by Emily Federici
Camp Oty’Okwa AmeriCorps Member
As Camp Oty’Okwa prepares to tackle HWA I had the opportunity, with the help of our Naturalist allies Levi & Rebecca Miller (Boch Hollow and Hocking SWCD), Jim Osborne (ODNR), and Joe Moosbruger (Crane Hollow) to learn how to take inventory of Eastern Hemlocks, and monitor for the Hemlock Wooly Adelgid, across several acres of forest at Sheik Hollow.
Monitoring for HWA is quite simple. As the name suggests, the Hemlock Wooly Adelgid has a “wooly” appearance coming from a covering created to protect itself and its eggs, which resembles the tip of a cotton swab. You’ll find these sacs at the base of the needles on the underside of hemlock branches. It is best to have on dark clothing to hold the branch up against when monitoring, as the white sacs will easily stand out.
Having precise inventory of how many trees are on your property is an important step in combatting HWA, as you need to have an estimate of the number and size of trees in order to know how much insecticide will be needed to treat when HWA presents itself.
To take inventory of tree stands, the use of electronic GPS mapping, ten-factor angle gauges, 12’ rope, flags, and DBH (diameter at breast height) measuring tape must be employed.
You begin with a GPS map that delineates one-acre plots within large hemlock stands. Once you are at the middle of a plot, as laid out on the map, you mark the point with a flag. From there the use of a ten-factor angle gauge is needed. This tool easily measures which trees will be considered “in” or “out” of the plot, by looking through at a fixed distance from the eye of the surveyor. Any tree that appears narrower than the angle gauge is not counted in the survey.
After the use of your angle gauge, you measure the tree with DBH tape, and record your diameter on a data collection sheet. Measuring for the diameter at breast height is a necessary step, as it gives an indication of how much product you will need to use on a given tree when it comes time to treat. 12’ rope is then used to smaller trees in what is known as the regenerative layer. These are also measured for DBH and recorded as well.
The loss of hemlock forest is cause for great alarm. Not only are the Eastern hemlocks that cover three hundred, of the seven hundred, acres of Camp property beautiful, but hemlocks act as an irreplaceable part of their environment as a keystone species. These trees create their own microclimate on which many other species, both terrestrial and aquatic, depend. Some species of birds, such as the solitary vireo, black-throated green warbler, and blackburnian warbler, exclusively use hemlock bench and ravine habitats. Native brook trout also depend on hemlocks to keep streams cool and stabilize water flow. During the summer, streams can cool as much as 5 degrees Celsius when flowing through a hemlock ravine. These are just a few of the many species that hemlocks support.
Here at Camp Oty’Okwa, we are taking steps to ensure that the hemlock trees can be saved on our land as well as yours. Keep an eye out for upcoming dates we will be hosting for HWA inventory, monitoring, as well as education classes to keep you further informed by Ohio’s leading naturalists. Join us and help in the fight to save our unique and vital conifers.