Why so different? Examining the methodologies used in two oldgrowth forest mapping projects
Norheim, R.A.
Geoscience and Remote Sensing Symposium Proceedings, 1998. IGARSS apos;98. 1998 IEEE International
Volume 3, Issue , 6-10 Jul 1998 Page(s):1620 - 1622 vol.3
Digital Object Identifier 10.1109/IGARSS.1998.691647
Summary:In 1990, two different projects simultaneously mapped old growth
in National Forests in the northern spotted owl region in the Pacific
Northwest. The two projects used significantly different technology and
techniques, and found amounts of old growth acreage that differed by a
factor of two. This paper investigates the procedures used in each
project to determine the sources of the differing results, using four of
the forests mapped as a case study. The project carried out by Pacific
Meridian Resources (PMR) for the U.S. Forest Service (USFS) used Landsat
TM imagery and sophisticated image processing techniques, whereas The
Wilderness Society project relied primarily on photo-interpretation but
also used Landsat MSS imagery. The USFS project quantitatively mapped
different size and structure classes, but The Wilderness Society's
project attempted to qualitatively categorize several variations of old
growth. The projects operated under tremendous deadline pressure, had
vastly different budgets, used very different hardware and software
systems and had very different techniques for ground truth and accuracy
assessment. Thus, despite the fact that their goals were identical these
factors caused significantly different results
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