Canadian Forest Service Publications
Preliminary assessment of Phellinus weirii-infected (laminated root rot) trees with high resolution CASI imagery. 1999. Leckie, D.G.; Jay, C.; Paradine, D.; Sturrock, R.N. Pages 187-195 in D.A. Hill and D.G. Leckie, Editors. International forum: automated interpretation of high spatial resolution digital imagery for forestry, Proceedings: Symposium. February 10-12, 1998, Victoria, British Columbia. Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre, Victoria, BC.
Issued by: Pacific Forestry Centre
Catalog ID: 5181
CFS Availability: PDF (download)
Root diseases caused by several endemic fungi are economically and ecologically important disturbance agents in the forests of western North America. Laminated root rot (Phellinus weirii) has particularly important impact in coastal Douglas-fir stands. Forest managers would like an economical survey procedure for detecting pockets of Phellinus weirii infected trees for the purpose of salvage, remedial activities and inventory. Aerial survey with multispectral imagers such as casi, coupled with automated detection of damaged trees may provide a cost-effective survey method. Casi imagery in eight spectral bands has been corrected to an orthoimage and radiometric corrections for the effects of illumination and view angle applied. Trees of varying levels of root rot symptoms were assessed in the field and related to delineated trees on the imagery. Visual symptoms on the ground ranged from subtle crown shape and growth rate changes, through gradual needle loss, to mortality. Chlorosis occurred on some trees. Preliminary analysis, including classification and regression analyses of symptom classes or levels, indicates that light crown symptoms will be difficult to consistently detect. However, moderate and severe damage including needle loss (e.g., > 25%) does appear to be detectable. Isolated trees of similar characteristics as root rot infected trees do appear on the imagery in scattered locations unrelated to root rot activity. It is anticipated that these false alarms can be largely mitigated by identifying the characteristic pattern of root rot damaged trees (i.e., stressed trees around a centre, the centre often being a hole or gap in the canopy).