Forest condition assessments and other applications of colour infrared (CIR) aerial photography in Ireland.

Abstract

Colour infrared (CIR) aerial photography is a long-established tool for monitoring forest health and condition in Central Europe. Before this technique could be used to classify forest health on a large scale in Ireland, it was necessary to develop photo-interpretation keys for Sitka spruce (Picea sitchensis (Bong.) Carr.) and lodgepole pine (Pinus contorta Dougl.). These were completed as part of an EU-wide programme for investigating methods of monitoring forest condition. With these keys, a trained operator can accurately classify the damage to individual tree crowns in terms of defoliation and discoloration, based entirely on their appearance on CIR aerial photographs. A number of important practical applications of this technique are demonstrated and discussed. These include national and regional forest condition inventories that were carried out using the interpretation keys. CIR aerial photography was successfully used to detect nutrient deficient forest stands on peat sites in midland areas of Ireland, and to monitor the subsequent response of these areas to fertilizer application. The phenomenon of top dying of Norway spruce (P. abies (L.) Karst.) was also successfully detected and the extent of damage zoned using this resource. Information on the habit of top dying was gathered from these aerial photographs and this is discussed. Other applications for CIR aerial photography have also been studied and these are briefly described.