Tree Climbing, while fascinating to watch or to read about is not merely done as a sport. One of the major aim of ENTS is to measure and quantify outstanding individual trees and stands of forest in the eastern United States. measurements are done using a combination of laser rangefinders, clinometer, and rudimentary trigonometry. In spite of the obvious advantages in accuracy obtained by this method, as are illustrated on this website, there is often a reluctance, resistance, or downright antipathy to any change in long standing measurement methods. How do you prove your measurements are accurate, or more accurate than than figures obtained by other methodologies? The only way to do that is to physically measure the tree and compare the results to those measured from the ground. Cutting the tree down to measure it defeats the purpose. The only other way is to climb the tree and measure it with a tape.
There are a number of people involved with this organization climbing trees and measuring them. Included are Will Blozan, Michael Davie, and Bob Van Pelt.. I had the opportunity to watch and videotape Will Blozan, ENTS President, climb and measure the Seneca Pine in Cook Forest State Park, PA in April 2003.(se link below). you see lumberjacks on TV using spiked boots to climb trees. That is not how we do it. The spikes damage the tree bark and provide an avenue for decay and infection into the tree mass. Will used a giant slingshot about eight feet tall. With it he shot a weighted bag tied to a thin rope over the lower branches of the tree. The goal is to get branches in the 100 to 120 feet off the ground range. Higher than that and the weight used is not sufficient to pull the cord up and over the limb as it slides back to the ground. Once the weight is retrieved, the attached cord is used to pull a climbing rope up to the limb. This rope is tied off on the ground. The rope itself is climbed using mechanical devices that grip the rope. Will Blozan used climbing devices called "Jumars", along with a seat harness and chest harness in his climb, in a setup called a modified frog climbing system. The climbing rope used was a special static rope (one that has very little stretch but is very strong). There are several brands used by fire and rescue crews, cavers, climbers etc. Most commonly used are PMI manufactured by Pigeon Mountain Industries, and a brand called Bluewater. I believe Will Used Bluewater III. In any case the rope is used to climb to the lower branches.
From these lower branches, the climber climbs up the branches making sure he is properly secured by safety rope. Eventually the limbs become to thin to safely support the climbers weight. At this point he hauls up a tape measure and drops a line to the ground, measuring his height at this point. He then hauls up a series of measuring poles and extends them to the very top of the tree. This pole is then lowered to the ground and measured. The height of the tree is the sum of these two measurements.
The climber then rapells (abseils) to the ground. Girth measurements are often taken at several different heights on the tree as the climb rapells down. He will stop and run a measuring tape around the trunk of the tree. His height above the ground can be measured using the same laser rangefinder/clinometer methodology used to measure the tree height. These measurements can then be used to calculate the trunk volume for the tree, adding additional information to the scientific database.
At meetings of the organization members of the press have been invited to observe the climbs. The climbs are spectactular, and articles about the climbs and ENTS generate additional awareness of the goals of the organization and help preserve these stands of spectacular trees for the future.