Natural History
{Introduction | Geography | Geology | Post Ice-Age History | Climate | Plants | Animals | The Sea | People}
Introduction
Between 58 and 60 degrees north latitude, in the Glacier Bay region, the margin of North America is thrown into a broad arc of rugged mountain ranges that intermingles with the Pacific in a maze of ice-scoured fjords, valleys, beaches, straits and islands, the whole comprising an amphibious landscape where no point of land or sea is more than 30 miles from a shore.
It is an austere place of big tides, strong currents, fall gales and frequent earthquakes, a landscape of great peaks hard against profound depths, of somber blues, greens and grays only occasionally relieved by the pastels of a grassy meadow or sunset sky. Though perhaps one quarter of the region remains under ice today, glaciers were much more extensive just two centuries ago, and during the last Great Ice Age coalesced into an all-pervasive plateau having the aspect of modern-day Greenland.
The world's greatest temperate rain forest extends into portions of the region longest free of ice, and is reassembling itself in areas recently reclaimed from the glaciers. Salmon abound in its many streams. The sea teems with halibut, crabs, seals and diving birds. The biota is presided over by a full complement of large predators such as orcas, brown bears, bald eagles and wolves.
It is a region long inhabited but not yet overwhelmed by people. Human residence and especially visitor use are growing rapidly but still may be within limits of sustainability. Recent industrial-scale timber harvest is controversial in this regard. Settled areas are few, in part because the vast majority of lands are under federal management, which for the most part, prohibits residence while allowing resource uses of various sorts. These resources, still available in their aboriginal abundance — notably fish, wildlife, timber and scenic beauty — support the regional economy and way of life today as they have for the 9,000 years of known human history.
Geography
The Glacier Bay region can be subdivided into four geographic provinces: Glacier Bay, Icy Strait-Cross Sound, the Outer Coast, and Admiralty Island.
Glacier Bay
The Glacier Bay province includes the present Glacier Bay watershed, plus large peripheral outwash systems at its southern margin that were distributors of glacial melt water at the peak of the Little 
Ice Age. The Glacier Bay watershed is a vast tract of land and water delimited to the east and north by the Chilkat and Takinsha Ranges, to the northwest by the high crest of the Fairweather Range, and to the west by the peaks and ridges forming the eastern margin of the Brady Glacier. From this peripheral rim a series of lower ridges extend radially inward, defining between them a complex of partially submerged and variously ice-occupied valleys which merge into two fjord systems — -Muir Inlet and the West Arm. These in turn coalesce to form the main trunk of Glacier Bay.
Probably because of its funnel-shaped geography, Little Ice Age advances and retreats were magnified compared to other parts of the Glacier Bay region. With the exception of some lowlands at the province's southeastern and southwestern margins, the entire province was under ice or ice-generated outwash about 250 years ago. The retreat since that time has been one of the best-documented in the world. Though ice remains pervasive in peripheral highlands to the north and west, it has bared an extensive series of known-age land and seascapes which have become the premier laboratory in the world for study of ice-recessional phenomena and post-glacial biotic succession.
Wildlife is diverse and locally abundant, varying considerably along the successional gradient. Large concentrations of harbor seals, waterfowl and seabirds, moose and mountain goats lead the list of prominent species.
Except for minor private in holdings and the 18,000 acre Gustavus area, the Glacier Bay province is entirely included within Glacier Bay National Park and Preserve. It is the Park's core area, receiving the vast majority of the Park's visitor and scientific use. It also hosts a variety of fisheries, the most important among them at present being Dungeness crab and halibut.
Park headquarters at Bartlett Cove and the Community of Gustavus, in the province's southeastern corner, are the only permanently settled localities. At the peak of the summer season, they may together have a resident and visitor population of perhaps 1,000 people. The great majority of park visits is via cruise ships, which do not disembark passengers on land in the area.
Icy Strait - Cross Sound
Glacier Bay is the principal tributary to Icy Strait-Cross Sound, a large passage that links the northern waters of the Alexander Archipelago to the open sea. Secondary inlets join this waterway from the north and south. At its western margin, Cross Sound broadens out into a complex of small fjords and offshore islets that face the open sea.
Icy Strait - Cross Sound and its complex of tributary inlets provide a wide array of open waters and sheltered estuaries with an equally wide array of water depths and bottom types. Consequently the area hosts important concentrations of a variety of marine species, notably halibut, salmon and Tanner crab, humpback whales, harbor porpoises and marbled murrelets. The recently reintroduced sea otter is thriving. Being along the northern terminus of sheltered waterways extending almost unbroken to Seattle, this waterway is a major conduit for animal movements into and out of Southeast Alaska waters, as it is for transient vessel traffic as well. These waters have been major commercial fishing grounds for over a century. Sightseeing, sport fishing and ecotourism are rapidly increasing activities.
Mainland portions of the province west of Glacier Bay are at present dominated by the Brady Glacier. Unlike Glacier Bay ice, the Brady is near its Little Ice Age limits, directly covering much land with ice, and indirectly influencing many valleys and inlets around its periphery with outwash and melt water. Other lands in the province have, with minor exception, been uninfluenced by ice for 13,000 years. A rich array of mature plant communities have developed on these older lands, including major tracts of luxuriant old-growth forest that host substantial deer and brown bear populations. Mainland plant communities, though generally younger, are far richer in mammal species, due to the difficulty of crossing the water barrier posed by Icy Strait.
Most of the mainland is in Glacier Bay National Park and Preserve. Most lands to the south, along with islands in Icy Strait and a strip along the Park's eastern margin, are included within the Tongass National Forest. Private lands are extensive around Hoonah and to a lesser degree along Excursion Inlet. Logging is prohibited on protected National Forest lands in the western half and eastern extremity of this province. Nearly every other valley of the remainder of the National Forest has been roaded and logged to some degree. Native corporation lands have been very heavily logged.
The largely Tlingit community of Hoonah, with a population of about 1,000, has traditionally been based on fishing and subsistence gathering. During the last two decades, however, timber harvesting has provided an additional sector to its economy. Primarily during summer, few hundred people reside along Excursion Inlet. Many of these seasonal residents work at the large fish processing facility. Elfin Cove is a fishing and tourism community of less than 100 people on the southeast margin of Cross Sound.
Outer Coast
This province extends northwestward along the Gulf of Alaska from Icy Point to Yakutat Bay. Riven by the seam between the Pacific and North American plates, it is being rapidly thrust upward by tectonic forces. This results in a landscape laid out in bands parallel to the coast. These bands are described below.
The Fairweather and Saint Elias mountains have been etched by intense glacial erosion into a high, jagged palisade separating maritime lowlands and the Glacier Bay watershed from the continental interior. These great ranges formed the principal source area for Little Ice Age ice, but acted as a barrier for ice flowing seaward off the continent during the Great Ice Ages. Their peaks are still surrounded by extensive ice fields today.
Desolation Valley, lying along the inter-plate rift, intercepts ice from the mountains like a huge gutter and channels it to a few outlet valleys. In several of these valleys, ice reaches to or nearly to the sea, but Lituya Bay is presently almost ice-free.
A foreland of raised marine and river deposits, often cut into striking raised terraces or series of beaches and swales, lies seaward of the high country and between the outlets issuing from Desolation Valley. Much of this country is vegetated with forest and rich wetlands, and crossed by highly-productive streams. These streams as a whole provide some of the most productive fish and wildlife habitat in North America. During the last Great Ice Age, this ice drainage system kept a few lowland areas from being overrun and hence free to host plants and animals, although the climate would have been very severe.
Sandy, wave-pounded beaches are interrupted periodically by glacial deposits where outlet valleys have conducted ice to the sea. To the northwestward, these beaches tend increasingly to trap estuaries behind them. This beach-estuary complex comprises critical habitat for a variety of fish and wildlife, notably brown bears, wolves, waterfowl and salmon.
Shallow inshore seas contain large populations of Dungeness crab and schooling capelin. During migration, large numbers of many bird and marine mammal species move through these coastal waters and the above mentioned beach-estuary complex. Much of the entire Pacific populations of such species as Pacific loons and gray whales pass through the area.
Yakutat Bay delimits the province's northwest extremity. This large glacial fjord was filled with ice about 1,000 years ago, and has been partially occupied by minor advances at least once since then. The Hubbard Glacier at the Bay's elbow has periodically advanced to block the tributary Russell Fjord and create a lake. The most recent episode occurred a decade ago. Yakutat Bay has important halibut and crab grounds, and hosts a large concentration of harbor seals.
Midway through the province, the Alsek River breaches the coastal mountains and flows to the sea, creating a large delta-estuary complex. This area, Dry Bay, with very high salmon fishery values hosts a seasonal human population of a couple hundred people and is managed as a National Preserve where hunting and fishing are allowed to continue under special regulation by the National Park Service. Southeastward from Dry Bay, all lands and most waters out to three miles from shore are part of Glacier Bay National Park and Preserve. Northwestward, most lands are within the Tongass National Forest, though in designations that preclude logging.
The only permanent community in outer coast province is the largely Tlingit village of Yakutat, with a population of about 800. The economy of Yakutat is based largely on commercial fishing, guided sport fishing and hunting, and subsistence, with a growing component of ecotourism. Logging of National Forest lands began about two decades ago, but was not supported by residents and is now administratively designated for other uses.
Admiralty Island
Admiralty, second largest island in the massive Alexander Archipelago, dominates the northern half of the Panhandle. The island is more or less half way between Juneau and Sitka. It is 96 miles long, northeast to south, and about 30 miles in width at its widest. It embraces 678 miles of coastline, highly irregular with many bays and estuaries, and a total area of over a million acres or 1,664 square miles.
Dense green spruce and hemlock forests cover much of the island although only about 20 percent of the area is attractive to timber harvesting. Only a few logging scars show, and many old harvest areas are heavily overgrown with second growth. There are broad valley systems that have never been harvested and are, except for occasional windthrows, literally unbroken carpets of green, pristine wilderness. The area is wet (100-inches-plus annually except for "dry" spots like Angoon, in the rain-shadowed lee of snowcapped Baranof Island to the southwest) climax forest in which underbrush and down trees frequently make foot travel difficult.
A spine of mountains runs up the northern portion of the island, where the treeline ends at around 2,000 to 2,500 feet, with dark forests giving way to alpine meadows and twisted little pines and dwarf spruces in a parkland of flowers, lush grasses, ground plants like the dwarf dogwood or bunchberry, heart leaves and other growth on which Sitka blacktail deer grow fat throughout the summer. To the north, this spine tapers needle-like to Point Retreat, a favorite fishing spot.
South of the spine, in the center of Admiralty, a strong geologic contract breaks the continuity of the mountain complex and a vast mid-island lowlands area embraces a myriad of lakes and streams across the island from west to east. the island reaches its greatest width. To the south of the lowlands, mountainous country slopes to bays on both east and west coasts.
The first of June still finds bears coming out of hibernation on the high slopes. The brown bear is prolific on the island. Population estimates are over 1,000 bears or about one bear per square mile — exceeding the number of people living on the island. Admiralty Island accounts for approximately 10 percent of Alaska's population of brown bears.
While bears outnumber people, bald eagles outnumber bears and provide one of the more outstanding features of Admiralty Island — an estimated 2,500 reside on Admiralty Island — more than all bald eagles known to exist in the remainder of the United States. A graphic plotting of nests in the area identified by U.S. Fish and Wildlife Service biologists results in the intricate outlining of the entire island's coastline.
Angoon, Admiralty Island's only permanent community, lies at the entrance to Mitchell Bay on Chatham Strait. Its people are mostly Tlingit Indians, descendants of the tribes that have controlled the Straits for centuries. Access to Angoon is limited to float planes and the Alaska Marine Highway ferry. This physical isolation from other population centers, coupled with the land in which they live, has served to set Angoon apart from other towns in Southeast Alaska in terms of culture and lifestyle. Angoon has been called the stronghold of Tlingit culture.
Geology
The Glacier Bay region's extreme topography indicates a landscape driven by immense energies, which derive from the area's position astride the active suture between the North American and Pacific plates. For over 100 million years, North America has been plowing obliquely into the Pacific plate, presently at a rate of several centimeters per year. Generally, the Pacific plate has been forced under North America, but occasional bits — island arcs, pieces of sea floor, fragments of continental margin — have been scraped off one plate or the other, shattered, and smeared along the leading edge of North American plate. Four such "terranes" have accumulated in a largely northwest-southeast pattern to form the Glacier Bay region.
The seam between the outboard-most terrane and the present continental margin remains active. Frequent earthquakes dramatically illustrate that plate motions continue to this day. The resulting compressional motion has forced some rocks upward to form mountain chains. Others are forced downward and melted in the process. Molten rock then moves volcanically through the shatter zone, where it cools and welds together one of the world's most complex geological jigsaw puzzles.
Highlands forming by this process intercept the predominantly onshore flow of Pacific air, wringing out its abundant moisture in the form of rain and snow. For at least seven million years, snows have accumulated in the uplands to form glacial ice, which has invaded the lowlands many times as the climate has periodically cooled. During the height of the most recent of these Great Ice Ages about 20,000 years ago, an ice sheet covered all of the Glacier Bay region except the highest peaks and certain headlands. Then it would have been possible to walk from Glacier Bay to Cape Cod without ever getting off the ice.
Post Ice-Age history
By 13,000 years ago, retreating ice revealed a scoured landscape of rounded hills and deep, U-shaped valleys and fjords. The precipitous peaks in this landscape were taller than the maximum ice depth, thus escaping its erosive action. The land was devoid of valley sediments and pushed down several hundred feet by the weight of the ice. This in combination with higher sea levels, resulted in the land being even more insular than at present. A few species enduring arctic conditions at the glacier margins may have survived to recolonize the emerging land. For the most part, however, life had to return from afar, slowly surmounting the physical barriers of saltwater, mountains and remaining ice fields, and the ecological barriers posed by the still-harsh living conditions.
Studies of pollen buried in lake sediments and bogs have provided a detailed record of the recovery of plant communities after the ice. For several millennia, tundra and pine-alder scrub dominated the post-glacial landscape. By 9,000 years ago, spruce-hemlock forests had come to predominate, suggesting that by then the climate was approaching the present wet and mild conditions. By 5,000 years ago, peat lands were forming along Icy Strait and glaciers were beginning to advance again into upper Glacier Bay.
All the while, the physical landscape was undergoing changes of its own. Post-Great Ice Age rebound, mountain-building and accumulation of sediments brought down from the uplands began extending valley bottoms at the expense of fjords and connecting islands to the mainland. Where these sediment met the sea, waves and currents worked them into beaches and estuaries.
Conditions for immigration and establishment of land and freshwater animals were improving, while breeding sites for colonial birds and marine mammals probably became fewer. We can imagine the salmon colonizing valley streams, and forest species like deer and black bear becoming ever better established, while puffins and sea lions diminished. As of now, this story is very sketchily known, but deposits of animal bones in recently-discovered caves in southern Southeast Alaska have begun to provide a more detailed record of mammal and bird reoccupation of the land. This cave topography extends into the Icy Strait province, where it remains almost totally unexplored at present.
Climate
Glaciers grew in response to climatic severity. When glaciers dominated the land, they tended to worsen harsh climatic conditions by reflecting heat rather than absorbing it. This generated cold high-pressure cells in the atmosphere that held the warm oceanic air at bay. By contrast, today with glacial ice at a relative minimum, we live in a period of greater than average mildness. The large, low pressure systems sweeping off the Gulf of Alaska are now the dominant force in the climate, bringing with them the abundant moisture for which Southeast Alaska is infamous. Since oceanic currents in the Gulf of Alaska are mostly from the south, Southeast Alaska is bathed by warmer waters than is customary for its latitude, so temperatures are particularly mild on average.
The sea's moderating and humidifying influence pervades the region as a result of the penetration of marine channels and bays, with the greatest influence being along the outer coast. Closer to the continental interior, especially near major passes, periodic influences of continental air reduce the average rainfall and bring more extreme seasonal temperature variations.
Plants
Glacier Bay provides the premier example in the world of how vegetation returns to a landscape following deglaciation. There, on moist lowland surfaces for example, post-glacial barrens succeed from tundra, through shrub land to young forest in about 250 years. Forests of ages 400-1800 years on moraines delimiting Lituya, Yakutat and Dundas Bays provide insights into later stages of forest development.
Mature vegetation of the Glacier Bay region can be subdivided into eight categories. At the shore, a few salt-tolerant species form productive salt marshes. At and above extreme high water, a lush, diverse beach meadow dominated by grasses and large umbels such as cow parsnip is often present. Beach meadow are a distinctive feature of the Glacier Bay region, where high rates of post-glacial rebound have caused the sea to recede faster that the forest can come forward. These biotically important meadows are often backed by a narrow band of alder and then the forest.
Lowland forests are dominated by Sitka spruce and western hemlock, plus cedar near the outer coast and toward the south. Moss, ferns, evergreen herbs and shrub species such as blueberry, menziesia and devils club cloak the ground, except where an even-aged forest canopy admits too little light to support undergrowth. With increasing elevation, mountain hemlock supplants western hemlock.
Forested lands generally forms an unbroken cloak on Southeast Alaska landscapes unless interrupted by disturbance, wetness or altitude. Disturbance can take many forms, such as avalanche, snow creep, flooding, disease, insect infestation, glacial advance, wind throw and logging. Infrequent or small scale disturbance does not erase the forest. In fact, it increases diversity by creating a mosaic of different ages, admitting light to the forest floor, making some of the region's best wildlife habitat.
Most trees take a long time to reestablish, however, so forest cannot persist if disturbance is too frequent or severe. It is replaced by shrub land, which can generally stand more punishment and bounces back faster if erased. Alder, salmonberry and copper bush withstand the deep snows of the sub alpine, and can extend far downhill in avalanche chutes, where they are joined by elderberry, devils club and currants. Willow and alder are prominent in river valleys frequently disturbed by flooding.
Forest habitat also gives way in places too wet to sustain good tree growth. Such conditions are encouraged by relatively level topography or impervious sediments such as silty glacial sediments or raised marine deposits. Wetness due to topography may be further exacerbated by soil hardpans and acidic, spongy peatmoss, resulting in a bog community. Here stunted trees and sparse heath shrubs eke out a sparse living on an-ever-thickening mantle of mossy peat which insulates the plants from access to minerals in the underlying rocks and sediments. At peat land edges where groundwater has contact with the substrate, or in young wetlands where the processes of bog formation are in their infancy, more productive sedge-dominated fens may form.
With increasing altitude, tree growth is first impeded, then halted by low summer temperatures, wind, and damage from snow creep or avalanche. Often a zone of brush interposes, but sometimes forest gives way directly to lush sub-alpine meadows much like those just above the tide. Farther up, where summers are brief indeed and winter winds tend to blow away protective mantles of snow, tundra mats of prostrate shrubs, tiny herbs, mosses and lichens predominate among the permanent snowbirds. Even higher, bare rock and ice reign supreme.
Animals
The distribution of non-marine animals is more complex than that of plants. Not being rooted in place, animals can roam through various plant communities. Birds and many flying insects are especially mobile, and so are able to overcome most physical barriers. But they are particular about habitat choice, and most are associated with a certain group of plant communities. Animals of this type tend to be more widely distributed, but are found in specific habitats.
The opposite tends to be true for mammals. The largest species often use a variety of habitats from the beach to the alpine. Yet because many mammals lack a dispersal phase in their life history comparable to the mobile seeds or spores of plants or the winged migrations of birds, their large-scale distribution is relatively incomplete.
For instance, of the approximately 48 mammal species living in the interior of British Columbia with ranges bordering on our region, only about 29 have made it across the mountain passes and become established at Haines. Only about 11 of these have made it past the water barriers to Chichagof Island. This excludes the marten, red squirrel, mountain goat, and feral dog, which were introduced by people. The relatively few land-based animals able to colonize the extremities of our region have often attained large numbers. Among these are bears, deer, mink and otter.
Only two fishes with no connection to salt water — round whitefish near Haines and northern pike near Yakutat — have made it to the fringes of this region. The bulk of freshwater fishes are salmon and char, which spend parts of their life cycles in salt water, and so can get past the mountains and marine channels that limit the distribution of strictly freshwater animals. Most of the region's streams, even most of those directly under glacial influence, contain spawning and rearing salmon. Some, such as the Situk and Alsek Rivers, are of world-class importance. These major river systems are in the minority. More salmon transit through the region's marine waters than spawn in the region's streams.
The Sea
A fortunate combination of characteristics make seas of the Glacier Bay region immensely productive. The waters are warmed and enriched by waters from the adjacent Pacific Ocean, then further fertilized by nutrient runoff from the land. Complicated shoreline and bottom topography combine with exceptionally high tidal energies to produce strong currents that stir nutrients to the surface. Two other factors are necessary to translate nutrients into productivity — enough light for plant plankton to photosynthesize rapidly, and enough water column stability to allow these tiny organisms to stay in the zone of light near the surface. All these factors come together in spring and early summer.
Then, for a few weeks, the concentrations of plant plankton reach astronomical proportions. Many animal plankton (e.g. krill, copepods) and bottom-dwelling invertebrates (e.g. starfish, sea urchins, worms, and clams) time their reproduction to coincide with this brief time of plenty. Vast shoals of small fishes such as herring, capelin and sand lance in turn feed upon this animal plankton. Salmon, sea lions, porpoises, cormorants, and murrelets forage on the fishes, while humpback whales come from Hawaii and Baja California to harvest small fish and the plankton by the ton.
Seaweed and salt-marsh vegetation also begins to grow in early spring. They support an abundance of grazers, from deer and geese (at low tide) to snails (at high). When this vegetation decomposes, it produces detritus for bottom-dwellers like worms and sand fleas.
Summer in the upper waters is a brief but exuberant season. Hordes of migrants arrive to join the winter holdouts in harvesting the bounty. Most marine birds and mammals raise their young and then put on fat while the good times last. Fishes exhibit a variety of reproductive strategies. Herring and cod release eggs that hatch into larvae which fend for themselves in the rich plankton soup. Skates produce large yolk-rich eggs produced from stored energy from the previous season. Ling cod males utilize stored energy reserves to defend their brood of eggs from predation.
As the snows and gales of winter come, and the sun moves ever lower in the sky, much of the marine world goes "on hold". Many species leave for the south or the warmer temperatures of the open sea. Most of the rest curtail their activity. Salmon eggs rest in creek gravels. Herring and rockfish school in a rocky deep to await the coming of spring when the drama will be replayed.
But the marine ecosystem does not grind to a halt over winter. A portion of the living matter from upper waters makes its way to the bottom in the form of detritus, where it is eaten by filter feeders such as barnacles, anemones and clams. What they miss is incorporated into bottom sediments to be eaten through the year by tiny crustaceans and worms. These in turn feed flounders, crabs, cod and diving birds such as scoters. Seals, sea otters and flounders provide the next link in this benthic food chain, which fluctuates much less through the seasons than that of the open waters, and thus becomes disproportionately important during winter.
Marine productivity comes ashore in numerous ways. Salmon carry it to the far corners of the region when they spawn. The young of some species remain in ponds and streams, where they are important food for mergansers and kingfishers. Eagles, otters and mink hunt at sea and carry their catch to land.
Most important, shores provide hundreds of miles of interface between land and sea. They provide thoroughfares and den sites; carcasses wash up on them; and they grow lush intertidal communities that are dry land when the tide is out. A large array of predators and scavengers from bears to shrews and ravens patrol the beaches, eating flotsam and some of the intertidal invertebrates. Herbivores like deer, moose, mountain goat, porcupine and voles graze on plants of the upper intertidal zone or eat kelp for salt.
People
The list of species for this region has included people for at least 9,000 years. Almost nothing is known of the early inhabitants, except that they left behind tools with a vaguely Siberian character. In recent millennia the Glacier Bay region has been home to the Tlingit people, whose permanent villages and high culture bear testimony to the abundance of both natural and spiritual resources. When first encountered by Europeans, the Glacier Bay region was occupied by Tlingits of the Yak'tat and Huna Kwans. Many descendants of these people reside today in the villages of Hoonah and Yakutat.
The Tlingit people were encountered (but not defeated) by the Russians during the 18th and 19th centuries, who pursued the sea otter and traded from their enclave in Sitka. The Russian then sold what they perhaps did not own to the United States in 1867. Into this "last frontier" have come people drawn from more crowded lands.
The great gold rush at the turn of the 20th century provided a brief surge of prospectors, especially to the outer coast. Processing plants were established in several places along Icy Strait to exploit strong runs of salmon; one remains the basis of employment today at Excursion Inlet. Homesteaders founded a small population in what has become the settlement of Gustavus. The Forest Service, then Native corporations have allowed industrial-scale logging along eastern Icy Strait during the last two decades, the economic nucleus of which has been the Whitestone Logging settlement adjacent to Hoonah. In the most recent years, tourism has burgeoned and promises to become the predominant industry of the region.
Through time, the Glacier Bay region's remoteness from European and then American centers of settlement, its rugged terrain and difficult climate have conspired to hold the human population to modest levels. Yet the recent decade has seen dramatic increases in the rates of population and visitor growth and in resource exploitation. Whether the future will sustain these trends remains to be seen.
