What comes to mind when you think of a healthy forest?
Probably an expansive vista of healthy, green trees standing straight and neatly spaced like regimental wooden soldiers in salute. Maybe a variety of woodland creatures scurrying about between moss covered stumps and rocks. Whatever scene you conjure up, it probably doesn’t include many (if any) gnarled, dead trees either standing or fallen. After all, healthy does mean full of life, right?
Wrong! In forests, anyway. The absence of dead trees in a forest is actually a sign of decline in structural complexity and biodiversity.
The idea that dead trees as a negative aspect of the forest is a relic of thought from a time before the irrefutable significance of dead trees was known. As a result, the idea has been erroneously passed down through the ages.
Or perhaps, and maybe more likely, it comes from our selfish view that only living trees matter because they are more economically valuable than dead trees. Predicated by sentiments from centuries ago, this idea treats dead trees as a waste of space, a hinderance, an annoying obstacle. Space which valuable living trees could be residing for the purpose of profitability and usefulness to us. This is probably the origin of the misguided term “deadwood” that refers to someone or something that is no longer productive.
As is common with many things, the purported truth is wrong. It’s a convenient generality that betrays the hard facts. More important than leaving dead trees of the forest to rot, perhaps, is leaving these ill-informed and misguided notions to rot and die out instead.
How Are Dead Trees Important To A Forest Ecosystem?
The benefits that dead trees provide to a forest ecosystem are seemingly endless. The impact one individual tree can have on just one individual organism is mind-blowing. Much more so once the effects on entire species are evaluated and then that species’ effect on other species and so on and so on – all stemming from dead trees.
Old growth forests (of which we have all but depleted in North America) are an example of healthy, robust ecosystems. They’re thoroughly riddled with dead trees, leaving a massive framework of decomposition. Here in Maine exists the largest stand of old growth forest east of the Mississippi – 5,000 acres. Most who visit are shocked to find out how much hurdling of downed trees is required to traverse this extensive patch.
The benefits that dead trees – the integral relics of a healthy forest – provide are simply too numerous to cover in such a brief article. So, in the interest of time, we will look at examples of two vital functions that dead trees play: providing homes for other organisms, and adding important nutrients to the forest floor to build healthy soil.
Dead Trees As Homes
Let us start with dead trees being the irreplaceable substrate for woodpeckers to perform their role as a keystone species. Woodpeckers, like beavers, perform functions that have a disproportionate effect on the ecosystem they live within and the species that reside there.
When a dead or dying tree is left to the forces of natural processes, it attracts bug life that utilize the weakened internal structure. This is the impetus for woodpeckers to hammer into the tree, seeking out the cloistered invertebrates. What is left over after the woodpecker’s persistent chiseling are cavities that serve as homes, both permanent and temporary, to an astonishing array of wildlife.
Small mammals, like squirrels, raccoons, opossums, martens, fishers, and bats, take advantage of the woodpecker’s hard work. This hard work is just as cherished by the 40 or so (probably more) different bird species in North America that cannot excavate their own cavities and rely exclusively on woodpecker borings for suitable homes. These birds range in variety from songbirds to wood ducks to raptors. The latter does not just utilize dead trees for homes, but many more make use of them as perching sites with which to spot prey. The use of snags for cavity sources is particularly important because cavity-nesting species often comprise 20-40% of the birds in a forest and sometimes up above 60%.
Dead trees don’t just need the expert craft of a woodpecker to provide refuge, though. Depending on the size, trees can produce large, natural cavities capable of supporting creatures from rodents to bears. Many of these species that find shelter are prey creatures that support important predators integral in keeping our ecosystems in balance.
Unfortunately, there is a very limited number of trees remaining that are of a size to produce these large cavities caused from internal decay. In fact, this fact is so drastically true that, according to a study by Frontiers in Ecology and The Environment, 99% of the cavities in North America used by birds and small mammals are created by woodpeckers, not natural decay.
This is a testament to our insatiable appetite for harvesting the woody products of our land and the need to develop forest for residential and commercial purposes. No substantial old growth forest has been preserved and forested land in secondary or tertiary growth stages are being reprocessed before they can blossom back into old growth prestige.
We are lucky that woodpeckers have taken up the slack to provide for the woodland community in the absence of natural cavities provided by long-standing trees. It is inspiring to see that one group of bird species can contribute so much to the vitality of an entire ecosystem.
It is also terrifying, however, to think that so much wildlife is dependent on these birds that could be wiped out by a catastrophic agent of change like disease, invasive species, drastic climatic variability, etc.
Keeping dead trees where they stand gives woodpeckers the indispensable resource they need to support our ecological communities. In addition, saving a percentage of your trees from harvest to let them age and grow big can improve chances of natural decay cavities.
So, dead trees do great things for the ecosystem when left standing, but they exhibit their virtues in other forms too. Naturally downed trees are incredibly important as well. Dead trees lying prostrate on the ground provide plenty of moist, decomposing detritus. This is where severely imperiled amphibians like salamanders, frogs, etc. can find protection and sanctuary. Much like standing dead trees, downed trees also attract a great number of invertebrates that are a food source for many creatures.
The stumps that may remain if a tree is cut down or a snapped at its base usually retain an intact root system, providing lodging/hibernacula for many species. Downed trees in, over and around water sources serve as crucial basking sites for turtles, snakes, as well as means of transportation for mammals to cross. Logs are also critical drumming sites for ruffed grouse as well as protection for ground nesting birds.
Dead trees, standing or fallen, are a treasure to our herpetofauna that can be the difference between preservation or total collapse of populations.
Dead Trees Building Healthy Soil
Aside from direct benefits to wildlife, dead trees deliver incalculable benefits to the fabric of the forest. Overlooked is the role of dead trees in providing vital nourishment and structure to the forest floor.
As these structures decompose, they recycle many years worth of locked up nutrients back into the ground below. This decay replenishes loamy soil and ensures that there is rich substrate for which new life can again grow. Fungi are often plentiful on and around dead trees, which further enable the recycling of nutrients, while acting, themselves, as a food source for many creatures. Bacteria is unable to breakdown lignin (the main component of wood) so fungi is necessary to get the job done.
As this decomposition gets mounded over with organic debris and plant life that take advantage of a critical new opening in the canopy, it helps to prevent erosion, lock in moisture, retain inorganic compounds, and add a unifying structure to the mezzanine below the treetops.
Doing Your Part To Preserve (Or Create) Dead Trees
Hopefully we have sufficiently extolled the virtues of dead trees. More so, we hope it has inspired you to preserve them. The first step in doing this is analyzing your property.
Analyze Your Property
Ideally, there should be a strong inventory of snags (dead trees) on the property that will facilitate gains in biodiversity and contribute to a thriving ecosystem. If your land is big enough to accommodate dead trees that pose no threat to falling on anything of importance, just leave them standing as they are. If, however, you live in a smaller lot or have dead trees that are precariously perched next to structures or foot traffic, you can still preserve your snags with just a little bit of effort – which we will discuss in the next section.
When people open up their minds and get past the subjectively aesthetic notion that dead trees are ugly, a new world will unfold. Previous preconceptions of worthlessness will be cast off, and dead trees will instead be viewed as beautiful. You will create wonderful opportunities for observing wildlife that will enhance enjoyment of your property.
Be Proactive – Methods for Creating Dead Trees
If your property does not have any dead trees, you can create them yourself through a couple different processes.
You can “top” the tree, which is simply removing the crown of the tree. Without the upper branches, the tree is much more stable and less susceptible to falling from strong winds or the weight of ice and snow. More importantly, it still allows for wildlife to utilize it. Soon animals (if they haven’t already) will take up residence in any existing natural cavities. Woodpeckers will then start to perform their work, which will further promote the immigration of fauna as they seek out the newly formed excavations.
As an added bonus, if you choose to top trees, you can use the the upper bole (trunk) and branches of the crown for firewood, chipping into mulch, hugelkultur, or even building a brush pile to act as shelter for ground-dwelling species.
There is also the process of girdling. This involves cutting away a strip of bark around the entire circumference of a tree, down to the cambium layer. This essentially kills the tree, or at least all of the tree above the girdling, because the flow of nutrients between roots and leaves is cut off. However, girdling can take quite a long time to put a tree on the fast track to decay. Topping may, therefore, be the better go-to option.
If you have trees that serve little value in the way of food or shelter for your fauna, are diseased, or are encroaching on another healthy tree you want to protect, consider topping or girdling it to create a vital dead snag.
As you consider creating them, think about varying the height of the dead snags if you have control over it. Though cavity sizes are generally the most important factor for wildlife, height matters too. Some wildlife simply will not utilize cavities that are too low or too high. If they have to reluctantly, it may come at the expense of lower survival and reproductive success.
We urge you to please consider retaining and, depending on if a lack of current stock exists, creating dead snags on your property. This is relevant whether the land is for personal, commercial, or public use.
For a long-standing property with built structures already in place, evaluate the composition of living and dead trees you have and take action to preserve or create what is needed. If you have undeveloped land that is destined for development, look at what is there and identify the areas that disproportionately contribute to the local ecology.
If, for example, dead trees are clustered in a particular area, then exclude that space from clearing and leave a buffer around it. Go one step further and leave an undeveloped corridor that connects the space to adjacent undeveloped areas, if there are any. This will allow wildlife to safely travel without encountering dangerous obstacles and enduring undue stress.
Dead trees greatly contribute to ecological health. They are a crucial factor in the vigor of our environment and its species – too important for us to keep harboring misinformed views towards.
Please reconsider your land, its overall health, and its contribution to big picture ecology. A greater degree of conscious consideration is so desperately needed in a time when the fitness of our planet is under such tremendous and unrelenting siege.
If you’re interested in getting more involved or learning more information about the benefits of dead trees, check out this amazing resource: The Cavity Conservation Initiative.