Canadian Forest Service Publications
Production of an Individual Tree Species Map for Forest Inventory in a Complex Forest Setting and Lessons Learned . 2017. Leckie,D.G.; Gougeon,F.; McQueen, R.; Oddleifson, K.; Hughes, N.; Walsworth, N.; Gray, S. Canadian Journal of Remote Sensing, 43:2, 140-167.
Year: 2017
Issued by: Pacific Forestry Centre
Catalog ID: 39053
Language: English
Availability: PDF (request by e-mail)
Available from the Journal's Web site. †
DOI: 10.1080/07038992.2017.1286974
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Abstract
A large-area trial of automated individual tree crown isolation and species classification on a 228-km2 site in central-eastern Ontario using 40 cm multispectral imagery gave insight into the complications and effectiveness of such approaches when applied to a complex mixed forest setting. Tree isolation was reasonably effective with few omissions and 77% of automated tree isolations (isols) were considered a good correspondence to ground truth delineations. There were issues with grouping several trees within 1 delineation, poor isols at the edges of stands and minor splitting (multiple isols per tree). Spectral characteristics of 18 species indicated considerable variability within species and overlap of signatures. To circumvent this, several spectral subclasses were created for certain species and the site was divided into broad and localized zones, which for ecological reasons had a reduced number of species. Mapping accuracy and classification accuracy of manually delineated trees for a main classification zone of 14 species, both typically ranged from 40% to 85%. For a simpler zone of 8 species, manual tree class accuracy averaged 76%. Possible improvements are discussed. Regardless of sophistication of techniques used, production of individual tree species maps in complex forests will require judicious use of human judgment and intervention.
Plain Language Summary
Six million automated tree delineations were identified and their species classified for the Petawawa Research Forest (PRF) of the Canadian Forest Service and its surrounds using operational high resolution multispectral imagery provided by the Ontario Ministry of Natural Resources and Forests. This produced an individual tree crown inventory map that can contribute to an enhanced forest inventory and used to help make forest management decisions and change the usual stand based management paradigm to one that utilizes more detailed spatial information. The Individual Tree Crown (ITC) Software Suite of the CFS was used as the primary tool. The PRF forest is complex and new techniques were developed to deal with the many species, the mixtures of species, height and density structures, and use mosaicked imagery from several flight lines. 77% of the tree isolations were of good quality and there were few omissions, however the product suffered somewhat from cases of multiple trees per delineation and poor delineations at open edges of stands. Species accuracy was in the range of 40-85% for 14 species, with better accuracies for the softwoods. For simpler areas with 8 species, accuracy averaged 76%. Accuracies were in keeping with that of current forest inventories.
