OVERVIEW OF THERMAL IMAGING FOR TREE ASSESSMENT

Abstract

Summary The value of thermography for trees is reviewed in relation to the needs of inspectors and diagnosticians in the fields of forestry, arboriculture and veteran tree management. Images obtained with an infrared camera allow the early detection of various kinds of alteration in trees, including bark necrosis, decay and the onset of adaptive growth in response to damage or mechanical stress. Advantages include total non-invasiveness, rapidity of use, the provision of ‘real-time’ information and the ability to work at a distance of as much as 25 m. In order to assess trees, however, the surfaces must be out of direct sunlight, free from running water and unobscured. The images do not distinguish between different kinds of alteration automatically, but they can usually be correctly interpreted in the light of appropriate knowledge and experience. The technique does not allow a truly quantitative assessment of the relative extent of decayed and sound wood, but it appears to be accurate enough to identify trees which merit either remedial action or more precise assessment.