Arthur Dawson, THE PRESS DEMOCRAT
Among individual species there will [also] be winners and losers. Redwoods are expected to remain stable in the western half of the county, but decline in places more distant from the coast. Douglas fir shows a similar pattern. The biggest loser may be Oregon or Garry oak. The real winner may not be a tree at all, but chamise, a shrubby chaparral species.
To look into the future of forests in Sonoma County requires finding a similar time in the past — or at least one as close as possible. And for that, scientists have turned to studying minute specks of pollen at the bottom of Clear Lake.
“When considering the future of our forests,” says Professor David Ackerly of UC Berkeley, “the closest analogy for the present moment was the warming at the end of the last ice age, 14,000 years ago.” Pollen preserved in sediment at the bottom of Clear Lake recorded a dramatic change at that time from conifer-dominated forests to oak woodland. That transition took place over 4000 years, as temperatures rose about 10 degrees Fahrenheit.
Today the Earth is heating up many times faster and, depending on who you talk to, warming over the coming century could match the rise after the ice age. Changes in rainfall are also expected for Sonoma County, although it’s uncertain whether we’ll see more precipitation or less. But even with more rain, warmer overall temperatures may increase evaporation to the point where less water will be available to plants. The timing of rainfall is important, too — a few torrential storms bank less soil moisture than the same amount falling slowly and steadily over the winter months. Soil moisture is an important factor controlling where trees can grow.
In this scenario, the survival of living things depends upon their ability to adjust to the changes more quickly than in the past. Animals are lucky — they can move to other locations; individual trees and plants are stuck to one spot. In the short term, many are already shifting their yearly cycles — the beginning of spring, as marked by budding and flowering, is two weeks earlier than it was 50 years ago. Long-term, trees move between generations, their seeds spread by wind, water, gravity and animals to more suitable places.
Read more at: Sonoma County’s forests face uncertain future | The Press Democrat