By Kristen Munson
A POWERFUL PLACE
F I E L D N OT E S / /
PAUL ROGERS IS COMFORTABLE WITH MESSINESS. Before he was a researcher monitoring the health of western forests, before he became a disturbance ecologist, Rogers studied geography. This is where things tend to get muddled. Because the study of place is also the study of people. People put lines on maps. People affect landscapes. And sometimes, people harm them. Rogers’ research examines the human impact on the environment, primarily, the ecology of quaking aspen. The species is found across the northern and western reaches of North America. While it doesn’t provide good timber, what aspen lack in economic impacts they make up for in biodiversity benefits. “Aspen are believed to be second only to riparian zones in western environments for biodiversity,” says Rogers, ’83, Ph.D ’07, director of the Western Aspen Alliance. And lately, the global picture for biodiversity isn’t pretty. In May, the first global assessment of wildlife found one million species threatened with extinction and that most of the planet is “severely altered” by human activity. Rogers witnesses these changes every time he visits one of his primary research sites, the Pando aspen clone near Fishlake National Forest. Pando, Latin for ‘I spread,’ is believed to be the largest living organism on Earth—at least, for now. When Rogers first visited the aspen stand about a decade ago, it was clearly in bad shape and on a bad trajectory, he says. The problem? The forest was old. Aspen primarily reproduce asexually and live, on average, about 100 years. The species evolved to favor reproductive speed over longevity. An extensive root system connects the above-ground stems and powers the whole operation through nutrient exchange. New suckers emerge to replace dead trees. This is how the 106-acre Pando clone operated for millennia. But walking through Pando, Rogers noticed the younger generations—needed to succeed the 47,000 older stems that are dying—were missing. Aspen are a finicky species. With thin bark that easily scars, aspen are vulnerable to infection and burns. Aspen get “injured by everything all the time,” Rogers says. But that vulnerability is also the source of strength. “Aspen thrive on death. It’s what happens next that is critical,” Rogers says. In ecology, there is a theory that in diversity there is resilience. Although genetically the same, aspen clones have diversity in the various ages of their stems, making the organism more resilient to threats. But a clone is only sustainable if enough suckers survive into adulthood. Rogers wanted to understand why Pando’s weren’t. In 2013 and 2014, researchers fenced off two plots within Pando to test various experimental treatments and to limit browsing from herbivores like deer and cattle. Then they waited. Four years later, the scientists found mule deer had breached the 2014 fencing and browsed new suckers to nubs whereas new growth was thriving in the 2013 enclosure where ungulates were kept out. The researchers published their findings in PLOS ONE, along with aerial images of Pando between 1939 to 2011. The most extreme changes occur in the ’60s and ’70s. So, how did an organism that coexisted with herbivores for thousands of years begin failing because of them? “It clearly points the finger back at us,” Rogers says. Human decisions shape landscapes, sometimes with cascading effects. Rogers suspects humans disrupted the balance between the deer, cattle, and aspen regeneration through management decisions. For instance, today there are significantly higher populations of elk in the West than in the past. There is an economic incentive to do so, Rogers explains. And the establishment of recreation areas