The wildlands of the Northern Rockies continue to diminish in size, primarily due
to new road building and the associated industries, such as logging and mining,
that demand, build, and utilize roads. As roadless lands decrease, secure
habitat for grizzly bears and other wildlife species sensitive to roads decreases
as well. The ecological effects of roads on wildlife and habitat quality have
been well documented as one of the most important factors that contribute to
ecosystem disruption and degradation. This analysis, known as the
"Roads Scholar Project,
" combined aerial
photo and map inventories with field surveys and GIS, to identify, assess,
analyze, and display the current conditions of roaded wildlife habitat in
selected management units in Montana, northern Idaho, eastern Washington, and
northwestern Wyoming. In each instance, the US Forest Service's management of
its roads system has been found to be inadequate, either due to unidentified
travelways that exist on the ground but not in agency inventories, ineffective
road closures, or both.
Figure 1 (77K JPEG)
The Interagency Grizzly Bear Committee's (IGBC) Grizzly Bear Recovery Plan
identifies roads as a primary factor in bear survival: "Roads probably pose
the most imminent threat to grizzly bear habitat today" (USFWS 1993).
Bear mortality occurs both directly and indirectly. Direct causes of death come from road kill as animals attempt to cross highways or other routes that carry high speed traffic. Train-bear collisions have been a recurring problem along the Burlington-Northern tracks on the southern boundary of Glacier National Park in Montana. Railway accidents have regularly spilled grain on and around the tracks, which subsequently attracts bears to feed on the grain and leads to bear deaths. Indirect mortality results from illegal poaching (and, until the early 1990s, legal hunting in Montana) by people using roads in grizzly habitat and from federal or state control actions in response to human/bear conflicts along roads. Even closed road systems may present potentially lethal conditions for bears. As the Grizzly Bear Recovery Plan notes in Appendix B:
Mortality is the most serious consequence of roads in grizzly habitat. Research has confirmed that grizzlies experience increased vulnerability to legal harvest and poaching as a consequence of increased road access by humans (Schallenberger 1980, Zager 1980, McLellan and Mace 1985, Aune and Kasworm 1989). McLellan and Mace (1985) found that a disproportionate number of human-causes grizzly mortalities occurred near roads. In Montana, Dood et al. (1986) reported that 48% of all known non-hunting mortalities during 1967-1986 occurred within one mile of roads. Aune and Kasworm (1989) reported 63% of known human-caused grizzly deaths on the east front of the Rocky Mountains occurred within 1 km of roads, including 10 of 11 known female grizzly bear deaths. Bears are also killed by vehicle collision, the most direct form of road-related mortality (Greer 1985, Knight et al. 1986, Palmisciano 1986).Habitat displacement creates a major impact on grizzly bear recovery that is widespread and difficult to quantify adequately. Displacement occurs as a result of grizzly bears' avoidance of areas frequented by humans. Bears tend to avoid habitat subject to constant or intermittent human use. This behavior has a serious impact on successful grizzly reproduction and occupation of habitat areas, especially when open roads occur in high-quality grizzly bear habitat or areas bears have historically used for den sites. Areas readily accessed by roads are often valley bottoms and ridge tops, both of which are preferred grizzly bear forage and travel habitat. Research shows that open road networks can displace bears and increase mortality (USFWS 1993). Bears can develop such a strong aversion to vehicle noise, human scent along roads, hunting and shooting around roads, and other human-related noise, that even after road closures bears may not return to roaded areas (USFWS 1993). (It is an interesting and relevant aside that the US Forest Service is the world's most prolific road-builder, with a road system that now spans more than 375,000 miles.)
The USFS manages large areas of critical grizzly bear habitat in the Northern Rockies. These areas are delineated by the Forest Plans for each National Forest. With input from the IGBC, areas are identified as Bear Management Units (BMUs), which roughly approximate the size of a female grizzly bear's home range, including seasonal and elevational distribution of habitats. The home range size, and subsequently the BMU size, varies according to habitat type. On the Flathead National Forest, for example, Mace and Manley (1993) found 48 square miles to be the size of the average home range for nine adult female grizzlies; for drier habitat types home ranges and BMUs are approximately twice as large and bear density is lower (IGBC Task Force Report 1994).
The IGBC has recently established its own standards and guidelines for assessing adequate secure habitat in BMUs. These rules emphasize secure area calculations derived from open and total road calculations without establishing raw road density rules. The IGBC also uses buffers or secure area calculations which recognize a distance from open roads as ineffective habitat for bears. The IGBC distance is 0.3 miles and some forests, such as the Idaho Panhandle NF, use a 0.25 mile buffer. This results in a discrepancy between USFS and IGBC standards and guidelines which is currently not reconciled in the field. The IGBC also calculates secure habitat using a computer modeling technique called "moving windows analysis." This technique assesses the exact density of roads within the square mile surrounding any given point in a BMU, by a calculation which breaks the entire BMU into 50-square-meter units. The resulting data can be queried to determine the percentage of each BMU with different classes of road density.
With recovery goals established, recovery depends upon maintaining a minimum amount of secure habitat or core area for bears within each BMU. Habitat protection is mandated through Forest Plan Standards and Guidelines and through IGBC Standards and Guidelines.
Figure 2 (43K JPEG)
We selected Bear Management Units to inventory from the Yellowstone Grizzly Bear Recovery Area, the Selkirk Grizzly Bear Recovery Area, and the Cabinet-Yaak Grizzly Bear Recovery Area (See Figure 2) at the recommendation of local conservationists and agency personnel. Field work was completed in June, July, August, and September, 1995.
The line coverages were then exported to workstation ArcInfo, and converted to
grids with a cell size of 50 meters in order to determine the total area of
various road density classes in each unit. To arrive at the total areas for
each of these density classifications in each management unit, we reclassed the
grids, then used the focalsum command in GRID, running the analysis with a
circular search for an area of 1 square mile. This analysis replicates the
"moving window analysis
" favored by the IGBC.
We again reclassified the resultant grid to create a grid suitable to be
converted to polygons for simple area queries. Following standards developed by
the IGBC, we used five classes of road density (0-.5; .5-1; 1-2; 2-5; and >5
The number in parentheses in Table 1 depicts the number of roads that showed
signs of access through the gate. Table 2 records these same figures as a
percentage of the closure devices inventoried. Be aware that the term
" as it is used in the table simply
means that the device is functioning as it was designed; this does not mean that
the closure device prevents all motorized use, since gates, by design, allow for
motorized use when they are open.
|Closure Effectiveness:||Steel Gate||Earth Berm||Other||No Device|
|2-not excluding ORVs||61||25||7||0|
|Closure Effectiveness||Steel Gate||Earth Berm||Other||No Device|
|2-not excluding ORVs||45.2%||54.4%||50.0%||0%|
Steel gates with key or combination locks are the most common closure devices. Yet, there is an inherent problem with the effectiveness of locked gates even when the gate is, by design and condition, totally functional (i.e., the gate is fully in place and cannot be circumvented by any size vehicle). These gated roads are susceptible to use by people who have either a key or combination to the gate, and who then drive their vehicle past an otherwise effectively closed gate. This access to an otherwise effectively closed road is either for administrative use of the road by agency personnel, or accomplished by someone who has acquired (legally or illegally) the key or combination to that gate. It is important to note that only five steel gates in the entire inventory showed no signs of having been accessed through the gate.
RSP field staff also documented the occurrence of "ghost" roads in their surveys. Ghost roads are roads that do not appear on agency travel plans, but do exist on the ground. Ghost roads do not appear on these maps since they are, by definition, roads that were found during ground truthing and not included in the USFS inventory. Additionally, field staff also documented the absence of roads that were on agency inventories, but did not exist. The agency inventory for the Bluegrass BMU, for example, contained 73.78 miles of road that do not exist on the ground (see Table 3).
|BMU||USFS Open||USFS Total||RSP Open||RSP Open/Restricted||RSP Total|
Secure Area (mi2)
Figure 3 (26K JPEG)
It is worth noting that the USFS' open/closed road classification differs somewhat from the Interagency Grizzly Bear Committee's (IGBC) classification of road types, which breaks roads into three categories: open, restricted, and reclaimed/obliterated. The first and third types are self-explanatory. A "restricted" road is a road on which motorized vehicle use is excluded seasonally or yearlong, the road requires a physical obstruction, and motorized vehicle use is legally prohibited. Under the IGBC's classification, "motorized use by personnel of resource management agencies is acceptable at low intensity levels..." and this "includes contractors and permittees in addition to agency employees." The majority of roads closed by steel gates on the Forest would come under the IGBC's classification of "restricted road." (See Figure 4)
Figure 4 (73K JPEG)
The Interagency Grizzly Bear Committee's classification of roads as open, restricted, and reclaimed/obliterated may help remedy the hazy distinction between roads that are actually closed versus those that are not-quite-wide-open. Regardless of which classification the national forests may choose to use in the future, it is legally and biologically imperative that the forests identify which roads are receiving occasional use, administrative or otherwise, and which are simply impossible to travel and can therefore be removed from the open or restricted road inventory.
All roads considered closed by the USFS should be closed with adequately sized and placed physical obstructions. These barriers (earth berms, tank traps, large boulders, etc.) should be placed so that no detour is possible around the structure. Also, the surface of the road behind the closure should be blocked (or the roadbed scarified) for the first one quarter mile with slash and logs to discourage ORV use of the road behind the closure structure. All roads not included as system roads should be obliterated, recontoured and revegetated. Roads that the USFS wants to keep open for administrative use can be blocked with a gate, but should not be considered "closed" roads in the travel plan. Gated roads should be classified as open or restricted, depending on the level of use anticipated and actualized. This would require the Forest Service to seriously assess whether administrative use was important enough to keep roads on the open road inventory, or decide that roads could be closed, obliterated, and removed from the travel plan. This would prevent casual use of roads that are listed closed by USFS personnel, and would also thwart illegal use by the public. Emergency access can still be assured by the ease of removal of physical obstructions (with the help of heavy machinery), as evidenced by widespread fire access through earth berms during the 1994 fire season.
The total road density, which generally is not considered by the USFS for bear management or habitat security considerations, has biological relevance and should be noted as well. Mace, et al., found that "avoidance of areas having a high total road density was evident for some bears, even though roads were closed to public travel." The same study found that female grizzly bears favored habitat with lower total road densities, and that bears did not use lands with a total road density of 6.0 miles/mile2.
Figure 5 (68K JPEG)
Perhaps the most relevant measure of the effectiveness of a Forest's efforts to manage roads to minimize their impacts on wildlife is the size of the area within the wildlife management unit which is available as secure habitat for wildlife.(See Figure 5.) The US Fish and Wildlife Service has identified 0.5 mile buffers as an acceptable security disqualification for grizzly habitat in the Northern Rockies (Lost Silver Biological Opinion). Further, research in the Cabinet-Yaak ecosystem of northwestern Montana by Kasworm and Manley in 1988 showed that grizzly bears avoided roads more than expected within 0.57 miles of a road. We used a 0.3 mile buffer along each side of a road in an effort to create comparisons that match with current agency management policy.
The inclusion of a "percentage of secure habitat" standard should also be incorporated as a Forest Plan revisions for species that rely upon roadless refugia for their survival. This secure habitat percentage, when combined with road density standards, can ensure to a fuller extent that standards will translate to adequate security for wildlife populations to survive. The specific percentage will vary from one species to another, so a percentage should be adopted that will provide security for the full range of the agency's management indicator species. The Idaho Panhandle National Forest, for example, uses a 70% minimum security level to provide for the safety of bears.
Restricted roads need to be carefully monitored to determine if they are receiving more use than bears and other road-sensitive species can tolerate. If use exceeds this level, then the agency must enforce closures and other restrictions to bring the Forest into compliance with its own management standards.
Studies lend support for considering total road density (rather than just open road densities) as the more important figure in determining impacts on grizzly bear habitat, since bears have been shown to avoid roads even after closure. With this in mind, the RSP and USFS inventories both demonstrate an excessive amount of land affected by road networks in the management units.
A final important policy measure that will contribute to wildlife security on these BMUs is a moratorium on all road building unit-wide until road closures, restrictions, and densities are demonstrated to be in full compliance with Forest Plan standards and NFMA regulations.
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