Fires create and consume snags (standing dead trees), an important structural and ecological component of ponderosa pine forests. The effects of repeated fires on snag densities in ponderosa pine forests of the southwestern USA have not been studied. Line intercept sampling was used to estimate snag densities in areas of the Gila Wilderness that had burned one to three times under Wildland Fire Use for Resource Benefit (WFU), a fire management policy implemented since 1974 aimed at restoring natural fire regimes. Twenty randomly located transects were measured in areas burned since 1946; six in once-burned areas, six in twice-burned areas and eight in thrice-burned areas. The mean density±standard errors of large (>47.5cmdbh) snags for areas that burned once, twice and thrice was 7.0±2.7, 4.4±1.1 and 4.1±1.3snags/ha, respectively. Differences in snag densities between once- and multiple-burned areas were significant (F-test; p<0.05). There was no significant difference in density of large snags between twice- and thrice-burned areas. Proportions of type 1 snags (recently created) were higher in once- and twice-burned areas than in areas that burned three times, likely reflecting high tree mortality and snag recruitment resulting from an initial entry fire. Type 3 snags (charred by previous fire) were more abundant in areas that burned multiple times. The lack of differences in snag densities between areas that burned two and three times suggests that repeated fires leave many snags standing. The increasing proportion of type 3 snags with repeated fires supports this conclusion.

The Mexican state of Nuevo Leon, located in the northeastern portion of the country, currently has 26 state and three federal nature reserves covering approximately 4.5% of its land area. These reserves were established for a variety of reasons not necessarily related to conservation purposes. In 2000 in response to a growing concern about the lack of organized conservation reserve planning to protect the important biological and physical features of Mexico, the Mexican Commission for Knowledge and Use of Biodiversity proposed 12 new terrestrial reserves for Nuevo Leon. The new reserves, if established, would increase the proportion of protected lands in the state to almost 24% of the state's land area. We compiled a Geographic Information System (GIS) analysis using digital thematic maps of physical and ecological features to examine how well the existing and proposed reserves incorporated the major biological and physical features of the state. The existing reserves are located primarily in regions with elevations > 1,000-1,500 m, on less productive soils, and are dominated by pine and oak forest cover types. As a result, the state's dominant biotic region - low elevation coastal plain with xeric scrub vegetation - is disproportionately under represented in the current reserve system. The new reserves would expand the protection of biophysical resources throughout the state. However, the inclusion of important resources in the low elevation coastal lands would still be limited.

Mexico currently has 144 nature reserves covering approximately 9.1% of its land area. These reserves were established for a variety of reasons—often unrelated to the protection of biodiversity. In 2000 in response to a growing concern about the lack of organized conservation reserve planning to protect the important threatened biological and physical features of Mexico, the Mexican Commission for Knowledge and Use of Biodiversity (CONABIO) proposed the establishment of 151 new reserves for Mexico covering 51,429,500 ha. We compiled a GIS analysis using digital thematic maps of physical and biological features to examine how the existing and proposed reserves serve to protect the biodiversity and physical features of the country. Using a conservation target of placing a minimum of 12% of the land area of each important biophysical feature in nature reserves, we found that the 144 existing nature reserves covering 18 million ha (9% of the country) only meet that target for elevation ranges >3000 m and areas with poor soils. These mountainous areas represent less than 1% of the country. The gaps in the existing nature reserves network occur mainly at lower and intermediate elevations (<3000 m) areas with xeric, tropical, and temperate ecosystems, and high productivity soils. The areas proposed by CONABIO increase the proportion of protected lands in the country to over 27% and most of the conservation targets for geophysical features, and land cover, categories are met. Whether this area would be sufficient to maintain viable populations and ecological integrity of species and ecosystems is unknown. Even with the new reserves, low elevation coastal lands would be below the conservation target in the nature reserves. To include a representative sample of these lands would be difficult as these are the same areas where the majority of people live.

The Mexican state of Tamaulipas located in the northeastern portion of the country currently has five state nature reserves covering slightly less than 3% of its land area. These reserves were established for a variety of reasons, many unrelated to the protection of biological resources. In 2000 in response to a growing concern about the lack of organized conservation reserve planning to protect the important biological and physical features of Mexico, the Mexican Commission for Knowledge and Use of Biodiversity (CONABIO) proposed 13 new terrestrial reserves for Tamaulipas. If established these new reserves would increase the proportion of terrestrial protected lands in the state to over 21%. We compiled a geographic information system (GIS) using existing digital thematic maps of physical and biological features to examine how the existing and proposed reserves might serve to protect the biodiversity and physical features of the state. We found that most of the existing protected sites occur in areas with elevations > 1000-2000 m with temperate climate and dominated by pine forest, oak forest, and cloud forest vegetation cover types. The state's dominant biotic region-low elevation coastal plain with tropical and and climate types and xeric scrub vegetation-is disproportionately underrepresented in the current reserve system. The creation of the proposed areas would substantially increase the protection of mid and high elevation lands. The largest gap in the protected lands network would be low elevation, level, coastal lands.

Park managers are concerned that moose (Alces alces), caribou (Rangifer tarandus), and grizzly bears (Ursus arctos) may be avoiding areas along the 130 km road through Denali National Park as a result of high traffic volume, thus decreasing opportunities for visitors to view wildlife. A wildlife monitoring system was developed in 1996 that used 19 landscape level view sheds, stratified into four sections based on decreasing traffic along the road corridor. Data were collected from 22 samplings of all viewsheds during May-August in 1996 and 1997. In 1997, nine backcountry viewsheds were established in three different areas to determine whether density estimates for each species in the backcountry were higher than those for the same animals in similar road-corridor areas. Densities higher than those in the road corridor were found in one backcountry area for moose and in two backcountry areas for grizzly bears. None of the backcountry areas showed a higher density of caribou. We tested hypotheses that moose, caribou, and grizzly bear distributions were unrelated to the road and traffic. Moose sightings were lower than expected within 300 m of the road. More caribou and grizzly bears than expected occurred between 601 and 900 m from the road, while more moose and fewer caribou than expected occurred between 900 and 1200 m from the road. Bull moose in stratum 1 were distributed farther from the road than bulls and cows in stratum 4; cows in stratum 1 and bul1s in stratum 2 were distributed farther from the road than cows in stratum 4. Grizzly bears in stratum 2 were distributed farther from the road than bears in stratum 3. The distribution of moose sightings suggests traffic avoidance, but the spatial pattern of preferred forage may have had more of an influence. Caribou and grizzly bear distributions indicated no pattern of traffic avoidance.

Current conservation strategies for plant and animal species rarely address the need to protect the species throughout its geographic range thereby capturing potential genetic and ecological variation. We examined the degree that existing protected areas in the western United States satisfied this goal for four widespread vegetation cover types. We used latitude and longitude to stratify the distribution of these types into 16 cells, each of which was further stratified by up to five elevation classes. While protection of some vegetation types was high in parts of their range, it was minimal to nonexistent in other parts. While it is yet to be shown that protecting a given species throughout its geographic range is essential for its long-term existence, in the face of often unpredictable environmental changes, it seems a prudent course to follow. Our results suggest that if full range protection is a conservation goal, the existing network of protected areas may be inadequate for the task.

Less than 6% of the coterminous United States is in nature reserves. Assessment of the occurrence of nature reserves across ranges of elevation and soil productivity classes indicates that nature reserves are most frequently found at higher elevations and on less productive soils. The distribution of plants and animals suggests that the greatest number of species is found at lower elevations. A preliminary assessment of the occurrence of mapped land cover types indicates that ∼60% of mapped cover types have <10% of their area in nature reserves. Land ownership patterns show that areas of lower elevation and more productive soils are most often privately owned and already extensively converted to urban and agricultural uses. Thus any effort to establish a system of nature reserves that captures the full geographical and ecological range of cover types and species must fully engage the private sector. For reprints of this Invited Feature, see footnote 1, p. 945.

We analyzed the conservation status of 73 vegetation cover types distributed across a 1.76 million km2 region in 10 states of the western USA. We found that 25 vegetation cover types had at least 10% of their area in nature reserves. These were generally plant communities located at higher elevations and thus more commonly associated with national parks and wilderness areas. All but three of the remaining 48 cover types occurred with sufficient area on publically owned lands in the region to imply that transforming land management intent on these lands could also increase their protection. We also analyzed the level of protection afforded each cover type across its entire geographic distribution in the region. Most cover types that were at least minimally protected in total across the region were also at least minimally protected in most areas of their occurrence. Our results show that there is a realistic opportunity to design a system of biodiversity reserves in this region that represent the full range of environmental conditions in which the various plant communities occur. Conducting this type of broad-scale analysis is a necessary first step in that process and provides a database for others to work from.

Informed management of large carnivores depends on the timely and useful presentation of relevant information. We describe an approach to evaluating carnivore habitat that uses pre-existing qualitative and quantitative information on humans and carnivores to generate coarse-scale maps of habitat suitability, habitat productivity, potential reserves, and areas of potential conflict. We use information pertinent to the contemplated reintroduction of grizzly bears Ursus arctos horribilis into central Idaho to demonstrate our approach. The approach uses measures of human numbers, their estimated distribution, road and trail access, and abundance and quality of bear foods to create standardized indices that are analogues of death and birth rates, respectively; the first subtracted from the second indicates habitat suitability (HS). We calibrate HS to sightings of grizzly bears in two ecosystems in northern Idaho and develop an empirical model from these same sightings based on piece-wise treatment of the variables contained in HS, Depending on whether the empirical model or HS is used, we estimate that there is 14 800 km(2) of suitable habitat in two blocks or 37 100 km(2) in one block in central Idaho, respectively. Both approaches show suitable habitat in the current Evaluation Area and in an area of southeastern Idaho centered on the Palisades Reservoir. Areas of highly productive habitat are concentrated in northern and western Idaho and in the Palisades area. Future conflicts between humans and bears are most likely to occur on the western and northern margins of suitable habitat in central Idaho, rather than to the east, where opposition to reintroduction of grizzly bears is currently strongest. (C) 1998 Elsevier Science Ltd. All rights reserved.

To better understand the dynamics of development and to illustrate the transition of a region from a natural to an agricultural environment, we developed a regional land use history of the Palouse bioregion of southeastern Washington and westcentral Idaho. We traced the history of European–American settlement and changes in biodiversity in the region, used this to understand how human activities have altered land cover and ecological integrity of the Palouse bioregion, and illustrated how this can assist local managers. We compiled and interpreted available information on people, plants, animals and physical resources over a period of time. Multiple spatial and temporal scales incorporating both sociological and ecological data were used to examine changes in the bioregion as a result of agricultural development and human settlement. Understanding the biophysical changes that have occurred provides a useful starting point for outlining future research needs, establishing conservation goals and targeting ecological restoration efforts, and can be used immediately in local land use planning efforts.

The conventional approach to maintaining biological diversity generally has been to proceed species by species and threat by threat. We suggest that piecemeal approaches are not adequate by themselves to address the accelerating extinction crisis and, furthermore, they contribute to an unpredictable ecological and economic environment. Here, we describe a methodology called Gap Analysis, which identifies the gaps in representation of biological diversity (biodiversity) in areas managed exclusively or primarily for the long-term maintenance of populations of native species and natural ecosystems (hereinafter referred to as biodiversity management areas). Once identified, gaps are filled through new reserve acquisitions or designations, or through changes in management practices. The goal is to ensure that all ecosystems and areas rich in species diversity are represented adequately in biodiversity management areas. We believe this proactive strategy will eliminate the need to list many species as threatened or endangered in the future.Gap Analysis uses vegetation types and vertebrate and butterfly species (and/or other taxa, such as vascular plants, if adequate distributional data are available) as indicators of biodiversity. Maps of existing vegetation are prepared from satellite imagery (LANDSAT) and other sources and entered into a geographic information system (GIS). Because entire states or regions are mapped, the smallest area identified on vegetation maps is 100 ha. Vegetation maps are verified through field checks and examination of aerial photographs.Predicted species distributions are based on existing range maps and other distributional data, combined with information on the habitat affinities of each species. Distribution maps for individual species are overlaid in the GIS to produce maps of species richness, which can be created for any group of species of biological or political interest. An additional GIS layer of land ownership and management status allows identification of gaps in the representation of vegetation types and centers of species richness in biodiversity management areas through a comparison of the vegetation and species richness maps with ownership and management status maps. Underrepresented plant communities (e.g., present on only 1 or 2 biodiversity management areas or with a small total acreage primarily managed for biodiversity) also can be identified in this manner. Realization of the full potential of Gap Analysis requires regionalization of state data bases and use of the data in resource management and planning.Gap Analysis is a powerful and efficient first step toward setting land management priorities. It provides focus, direction, and accountability for conservation efforts. Areas identified as important through Gap Analysis can then be examined more closely for their biological qualities and management needs. As a coarse-filter approach to conservation evaluation, Gap Analysis is not a panacea. Limitations related to minimum mapping unit size (where small habitat patches are missed), failure to distinguish among most seral stages, failure to indicate gradual ecotones, and other factors must be recognized so that Gap Analysis can be supplemented by more intensive inventories.

Four areas in the state of Idaho, U.S.A., have been proposed by various interest groups to be designated as national parks. The four areas average 220,000 ha and contain important biological, scenic, recreational, and geological resources. However, the biological resources that would be protected by these proposals have received relatively little consideration. We used the U.S. Fish and Wildlife Service’s Gap Analysis Project databases to evaluate the vegetation types contained in each proposal. The scale of analysis was an ecoregion with the proposals falling within three of six ecoregions that encompass Idaho. Databases included vegetation type, land ownership, and land protection status, which were analyzed using a geographic information system. Vegetation types were used as surrogates for information on the distribution of other biological resources (ie., biodiversity). A conservation strategy was evaluated that would preserve at least 10% of each vegetation type in an ecoregion. Only 15% of the vegetation types in the three ecoregions were protected under this criterion. The four proposals added little to this figure because 67–78% of the vegetation types found in the proposals were already protected elsewhere in each ecoregion. Between 16–30% of the land areas in the proposals provided protection for vegetation types that were previously unprotected. We increased the size of each proposal by including vegetation types in a 15 km zone around each proposal in an attempt to enhance protection. None of the proposals could be feasibly modified to reach the 10% protection goal for all of the vegetation types. However, the protection provided by each proposal could be enhanced to varying degrees with the addition of relatively few hectares to their land area. Although national parks throughout the world play an important role in the conservation of biodiversity, this attribute is often accidental, and as our analysis showed, more attention needs to be devoted to biological data in the selection and design of new parks.

Information on human/wildlife interactions and wildlife viewing habits is essential to park management. To help fulfil this need, mountain goat behaviour and use of specially constructed highway underpasses and an adjacent mineral lick were monitored simultaneously with visitor activities at an observation area in Glacier National Park, Montana. We found that, although the site was very popular with park visitors, those using the observation area did not appear to have an adverse effect on mountain goat use of the mineral lick. Traffic on the highway and visitors standing above the underpasses did, however, influence behaviour of mountain goats crossing the highway, causing run backs, hesitation, and eliciting visual alarm responses. The relatively short time-period visitors spent at the site was also noted and suggestions are made for improving the education value of the area as well as minimising the problems which occur at the underpass.