As long as there have been forests, there have been natural events that change them. To understand the effects of the recent ice storm, it may help to review forest form and function.

Forests are ecosystems comprised of living plants and animals as well as nonliving materials such as dead plants/animals, air, and water. The suite of plant and animal species in a forest is called “composition,” and how these elements are arrayed is called “structure.” For instance, compared to a natural mixed-pine forest, a pine plantation has more limited composition (fewer tree species) and less structure (one size and age class of tree, a sparser understory, and little dead material on the ground).

What are ecological disturbances, and how do they impact a forest?

“Ecological disturbances” — such as ice storms, wildfires, or herbivory — initiate different types of “ecological processes” and impact forest composition and structure. Common ecological processes include photosynthesis, decomposition, etc.

Disturbances help to regulate where nutrients are found in a forest. For instance, when a tree falls to the ground and begins decomposing, nutrients found in the tree’s biomass are released. Most nutrients are found in the finer twigs and branches less than one inch in diameter. These smaller items break down relatively quickly, and their bound nutrients are released. These nutrients are then incorporated into the pool of nutrients in the topmost layer of the soil or quickly absorbed by surrounding living organisms.

Competition is also set into motion by disturbances. Competition is one of the underlying theories that shapes our understanding of the natural world. In a forest, plants and animals compete with other individuals for resources. For instance, plants, whether seedlings, saplings, or overstory individuals, compete for sunlight with surrounding plants. Ice storms release some trees from sunlight competition. Canopy gaps created by falling trees or large limbs provide an influx of sunlight to the plants found below.

Ice storms and wildfires also create complexity on the forest floor by providing dead and downed material (“coarse woody debris”). Coarse woody debris provides habitat structure for many plants and animals. For instance, large areas of downed wood can be used by black bears as winter denning sites. Downed logs can also be used by male ruffed grouse as “drumming logs” for mate advertisement. Winter wrens nest in root balls of blown-over trees. Numerous small mammals, from deer mice to the least weasels that prey on them, use brush piles. Finally, downed wood in streams and lakes provides habitat for many insects, amphibians, and fish, including substrates for egg placement.

Decomposition, one of the more important ecological processes in a forest, makes some downed trees into “nursery sites” for other plants; look at a mature eastern hemlock stand and see how rotting logs are covered with many seedlings of different plant species. Rotting logs are also preferred locations for many species of forest fungi, including oyster mushrooms.

What are some things landowners can do after the ice storm?

The impacts of the ice storm will vary depending on storm conditions at a site and the composition and structure of the pre-disturbed forest. Some forests will see more impact than others.

When managing forests post-disturbance, remember to consider the pros and cons of management actions. For instance, as stated above, coarse woody debris in a forest can drive biodiversity. However, access trails will need to be cleaned up in many instances and some material will need to be piled or chipped. Landowners may want to think about the location when making new brush piles. For instance, piles close to a cabin can encourage pests, such as some insects, to be too close for comfort.

Remember too that disturbances also create an increased amount of fuel for wildfires. In fire ecology, the diameter of the dead and downed material corresponds to the time it takes to dry out under fire weather conditions. Larger fuels (such as “100 hr fuels” comprised of logs) take longer to dry out, but can have a big impact on the severity of a fire. Finer fuels (such as “1 hr fuels” comprised of twigs and leaves) help to ignite and carry a fire. Again, landowners should avoid having piles of larger fuels next to cabins to reduce fire hazards.

Decomposition can also be managed if so desired. Spreading brush, keeping brush periodically moist, and crushing brush so that it is in contact with the soil surface can all increase the rate of decomposition.

Numerous scientific studies over the past half century have shown that forest management by humans tends to decrease complexity and diversity relative to natural disturbances that have regulated forests for eons (see “Ecological Forest Management” by Franklin et al., 2018, Waveland Press). Our current understanding is that natural diversity and complexity aid forests by enhancing their resistance (ability to persist) and resilience (ability to recover) after disturbances.

Both resistance and resilience should be the focus of forest planning and management under a quickly changing world. Understanding and incorporating the findings of contemporary science is the starting point.

Dr. Greg Corace is the forest and wildlife ecologist for the Alpena-Montmorency Conservation District. For more information, including assistance with the Qualified Forest Program and related forest planning and management, email Greg: greg.corace@macd.org