2023 was exceptionally hot and dry in the sand counties.
If you had the chance to visit the Leopold Shack last year, you might have seen the impacts of record-low precipitation and blazing heat on the flora and fauna of the Leopold-Pines Conservation Area. Phenological timelines jumped weeks ahead. The typically healthy and towering Shack Prairie was left stunted, inches shorter than in previous years. Migrating sandhill cranes left the area for a mere four weeks, most traveling only a short distance to stopover sites in the Lower Midwest before turning around.
One of the most visible changes, though, lay in the pines.
Just after Aldo Leopold purchased the Shack property in 1935, the family began planting upwards of 3,000 pine seedlings every year. It seemed the perfect intervention for the time: soil erosion was rampant, pines grew quickly, and the government was providing people with seedlings for dirt cheap. When the trees finally began to put down roots a few years later, they cemented the Leopolds’ legacy of ingenuity, hard work, and ecological experimentation on this “sand farm in Wisconsin, first worn out and then abandoned by our bigger-and-better society.”
Fast forward to today. Just off the winding footpath to the Shack, a small pocket of 18-25 red pines stirs in the wind. The thinning crowns are nothing but brown needles and brittle branches. These historic trees, planted by Aldo Leopold, family, and friends, have met their untimely end.
In southern Wisconsin, the last part of this story is becoming all the more common. Our land stewardship team recently met with Wisconsin DNR Forest Health Specialist Michael Hillstrom to investigate just why these and other red pine stands in our area are in rapid decline. Peeling away the bark from the decaying trees reveals one answer: infection.
String-like webs of white, black, and red fungus found under tree bark are a tell-tale sign of Armillaria root disease—a fungal infection that dries out roots and prevents trees from taking in the water and nutrients they need to survive. While Armillaria occurs naturally and even helps Wisconsin’s forests by recycling nutrients stored in wood back into the soil, it can also behave like a parasite and kill its host plant. This particular stand of red pine was ripe with the fungus in all different life stages.
Armillaria can spread through spores produced by mushrooms or underground via shoestring-like rhizomorphs that infect the root systems of surrounding trees. Unfortunately for these Leopold pines, trees already facing stressors like drought, overcrowding, pests, or periods of heavy rain are especially susceptible.
Fungus is not the only concern, though. Where drought and infection strike, insects quickly move in.
During their investigation, Michael and our stewardship team also found evidence of bark beetle activity in the pines. Species like the red turpentine and pine engraver beetle bore into the bark of conifers to feed, mate, and lay their eggs. Larvae and adult beetles carve pin-sized holes and tunnels around the inside perimeter of the tree, creating striking patterns in their wake. These tunnels, called boring galleries, disrupt the flow of water and nutrients throughout the tree.
Like the fungus, these beetles are opportunists and tend to strike trees whose defense mechanisms are compromised by disease, drought, or other stressful conditions. To make matters worse, beetle larvae develop faster in hot and dry conditions like those we experienced last summer.
What does this mean for the pines, and for the Leopold legacy?
While there are no surefire remedies for Armillaria or bark beetle infestation, removing infected trees from the stand can help slow their spread. At the recommendation of the Wisconsin DNR and other experts, our stewardship team plans to remove the dead or dying red pines in this portion of the stand this fall and continue exploring further interventions to protect the surrounding trees. Luckily, many other stands of Leopold pines are in no danger of mortality from Armillaria infection and have long, healthy futures ahead.
Though a somber decision to fell trees the Leopold family so carefully tended, the longevity of the remaining pines and the health of the entire ecological community remain our top priorities. In Leopold’s own words, “a conservationist is one who is humbly aware that with each stroke [of the axe] he is writing his signature on the face of his land.” With rising temperatures, droughts, and increasing pest populations accompanying climate change, it seems our signatures must readily evolve, along with our pens.
While the Leopold pines face an uncertain future, their legacy should not. Over the last 89 years, these trees bore witness to the complete transformation of the Shack property, the restoration and recovery of 4,500 acres of land now protected as the Leopold-Pines Conservation Area, and countless "little dramas of the woods" playing out below. They have shown us their own resilience, surviving storm, drought, flood, fire, and likely impacts of human-caused climate change yet unknown to us. No doubt they have inspired you if you have stood under their wobbling boughs. It would be difficult to forget such giants—and we must not.
You can follow along on this developing story by following us on Facebook or Instagram where we post weekly Stewardship Saturday updates, or by subscribing to our e-newsletter here.
Learn more about Armillaria root disease and bark beetles on the Wisconsin DNR website.
The Aldo Leopold Foundation was founded in 1982 with a mission to foster the land ethic through the legacy of Aldo Leopold, awakening an ecological conscience in people throughout the world.
