate the frozen ground and instead ran straight into the creek, muddying the water and killing all sorts of young-of-the-year trout. Precipitation is projected to increase in Minnesota by more than 15 percent by mid-century, compared to historical averages, with increases in the number of extremely heavy rainfalls.

“Rush Creek got hammered two years in a row,” Broberg said. “(In the ensuing years) you’d go fishing and it was easy to see you’re missing fish of a certain size. Pretty soon, there were no fish at all under nine inches. So those year-class failures become noticeable in the fishable population.”

Jeff Broberg
^{Trout angler - St. Charles, MN}

There was a time in Mark Tuchscherer’s life when ice fishing trips with friends could come together in a matter of hours or days, untethered as he and they were by careers, families and the responsibilities that come with adulthood. Those days are largely are in the past now. While the desire to rent a fish house and go ice fishing remains, there’s a lot more planning that goes into pulling off a trip.

But here’s the Catch-22: Over time, the state’s lake ice season has shortened, and the loss of ice has been accelerating in recent decades. For example, Lake Osakis – an average-sized lake in central Minnesota – experiences "ice out" more than a week earlier now than it did in the 1940s.

“With everyone’s busy schedules, we have to plan trips well in advance,” said Tuchscherer, whose group often sticks to lakes including Leech and Mille Lacs. “But it seems like now we have a narrower window of opportunity because you just don’t know how late freeze-up will occur, or how rapidly the ice will become unsafe.”

For the time being, Tuchscherer and his group have been able to settle on a weekend in January to go fishing, yet there’s also been talk about traveling farther north in the state – where the walleye season stays open longer and the ice generally takes longer to melt.

Mark Tuchscherer
^{Ice angler - Hanover, MN}

Nicole Hansel-Welch’s family has lived on Hansel Lake in Otter Tail County for four generations. Her grandfather leased hunting blinds on the lake, which attracted diving ducks. The ducks were there because there was abundant food for them including amphipods (or freshwater shrimp). But as the years went by, winters became warmer and the water became deeper due to increased precipitation. Fish gained a foothold in the lake because increased water depths combined with mild winters reduced fish kills during the winter. That was to the detriment of migrating ducks because the lake is now a little too deep to be a good diver lake. In addition, fish compete directly with ducks for some food sources like the freshwater shrimp. By the early 1990s, duck use on the lake had pretty much ended.

“For the past 20 years or so, it has been somewhat of a secret fishing lake,” Hansel-Welch said. “My generation didn’t get a chance to experience the duck hunting on Hansel Lake like my grandpa’s and dad’s generations did, but I can’t say we don’t enjoy the fishing. We do, and my kids don’t know what it’s like to fish and not catch anything.”

Hansel-Welch figures there are hundreds of other lakes in the county that once were duck lakes but now are fish lakes. Some can be managed for ducks by drawing down water levels, killing fish and rejuvenating vegetation, but that’s not an option on all of them.

“The DNR is under pressure to make duck hunting what it was decades ago, but given the overall impacts of climate change across the state, that is a challenge when we have to work on a lake-by-lake basis, and climate change impacts all of them,” she said.

Nicole Hansel-Welch
^{Angler, DNR Shallow Lakes Program Supervisor - Brainerd, MN}

Since he learned about it 50 years ago from his grandfather, it’s been an annual tradition for Scott Roemhildt to make maple syrup. He savors the solitude of trudging through snow to tap trees and collect sap on winter days.

“Feeding hand-split oak into the crackling fire of my cooker, seeing wood smoke and sap swirl together into a cold night sky and tasting almost-ready warm maple syrup are late-winter rituals for me,” Roemhildt said. “They contain a lifetime of memories.”

As winter warming has led to earlier springs in Minnesota, he’s had to adapt to collect the sap he needs to boil into syrup. The best collection opportunities occur when there are seven-day periods when temperatures are above freezing during the day and drop below freezing at night. These variations create a pumping effect in trees and cause sap to flow. Whereas the most common sap runs used to begin in mid- to late March and wrap up by the end of the first week of April, it isn’t uncommon now for Roemhildt to collect sap in January.

“The biggest change for me is closely watching week- and month-long forecasts from January on, to make sure I’m ready for an early sap run,” he said. “I prepare my equipment six weeks earlier than Grandpa used to, just in case.”

Scott Roemhildt
^{Maple syruper, DNR Regional Director - Elysian, MN}

It doesn’t take much to get Ted Dick to extol the virtues of harvesting wild rice: It makes delicious table fare, it’s a good reason to spend time in the marsh late in the summer, and it’s simply another way to commune with nature. For the past 20 years or so, Dick has made harvesting rice a tradition in the Cass County area where he grew up.

“It seems like it’s been more boom and bust lately,” he said. “If you can find those places that miss big rain events in June, you can have a pretty good year.”

Stable or declining water levels are ideal for wild rice development. But the extreme weather events associated with climate change can cause water levels to spike in short order and result in failed rice crops. Extremely heavy rain events are increasing in Minnesota, with seven of the state’s ten largest two-day rainfall totals on record occurring after the year 2000.

“That water level bounce is a destructive thing in terms of rice development, and it seems like it’s been happening more frequently in the past 10 years or so,” Dick said. “You can always find a lake somewhere that has a good rice crop, but you do have to search harder.”

Ted Dick
^{Wild rice harvester, DNR forest gamebird coordinator and wild rice harvester - Grand Rapids, MN}

Jon Hansen spent years living and working in Wisconsin before moving to Minnesota. He fished several lakes in northern Wisconsin with regularity and spoke with people who had a longer history of fishing them. One in particular historically provided anglers with good walleye fishing, but as time went on largemouth bass gained a noticeably stronger foothold in the lake.

“In two hours of fishing, I caught about 10 largemouth bass,” Hansen said. “Between our group of five, we caught about 50, and that’s in a lake where in the past you really couldn’t find largemouth bass.”

Research from Wisconsin suggests higher temperatures lead to a loss of natural walleye reproduction and increased largemouth bass abundance. As the climate continues to warm in Minnesota, walleyes are expected to persist in larger lakes and fade from smaller, warmer lakes where largemouth bass will continue to thrive.

That projection bothers Hansen.

“I’m not necessarily a die-hard walleye angler, but I like the fact we have this diverse fishery,” Hansen said. “Walleyes – and diverse fisheries – are part of our northern identity and part of the reason people like to come here.”

Jon Hansen
^{Angler, DNR Fisheries Management Consultant - Minneapolis, MN}