Across the United States, bits and pieces of an ancient — but man-made — ecosystem are being restored, sometimes at the expense of more common natural landscapes. For thousands of years, fires lit by indigenous peoples maintained oak savannas. Such forested grasslands were once abundant across the western US, but agriculture, lumber industry, and fire suppression have combined to bring them close to extinction. In Oregon's Willamette Valley, bringing them back is laborious work that sometimes involves sacrificing stands of other native trees.
Why it matters: Oak savanna are among the most diverse ecosystems in the U.S. and support species that aren't seen anywhere else. In the 1800s, 1.5 million acres of the Willamette Valley were oak savanna. Today, just 1-2% of that remains, echoing a decline in oak grasslands across the country.