National Geographic : 2016 May
Elk Fireweed Heartleaf arnica Lupine Aspen seedling Mountain bluebird Ross’s sedge Lodgepole pine Lodgepole pine Serotinous cone ART: MATTHEW TWOMBLY. SOURCE: MONICA TURNER, UNIVERSITY OF WISCONSIN Ecologists Monica Turner and William Romme witnessed the 1988 fires that burned more than one million acres of the Greater Yellowstone Ecosystem and are still studying the aftermath. They’ve seen the charred landscape rebound with a great diversity of species. Their research suggests that far northern coniferous forests like Yellowstone’s can regenerate after severe fires if they occur every 100 to 300 years, Turner says. “Infrequent high-severity fires are business as usual.” But what if severe fires become more frequent? During several summers since 1988, multiple fires have burned in Yellowstone, Turner says. And the hot, dry conditions that set records in 1988 may be the norm by mid-century. As climate change advances, it could significantly affect the frequency, size, and severity of fires; the conditions under which forests grow and regrow; and ultimately the health of places like Yellowstone. —Patricia Edmonds Yellowstone Fires, Past and Future SOON AFTER A FIRE Roots of perennial flowers and grasses can survive large fires. Heat triggers lodgepole pines’ serotinous cones to release seeds; those that survive take hold in newly mineral-rich soil that’s open to sunlight. 1 YEAR AFTER Aspen and lodgepole pine seedlings start small but establish quickly. Studies of the 1988 fires show that most pine seedlings germinated from seeds released from cones on fire-killed trees. 2 YEARS AFTER Flowering plants and wildflowers take hold. Elk and foraging mammals return to burned areas, as some of their food sources, such as aspen seedlings, grow larger. 25 YEARS AFTER Most burned trunks have fallen, and new lodgepole pines have grown to be 10 to 15 feet tall. The ecosystem has shown it can adapt well to severe fires—when they hap- pen only every few centuries.