“To put it into perspective, there’s nobody alive today who has been in a cycle quite like this in Colorado. These are less than once in a lifetime cycles. They’re quite rare. It provides a rare opportunity to get insights into a few things. One is what is the set-up necessary to produce these kind of events? We can try to get some insights into the frequency or return intervals of these events.” –Brian Lazar
Colorado Avalanche Information Center has harvested 730 tree disks or cookies so far over the past two summers for research by its partners to better understand the historic avalanche cycle of the 2019 winter. CAIC recorded about 1,000 avalanches in the Colorado mountains during the cycle but the total number could easily be five times greater.
The Colorado Sun reports cookies cut from the tree trunks that were effected by slides are key to researching avalanche flow dynamics and impact pressures. Dendrochronologists with the U.S. Forest Service and U.S. Geological Survey will also be using the samples to extract clues about Colorado’s climate from the tree ring growth.
They will also look for the presence of “reaction wood” abnormal growth on the lower side of trees positioned on an incline. It can signal impacts from major events like avalanches or small incidents like a boulder crashing down. The presence of reaction wood can tell a dendrochronologist if the trees that were felled in the 2019 avalanche cycle suffered major, prior impacts and how long ago.
CAIC targets Engelmann Spruce and other conifers, which grow slow and therefore provide a longer picture than faster growing aspen trees. By providing lots of samples, researchers can look for longer-term trends in climate and avalanche activity.
In the field, CAIC members measured the length of the tree trunks and diameter at human breast level. They noted factors such as a “broken butt” and “broken tip” and whether the subject tree was in place where the force of the avalanche knocked it down or if it was swept away. The data is entered into an app on their smartphones and once they return to cellular service, it automatically downloads into the CAIC database.
After the cookies are carved from the trees, the workers use a Sharpie to label the location. After that, they are delivered to the Forest Service’s Fraser Experimental Forest in Fraser, Colorado where the cookies are sanded, labeled with metal tags and mounted on material before they are shipped to a U.S. Geological Survey facility in Bozeman, Montana, where they will be analyzed. Truly fascinating subject matter. To read the full Colorado Sun article GO HERE.
images from COAvalancheInfo FB