BLOOMINGTON — Climate change and an altered landscape are taking a toll on wildlife, and it’s only going to get more challenging, according to managers in the division of Fish and Wildlife and the division of Ecological Services and Water Resources within the Minnesota Department of Natural Resources.
Extreme rain events, flooded lands and eroding waterways are taking a toll on everything from deer and upland bird species to migrating songbirds, four managers from the two divisions told an audience Jan. 24 at the annual Roundtable hosted by the department in Bloomington.
It’s all impacting the ability to produce wildlife for today and the future, Dave Trauba, regional wildlife director in New Ulm, told the audience. “It is going to get a lot harder for us to do that,” he said.
He pointed out that the majority of the lands protected for wildlife are in low areas which are increasingly prone to flooding.
Trauba is 28 years into a career in wildlife with the DNR, with 24 of those years spent at the Lac qui Parle Wildlife Management Area. There, he watched as flood events that occurred every few years became events that happened multiple times during a summer season.
Trauba has watched spring nesting success for upland birds decline due to extremes in weather, everything from an April snowstorm to sudden, three- and five-inch rain events. What does flooding and high-intensity rainfall events mean for wildlife, he asked. “Direct mortality. It kills wildlife,” he said.
He’s worried about the deer population in southwest Minnesota, where river corridors provide the main habitat. The floodplain is submerged for extended time periods, harming even water-tolerant tree species and the undergrowth. When the waters finally recede, there isn’t the vegetation the deer need for the winter months.
“The best deer habitat in the southwest part of the state is compromised,” he said.
The southeast corner of the state is facing problems every bit as extreme.
Brian Nerbonne, with 20 years of experience in fish and wildlife, pointed to areas of the Mississippi River where floodplain lands have been submerged well into the summer. Cottonwoods and silver maples can survive a month or two with their roots underwater, but not for an entire summer, he explained. As these trees die, the river banks and floodplain islands they hold together will erode away, to the detriment of fish habitat.
Every bit as disturbing, he warned that the loss of these trees portends trouble for the migrating songbirds that rely on the Mississippi River Valley corridor. He asked: Will they need to find new migration routes?
Cold-water trout streams in the state’s southeast bluff lands have suffered as well. Erosion from land practices dating to early settlement days have caused eroded soils to pile up along the streams, and have a levee-like effect of confining the stream flow to within the banks. When heavy rain events occur, all that extra energy from the flow is trapped in the banks and scours out the stream, reducing habitat for trout, he said.
Erosion along waterways is prevalent throughout all of southern Minnesota.
“In the south region, I’d say our streams are unraveling,” said Robb Collette, a nearly 30-year veteran with the Ecological and Water Resources Division. He’s witnessing everything from streams that are losing waters because they’re refilling aquifers pumped hard by irrigation to streams where high flows are eroding their banks to the point that houses on top of them are threatened.
Collette said there is a need for more upland water storage, where the prairie potholes have been drained.
He said much of the flood-control focus to date has been on “steep and deep,” or placing dams on creeks to hold floodwaters back. But this strategy has not worked.
The small reservoirs fill up in a few hours' time, and once they are full, the flow continues unabated. These small reservoirs also fill up with the sediment they’ve trapped.
Collette said the flashy hydrology of waterways is increasingly threatening everything from homes to public infrastructure such as bridges and roads.
Homes and cabins along many lakes are increasingly in harm’s way as precipitation levels rise.
Randall Doneen, with 25 years of experience in ecological and water resources, started the session by pointing to a trend line showing that, in recent years, water levels on Lake Shetek in Murray County are exceeding the ordinary high-water mark.
Along with an overall increase in precipitation, the state is seeing greater precipitation during time periods it didn't see before. And, there are more extreme rain events, according to information at the Roundtable.
The extreme rain events can threaten the ability to induce winter kill and re-establish aquatic vegetation when shallow lakes and wetlands are purposely drawn down with control structures, Trauba said. He pointed to the $7 million control structure being installed on Marsh Lake for that purpose. One rain event could negate a season-long drawdown, he explained.
The resource professionals urged a statewide approach to solving the challenges that climate change and an altered landscape bring. Whether it can be done — and in a timely way — is a question they did not address, but their concerns were obvious.