Crowning Achievements: How to measure the DBH of a multi-stemmed tree

Diameter at breast height (DBH) measurements are a core element of forest inventories and monitoring. However, DBH—and, specifically, breast height above the ground—has notable shortcomings. The height at which this measurement is taken varies between continents, researchers and tree types. This is where the research of  Mr. Yasha A. S. Magarik of the Yale School of Forestry and Environmental Studies and co-investigators, Dr. Lara Roman, USDA Forest Service, and Dr. Jason G. Henning, The Davey Institute and USDA Forest Service, comes in. In his project, “Dendrometry of Multi-Stemmed Urban Trees,” partially funded by TREE Fund, Magarik specifically tackles the problem of applying traditional DBH (approximately 137 cm) measurements to small statured, multi-stemmed trees, which his research has shown are a growing population of trees in urban environments.

In this project, 25 urban forestry practitioners were surveyed in 12 cities across the northeastern United States on how they approach measuring the DBH of multi-stemmed trees in real-world situations. Among his findings were that practitioners employ alternatives to the current protocols for measuring at 137 cm, and that current measurement practices for multi-stemmed trees can be burdensome. In addition to conducting this survey, Magarik and his team measured the stem diameter of 569 trees of three frequently planted, commonly multi-stemmed genera: Malus, Prunus, and Zelkova. Several distances above the ground were recorded: (1) at the root collar, (2) at 30 cm, just below the fork (which occurred between 30 and 137 cm), and (3) at 137 cm (up to six stems following established protocols).

Access Magarik’s research here to find out what insights this rich data revealed about measuring the diameter at breast height of multi-stemmed trees. And mark your calendar now for his and Roman’s webinar at 12:00 p.m. (CT) on Tues., Oct. 13, 2020.

Click here for the complete, January 2020 issue of TREE Press.