Dr. Nicholas Brazee uses sonic and electrical resistance tomography to study decay in the heartwood of trees
How do you determine if a tree has internal decay when there are no visible symptoms? Decay in the heartwood of a tree is common throughout natural forests and managed landscapes and is caused by a diverse assemblage of native wood-rotting fungal pathogens. At times, decay in the roots and lower trunk can make trees more susceptible to failure after exposure to strong winds. Dr. Nicholas Brazee, Extension Plant Pathologist at UMass, uses a minimally invasive technique to better understand both the incidence and severity of decay in trees. Specifically, he uses sonic and electrical resistance tomography to determine if damage is present in the lower trunk. The equipment generates tomograms that provide an internal view of the tree’s health. Brazee and his colleagues have completed studies focused on internal decay in northern hardwoods (beech-birch-maple), oaks and American elms. A primary goal of these studies is to better understand the occurrence of decay so infected trees can be better managed and preserved. Improving the interpretation and utilization of tomograms have been other main objectives. Additionally, Brazee uses tomography to assist arborists performing tree risk assessments in urban and suburban settings. This service is provided through the UMass Plant Diagnostic Laboratory, which provides disease and insect diagnostic support for green industry professionals throughout the region.
Dr. Brian Kane's research focus in arboricultural biomechanics
In 2019, Dr. Brian Kane received a grant from the Florida Chapter of the International Society of Arboriculture to study the effects of installing support systems (cables and brace rods) on how trees sway. We conducted the study in the Kane Lab research plot next to the Utility Arboretum. The study involved installing cables or rods in two species in the plot—littleleaf linden and Princeton elm. Some trees of each species were left as control trees and no support system was installed. Over the course of three years, we’ve measured how much the trees move when pulled from vertical—this gives us a sense of whether the cable or brace rod supports the weak union between co-dominant stems. We’ve also measured how fast the stems sway and how soon they stop swaying. The latter two measurements are important because they help us understand whether the cable will support the tree under dynamic loading of the wind. Graduate students Amanda Halperin and Stella Dee helped collect data. Dr. Kane’s position at UMass is supported in part by an endowment from the Massachusetts Arborists Association.
Stella Dee awarded research grant to study the mechanical and physiological effects of pruning trees
In 2022, Stella Dee, a current Ph.D. student in Environmental Conservation supervised by Dr. Brian Kane, was awarded a TreeFund Hyland R. Johns Grant to research the mechanical and physiological effects of pruning trees in the Kane Lab Research Plot. This grant supported an experiment in which Stella pruned three species of tree in six different ways, with different intensities and locations of cuts. Stella is measuring the changes in mechanical behavior of the trees before and after pruning, as indicated by natural frequency and damping ratio, to get a sense of how these differing pruning styles may or may not affect the behavior of trees in wind and their likelihood of failure. She is using invertebrate traps to assess the changes in herbivory caused by pruning, as well as assessing the difference in leaf area index between pruned and unpruned trees. In collaboration with Thomas Vitalis, a Ph.D. candidate in Structural Engineering and Mechanics, she is also comparing the baseline strength of wood in two species of tree, as well as how this varies between trees and along branches. Stella hopes that once published, her work will help commercial and municipal arborists better understand the mechanical and ecological consequences of their pruning decisions. Stella and her research are additionally supported by the Dr. Malcolm A. McKenzie Scholarship from the Massachusetts Tree Wardens and Foresters Association, the New England Chapter of the International Society of Arboriculture, and The Garden Club of America Zone VI Fellowship in Urban Forestry, as well as undergraduate research assistants including Jeffrey DuFour, Athena Vasilopoulos, Hannah Bruno, and Lilly Reeves.