A primer on island biogeography
Biogeography is the study of the geographical and historical distributions of plants and animals. Island biogeography is the study of the distribution of plants and animals on islands. The equilibrium theory of island biogeography holds that the number of species living on an island is a function of extinction and immigration rates on the island. As some populations go extinct through natural processes, other populations are established by organisms which migrate to the island and colonize it. Over time these two processes balance each other out. Although the actual species living on the island constantly change, the total number of species remains relatively constant.

The equilibrium number of species on an island depends on the island's size and its distance from sources of immigrants (other islands or the mainland). A small island will experience more extinctions than a large island, mainly because smaller islands support smaller, more extinction-prone populations (see Information Paper 5). An island that is far from the mainland will receive fewer immigrants than an island that is nearby, because fewer organisms will be able to cross the large barrier of water to get to the island. Also immigrants will be less likely to reach a small island than a large island at the same distance from the source population. Therefore, we expect to find more species on large islands that are close to each other and to the mainland, and fewer species on small islands that are isolated from any other land. The actual number of species belonging to a particular group (birds, small mammals, etc.) can be predicted for islands of different sizes using an empirically derived formula known as the species-area relationship (see Wilcox 1980).

No park is an island, yet
What does island biogeography have to do with Glacier? First, Glacier and other protected areas are only samples of larger ecosystems and most species have patchy distributions within those ecosystems. In Glacier, for example, many species are more likely to be found on one side of the Continental Divide than the other, and some species, especially naturally rare plants and invertebrates, are found only on one or a few small habitat patches. When a nature reserve's boundaries are drawn, inevitably some of these species will not fall within the reserve. The species-area relationship predicts that, as a result of this so-called sampling effect, any reserve will initially exclude roughly 30 percent of the species in the greater region for each 10-fold decrease in area (Wilcox 1980:103). We would predict that Glacier, for example, with an area of 1,013,595 acres, is missing three out of every ten species found in the surrounding 10 million acres of habitat.

Only two species are known to be missing from Glacier bison and woodland caribou (invertebrates such as mites or fleas that were associated with these mammals have probably also disappeared from the area). Since much of the area surrounding Glacier is protected as wilderness, the sampling effect described above probably has not resulted in many other species extinctions; the three out of ten species not protected in Glacier are likely protected on Forest Service land, in Waterton Lakes National Park, or in other protected areas in the Crown of the Continent Ecosystem. But there are activities going on in the CCE, including timber harvesting, mineral, oil, and gas exploration and extraction, livestock grazing, and housing development, which are beginning to fragment and reduce habitats on private and multiple-use lands in the ecosystem, and to create barriers to the dispersal of organisms between habitat patches. As islands of habitat are created, they will be subject to some of the same processes seen on true islands: species will disappear from patches too small to support them and organisms will not be able to recolonize patches that are too isolated or are surrounded by barriers. (What constitutes a barrier depends on the taxon: small mammals, reptiles, and amphibians may experience high mortality attempting to cross roads; dams and drained streambeds prevent movement of fishes and other aquatic species; some birds are reluctant to cross clearcuts; and many species are unable or unwilling to traverse areas occupied by human settlement.)

Calculations using the species-area relationship for mammals in western North America (Newmark 1986) indicate that if Yellowstone and Grand Teton National Parks were to become completely isolated by development on the surrounding lands in the Greater Yellowstone Ecosystem, eventually the number of mammals living in these parks would decline from 69 species to a new equilibrium of only 17 species 75% of Yellowstone's mammals would disappear (Schmidt et al. 1990). Notice that the species-area relationship does not tell us how long such a faunal collapse would take (Soule et al. 1979); it might occur slowly, over thousands of years. But these figures also are only for mammals; complete isolation of Yellowstone and Grand Teton National Parks would undoubtedly result in the eventual loss of thousands of other species across the entire taxonomic spectrum.

If Glacier and Waterton Lakes National Parks were to become a completely isolated habitat island within the Crown of the Continent Ecosystem, we would expect a similar loss of biological diversity to occur. The first species to disappear would mostly likely be the animals with the largest area requirements large mammals and, in particular, large carnivores. Picton (1979) indicates that some mountainous areas of Montana have already lost from 4 to 42% of their native large mammals as a result of human activities. The two native species that are extinct in Glacier NP are both large mammals; Newmark (1985) calculated that at least four others in Waterton-Glacier wolverine, grizzly bear, mountain lion, and gray wolf have area requirements for population viability (see Information Paper 5) that cannot be met by the parks alone. Thus the species most vulnerable to extinction also may be the ones to which we as a society attach the most cultural and symbolic value (see Information Paper 3).

Fortunately, much of the Crown of the Continent Ecosystem is legally protected, and, furthermore, is buffered by the chain of protected areas stretching from the Greater Yellowstone Ecosystem to the south up to the Banff and Jasper National Parks to the north. It is highly unlikely, therefore, that the worst-case scenario of total isolation of Glacier and Waterton Lakes National Parks will ever come about. Nevertheless, protected areas around the world are in fact becoming increasing isolated as human populations and demands for natural resources continue to accelerate. By enabling us to predict the consequences of habitat loss and fragmentation, island biogeography can help us to avert extinction crises in the CCE and elsewhere. Activities which may be critical to this endeavor include safeguarding habitats on private and public lands outside of the parks and wilderness areas, establishing and maintaining corridors that link habitat islands both within the CCE and between the CCE and surrounding regions, and developing ways to get needed resources from the ecosystem without diminishing its diversity and integrity (see Information Paper 2).

Inventory and monitoring
Essential to the value of these conservation activities, however, is establishing just what species do live in the CCE. Glacier National Park's species lists are among some of the most complete in the Park Service, at least partly due to studies early in the century by the original Bureau of Biological Survey. Although, as Table 1 shows, many questions remain to be answered, Glacier National Park is ahead of many Park Service units in achieving the Service's goal of an 80% complete list for vascular plants and vertebrates.

Currently the National Park Service conducts its own extensive inventory and monitoring program, but the structure of the program may change substantially in the fall of 1993. As of October 1, 1993, all research scientists throughout the many government agencies will become part of a new umbrella agency, the National Biological Survey. The implications of this change for specific research topics remain to be seen. This report will discuss the status of the NPS program to date (April 1993).

The Glacier National Park inventory and monitoring program began in 1988 with the purchase of a Geographic Information System (GIS) computer and the beginning of a sources database in the park (see Information Paper 8). In 1989 the current comprehensive monitoring project was first funded. It encompasses both biotic and abiotic components. Abiotic monitoring includes air and water quality studies which have now continued for sixteen years. Biological monitoring is conducted at three levels: landscape, community, and population.

Of these, landscape monitoring is the most long-term and widest in its view of change. Satellite data are gathered and charted through the GIS system, providing information on large-scale change such as habitat fragmentation and loss of habitat to housing development, road building, and extractive industry. The scope of the study includes buffer areas around the park such as National Forest land.

On the ground, changes in community structure and species diversity are being monitored through a number of studies. Eighteen plots in the Lake McDonald valley are the focus for surveys of vascular plants, birds, small mammals, and ground beetles. The plots represent four different plant communities--lodgepole forest grown up since the fires of 1929 at the foot of Lake McDonald; the older forest around Park headquarters which hasn't burned since 1865; the cedar-hemlock forest at the head of Lake McDonald, unburned since approximately 1735; and the true old growth forest around Avalanche campground, unburned since at least 1516. Already data indicate that the least diverse forest types are the lodgepole forest last burned in 1929, and the cedar-hemlock forest which dates back to 1735. Both of these communities are relatively monotonous, dense forests which admit little light to the forest floor. In contrast, both the 1865 forest near headquarters--biologically the richest of the areas being studied--and the 1516 forest near Avalanche campground show greater numbers of the surveyed species. Both these forests offer a greater variety of habitats--when a very large, old tree topples over, it leaves a large gap in the overstory which admits more light and moisture to the forest floor, creating more microclimates which in turn support a broader range of plant and animal life. As time goes on the forests pass through stages of succession where their growth may raise or lower the number of species which can thrive there--the reopening in the canopy of the true old growth forest allows more species to flourish than in the greater shadow of the old, but not truly climax, cedar-hemlock forest. Of course this process of succession may be interrupted or altered by other events such as fire, flooding, and avalanche as well, all of which will return the growth succession to an earlier stage.

The old growth found at Avalanche campground represents the easternmost extent of the Pacific Northwest rainforest and includes species such as the chestnut-backed chickadee which are peculiar to it. Old growth forest is obviously the subject of much current controversy as well as interesting in itself; this study contributes to our ability to resolve practical questions of policy as well as adding to our general knowledge of Glacier National Park.

Finally, research continues at the level of population studies. In particular, threatened and endangered species such as wolves, grizzly bears, and bald eagles are monitored in the Park (see Information Paper 5). Other "keystone" species, such as sapsuckers and woodpeckers in general, are studied because of their known relations with other species. Woodpeckers, for example, create nests later used by other birds as well as squirrels (see Information Paper 3).

Currently a study of the effects of fire on beetle communities in Glacier is attracting international attention. Researchers are investigating how fire affects the makeup of beetle communities while at the same time learning how to measure the effects of natural disturbance and its role in maintaining natural biodiversity (see Ivie and Ivie 1993). Three different types of traps are being used in a variety of habitat types (light burned, hard burned, and unburned lodgepole forest, old growth forest, and burned and unburned wet meadow). So far over a thousand species and eighty families of beetles have been identified, including one previously undescribed new genus (which is noteworthy as the beetles of North America have been well studied). Many of these species are highly localized within habitat and burn types. Because beetles inhabit virtually every life-zone--from roots to tree-tops to talus slopes--any change in the Park's environmental system is bound to affect them. Studying beetles thus allows researchers to answer questions such as what species would be lost by eliminating fire from old growth forest or, conversely, what species would be lost by burning an old growth forest. Such information is crucial to formation of responsible resource management policies.

Author: Karen J. Schmidt.

References

Beiswenger, R.E. 1990. Analysis of potential sensitive mammal species for long-term monitoring in Glacier National Park. Univ. Wyoming, Dept. of Geography and Recreation, Final Proj. Rpt. to NPS. Univ. Wyoming, Laramie, WY.

Wilcox, B.A. and D.D. Murphy. 1985. Conservation strategy: the effects of fragmentation on extinction. American Naturalist 125:879-887.