Living The Dream: Insights On Quaking Aspen

By Paul Rogers

Journey with me through seasons of aspen foliation: winter’s deep powder punctuated by pale stems and trembling twigs; spring’s dangling catkins and bursting buds; summer’s bounteous green canopy of shuddering leaves; fall’s glowing assault followed by a slow-dropping, one-by-one, of golden garments. Even in this yearbook of arboreal images, we see aspen as a shapeshifter of visages.

Beyond mere glances, a deeper dive into these iconic forests of the West reveals characteristics that distinguish aspen from much of the surrounding environment. For instance, as we stroll together it is notable that Quaking aspen is our only widespread broadleaf tree in the region. As such, these islands of aspen among seas of conifers and sagebrush act as refugia for many species, notably avian, but also diverse arrays of flora and fauna.

Most aspen lovers are well aware of this species' clonal reproductive habit. A clone is simply a group of aspen stems—not really “trees” in the conventional sense—that are genetically identical, but also (mostly) linked in a root network. This characteristic drives almost all broader ecological linkages, direct and indirect, in aspen communities. How aspen responds to fire; how they repel insects, diseases, animals; how fast they grow; their susceptibility to internal rot and its relation to cavity nesting; and so many other critical connections. To know aspen you must understand that genetics and root sprouting set these species apart and provide critical insights into effective coexistence with the trees, the landscape, and the vast span of aspens around the northern hemisphere.

Listen. Set aside your binoculars, life list, notepad, camera, and listen. Quiet and sitting among stately white stems, close your eyes and extend a finger to count each distinct sound. Of course, the gentle flapping of aspen leaves, even with a small waft, permeates these forests. The snapping of a twig, birdsong, perhaps the scuttle of a rodent, as well as other human sounds (e.g., planes, cars, motors, shouting campers) enliven the aspen experience. A rich audioscape adds dimensionality. Listen in, next time you tour the trembling giants.

Perhaps this calming exercise has inspired you…to recline amidst Populus tremuloides. Supine, with intention. Breathe in, breathe out. Looking up, we see cottony clouds on an azure canvas through trembling crimson tides. For me, a sensory suite of soothing scenery. Resisting slumbering (for now!), my mind tracks to layers of biomass. From the lush understory of flowering plants, to the complex architecture of multiple stories, to the tips of the quavering foliage these layers facilitate wildlife specialists. Among birds, the ground-dwellers, scavengers, fly-catchers, nut crackers, gleaners, cavity nesters (primary, secondary, tertiary), and raptors utilize aspen’s layers differently. Performing this very exercise at the famed Pando clone near Fish Lake, Utah I spied the graceful arc of a bald eagle just above the tree tops.

Below ground, hidden layers of roots upon roots, intermingled with organic water-holding soils compound the complexity of aspen environs. Many forest visitors overlook the lichens; I once spent a full field season examining species diversity in lichens of the Bear River Range which lived on aspen. Spoiler alert: lichen variety and abundance decreased with declining moisture from forest floor to branch tips. (Pro Tip: retrieve your binoculars, flip them over, looking through the big end, and marvel at mighty, miniature lichen landscape with your converted hand lens).

Still prostrate, you may have dozed off. Or maybe not? The forest floor displays a soft dappling, a toggle of on/off sunlight. This pattern of intermittent light sets aspen apart from its conifer neighbors, facilitating a broad array of flowering plants. This diversity invites varied wildlife. In fact, aspens are second only to riparian areas as the most biodiverse forests regionally. Globally, preservation of sister aspens extending around the northern hemisphere—each foundational to regional biodiversity—have enormous potential for world conservation. Yet, threats to a species historically undervalued, even removed in favor of timber interests, may cause widespread species declines.

Realizations flicker. At the frontier of consciousness random thoughts spark new connections. Aspen, as a clonal species, is continuously reaching, one stem to another. One generation to the next. Linkages seen and unseen flourish. Aspen differs by clones in their defense chemistry. Though we cannot readily observe how good or bad leaves, shoots, and bark taste, this key attribute allows some clones to survive herbivory of both insects and browsing mammals while neighboring groves may be eaten out of a next generation. Hidden connections in the roots and their partner fungi convey water and nutrients not only within clones, but potentially to nearby genotypes where root grafting occurs. Other veiled attributes of aspen include susceptibility to stem rots, growth rates, landscape-level water retention, fire protection, and wildlife habitat. The science of aspen ecology is clear on these qualities, though humans understandably overlook them.

For me, perhaps the most intriguing element of aspen is ambiguity. That’s right, the more time I spend in these systems, the more the lines become blurred between the individual and the community.  Understanding aspen leads one to dispense with “trees” and engage with clones. Root networks are expansive and function as superorganisms. The richer organic soil under aspen landscapes holds more water, which (alongside sun-flickering leaves) bolsters great plant biomass and diversity, in turn holding additional water. Overlapping linkages compound; I cannot easily distinguish the forest for the trees, the insects, the blooming flora, or myriad wildlife. I’m willing to concede confusion, ignorance--even magic!

So, a lifetime of study has ultimately led to many unanswered questions, but aren’t these gaps in knowledge the source of wonder, further seeking, and simple mystical enjoyment? As we move between lucidity and dreams, surely an aspen grove lingers on our collective horizon.

Paul holds degrees in geography from Utah State University (BS) and University of Wisconsin (MS). His doctorate is from USU in Ecology.  Dr. Rogers’ ecosystem monitoring research has taken him around North America, Europe, Asia, Africa, and Australia. He is an Adjunct Professor in the Dept. of Environment & Society, a USU Ecology Center Associate, and the Director of the Western Aspen Alliance. He has published more than 50 professional and technical papers and appeared in media print, video/TV, and online content more than 100 times. Paul has taught Environmental Problem-Solving, Natural Resource Monitoring, Intro. to Environmental Science, and Planet Earth for honors students, as well as co-organized and spoken at more than 40 professional workshops.

Supplementary Readings:

Rogers, P.C. 2021. Pando to Pangea. Earth Island Journal. January 15, 2021 [online]: https://www.earthisland.org/journal/index.php/articles/entry/pando-to-pangea

Rogers, P.C. 2019. Biodiversity within aspen forests. Western Aspen Alliance, Utah State University Extension, Logan, UT. WAA Briefs #7, 2 p. https://western-aspen-alliance.org/files/briefs/WAA_Brief7_Biodiversity_final.pdf

Rogers, P.C.; Pinno, B.D.; Šebesta, J.; Albrectsen, A.; Li, G.; Ivanova, N.; Kusbach, A.; Kuuluvainen, T.; Landhäusser, S.M; Liu, H.; Myking, T.; Pulkkinen, P.; Wen, Z.; Kulakowski, D. 2020. A global view of aspen:

Conservation science for widespread keystone systems. Global Ecology & Conservation. Vol. 21: e00828 https://doi.org/10.1016/j.gecco.2019.e00828.

Kohl, M.; Sandford, C.; Rogers, P.; Chi, R.; Messmer, T.; Dahlgren, D. 2024. Function over form: The benefits of aspen as surrogate brood-rearing habitat for greater sage-grouse. Ecosphere. 15(12): e70060. https://doi.org/10.1002/ecs2.70060

Rogers, P.C. 2022. Pando's pulse: Vital signs signal need for course correction at world-renowned aspen forest. Conservation Science and Practice, Vol. 4: e12804. https://doi.org/10.1111/csp2.12804