Ep.7 Life After Death, the Snag Forest
Written by Kenneth on February 21, 2022
Tree of Week: Quaking Aspen (Populus tremuloides)
Aspens are easy to pick out of a crowd due to their greenish-white bark, and in the case of the quaking aspen have leaves that dance delicately in the wind giving the tree its name. The leaves have a darker green on top and are much paler on the other side. It is rarely found in Oregon and is much more common in states like Idaho, Utah, and Colorado. It is a deciduous broadleaf tree that turns a beautiful gold in the Fall season. This tree does not grow the longest or tallest, only reaching upwards of 80’ and normally only a few inches wide. The short-lived Aspens (short is relative to tree time, they live to around 150 years) rely on shoots off of their roots to spread and survive. The Pando is a good example however this can happen everywhere. Each sprout is a clone of the parent tree having identical DNA. Disturbances such as fire are essential in the management of aspen forests. When an Aspen tree is injured in some way it sends many sprouts up from its roots that will eventually become the next generation. Issues with fire suppression and overgrazing from farm animals and especially mule deer are hurting many groves. Now, what if I told you the largest organism on earth was the quaking aspen? Well, it sorta is.
Pando is one male quaking aspen clone connected by a giant root system. It is found in Central Utah in a large grove of aspens that seem like a forest of individual trees of the same species. This would be only partially correct as it is the same species (in fact all with identical DNA) but not individual at all. Just under the soil lies the complex system of roots that make up one of the largest living organisms on earth. The Pando stretches 108 acres and weighs in at about 6,000 metric tons (roughly 50-60 blue whales, the largest animal on earth) making it the largest organism on earth. It’s made up of over 40,000 “stems”, which is what each tree is referred to as. The large Pando organism has been decreasing due to this human interference and lack of correct management. When the fire is suppressed in these environments shoots will come up and more shade-tolerant trees and plants will take the place as the next generation after the older aspens die out. This issue is becoming prevalent in Pando has fewer shoots growing (and those that are becoming snacks for dear) leaving only the eldest trees left with no upcoming sprouts to take their place.
If every bunch of Aspens is clones then how did they ever reproduce in the first place? Well according to an Organization for Economic Co-operation and Development (OECD) they say:
Clonal groups of P. tremuloides in eastern North America are very common, but generally, less than 0.1 ha in size, while in areas of Utah, groups as large as 80 ha have been observed (Kemperman and Barnes 1976). In the semi-arid western United States, some argue that widespread seedling establishment has not occurred since the last glaciation, some 10,000 years ago (Einspahr and Winton 1976, McDonough 1985). Indeed, some biologists feel that western clones could be as old as 1 million years (Barnes 1966, 1975).
Smokey the Bear has been a beloved character defending the forest and teaching proper fire etiquette to prevent forest giving us the catchphrase “only YOU can prevent forest fires.” Now I still love Smokey however this notion has built up a dangerous attitude towards the fire and how it works in our forests. While it is dangerous and damaging to leave a campfire unattended or throw a cigarette onto the ground, fire can be a positive thing, and in fact, can be necessary to sustain a healthy ecosystem. We’ve discussed these ideas before in the past, how fire can clean out the understory, eliminate dead organic material, and facilitate healthy growth, but what about the more destructive we see every year. These are also very much natural (although less so with so much human activity). These high-intensity fires have been a part of the PNW environments long before any European settled, and natives to the land respected and use fire to keep their forests healthy. The unique and now rare habitat created by these fires is called a snag forest.
A snag is a standing dead tree, which is exactly what this forest is made up of. In Oregon, we have a few, one very noticeably along the Santiam pass in the Willamette National Forest, and another in the Sisters Wilderness. These post-fire environments provide a habitat for an abundance of animals, plants, and insects. Many have evolved to depend upon severely burned areas to live. Scientists have found that sang forests are among some of the most ecologically rich and biodiverse habitats. Species like the American Robin thrive in these environments and the Blackback Woodpecker is found almost exclusively in these areas (Lens, 2017). This is due to an abundance of larva laid by wood-boring beetles who lay the grubs in the now deadwood that is nutritious and an easy feast now that there is no longer any pushback from the tree. This attracts many different species of birds. Larger herbivores like deer or elk are drawn in by the new growth that sprouts up after a fire. Mice moles and gophers are also among the mammals that inhabit this area feasting on the seeds and fresh growth. Along with these herbivores come the predators to even out the playing field. Even the spotted owl is often seen in severely burned areas. The dead trees provide structure and nutrients for the next generation of plants and animals.
Sadly, aggressive salvage logging destroys any chance of these habitats forming. States will sell timber to private companies in order to “clean up” after a fire. This destroys the landscape and rips away the nutrient-rich wood and soil that would have been the foundation for the next generation of forest. Instead, it becomes a monoculture of planted trees that have no habitat and don’t facilitate a healthy and functioning ecosystem. In Oregon after an intense fire season in 2021, many of the burned areas are being recklessly cut and many arborists working on these sights state that “reckless tree-cutting operations across the state are being mismanaged and need to be stopped.” (Profita, 2021) Such crazed cutting has caused many issues with landslides and sediment building up in creeks all around Oregon damaging these ecosystems even more.
There needs to be a different attitude towards these intense fires. They may not be the old-growth we love, but different does not mean bad. In order to have better forests in the future, we have to start by allowing nature to run its course and protect these important habitats.
Thank you for tuning in! Join me every Monday at 11am to learn more about the nature around you.
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Klein, J. (2018, October 17). Pando, the Most Massive Organism on Earth, Is Shrinking. The New York Times. https://www.nytimes.com/2018/10/17/science/pando-aspens-utah.html
OCED. (2001). Consensus Document on the Biology of Populus L. (Poplars). https://www.oecd.org/env/ehs/biotrack/46815678.pdf
Lens, W. (2017, June 6). A New Message For Smokey. https://vimeo.com/220546582
Profita, C. (2021, April 14). Arborists say ODOT post-fires tree cutting is excessive, rushed. Opb. https://www.opb.org/article/2021/04/14/arborists-say-odot-post-fires-tree-cutting-is-excessive-rushed/