Advanced Tree Assessment

Steffen RUST

Institution: HAWK University of Applied Sciences and Arts – Germany

Contact: steffen.rust@hawk.de

Keywords: Tree Assessment, Tomography, Ground-Penetrating Radar, Static Load Tests

Methods and devices for the non-destructive assessment of urban trees have developed rapidly in recent years. I am proposing a practical, hands-on session with static load tests, sonic and electrical resistivity tomography and geo-radar on the site of the conference.

Comparison of two methods to assess the vitality of old trees – a test on beech and sycamore maple

Steffen RUST

Institution: HAWK University of Applied Sciences and Arts – Germany

Contact: steffen.rust@hawk.de

Keywords: Vitality Assessment, Old Trees, Tree Inventory

Vitality assessment is a key element of urban tree management. However, it is less well understood than often assumed. After a review of current research, two controversial methods are compared in an experiment.

Vitality of trees is often defined in relation to survival, growth, or response to stress. A wide range of methods is used to assess vitality, often based on crown architecture, crown condition, or epicormic growth. This study applies two methods to assess old Fagus sylvatica and Acer pseudoplatanus and compares the results quantitatively. One method is based on the architecture of the upper part of the crown, the other uses a wide range of parameters, most of them related to the trunk. Both use an ordinal scale ranging from 0 (best) to 3 (worst).

Both methods were applied equally fast, and their results were statistically highly significantly correlated, albeit with large scatter. Vitality based on crown architecture was on average 1.5 grades worse and explained a third of the variation of the other method.

Crown architecture should remain the basis of vitality assessment, because it is easy to learn, repeatable and based on a physiological model. In old trees, where the growth of crown and trunk can be de-coupled, a low vitality score should be adjusted when the trunk shows signs of vigorous growth.