What comes to mind when you think of a healthy forest? Is it an expansive vista of healthy, green trees towering in salute like regimental wooden soldiers? For a lot of us, we envision and expect healthy stands of trees with minimal dead and rotting timber when we visit woodlands. However, this notion is a fallacy and the absence of dead trees is far from healthy. In fact, the lack of dead trees is a sign of biodiversity’s moribundity. As is common with many things, the purported truth that is accepted as conventional knowledge is often wrong. Convenient generalities that betray the hard facts. Maybe the idea of dead trees as a bad thing in a forest is a relic of thought from a time before the irrefutable significance of them was known, and then erroneously passed down through the ages as a result. Or, perhaps, and more likely, it comes from the selfish view that only living trees matter because they are more economically valuable in that state of being – an idea of thought predicated by the lumber industry centuries ago, no doubt. Whereas trees that have died are a waste of space, space where valuable living trees could be residing for the purpose of profitability and usefulness to us.
Maybe more important than leaving dead trees to rot, we should leave these ill-informed and misguided notions to rot and die out instead. In fact, old growth forests (of which we have all but depleted in North America) are an example of healthy, robust ecosystems. And they’re riddled with dead trees, leaving a massive framework of decomposition. Here in Maine, there is 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. Dead trees are essential in more ways than this brief article can cover. They are in many regards the lifeblood of the forest, just as important as their living brethren. They are a natural part of a dynamic environment in which all trees age and eventually die. But, all too often, these demised trees are targeted for disposal because of their aesthetics, perceived worthlessness, or simply caught up in the mix when other living trees are harvested. This is a great tragedy. By not preserving these forest fixtures (and, worse, targeting them for removal), we are engendering great harm within our ecosystems by not allowing these trees to run their course. We need to reconsider these integral and indispensable parts of the forest for what they are.
Let us start with dead trees as the irreplaceable substrate for woodpeckers to perform their role as an integral 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 utilizes 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, for 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.
Dead trees don’t just need the expert craft of a woodpecker to provide refuge, though. Depending on the size, trees produce large, natural cavities capable of supporting creatures from rodents to bears. Not only are they directly beneficial to certain species as shelter, many of these species are prey creatures that support predators. Unfortunately, there are a very limited number of trees remaining that are of a size to produce large cavities caused from internal decay. In fact, this 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. 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 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. So keep your dead trees and give woodpeckers the indispensable resource that they need to support our ecological communities. The easiest way to be a hero is by just letting your dead trees stand and setting aside some trees to be free from harvest that can grow to the size needed for natural decay cavities to form.
I’ve talked about dead trees primarily in their unfallen form, but they don’t need to be standing to exhibit their virtues. Downed 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. The stumps that may remain if a dead tree snaps usually retain an intact root system that provide lodging/hibernacula for many species. Downed trees in and around water sources serve as crucial basking sites for turtles, snakes, and more. Dead trees, standing or fallen, are a treasure to our herpetofauna that can be the difference between preservation or total collapse of populations.
Aside from direct benefits to wildlife, dead trees deliver incalculable benefits to the forest framework. 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 putrescence 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. As this decomposition gets mounded over with organic debris and plant life that take advantage of an opening in the canopy, it helps to prevent erosion, lock in moisture, retain inorganic resources, and add a unifying structure to the mezzanine below the treetops.
Hopefully I have sufficiently extolled the virtues of dead trees. More so, I hope it has inspired you to preserve them. And the first step in doing this is to analyze your property. Ideally, there should be a good mix 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, then just leave them standing as is. 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. 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. And 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 to inhabit the newly formed excavations. When people open up their minds and get past the subjectively aesthetic notion that dead trees are ugly, a new world will be unlocked. Previously perceived conceptions of worthlessness will be cast off and dead trees will be viewed instead as beautiful. You will create wonderful opportunities for viewing wildlife that will enhance enjoyment of your property. And, as an added bonus, if you choose to top trees, you can use them for firewood, grinding into wood chips for mulch, hugelkultur, or even building a brush pile to act as shelter for ground-dwelling species.
If your property does not have any dead trees, you can create them yourself through the process of girdling trees. This is the process of cutting a strip of bark around the entire circumference of a tree, down to the cambium layer. This essentially kills a tree, or at least all of the tree above the girdling, because the flow of nutrients between roots and leaves is cut off. If you have trees that serve little value in the way of food or shelter for your fauna, have become diseased, or are encroaching on another healthy tree you want to protect, consider girdling it and creating a vital dead snag.
I 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. If you have 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 benefit of 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.