Cambria’s rare Monterey pine forest is changing as it is exposed to increasingly frequent droughts that stress trees. The forest is not dying, but responding to the stress of extreme climate conditions.
“The recent drought generally took out the weakest and oldest individuals,” said Sarah Bisbing, assistant professor of forestry at University of Nevada, Reno, “but I’m not concerned about wholesale loss of Monterey pine. We are continuing to see regeneration and growth in residual trees.”
Bisbing will present her findings at the Cambria Forest Committee meeting set for 6:30 p.m. Wednesday, Jan. 10, at Rabobank. Her subject is “Drought and disease shape demographic processes in endemic Monterey pine.” The talk is free. The Committee’s Invasive Weed Guide will be available for sale, $8. Donations are always welcome. The Forest Committee is a 501c(3) nonprofit organization.
Bisbing is a forest ecologist who has made the forest the focus of her work. She studied data collected between 2001 and 2016 to determine what influenced which trees survived and which ones died.
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Bisbing used a measure of climatic stress to evaluate how local climate and environmental factors drive tree response to changing conditions. This metric provides a surrogate for tree stress and is calculated using the local variables, such as total moisture, extreme temperatures, aspect and soil depth. She additionally tracked the influence of non-native pine pitch canker on the forest over time, and discovered that many did not die from infection. Mature trees tolerated infection, while some saplings died.
“Conifers can handle a few years of extreme stress,” she said. “They have evolved to grow in more stressful environments deciduous trees can’t tolerate.”
Over time, the forest has continually changed. Historically, Monterey pine occupied much of coastal California. It expands and contracts in response to climate conditions. Following the last El Niño, for example, many seedlings got started, but few persisted. Seedlings crowd each other out, competing for resources. Only those in the right place and with the greatest access to resources survive.
Monterey pine has a limited range on the California coast, although it’s the most widely planted conifer globally.
“The number one threat to the Monterey Pine forest is human development and urbanization,” she said. “This species has nowhere to go.”