Lloyd Nathanael
GIS Coordinator
Massachusetts Department of Environmental Management
Boston, MA

Eastern Hemlock Mortality Risk Analysis in Massachusetts

The Hemlock Woolly Adelgid (Adelges tsugae) is a parasite of the Eastern Hemlock (Tsuga canadensis) that is rapidly spreading in the Northeast. With a small grant from the USDA Forest Service we have taken an initial look at the mortality risk faced by Eastern Hemlocks in Massachusetts. Hemlocks in Massachusetts do not tend to grow in large stands. Our existing information on the composition of Massachusetts’ forests is based on large stand level information and therefore did not contain sufficient data on Hemlock distributions. However, the Forest Service has established permanent plots on private lands to monitor forest change, and by using an ordinary kriging statistical technique on this information we were able to derive an estimated distribution for Hemlocks in Massachusetts. Using data on expected mortality rates weighted for various environmental factors it was possible to create mortality risk maps for Massachusetts Hemlocks.