University of Washington Department of Geography

and

USGS Forest and Rangeland Ecosystem Science Center

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University of Washington

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email: norheim@u.washington.edu

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Keywords: REMOTELY-SENSED DATA, CLASSIFICATION ACCURACY,

NATIONAL FOREST, OLD-GROWTH FOREST, INSTITUTIONAL CONTEXT

Institutional and geographic factors affected the outcome of two old-growth forest mapping efforts undertaken in 1989-90 in the Pacific Northwest of the USA. The two projects, by the U.S. Forest Service and The Wilderness Society, obtained very different results, despite their identical goal of mapping old growth. Differences can be attributed at least in part to the organizational constraints of each project, particularly factors such as deadline pressure, budgets, staffing, and technology employed. This analysis of four of the national forests indicates that the two projects did not even map the same areas, and that the two studies are in even worse disagreement when only areas mapped by both are compared. It is inappropriate to infer that the results of either project are better or more ‘correct’. However, it is critical to understand the causes of the disparate project results, so that the datasets can be used in appropriate scientific and social contexts.

This paper has not been submitted elsewhere for publication.

In 1990, two different projects were conducted to map old-growth forests in the Pacific Northwest of the USA. The projects had many similarities. Both used the same ecological definition of old growth forest. Both intended to map the same National Forests. Both used remote-sensing data and GIS. Both used source data from the same time period, were conducted simultaneously, and took about the same amount of time. Despite these similarities, the two studies produced very different results. The United States Department of Agriculture Forest Service (USFS) reported a total of 1.5 million hectares based on their project, while The Wilderness Society reported only 0.8 million hectares. How could two such apparently similar projects disagree by nearly a factor of two? This paper examines the institutional context of each of the projects, how that context affected the way the projects were conducted, and implications for the geographic results.

The relationship between GIS and the context in which it is practiced has become a prominent research theme. Recent initiatives by the National Center for Geographic Information and Analysis , and the University Consortium for Geographic Information Science have promoted this line of research. The topic is the subject of a recent edited volume and special journal issue , and is an organizing principle for a recent GIS textbook .

Much of this research examines how GIS affects the society around it. However, the interaction works in the reverse direction as well as Chrisman convincingly points out. Both institutional and cultural contexts can affect the practice of GIS . The political nature of an institution — and its budget — can affect staffing, technology, and schedules. Outside pressures on an institution also can have effects. For example, two investigations of the procedures surrounding the siting of low-level radioactive waste disposal sites demonstrate that political pressure can have significant influence over how the GIS operations in the siting projects are carried out . A comparison of two local government agencies in two different countries reveals how the differing political natures of the organizations create significant differences in how they manage their GIS . All of these factors can directly affect the technical decisions made in pursuing a project . The term ‘cultural context’ often means a national or indigenous culture . However, it can also refer to a professional culture , such as the different ways that foresters, ecologists, and environmentalists construct and interpret forestland. Six different agencies have responsibility for mapping wetlands in the US, and each has their own goals for mapping, which can create significant differences in the results . Such differences can come to a head when compared objectively in a GIS; as Campari and Frank note ‘GIS . . . hits problems of cultural differences squarely’.

In practice, it is often difficult to isolate the effects of varying institutional and cultural contexts on projects, because most projects are conducted singly and are unique. With the two old-growth mapping projects, however, we have a pair of projects that are very similar in their goals, timing, spatial extent, and tools. Thus, we are able to focus more directly on those aspects of the projects that are different, i.e. the institutional and cultural context in which they were conducted.

The two projects were undertaken in 1989-90 during the height of the controversy surrounding the protection of northern spotted owl (Strix occidentalis subsp. caurina) populations. This species was first identified as dependent on old growth in 1972. The Forest Service had an ambitious schedule for harvesting old growth, and planned to log most of the old-growth forest on public lands over the following decades, which would have endangered the long-term viability of owl populations. However, because the US Fish and Wildlife Service had not yet officially listed the owl as an endangered species, the Forest Service was not required to make any provision to protect it, and thus continued its harvest program. Over the next 16 years, Forest Service management often avoided the owl issue, despite the efforts of biologists and conservation groups, until the Forest Service was ordered in 1984 to produce an Environmental Impact Statement (EIS) on owl management. The EIS was not produced until 1988. By this time, biologists had determined that each owl required a large tract of old-growth habitat (approx. 400 ha) . However, the Forest Service had now harvested so much old growth, and residual old-growth stands were so fragmented, that it was clear that the habitat requirements of the owl were likely to cause it to be listed as an endangered species .

Conservation organizations contended that the Forest Service did not actually know how much old growth still existed on the national forests and maintained that an accurate figure was needed in order to assess management impacts. The agency traditionally used a figure of 2.5 million hectares , p. 551). However, this figure relied on data that dated back to the early 1970s and were not completely corrected for subsequent harvest and fire damage. Also, the agency did not perform inventories in areas that were protected from timber harvesting, such as designated wilderness. Furthermore, there was not a consistent definition for old growth, because some national forests used a strict ecological definition and others used definitions based mainly on timber values. The Wilderness Society conducted a project that used the Forest Service’s inventory, harvest, and fire data to apply a strict ecological definition across six national forests. The project estimated that less than half the land area that the Forest Service claimed to be old growth really was old growth .

In 1988, upon seeing the discrepancies revealed by this study, Congress directed the Forest Service to inventory and map its old-growth forest, and gave them two years to complete the work. The Forest Service hired Pacific Meridian Resources (PMR), which had an established relationship with the agency, to complete the work. Not trusting the Forest Service to perform the work correctly, and wanting its own dataset for use in advocacy activities, The Wilderness Society initiated its own mapping project at the same time. Thus, the stage was set for comparisons to be made between the two projects.

The Forest Service is a unique and much-studied agency in the U.S. federal government . One of its most remarkable qualities is the acculturation process experienced by many of its employees. While the agency is decentralized, there are strong lines of authority and organizational mores. Frequent transfers result in many employees identifying more with the agency than with their local community; nation-wide standard policies and procedures facilitate these transfers. Internal promotion is the norm throughout the agency, and following established agency procedures and meeting timber quotas typically enhances an individual’s professional status. There has traditionally been a strong loyalty to the organization. By the time employees are promoted to positions with decision-making authority, they generally are sufficiently indoctrinated in agency traditions that they are likely to make decisions favored by the agency. Forest Service employees strongly believe in their mission of stewardship and their ability to carry it out .

Despite the commitment of the Forest Service to ‘multiple use’ of natural resources, timber harvesting has been a dominant use since the 1950s, when Congress ordered the agency to provide a large supply of inexpensive lumber for home building and other construction activities. Timber harvest goals were continually raised above what had previously been considered a maximum allowable cut, with the belief that improving technology would lead to higher yields demanded of the agency. District Rangers, subscribing to the ‘can-do’ nature of the organization, typically did not question the harvest goals, and often believed that improved technology would indeed allow them to meet their goals without sacrificing the health of the land. Congress also participated in the self-delusion, and typically provided adequate funding for timber management but not for reforestation, watershed, wildlife, and recreation activities.

It is relatively easy to characterize the behavior of the agency regarding the spotted owl in light of the preceding discussion. The ability of the Forest Service to maneuver was constrained by the traditional role that the agency assumed, that of the wise manager of the land. The agency tried to respond pressures to protect the owl by manipulating timber outputs. Proposed special set-asides of land to be preserved for owl habitat were denigrated by the agency as being ‘single use’ instead of ‘multiple use’. However, events outside the Forest Service changed so quickly that the agency could not adapt. The agency had no institutional basis for understanding the increasing value that the public was placing on their national forests and the wildlife that lived in them.

The owl controversy caused problems within the agency as well, as wildlife biologists ultimately gained a much larger voice than they had ever experienced in the agency. Timber management personnel often felt threatened by lower timber sales, which would affect agency budgets and staff, and by criticism of their ability to solve the problem. However, the agency’s stifling of internal criticism and failure to incorporate biological information discouraged a faster and more innovative approach to the owl issue.

The Wilderness Society has cultivated a careful image for itself and has traditionally focused on public land stewardship. The Society first advocated the passage of the Wilderness Act of 1964, and then advocated the designation of wilderness areas under the act. While the Society continues to press for more wilderness, it also advocates responsible management of all public lands, including the national forests. Due to the owl issue, old-growth logging in the Northwest was singled out for particular attention. The Society has also built up a reputation for careful ecological research, and has published many well-regarded books, reports, and papers. This research focus led to the Society hiring Peter Morrison to undertake the old-growth inventory work mentioned above, and then to begin its own old-growth mapping project.

Large environmental organizations such as the Society have been criticized for becoming part of the establishment, and become too willing to compromise. The charges seem to ring true, because even during the spotted owl controversy, some conservation groups avoided battles when the timing seemed wrong. Critics also argued that many of the national organizations are more interested in their own self-perpetuation than in their role as advocates. Indeed, Morrison mentioned that, while the Society used his project’s results very successfully for fund-raising, he saw little of the money returned to his budget for improvement of project resources.

Old-growth definitions were a key institutional factor for both projects. As mentioned earlier, the various national forests used a variety of definitions for inventorying old growth in the national forest management plans that were developed in the mid 1980s. These two mapping projects adopted the same definition, one based on ecological characteristics. This definition, known as ‘PNW-447’, specified a number of criteria that a stand must meet to qualify as old growth, including size, density, age, number of snags and downed logs, structure of the canopy, and species mix .

However, even though both projects used PNW-447 as their old-growth definition, they implemented the definition differently. A major difficulty for both projects was that not all of the components of the definition – in particular, snags and downed logs – can be ascertained by the remote-sensing devices employed by the projects. Thus, the definition used by PMR for the USFS project simply specifies that a stand must be multi-storied and have a minimum crown closure among trees of a certain size (dependent on elevation and latitude), and be a minimum of four hectares to be considered as old growth.

It is also worth noting that the first set of maps that PMR delivered to the USFS had the title Potential Old Growth Map , suggesting that PMR felt that the stands identified by their methodology were likely, but not certain, to be old growth. The Forest Service insisted that the term ‘potential’ be dropped from the title of the maps presented to Congress and the public .

The Wilderness Society’s use of the definition is more complicated. The Society mapped what it called ‘ancient forest’, rather than ‘old growth’. ‘Ancient forest’ consists of three categories: true old growth (meeting the PNW-447 definition), high-elevation ancient forest (old growth at higher elevations), and ‘other ancient forest’ (consisting of stands that meet only some of the characteristics of old growth). The Society’s project used a stand size of about two hectares in the photo-interpreted forests and one 80-m square Landsat Multi-Spectral Scanner (MSS) pixel (0.64 hectare) in the forests mapped using satellite imagery.

PMR used an innovative and rigorous technique of interpreting Landsat tm imagery to conduct its mapping project. Specifics about the techniques are available in a variety of sources .

The technique involved several stages. During the image classification stage, PMR used both supervised and unsupervised classifications and merged the results using cluster analysis. PMR then manually compared the resulting classified image to aerial photographs, plot data, and other similar data. The manual editing corrected about 15% of the pixels. The procedure was repeated four times to produce four pixel maps: species, canopy structure, size, and crown closure.

The next stage was polygon creation. Because USFS personnel were familiar with maps that were products of photo interpretation, i.e. maps that had vegetation polygons, the deliverables for the project were not raster maps but rather polygon maps. PMR used decision rules similar to those used by photo interpreters to create polygons from the classified pixels. As part of the process, agency personnel reviewed several such methods designed by PMR and selected the method that best suited their needs.

The crown-closure pixel map was processed first. The map was scanned using two different neighborhood algorithms to smooth the data into polygons. For each crown-closure polygon, structure pixels were scanned to produce sub-polygons of homogeneous crown closure and structure. The procedure was then repeated for size-class pixels, creating homogeneous polygons of crown closure, size, and structure. The species pixels were grouped together into classes of like species using USFS classifications, then the grouped species were scanned, converted to polygons, and overlaid on the first set of polygons. Density operations were also used throughout this process to determine a threshold for homogeneous versus heterogeneous areas.

Lastly, PMR used several methods to check the resulting polygon maps for accuracy. Draft maps were distributed to USFS personnel for review. Also, both guided and random approaches were used to compare subsets of the draft maps to photo-interpretation.

All the raster processing was performed in ERDAS Imagine on Sun workstations. The polygons were created by conversion to GRID and then Arc. SAS was used for the cluster analysis, and Oracle was used for some database work.

The Wilderness Society project can be broken into two stages. The first four forests were mapped by photo-interpretation, and the remaining eight were mapped using Landsat imagery . Work on the first forest, the Olympic (in Washington State), took over one year. Morrison felt it important to map past as well as current forest conditions, to determine how the forest had changed over time. Thus, four sets of photographs were photo-interpreted, from 1940, 1962, 1980, and 1982. Morrison selected ‘reference stands’ that represented each of the classes that were being mapped. Two photo-interpreters each interpreted every quadrangle on the forest, comparing each stand to the nearest corresponding reference stand, and Morrison checked each quadrangle as well. Morrison used a 1988 Landsat MSS image only to determine which areas had been logged since 1982.

A variety of software was used in the process. Volunteers digitized the interpreted stands in Atlas-Draw. From Atlas-Draw, the polygons were transferred to workstation Arc/INFO and rasterized in GRID at the Washington State Department of Wildlife. These coverages were transferred to PC-Arc/INFO and EPPL7 on a 386 PC at the Society’s Seattle office. Morrison used ERDAS to perform the classification of the Landsat image.

The Society was quite pleased with the results of Morrison’s work on Olympic National Forest, but they were not pleased with the time that it took or the amount that it cost. The spotted owl was proposed as a candidate for listing under the Endangered Species Act the month after the results of the Olympic study were released, and a final decision was due within a year. The Society needed to know how much old growth was left and where it was in 11 more forests, but they were not interested in the historical reconstruction. Therefore, they asked Morrison to make faster progress.

Under pressure from the national office to complete the work, Morrison took more and more shortcuts in photo-interpretation techniques on the next three forests, feeling that accuracy was suffering as a result. Only one year’s worth of photos was examined. Only the Mt. Hood National Forest was dual-photo-interpreted; Gifford Pinchot National Forest and the Mt. Baker-Snoqualmie National Forest (MBS) were examined by only one interpreter, plus checking by Morrison. The amount of field verification was very limited and focused on ambiguous areas.

With continued pressure to get work completed even more quickly, Morrison used Landsat MSS data for all of the work inventorying old growth on the remaining eight forests. He used ERDAS to do a stratified, unsupervised classification for these forests, using orthophotos and aerial photos to check the classification. The images were topographically normalized. Also, Morrison did not map ‘old growth’ separately from ‘other ancient forest’ for these forests, but instead simply mapped low- and high-elevation ancient forest. The last forest on which Morrison’s team worked (the Siuslaw National Forest in Oregon State) lacked topographic correction of the Landsat image due to a shortage of time. Morrison (an ex-Forest Service seasonal employee) used many Forest Service records, such as inventories and field plots. He also tried to involve agency field staff in accuracy checking his project, but said that the Forest Service Pacific Northwest regional office set up an antagonistic atmosphere and refused to co-operate with him.

A companion paper contains a more detailed description and comparison of the techniques of the two projects.

Because the Wilderness Society project mapped ‘old growth’ as a subset of ‘ancient forest’ for only the four forests that were photo-interpreted, a direct comparison between the two projects is possible only for those four forests. For the other forests, only the Wilderness Society project’s larger category of ‘ancient forest’ can be compared to the USFS/PMR old-growth figures. However, based on his earlier inventory work and the four forests studied in more detail, the Wilderness Society project did publish estimates of old growth for the other forests, aggregated to totals by state.

The two studies also differ in how they classify high elevation forests. The USFS/PMR project considered this category to be old growth, whereas the Wilderness Society project considered it to be ancient forest but not old growth. This approach has some justification given that the spotted owl generally does not live at higher elevations, and that the underlying purpose of the studies was to determine suitable habitat for spotted owls.

The charge from Congress to the Forest Service for this project was to develop old-growth maps for those national forests in the Pacific Northwest region that are west of the Cascade Range crest. This includes portions of nine national forests in Oregon and Washington (two of the forests extend slightly into California). The Wilderness Society project mapped all forests that included spotted owl habitat, which includes the same nine forests as the Forest Service plus three more in California. Although both projects ostensibly mapped the same nine forests, they actually did not map the same areas within those forests.

For example, several portions of the MBS are administered by other national forests (Figure 1, Table 1), labeled A, B and C. Area A lies between the North Cascades National Park Service Complex and the Cascade crest, and was severed from the rest of the MBS when the park complex was designated. Because it is contiguous with the Okanogan National Forest and because much of the area is in the Pasayten Wilderness that also extends into the Okanogan National Forest, the area is administered by the Okanogan. This area was mapped in the USFS/PMR project, but not by the Wilderness Society project (perhaps because much of it is already protected in designated wilderness). Similarly, Area B consists of two tracts that are administered by the Gifford Pinchot National Forest. Area B was included in the Gifford Pinchot National Forest by the Wilderness Society project, but the USFS/PMR team mapped it with the rest of the MBS. For the purposes of this study, Area B is included in the figures for the Gifford Pinchot National Forest only.

Three areas east of the Cascade crest were also treated differently by the two projects. Area C is a portion of the MBS administered by the Wenatchee National Forest. Neither project mapped the area. Like area A, over half of this area is already protected by wilderness designation and so would be of less interest for the purposes of The Wilderness Society.

However, the other two areas east of the Cascade crest, portions of the Gifford Pinchot and Mt. Hood National Forests (areas D and E), have no administrative complications. These areas were not mapped by the USFS/PMR project, but were mapped by the Wilderness Society project. Because the boundary of these national forests is not at the crest (as it is in most other parts of the project area), the USFS/PMR project used county lines (usually coincident with the crest) as a boundary.

It should be noted that in all cases the Forest Service project followed a consistent definition of the areas mapped: those portions of national forests in Region 6 that are west of the Cascade crest. In contrast, the Wilderness Society project usually (but not always) followed the boundaries of the administering forest. There are also some ownership discrepancies that involve border adjustments and inholdings. The two projects did not have identical boundary coverages for some of the forests.

To overcome the problems described above, both of the datasets were modified and put into a format in which they could be directly compared. All of the geographic discrepancies mentioned above are accounted for. Also, only the forests that the Wilderness Society project mapped using photo-interpretation (Olympic, MBS, Gifford Pinchot, and Mt. Hood National Forests)—where old growth is identified as a separate category—are compared. Because the USFS/PMR project identified far more old growth than the Wilderness Society project did, and because PMR was initially identifying ‘potential old growth’, this analysis compares the USFS/PMR project’s ‘old growth’ category to both The Wilderness Society’s overall ‘ancient forest’ and more specific ‘old growth’ categories.

Table 2 shows the amounts of old growth (USFS/PMR) and ancient forest (Wilderness Society) that were originally published by the two projects, and the amounts that resulted from correction of the geographic discrepancies described above. The corrections for the different geographic extents of the two projects resulted in some significant changes in the comparison. In particular, the removal from the comparison of the ancient forest that the Wilderness Society project found east of the Cascade crest on the Mt. Hood and Gifford Pinchot National Forests (areas D and E) caused the two project results to be in greater disagreement.

Once these discrepancies were accounted for, we overlaid the results of the two projects and compared how well their identification of the various categories matched. Figure 2 is a map of a portion of the MBS, showing the pattern of disagreement between the two projects. This pattern (or lack thereof) shown in this region is typical of the entire study area. Maps of each National Forest in their entirety are available on a companion web site (see further information, below).

Confusion matrices, or misclassification matrices, for each of the four forests, show the full comparison amongst the different categories mapped (Table 3). The results for the four forests are all quite different, although some trends are evident. Eight to twelve percent of each forest is classified by both studies as low-elevation old growth. On the other hand, the amount of forest that both agree is not old growth or ancient forest ranges from 40 to 62 percent. The USFS/PMR project classified 69 to 75 percent of the Wilderness Society project’s low-elevation old growth also as old growth (upper left cell as percentage of first column, also Table 4(a)). However, given that the USFS/PMR project reported higher land area of old growth for each National Forest than did The Wilderness Society, it is surprising that the latter is not closer to being a proper subset of the former. One might at least have expected a higher rate of agreement on forests where the USFS/PMR project found significantly more old growth than The Wilderness Society did, but this is not the case.

One also might expect that the USFS/PMR project would classify less of the Wilderness Society project’s other ancient forest category as old growth than of the Wilderness Society project’s old growth category, given the looser definition the latter project applied to the ‘other’ category. If both projects were truly working from the same definition, then the Wilderness Society project’s ‘other’ category should not be classified as old growth by the USFS/PMR project. On the other hand, given the larger amount of old growth that the USFS/PMR project found on each forest, one would think that the Wilderness Society project’s ‘other’ category would typically be classified by the USFS/PMR project as old growth. Indeed, the USFS/PMR project classified 68 to 70 percent of the ‘other ancient forest’ as old growth on the Gifford Pinchot and Mt. Hood National Forests, very similar to the agreement rate on low-elevation old growth. However, the equivalent rates on the Olympic National Forest and MBS are only 35 and 50 percent, respectively. This discrepancy is difficult to interpret; the USFS/PMR project’s classification of the ‘other’ stands should not vary across forests. However, given that the Wilderness Society project actually found more ancient forest on the Olympic than the USFS/PMR project found old growth, the 35 percent rate of agreement on ‘other’ is less surprising.

The comparison shows that the USFS/PMR project found significant amounts of old growth not found by the Wilderness Society project, not a surprising conclusion given the discrepancies between the two studies. For low-elevation old growth, about 25% of forest classified as old growth by the USFS/PMR project was found to not be ancient forest by the Wilderness Society project on the Olympic National Forest and MBS. On the Gifford Pinchot and Mt. Hood National Forests, where the overall area found by the USFS/PMR project is significantly higher than The Wilderness Society’s figures, this proportion rises to over one half.

Table 4 collapses the larger confusion matrices into a more direct comparison of the USFS/PMR project’s old-growth category to the Wilderness Society project’s old-growth and ancient forest categories, with a comparison between low-elevation old-growth categories in the two studies. The first two columns give total low-elevation old-growth area in the two studies, and the third column shows the area that both studies agreed were low-elevation old growth. The last two columns indicate what proportion of the total area found by each study is in the area of agreement. Table 4(b) shows a similar comparison between the USFS/PMR project’s ‘old growth’ category and The Wilderness Society project’s less restrictive ‘ancient forest’ category. However, even given the looser definition, the results still do not compare favorably or consistently.

Thus, there are few trends evident across the four national forests. Similarly, an examination of maps from the overlays reveals few trends that one can attribute to geography. An attempt to further characterize the disagreement in the two projects, using the methods of Chrisman and Lester , also was not able to detect any regularity in how the projects differed . It is interesting, and perhaps troubling, that there is so little consistency in how the two projects compare.

Several factors had major effects on how the two projects were conducted. The short timeline is perhaps the most important constraint. Both organizations needed to have their projects finished in order for the data to be useful in the debate surrounding the spotted owl, which was coming to a climax in 1991. But two years is a very tight deadline to perform an inventory of such a large area. This is most clearly seen in the Wilderness Society project in which the methodology changed significantly as the Society pressed for quicker results.

The Forest Service, too, was reluctant to switch from photo-interpretation to remote sensing, but was forced to change for this project. Nevertheless, they still required PMR to deliver products that mimicked photo-interpretation. The short schedule imposed by Congress also compelled the agency to develop a sole-source contract with PMR, rather than get competitive bids. The Forest Service also split the contract with PMR into two stages. The first stage was to map old growth; the second was to map all vegetation types. It is likely that the results from mapping old growth in a more holistic context of all vegetation types were likely to have been more accurate.

However, it should be noted once again that the frenzied schedule of both projects was a result of the Forest Service's refusal for many years to perform a comprehensive, reliable, and uniform inventory, which in turn was a result of its organizational culture.

The two projects had very different budgets. The Forest Service effort was well funded by Congress, and the agency purchased Landsat TM imagery and hired a consulting firm that had state-of-the-art software and hardware and a well-educated staff. The Wilderness Society project had to rely on poorer resolution Landsat MSS imagery, had a donated 386 PC, patched together various software systems, and had a much smaller staff that included a large number of volunteers.

The differences in the areas mapped also reflect the institutions that backed the projects. The Forest Service mapped only those areas specifically directed by Congress, i.e. areas in the Pacific Northwest Region west of the Cascade crest, although the spotted owl lived in neighboring forests in California and east of the Cascade crest. Thus, the Forest Service did only what was required and no more, similar to its earlier approaches to handling the spotted owl.

The Wilderness Society mapped areas where it felt there was unprotected old growth, including areas in California that fell outside the Pacific Northwest Region and areas east of the Cascade crest. On the other hand, the Society’s project did not map non-contiguous areas of the MBS that are west of the crest but which are already mostly protected wilderness. The Society’s motivation was to find where there was unprotected old growth, so that they could advocate for preservation. Thus, they resisted Morrison’s attempts to widen the scope of the analysis to historical patterns. It is ironic that the maps that are most powerful and most often reproduced are those of the change of the amount of old growth on the Olympic National Forest over time, the one forest where Morrison was able to carry out that research. Perhaps the implicit goal of the Society was to not allow the Forest Service results to exist in a vacuum and be accepted without question. Providing alternative maps would raise questions raised about the accuracy of the Forest Service maps. While there would also be doubts about The Wilderness Society’s maps because of the differences between them, the Society needed only to cast doubt on the Forest Service maps to make its point.

The insistence by the Forest Service that the term ‘potential’ be dropped from PMR’s maps is worth mentioning again. This is a clear imposition of institutional biases on what was ostensibly an objective study. It was in the interests of the Forest Service to identify as much old growth as possible, and not to confuse the issue with words like ‘potential’. The more old growth found, the more reliable the agency’s earlier estimates would appear and the less credible the criticism of the environmental organizations would be. Also, the more old growth found, the more would be available for allocation between ecosystem protection and the agency’s traditional timber management objective.

Our analysis demonstrates that the respective institutional cultures of the Forest Service and The Wilderness Society had significant effects on the way that the two projects were conducted. In addition, several forces outside these two institutions (including the judicial system and Congress) also influenced the projects. The lack of any evident patterns when comparing the two datasets leads one to suspect that there was a significant amount of inconsistency in the way one or both projects were carried out. While the techniques used by the Wilderness Society project clearly changed over time, the USFS/PMR project also had the opportunity to modify and refine their procedures. However, an independent accuracy assessment would be necessary to identify one or the other as inconsistent.

Regardless of the accuracy of the studies, we have identified several institutional factors that affected the project's outputs, namely budget, technology, staffing, study area, and institutional agendas and requirements. It is hoped that an understanding of these factors will help users of the two datasets understand the biases inherent in them. It is worth noting, however, that despite its much smaller budget, many ecologists and GIS analysts, including Forest Service employees, consider Morrison’s work for The Wilderness Society to be as good as or superior to PMR’s work for the Forest Service .

Were the goals of either project realistic? Is it truly possible to split out old-growth forest precisely from all other forest types in the continuum of forest succession? It could well be that both projects are correct. In fact, both probably are correct, within their own institutional context, and it may be unrealistic to expect that GIS and remote-sensing technology can develop the absolute and unbiased answers that society expects to questions that are inherently subjective.

Further results of the direct overlay between the two projects, more detailed confusion matrices and color maps of each forest, details of geographic discrepancies, and other results from this work are available on the World-Wide Web at http://purl.oclc.org/net/norheim/oldgrowth.

I thank Nick Chrisman for encouraging me to work on this project and for his support in seeing it to completion. Dave Peterson also provided valuable support and review. I also wish to thank Kass Green, Peter Morrison, and Mike Golden for their generous assistance in the research. The Department of Geography at the University of Washington provided support while I carried out this project, and the USGS Forest and Rangeland Ecosystem Science Center provided funds for publication.