A burning problem

Spring is in its early stages, which means the wilderness parks are still abloom with red paintbrush and blue-eyed grass. In Chino Hills State Park, though, the palette is markedly different: pale yellow mustard, purple thistle and the white-and-lavender flowers of wild radish, none of them native plants. It’s a pretty scene right now, but one that tells a story about a worsening cycle of wildfire that threatens to transform the Southern California landscape.

Ravaged by two brush fires in November, both accidentally started by machinery -- a spark from a car and arcing from electrical lines -- the park is now firmly in the grip of opportunistic invaders. Aside from a lone poppy hidden amid the radish, there wasn’t a native plant to be found on a recent hike along a mile and a half of Aliso Canyon.

Fire can be good for Southern California’s wilderness and has always been a part of the natural landscape. Some plants have evolved to require fire for germination. Fire clears out old brush, allowing new plants to grow. But the cycle of beneficial fire is delicate. If burns occur too frequently, perennial natives might lack time to mature. If the fire blankets the ground instead of burning in patches, there are no plants to spread to the burned area. And if it burns too hot, it kills bacteria and fungi in the soil that nourish the growth of new plants.

The 2008 fires came too soon after other wildfires. They burned with particular intensity and blackened 95% of the park. The combination provided a perfect opening for weeds such as mustard to choke out native flora.

According to Claire Schlotterbeck, executive director of Hills for Everyone, a nonprofit advocacy group for the park, it will take a year or two to see how many trees survived the fire. But one thing is clear, she said: The park is undergoing a profound ecological change, as the woodlands and hillsides of native bunch grasses and scrub die out, replaced by a monotonous landscape of invasive annual grasses. The park has money only for limited rehabilitation, mainly to eradicate fire-fueling giant reed in one of its creeks. Volunteers are restoring trails, one at a time.

Noxious plants make an inferior habitat for wildlife; they also turn brown and dry faster than native plants, lengthening the fire season. As global warming accelerates the fire cycle, Chino Hills could be an early example of sweeping, long-term change in the open spaces that Southern Californians cherish. That change was set in motion by decades of warming that cannot be undone in time to prevent worsening fire seasons. At this point, state and regional officials must focus on practical steps to combat fire’s effects through better land-use planning that stops placing homes at the edge of wilderness, a fund for restoration after fires and an emphasis on maintaining natural habitats that have a better chance of surviving firestorms to come.