Arthur Dawson, THE PRESS DEMOCRAT
Coastal prairie once roamed by mammoths, covered with bunch grasses
The Lomas Muertas, or Dead Hills, appear on a Mexican map of a ranch that stretched between Two Rock in Sonoma County and the modern hamlet of Tomales in Marin County.
Ghoulish as it sounds, the name doesn’t imply any ghostly spirits. Found in several places along the coast, it refers to grasslands where trees are virtually absent.
Botanists classify our local lomas muertas as coastal prairie — a grassland type found within 50 miles of the ocean. An account from the 1850s described the prairie near the mouth of the Russian River as “waving grasses higher than a man’s head, with deer, bear, and other big game everywhere … ” that included tule elk and pronghorn.
Prior to the 19th century, coastal prairies were largely perennial bunch grasses like purple needlegrass (our state grass), oat grass and several fescue species, as well as many kinds of wildflowers. Bunch grassroots can grow 16 feet deep, providing water during the dry months. Summer is also when coastal fog creeps inland — some prairie plants are able to harvest this moisture as well.
If you had visited our coastal prairies 15,000 years ago, you would have found wildlife rivaling East Africa’s today. Grizzlies, short-faced bears, herds of bison, elk, pronghorn and mammoth, and many other large animals roamed the coastal prairies. By trampling the ground, wallowing in water holes and consuming huge amounts of leaves, bark and twigs, mammoths in particular may have played a key role in creating and maintaining a nearly treeless landscape.
Coastal grasslands are considered a “disturbance dependent habitat.” Now that the mammoths are gone, grazing and burrowing by other animals, as well as fire and drought, keep it from converting to shrubs or trees.
Before Spanish settlement, indigenous people also kept the landscape open by setting fires on a regular basis. Burning recycles nutrients back into the soil, resulting in healthier plants, which means more food for humans and game animals.