Into the woods: Windthrow and salvage

By

Ethan Tapper

Many of us awoke on Monday, Oct. 30 with trees on houses, cars and powerlines, our homes and businesses without power, our roads and driveways impassable. I would be interested in hearing from you about how it was in your part of the world.

Why do blowdowns occur? When trees fall due to wind events, it is called “blowdown” or “windthrow.” Blowdown is caused by the interaction between trees (species, age, size and quality), site conditions (soil depth and quality, topography, aspect) and the intensity, direction and qualities of the wind event. While windstorms are sometimes powerful enough to knock over nearly any tree, they disproportionately affect unhealthy trees, those dealing with various stressors, with restricted or shallow root systems or those that happen to be especially exposed.

Like the 2010 windstorm, the Oct. 30 windstorm was so devastating primarily because it toppled areas of unhealthy softwoods, mostly field-grown white pine. The scale of these disturbances can be generally attributed to the many agricultural fields that succeeded to forest in the 1930s-’60s. In my survey of the damage, most of it was caused either directly or indirectly by the effects of field-origin stands.

What are the effects of windstorms? The most obvious effect is on our visual landscape. Following a windstorm, the view can be catastrophic, our orderly forests turned into a jumble of trunks and branches. Trails can be lost, vistas obscured. A woodlot that we may have watched grow for decades can be suddenly and irreversibly changed.

From an ecological perspective, the effect of blowdown is different. Windthrow is a natural part of forest disturbance regimes, and forests respond to them with abundant growth. What looks like a big pile of sticks at Year 1 will be transformed by Year 5 into a thicket of blackberries, raspberries and young trees. Openings in the forest’s canopy create an ideal foraging environment for insectivorous birds, and young plants and trees provide browse for deer, moose, bear, rabbit and many other species. Dead wood on the forest floor provides wildlife habitat, future soil and carbon storage. These events also allow young trees to grow, promoting structural diversity and species diversity, tree of a variety of ages and species, which benefit the long-term health and resiliency of the forest.

However, blowdowns can encourage invasive exotic plant species, such as buckthorn, honeysuckle and Japanese barberry, especially if they are already present. Anyone with a blowdown should check out VTinvasives.org for more information on these species.

Salvaging. If your woodlot is larger than five to 10 acres, you may consider having a logger “salvage” your woods. This means harvesting fallen trees, usually in addition to some standing trees that are either damaged or at risk of falling in the near future. Salvaging is unnecessary from an ecological perspective and actually eliminates some of the aforementioned benefits, but it clears trails, roads and sugaring lines and diminishes the negative aesthetic impacts of blowdowns. Depending on the quality and amount of the wood, salvaging can also help landowners capture some of the value in their blown-over trees, though salvaging is dangerous and laborious work, and loggers rarely pay landowners for salvaged timber. For most landowners, I encourage them to clear their trails and lawns and learn to embrace the positive ecological benefits of the disturbance. While it may be frustrating or counter-intuitive, these blowdowns are a positive for our forests in many ways.

Residential work. Following windstorms like this, many people become suddenly hyper-aware of the trees near homes, powerlines and property. The calls from landowners with problem trees have started to trickle into my office over the last few weeks. If you have a small property or the trees of concern are near homes, structures, powerlines, etc., call an arborist, tree-care professionals that specialize in working in sensitive and residential areas and with problematic trees. You can find an ISA-certified arborist near you at ISA-arbor.com

If you have any other questions or reports of wind damage, please feel free to contact me by any of the means below. Good luck!

Ethan Tapper is the Chittenden County forester. Reach him at 585-9099, ethan.tapper@vermont.gov or at 111 West St., Essex Jct.