Life on the Edge
At the Wildflower Center in south Austin, acres of native plants and trees abut suburbia. Credit: Nolan Zunk
By Marc Airhart.
LIFE IN AN EDGE STATE can take on many looks. An Inupiat village on the Arctic coast surrounded by sea ice, frequented by polar bears and seals. A world-class astronomical observatory perched high above the Chihuahuan desert. A botanical garden in Central Texas with wheelchair accessible walkways meandering through an oasis of native plants and burbling fountains.
As edge habitats, they represent real places where two or more ecosystems rub shoulders, making them among the best places in the world to study long-term ecological change. As patterns of land use shift and as pollution, invasive species and global temperatures fluctuate, these are among the places changing most quickly. They effectively serve as early warning systems for the rest of the world.
That’s why University of Texas at Austin scientists study in these places, whether far away or closer by within UT’s own Texas Field Station Network, recently established with the largest-ever philanthropic gift to the college from Winn Family Foundation.
At the Beaufort Lagoon Ecosystems Long-Term Ecological Research Station (BLE-LTER) in Alaska, rivers ferry freshwater and nutrients from the land into the sea. At the McDonald Observatory in West Texas, a cooler, wetter microclimate harbors stands of Ponderosa Pine and pinyon trees, as well as rare fireflies and hummingbirds, encircled by an increasingly warmer and drier lowland desert. At the Lady Bird Johnson Wildflower Center, the oaks and junipers of the Edwards Plateau meet the grasslands of the Blackland Prairie – and also the human development of an Austin suburb.
“Those are edges for a reason,” says Ken Wray, director of the Texas Field Station Network. “Whether it’s moisture or temperature or something else, species there have come to their biological limits. And when you start to see changes, it’s going to be at the edge of that limit.”
Credit: Eloise Brown
Top of the World
Spring on Alaska’s Arctic coast is bursting with activity. As the days lengthen, the icy shell covering lagoons cracks and dissolves like marshmallows bobbing in hot cocoa. Cod, Arctic cisco and Dolly Varden feed on crustaceans, marine worms and microalgae. Having traveled thousands of miles, an aerial armada of migrating birds descend to sample the buffet.
Ken Dunton, a UT professor of marine science, and his colleagues have come to document all the biological goings on. They use remotely operated vehicles to collect data and images under the ice, drones to monitor the landscape from above and low-tech methods, too. They examine nutrients in seabed sediments and identify what organisms are living in the water, on the land and even on the underside of the ice.
The Arctic is warming four times faster than the rest of the world.
“What goes on in the Arctic really will have an effect on the rest of the global climate,” says Dunton, who is principal investigator for the BLE-LTER.
Scientists here work to track and understand how phenomena like thawing permafrost, shifting precipitation patterns and losses of sea ice alter coastal ecosystems and impact the people who depend on them. Dunton works among the local communities of the Inupiat—largely subsistence hunters and fishers, already experiencing dramatic change, alongside the fish and wildlife they depend on. Dunton has been doing ecological research along the Arctic coast since the 1970s, watching as a “slow and insidious process” unfolds. Much more work to understand the implications remains.
“To understand how ecosystems are changing,” Dunton said, “it will take decades of tracking incremental changes in the physics, biology and ecology.”
Sky Island
It’s obvious why astronomers, who study faint little twinkles out beyond the range of human vision, love the primordial darkness at McDonald Observatory. But in recent years, biologists and ecologists also have been making the trek to far West Texas to study the world at their feet in a “sky island,” another distinct edge habitat.
Atop the more than 2,000-meter high Mount Locke, the site is another bellwether for global change. For example, when, as is increasingly the case, summer rainfall is lower than usual, wildfires grow bigger and more common, rare species such as the sky island firefly decline, and Ponderosa pines become stressed and more susceptible to an invasive boring beetle.
“These pockets of the desert have very particular rainfall patterns, climate and plant life that you don’t see at the lower altitudes,” says Teznie Pugh, superintendent of the observatory. “Biologists are really interested in these unique species, why they’re here, what the threats are to them.”
The same inky firmament that attracts astronomers provides biologists with unique opportunities.
The same inky firmament that attracts astronomers also provides biologists with unique opportunities to study the relationship of the living world to light. For example, some desert plants, like cacti and agave respire at night. Light pollution can cause them to respire less, essentially forcing them to hold their breath. Biologists are studying how that stress on plants can in turn affect animals who depend on them, such as moths and bats.
“The dark skies movement has grown beyond just astronomy,” says Stephen Hummel, the dark skies coordinator at McDonald Observatory. “It’s no longer astronomers alone who care about the issue of light pollution. Increasingly, it’s biologists, conservationists and others who are some of the biggest voices for preserving nocturnal environments.”
Suburban Oasis
UT ecologists, including assistant professor of integrative biology Amy Wolf, recently set up an experiment simulating the effects of drought in another edge habitat, this one in a south Austin suburb. At the Lady Bird Johnson Wildflower Center, car-sized rain-out shelters prevent half of all rainfall from reaching thirsty plants below – just one part of a larger global scientific experiment at 100 sites on six continents, including others in the Texas Field Station Network. Wolf and her colleagues already have learned about threats from extreme droughts. One year of simulated extreme drought – increasingly common in the real world – was found to slash plant growth 60% more than earlier, more typical droughts.
“The global impacts of projected increases in drought severity have been significantly underestimated,” Wolf and her fellow authors wrote. And drier places like Texas “are likely to be most vulnerable to extreme drought.”
At the Wildflower Center, land managers and researchers also have been studying the effects of prescribed burns for more than two decades. Fire, a natural feature of many healthy ecosystems, is known to drive increases in plant diversity that can help mitigate against threats. On the other hand, fire suppression can contribute to bigger, hotter wildfires and a proliferation of invasive species. Fire timing is critical, the researchers found: fall and spring burns result in more wildflower blooms and pollinators, while summer burns can reduce invasive species.
Shalene Jha, a UT professor of integrative biology and the center’s academic director of research, points to increasing fire risk as just one example of the importance of having stable research stations such as these in edge habitats.
“You can do a short-term study in any garden or park,” Jha said, “but to be able to go back year after year and really document how the landscape is responding to climate, that’s only possible with long-term monitoring, science’s gold standard.”