Following a particularly nasty ice and wind storm that damaged or took the life of many mature trees in Northwest Oregon, it’s time to clean up nature’s ragged pruning job and literally pick up the pieces. Or is it?
Clean up sparingly
If there are damaged limbs on a street tree or yard tree close to your house, hire a certified arborist to remove any dangling branches and clean-cut any ragged wounds and stubs left by breakage, particularly if you have a tree that is prone to disease, such as an elm. Sharp cuts that don’t leave stubs (partially amputated branches not cut back to the branch collar that look like you could hang a hat on it) will allow for faster healing and may prolong the life of the tree. But if safety is not an issue, consider that natural, important habitat is created when damaged limbs are simply left on the tree. As I wrote in my book, “interactions between wildlife and decaying wood are fundamental to ecosystem functions and processes in forests, aquatic habitats,” and your garden, whether they be wooded or more open.
We’re usually far too eager to remove anything and everything that’s fallen to the ground to keep our yards neat and orderly. Unfortunately, this sort of maintenance can be harmful not only to our backs, but also to dwindling
wild species that need natural, woody “litter” and some disarray, not homogenous expanses of bare soil, bark mulch, or clipped lawn. In fact, “cleaned up” landscapes are usually outright harmful to wild species, including pollinators and recently fledged birds who need low cover to stay safe. Like fallen leaves, “dead wood” or “downed wood” is so essential that many creatures (and plants) cannot survive without it. So, instead of hauling away branches, logs, bark debris, stumps, twigs and such, be compassionate and leave it (or move it to an appropriate, out-of-the-way part of your yard) so that it can decompose naturally and begin to provide food, shelter, nesting material, or places to raise young. Decomposing dead wood has many other unnoticeable yet complex eco-functions, like supporting fungi that live in symbiotic relationships with plant roots. Eventually, the stuff that may look messy to us turns into fertile soil which supports plants which support insects which support birds, and so on.
Snags are a good thing
What about dead or dying trees? Known as snags, with their hollow cavities, broken branches, and loose bark, they actually may provide more varied habitat for all sorts of creatures than living trees do! In addition to providing essential housing for many types of insects (including pollinators), cavity-nesting birds, amphibians, reptiles, and small mammals (including bats), they provide food, open perches and double as storage lockers. Woodpeckers also use them to communicate during breeding season.
Snags are in very short supply as forests are increasingly decimated, and they’re extremely rare in urban areas. Removing them not only steals crucial habitat; it’s expensive. Leave snags in low activity areas that won’t pose a problem if they fall apart; when they do fall they’ll continue to give back in the understory. If safety is a concern but you want to retain a dead tree’s benefits, consult with an arborist to shorten its trunk to roughly 15 feet tall and cut back branches. If that’s not possible and you must cut it down, leave the trunk on the ground where it won’t get in your way and leave the stump. If you already have a snag, retain or add native shrubs near its base. They will help keep it protected from weather extremes and provide connectivity, leafy cover, and additional forage for wildlife.
The Washington Department of Wildlife has more detailed info on these “wildlife trees” and the Cavity Conservation Initiative has an enchanting video that documents, up close, the lives that they support.
Designing with dead wood
Although some people view snags and other dead wood as unattractive, more and more of us see them as aesthetically pleasing natural sculptures, issued gratis to the landscape and priceless for wildlife. Keep them, work around them, and incorporate them into your landscape, and the wild ones will thank you.
Consider grouping logs and branches in layered piles, with the largest at the base, in quiet places under trees where they can provide shelter from predators and roosting sites for little ones. Fallen trunks or massive logs can recline individually on the ground, where they might act as lovely focal points that will change over time, displaying the quiet beauty that unfolds during all stages of natural decomposition and regeneration. Imagine a “nurse log” in your own yard that will increase biodiversity by providing decades of nutrients and moisture to other plants and soil organisms. While natural, moss-furred nurse logs (fallen forest trunks and limbs) provide complex substrates for regeneration of trees in intact forests, there’s no reason you can’t foster similar function in your yard (but never remove nurse logs from a forest). Surround a fallen giant with native ferns and other shade lovers to blend and complement, and the mystery and magic begins. It rots slowly at first, then begins to crumble away, providing more sustenance for other species. After a few decades, the log will be reduced to nothing but fragments, but the soil—nurtured, enriched, and full of life—will pass on its riches.
A few plant species do best when growing on or next to downed wood. In the Pacific Northwest, Vaccinium parviflorum (red huckleberry), that deliciously berried shrub that hikers know and love, is almost always found growing on a stump, nurse log or other decomposing wood in forests. When I planted red huckleberry shrubs in my yard a few years ago, I buried some rotting wood in the planting hole and added dead branches and conifer cones on top of the soil. So far they seem to like it.
Nest boxes and more trees to the rescue
If you’re like most people and don’t have a snag or a mature tree with decay on your property, consider adding a species-appropriate nest box for cavity nesters like chickadees, nuthatches, woodpeckers, swallows, or owls that is sited correctly and is accessible for annual cleaning. Though not as good as natural nest sites due to their inability to insulate as real tree cavities do, boxes are better than nothing.
Lastly, if you’ve lost a tree or have the space for one more, consider planting a regional native replacement (or two or three) that will thrive in the site’s conditions. It’s crucial that we keep planting and protecting, so the cycle can continue.