Rialto Beach, north of La Push along Washington’s active, dynamic Pacific coast, is home to a stretch of Sitka spruce trees that are teaching geologists about how shoreline forests react to and recover from large-scale storms. Staff Geologist Chelsea Bush, GIT, will present this at the Geological Society of America’s Connects conference in Portland on Wednesday, October 13.
Her presentation, “Determination of Forest Age in a Coastal Setting Affected by Both Landsliding and Catastrophic Storm Events,” explores how she and her study group, part of her masters’ thesis at the University of Washington, started out trying to determine the age of the Sitkas in an effort to figure out when a landslide on site occurred. But after they’d researched Carbon 14 and LiDAR data, the results showed that the modern forest is younger than expected.
After further investigation, they determined that the diameter of the trees and the age of the trees weren’t related–most of the trees on site had been knocked down by the Olympic Blowdown of 1921 or had been shaped by other geomorphic processes. Understanding the true age of the trees will help geologist determine how they will respond to geomorphic or weather events and estimate how long it will take for the trees to succumb to erosion and fall to the beach below.
Chelsea and her team’s research shows that it’s easy to assume certain things about the age of a forest based on looks and the sizes of the trees – but when you look further, there may be more than meets the eye.