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  • Writer's pictureEmma Gould

Dead Trees Standing: Creating Vital Habitats

Snags support more life than living trees,

Good news! There is life after death! Well, at least there is for trees. That dead tree in your

backyard, or “snag” as we in arboriculture call it,  hosts more life than the living tree next to it. The ecological functions of dead and decaying trees are tree-mendous, and incomparable to living trees. Snags are probably the most undervalued feature in the natural world. A multitude of species from birds to mammals, reptiles to insects, and more depend on dead and decaying trees for their livelihoods. Snags serve as nurseries, multi-family homes, food storage, hunting grounds, places to perch and sing from, and shelter from storms, winter weather and predators. In time, when these trees fall to the earth, they become logs that decay on the forest floor. As they break down, they create a moist substrate for seeds to germinate in and seedlings to grow. Decomposers like fungi, bacteria, insects and earthworms feed upon the logs and facilitate further breakdown of the tree which greatly increases the nutrient content of the surrounding soil, and provides fertile ground for living plants to thrive in.

Safety: Assessing Snags and Dying Trees

Arborists can assess snags located near buildings for safety.

Snags are a common feature in natural and unmanaged forests, but not so much in human habitats and managed woodlots. To be fair, one reason there are a lack of these amazing wildlife trees in human-populated areas is their higher likelihood of falling which could put people and property in jeopardy. A certified arborist can provide an expert assessment of snags or trees that are in the process of becoming snags, and discern whether or not they are a risk to their surroundings. Tony, our certified arborist at Honorable Tree Service, is very conservation-minded and recognizes the valuable ecological roles of dead and decaying trees, and he can help you determine which snags are suitable to remain standing to fulfill their vital role in our environment.

Challenge: Perception and What the Neighbors Might Think

Many animals, including endangered species, use the cavities in snags as burrows and nests.

If a snag has been determined to be not a risk or safety hazard, the next obstacle to leaving a dead tree standing is perception. Most of us have negative associations with the word “dead”. It is a common cultural practice to avoid death and view anything connected with it as fearful or sad or undesirable. We carry this cultural bias into our view of forests, gardens and trees. Like most people, I once viewed dead trees as an indicator that “something was wrong”. A “healthy” forest or garden was one without dead trees, free of insects, fungi and disease. The author of Humane Gardening, Nancy Lawson, writes an eloquent description of how many commonly view death in the garden, “we all too often chop down, rake away, chase with leaf blowers, bag up to be hauled off like trash [these decaying materials which] are homes for other species, not to mention restaurants, kitchen and nurseries. For so many animals, life begins in the decay.”  The more I learned about ecology, the more I realized my assumptions about death in the ecosystems were wrong, dead wrong. I now understand that dead trees are critical to functioning ecosystems. 

Snags provide birds and mammals with shelter to raise young with unobstructed vantage points

As we begin to realize the amazing potential for life that exists within death, snags become special points of pride and treasured features of our landscapes, not examples of neglect. Installing signage to identify Wildlife Trees can create awareness and provide information on the immense importance of snags. The Cavity Conservation Initiative is a unique organization that promotes the existence of dead and decaying trees, provides education to land stewards, and works to change the perception of snags. CCI founder, Gillian Martin says, “when we haul away a dead tree needlessly, we take away half of it’s life’s destiny.”

Many species ONLY nest and forage for food in standing dead trees, which is why it is essential to preserves these habitats.

Most of us recognize the ecological importance of the services that living trees provide. Trees produce oxygen, handle stormwater, prevent erosion, cool their surrounding environment, provide food to us and other animals. We should also be aware of the intangible benefits of trees, the peace of mind we feel when we live among trees. When we sit beneath the sprawling branches of a tree, our backs supported by its trunk, we can not help but feel the interconnectedness of the natural world around us. If the tree we are leaning against has dropped a limb or two, leaving cracked and shaggy barked, cavities have been created, then the tree has become a vital habitat for even more wildlife than its undamaged neighbors. Numerous birds and critters have come to roost in the cavities that were cleaved by the fallen branches. Decay has set in, no doubt, at the site of these broken limbs, which is attracting a smorgasbord of insects for the roosting animals to feed upon. Some species are almost never found anywhere except where there are snags, like the black-backed woodpecker. There is a high density and diversity of native bees that are found in snags and decaying trees. The chimney swift, an endangered species, nests in the hollowed out cavities of dead trees, along with owls, chickadees, nuthatches, woodswallows, and so many more. Fallen logs create habitat for small mammals like voles and mice, which in turn help support small predators like weasels, martens, wolverines, foxes, bobcats, hawks, and more.

Signs can educate the public on the importance of preserving snags for wildlife habitat.

Adding signage to wildlife trees can educate other people on the importance of snags in the ecosystem and inform them of ecological processes that they may not have been aware of. Signs that identify a wildlife tree can go a long way with helping neighbors understand why a snag has been left standing, who might otherwise deem it an eyesore.

Types of Snags: Hard and Soft

In the beginning of a dead tree’s new life it is considered a hard snag. After it begins to decay it becomes a soft snag. Both hard and soft snags have essential value in our ecosystems. A hard snag has dense bark, cambium (the living part of the tree just beneath the bark), and heartwood. Excavating birds prefer hard snags. A soft snag is in the more advanced stages of decay. Typically insects and fungi have colonized soft snags. Eventually, the soft snag will become more weathered and will fall over. It will continue to decompose on the ground and feed the circle of life. The Virginia Department of Forestry has declared “when possible, six to eight large, well-spaced cavity trees per acre should be left standing.” There should be both hard and soft snags, and they should remain among living trees and shrubs to provide protections to them from extreme weather. 

Snags: Protected Wildlife Habitats

The Federal Migratory Bird Treaty Act of 1918 has made it illegal to disturb any active nest of 1026 species named by the Act. The MBTA applies to any kind of disturbances of these birds’ nests, as applicable to tree care. A permit for the removal of the nest is needed from the US Fish and Wildlife Service and a wildlife biologist or permitted wildlife rehabilitator must assist with the rescue. Rehabbers work to reunited adolescent wildlife with their parents through renesting attempts. You should always work with a permitted rehabber before doing anything with babies like bringing them into your home, feeding them, etc. A pre-work inspection of trees is considered a best management practice within tree work to prevent unintended wildlife disturbances. 

A certified arborist can assist with making a snag in your home landscape. A snag can be the remnants of a dead tree, or if a living tree needs to be removed for some reason, it can fulfill its destiny as a snag. To create a snag, the top one third of a tree should be removed as well as some of the side branches. “Topping” is a dirty word when it comes to live tree management, but when creating a snag trees should be topped to between 30 to 60 feet. The tree will stand longest when it’s sail of upper branches is gone. An arborist can create a jagged top of crisscrossing cuts with a chainsaw. This will allow moisture to collect more readily and will encourage decomposers to colonize the tree. Decay begins at the top and tracks down the trunk of the tree. 

For those with an ecological eye, if you know how to look, snags are magical coves within our landscapes that are teaming with life. Rather than lifeless, snags are a gift of nature and one of the most critical habitats found in the environment. We should think twice before removing these homes. Make snags part of your habitat garden, and create an unrivaled diversity of life within your ecosystem. 

The Creation of a Wildlife Tree by Honorable Tree Service

This massive Silver Maple tree had lost many limbs and trunks over time. Our arborist, Tony, was able to assist the property owner in determining that the tree was not a danger, or at risk of damaging anything around it. The owner was interested in the ecological benefits of snags and excited to create a wildlife tree on his property.

Tony then went about removing the remaining upper limbs of the tree.

With its branches removed the main trunk of the tree was able to be safely left standing and begin its journey as a habitat tree for the myriad of animals, insects and fungi that make their livelihoods in snags. The property owners who see the value in allowing their dead trees to become such a vital part of the ecosystem will always have a special place in our hearts at Honorable Tree Service.

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