Saving Pando Humans are taking measured steps to rejuvenate an ailing giant.

By Paul C. Rogers

ast fall, intrepid teenagers in groups of threes and fours fanned out across the in central to put their ideas to the test. The Ogden High School Internation- L al Baccalaureate class, along with their instructors, came to a place in the forest to see and to learn about what is thought to be the world’s largest living organism: a 106-acre clone of quaking as- pen () stems estimated to weigh thirteen million pounds. Though are the most widespread tree species in , the deteriorating state of this clone may bear lessons not only for these students or for the fate of aspen continentally, but for human interactions with nature in general. How this clone came to be and its ultimate arrival in the present predicament is a story of evolving science and shifting stewardship; a partnership born of necessity and urgency. In 1968, forest ecologist Burton V. Barnes (1930–2014), professor in what is now the University of Michigan’s School of Natural Resources and Environment, identified this huge clone by discerning the difference in annual patterns in leaf color and development from adjacent aspen stands. Twenty-five years passed before evolutionary biologist Michael C. Grant, at the University of Colorado- Boulder, named the clone “Pando” (Latin for “I spread”) and dubbed this specimen the World’s Largest Organism. In 2008, a team of researchers led by Karen Mock, associate dean of the Quinney College of Natural Re- sources at , confirmed Barnes’ original estimate of Pando’s size, but also noted a curious ring of much smaller as- US D A Forest S ervice pen clones surrounding the giant. How these

The Pando clone in central Utah’s Fishlake patterns of genetic growth developed over time—perhaps one clone National Forest is composed almost pushing the others aside, or opportunistic seedling establishment exclusively of mature stems that are near the edges—continues to puzzle modern scientists. Moreover, dying off and are not being replaced. c. rogers paul though we have no dependable method for determining Pando’s age,

March 2016 natural history 33 we do know that this huge, In fact, recent research, such as of years old, how did it come to this perilous state in so Resources, and Grand Canyon Trust to enclose about genetically identical organ- that coming from Mock and her brief a time? There may be several contributing factors, but fifteen acres (fourteen percent) of Pando with eight-foot ism comprised of an estimated associates, clearly describes pat- there’s little doubt that people have played a role. Contem- fencing and to conduct experimental treatments within 47,000 stems (called ramets) terns of offspring indicative of porary domestic and wild ungulates are regulated by that area. It was hoped that outcomes of this experi- originated from a single seed regular seedling development— human agency. Further, over the past century we’ve been ment would provide a course of action for sustaining the size of a pepper grain. The i.e. sexual regeneration. Both quite successful at reducing or eliminating apex predators Pando’s future. The goal was to allow new aspen stems nature of this beast causes us suckers and seedlings have that previously swayed herbivore numbers, movement, to grow beyond the height of ungulate reach, as well as to re-examine what it means played a role in the life of Pando, and habitat. There are economic incentives for keeping to determine which treatment method resulted in the to be an individual speci- though we don’t fully understand both livestock and game animal numbers high. A great- best growth response for money spent. Monitoring be- men when what appear to be the relative importance of each. er degree of control over gan just after the fence was free-standing trees are actu- livestock allows innovative erected and an annual re- ally small elements of a much s the young scientists of grazing strategies to keep measurement is ongoing. larger being with a root system Ogden High School quick- producers in business while Thirty-five sample plots, that exchanges life-supporting A ly discovered, all is not concurrently preserving im- each containing two 100- energy among ramets. well with Pando. A casual walk portant resources. With wild by 6-foot transects, were Traditional aspen science through this immense grove game, day-to-day manage- located inside and outside leans heavily on the fact that soon reveals a decided lack of ment is more difficult, but the fenced area and vari- the species propagates via root young ramets, the lifeblood of long-term populations may ous combinations of treat- sprouting, also known as suck- any healthy aspen forest. The be manipulated through ments—burning, juniper ering. In response to forest giant that thrives on continuous regulation and licensing. So, removal, and partial cut- disturbance, such as , reproduction appears to have the “naturalness” of this sys- ting—were applied on both logging, or blowdown, aspen stopped reproducing. If this were tem has been significantly sides. Inside the fenced area,

sucker profusely to initiate new c. rogers paul a human community, it would altered over recent decades control plots also tested the cohorts. This rapid succession- This six-inch-tall aspen sucker arising from the parent be as if there were almost no ba- and the symptoms of decline effect of only fencing with- al response favors aspen over of Pando represents future “generations” of the giant clone. bies, teenagers, young adults, or are now becoming evident out any other treatments. In competing vegetation in the Repeated browsing by ungulates results in clipped tops and even middle-aged people. The within Pando, which is con- addition to tallying differ- early years, but eventually co- multiple stems. Pando clone is made up almost sidered a keystone species for ent aspen stem sizes and sta- nifers outmuscle aspen for such entirely of senior citizens and, as numerous plants and ani- tus (alive or dead), field per- resources as sunlight, water, and space. Not all aspen, as would be the case were this a village, concern for the mals. Similar aspen stories sonnel noted browsing level in the case of Pando, compete with conifers; some grow future of this western icon is well founded. are playing out across the on small aspen and counted While we cannot age aspen clones with accuracy, we American West; a combina- both deer and cattle scat to can determine the ages of stems by taking core samples, tion of -plagued for- gain measures of animal use just as we do with most tree species. We know that the ests and overabundant her- and presence. It was impor- mature ramets of Pando are predominantly 100-120 bivores sets up a slow march tant for researchers to clear- years old; elderly specimens for aspen, but not for co- toward system failure. ly understand what actions nifers in this region. The aspen lifestyle, or functional Natural resource issues were effective and which ecology, is to live short lives and reproduce quickly us- often involve “messy” so- animals, if any, were caus- ing carbohydrate energy produced in the leaf canopy and lutions, in which multiple c. rogers paul ing recruitment loss. stored in the expansive root system. With such aggres- players represent divergent These have found ways to crawl under eight-foot-tall Preliminary test results sive reproductive mechanisms in place, one would guess philosophies, and degrees fences to access nutrient-rich aspen suckers. The difficulty and are beginning to shed light expense of maintaining fences present significant challenges to the clone abounds in young suckers. So, why is Pando of intrusion and ecologi- sustaining Pando’s future. on Pando’s situation. Since missing these age groups? cal outcomes are far from the 2013 fence was erected, One likely group of suspects threatening Pando are certain. An iterative approach for combating complex browsing inside the fence has essentially stopped—al- herbivores. Deer and cattle eat suckers soon after they socio-ecological issues is to develop tentative approaches though not as completely as expected—and aspen suck- emerge from the ground. Young aspen stems contain based on limited information and to monitor progress, ers are growing between two and three feet annually supple twigs loaded with nutrients intended for fast making adjustments along the way based on new find- in both treated and untreated areas within the fence. growth. A consistent pattern of herbivorous behavior, ings. So-called “adaptive management” prevents the One hundred percent browsing and almost no surviv- US D A Forest S ervice/B. C amp b ell lasting over decades, has resulted in a very uneven stem employment of policies assumed, without supporting ing regeneration is taking place outside the fence. Initial Stems of the same clone may stay connected for decades, although many separate over time. demography. As with all tree species, death of old data, to have positive outcomes, and their pursuit to po- data indicate a slightly higher rate of aspen regeneration occurs naturally from a variety of causes, such as inter- tentially deleterious ends. When managers implement where sites were purposely disturbed versus those that in nearly pure stands where disturbance does not play a nal decay, insect infestation, wind throw, and physical actions without ongoing monitoring, they miss oppor- were only protected. There was no significant difference major role. Instead, continuous asexual reproduction from wounds from animals and humans, but mortality with- tunities to learn from either successes or mistakes. among manipulations (burning, juniper removal, and thriving root systems produces patches of aspen stems out replacement spells potential systemic collapse. In 2013, a plan was developed by Utah State Univer- partial cutting) in terms of their regeneration response. growing, at any given time, in a variety of sizes and ages. If Pando represents a natural system, possibly thousands sity, USDA Forest Service, Utah Department of Wildlife Overall, it is clear that the temporary fence is having a

34 natural history March 2016 March 2016 natural history 35 revealed only one young as- tinkering.” If a single plant of such size and putative age across the entire region. Moreover, solutions found at pen stem. Students also spot- were to collapse now, we should regard this as a faltering this scale, such as fencing out large herbivores, are not ted deer within this protected of our society to preserve that which has survived the ages. feasible on much larger landscapes due to cost, public area. Given current numbers Pando probably arrived at its current state due to negli- outcry, or policy restrictions. of live mature trees, this plot gence in human decisions regarding livestock, wildlife, or The value of aspen ecosystems reaches far beyond the would need at least twenty- both. Prior to fencing, based on circumstantial evidence beauty and elegance of a single clone or even the entire two young stems to replace the of browse levels and scat deposits, cattle, deer, and possibly species. Quaking aspen, as the most dominant broadleaf current overstory, or canopy, reduced the ability of the clone to survive without in- in a region of conifers, is widely recognized as a foun- of Pando. This number as- dational element with sumes, however, that none of numerous obligate plants the new recruits die before Pando is visible in the middle ground, while the non-forested foreground depicts an and animals. Therefore, area that was cut, but not protected, in the late 1980s. Subsequent treatments have maturity; in reality, there is involved mandatory fencing to avoid such losses. thriving or failing aspen great attrition over the lifespan clones engender cascad- of aspen. Thus, the number of ing effects on biodiver- recruits should be double or sity at large. This ex- paul c. rogers paul triple the number of mature ceptional being called Experimental burning within an ungulate exclosure was conducted in 2014 to clear undergrowth and stimulate aspen suckering. trees they replace in order to Pando represents not maintain the overstory. As the only a milestone of sin- positive effect on recruitment success, even in control mortality of larger aspen trees continues, it further re- gle organism size, but a plots where no active manipulation, other than fencing, duces total clone leaf area. Fewer leaves means reduced potential laboratory for was undertaken. photosynthesis, which produces carbohydrates banked broader aspen steward- Apparent success after the first year of monitoring in the roots—the “fuel in the engine” for future sucker ship, as well as an essen- prompted USDA Forest Service officials to greatly ex- production. The stop-gap fencing is intended to pro- tial forest component for pand in 2014 an older fenced area. This original fence mote juvenile stem survival in order to stymie this neg- creatures that reside in its was constructed in 1992 after earlier trials of clear- ative feedback loop by replacing decaying portions of shade. cutting aspen within a section of Pando resulted in a this immense organism. By continually taking the pulse Diverse organizations complete loss of forest cover and regeneration due to of Pando’s regenerative capacity, and remaining open are coming together browsing animals. After one year, the expanded fenced to course corrections where the data warrant change, to save Pando. We will area showed little positive response, though there is a sober strategy for saving Pando seems to be in place. surely learn as we go and, evidence that mule deer have found ways to crawl un- hopefully, remain vigi- der older, deteriorating portions of this fence. In fact, he Ogden High School students who prowled the lant as we make inevi- monitoring conducted by the visiting high school stu- forest floor last fall were probing basic research ques- table adjustments along dents over a twelve-acre portion of this larger exclosure Ttions. How is plant diversity related to aspen cover? the way. The greatest Do soil properties affect ramet optimism is lodged in health? What is the relation- the simple acts of curios- ship between tree age and size; ity and discovery found can one predict the other? Les- c. rogers paul in the minds of budding sons learned at Pando not only tervention. Presumably, there is a threshold beyond which scientists. To wander the woods, to daydream, to form add to their intellectual growth, further death of overstory trees decreases the ability of hypotheses, and to test them—sometimes succeeding, but have the potential to inform root systems to produce enough offspring to survive even sometimes failing—presents a model for our society to future aspen stewards. Conser- with low levels of ungulate herbivory. It appears we are at embrace. Pando represents vital links: plant to animal, vationist Aldo Leopold advised, that point. Current efforts to fence Pando piecemeal are soil to tree, water to roots, humans to environment. “To keep every cog and wheel is showing positive results, although continual browsing in Pando’s peril points to broader disconnections, while its the first precaution of intelligent unprotected areas leaves little hope that peripheral por- perseverance spells hope. tions of the clone will sustain themselves. Across the West, quaking aspen face myriad chal- Though cattle are excluded from por- tions of Pando, short-term access in lenges, such as fire suppression, drought, warming tem- Paul C. Rogers is an adjunct associate pro- early summer and autumn, alongside peratures, development, and hydrologic re-engineering. fessor in the Department of Wildland Re- continuous deer browsing, appears to Where herbivory is problematic, it exacerbates these sources at Utah State University, an associ- be keeping all young aspen growth problems. For example, drought-induced instances of ate at USU’s Ecology Center, and director of in check. The US Forest Service and mature aspen die-off increases the pace of clonal collapse the Western Aspen Alliance (http://western- partners are collaborating to reduce aspen-alliance.org/). He worked for sixteen animal grazing and allow success- where few young trees survive browsing. Still, there are years for the U.S. Forest Service conducting ful aspen recruitment before aging many places where healthy communities persist, so we monitoring activities. His primary area of study has been human

paul c. rogers paul canopy stems die off. should use caution in projecting the ills of a single locale impacts on vegetation in the western .

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