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Prairie preservation here slowly takes root By
Craig Welch 2/23/03 Three years ago, restoration crews at this state sanctuary south of Olympia hacked away snarled branches of insidious Scotch broom, a destructive non-native weed that spreads like a bad cold. Underneath, biologists found the delicate pink petals of a rose checker mallow, a flowering plant that hadn't been seen in this state since 1983. Biologists eventually harvested its seeds and last fall transplanted the rare species, hoping new plants would take root from this lone survivor. Salvaging what remains of one of Puget Sound's remnant prairies requires a vigilant mix of forcefulness and grace. Failure to do so could threaten the survival of some of the state's rarest wildlife and sever a thread that links the region to its own natural history. Native Puget Sound prairies — open grasslands and oak savannas reminiscent of the Midwest — used to dot the region's lowlands from Olympia to Everett. Defined by boot-high dry meadows and sparse open woodlands, they once covered more than 160,000 acres, primarily near the southern reaches of the Sound. Packed with sunflowers and violets in spring and dry, haylike slender grasses in summer, these areas percolated with plant and animal species not found elsewhere in the state. Today, scientists believe less than 3 percent of these lands remains, most in isolated chunks of a few hundred acres. Most are separated by roads and development and crowded with invasive, non-native species. What remains is home to several of the state's rarest species, from butterflies and gophers to pond turtles and spotted frogs, nearly all of these species believed to be declining in numbers. Volunteers and Washington Department of Fish and Wildlife staff are working to restore what's left of these state-owned native grasslands. But the ecosystem is complex, and its problems even more so, and each species is intertwined in ways that make revitalization difficult. "People like us to protect rare places and rare things — and this is a rare place with rare things in it," said Dave Hays, a Fish and Wildlife biologist. "The idea isn't to restore these areas to their past distribution or abundance, but simply keep them around at all. But doing so is a process more than an event." And nowhere is that more clear than here at Scatter Creek. Dry landscape Created by meltwater 10,000 years ago from the continental ice sheet, Puget Sound's prairies technically are "gravelly outwash plains." The soils aren't rich, but shallow and rocky, and hold water so poorly they are prone to drought. That dry landscape isn't suitable for Douglas fir trees, which is why the region's thick, towering forests once opened onto lowland grasslands — primarily in Pierce, Thurston and Lewis counties. To wildlife managers, it's magical, the way this tiny ecosystem's functions intertwined. Burrowing pocket gophers created disturbances in short, stout bunch grasses, which in turn allowed new grasses to grow on the mounds. Taylor's checkerspot butterflies drew nectar from their flowers or on flowering plants in nearby oak trees. Rare water howellia plants grew out of wetlands, which also provided habitat for Oregon spotted frogs. For centuries, frequent burning by Native American tribes kept the conifers at bay, ridding the flatlands of weeds and other tree seedlings. It released nitrogen that stimulated the growth of camas bulbs, which the Indians grew as food, and Idaho fescue and paintbrush. And the openings among the trees created habitat for Western gray squirrels. "It all fit together nicely," said Fish and Wildlife biologist Kelly McAllister. "It was this amazing mosaic." But as settlers reached the Northwest, such openings were ideal for homesteads, and prairie land was quickly taken over for agriculture. (The Scatter Creek refuge once was home to the original county seat.) Settlers introduced non-native species such as Scotch broom and tall bent grass, a popular pasture grass. They halted traditional burning, which allowed non-native grasses to explode. Ongoing restoration On a crisp winter morning, dew crackles underfoot as visitors survey ongoing restoration. Oak trees are scarred black from fires lit to keep understories open, and vast, open fields of bent grasses roll west into the mist. "Don't step there ... please," said Patrick Dunn, with The Nature Conservancy. This particular spot is home to rare Mardon Skipper butterflies, and helps show just how delicate restoration here can be. The same pocket-gopher mounds that allow native grasses to flourish now instead help invasive oats in their bid to take over. But the butterflies winter as larvae buried deep in these grasses, so volunteers plucking weeds have to tiptoe so as not to crunch them. Meanwhile, the same fields are dotted with table-size clumps of Scotch broom, once brought in as an ornamental flowering plant and to stabilize steep slopes. With thumb-thick branches it shades out many native grasses, sunflowers and violets, and increases the soil's fertility, which makes it easier for invaders to take root. Yet to destroy it, workers must cut it back, mow it down and then burn it, a repetitive process that can take years before it's eradicated. If workers aren't careful, butterflies can die in the mowers. And too much burning at once could release excess nitrogen, which might in turn make it easier for invasive tall grasses to take hold. Meanwhile, this area has historically been popular with hunters who use it to train dogs, which can trample the many delicate flowers. It's hard to say just how the restoration effort is working, in part because it's difficult to measure success. "We're definitely making progress, but it's really one of those cases where time will be the judge," Dunn said. But there are, at least, a few promising signs. After removing Scotch broom and burning, Mardon Skipper butterflies began nectaring near the oak trees, the spot scientific literature suggested they ought to be. And at last check, Hays said, at least half of the 80 rose checker mallows he planted last fall have begun to grow. Craig Welch: cwelch@seattletimes.com or 206-464-2093. |