Дата публикации: 18 ноября 2021
Автор(ы): Nikita OVSYANIKOV →
Публикатор: Научная библиотека Порталус
Рубрика: РАЗНОЕ →
Источник: (c) Science in Russia, №3, 2014, C.105-112 →
Номер публикации: №1637242684
Nikita OVSYANIKOV, (c)
by Nikita OVSYANIKOV, senior research fellow, "Wrangel Island" State Natural Preserve
Wrangel Island, 7,608.7 km2 large, lies in Russia's extreme northeast close to the Bering Strait linking Eurasia and North America, and the Pacific and Arctic Oceans. About 56 km to the east is Herald Island, 11.3 km2 in area. This is an oceanic mountain rise forming one natural complex with Wrangel Island. The location, size and evolutionary history of Wrangel Island account for its ecological uniqueness in that it offers a great biological and landscape diversity not found elsewhere in the arctic regions. What with the ongoing climate change, this wonderful natural object should stay as it is. This is a matter of all-out nature conservation importance.
All thorough the Cenozoic* this territory was free of glaciers, it was not flooded by sea water during regular transgressions (ocean encroachments), and owing to that the landscape and biota (plant and animal kingdom) had been evolving non stop from the Late Mesozoic** on, with no catastrophic breaks.
* Cenozoic, the ongoing era of geological history, began ~66 mln years ago.---Ed.
** Mesozoic, a geological era ~252 to 66 mln years ago.---Ed.
These two patches of ancient Beringia, a great geographical "bridge" connecting Eurasia and America into one megacontinent, drifted apart about ten thousand years ago with the onset of the Holocene*, and became islands. And in the Plestocene**, when
* Holocene, the present geological epoch over the last 12,000 years.---Ed.
** Pleistocene, the first geological epoch of the Quaternary period of the Cenozoic era. During the Pleistocene, glaciers advanced, and then receded, over large areas of North and South America, Europe and Asia, and man appeared. Also known as the Ice Age.---Tr., Ed.
the arctic shelf was still dry land, Wrangel Island remained a large highland rising amidst a great plain stretching between two main fluvial systems, the boundless basin of the Kolyma westward and the Herald canyon to the east, both collecting the northward streamflows of Beringia, from eastern Chukotka to Cape Barrow in Alaska. The mountain ridge that became Herald Island afterwards was the board of that canyon.
Large fluvial systems are the principal routes of animal kingdom and biological diversity propagation. Small wonder that with the rising ocean level in the early Holocene, Wrangel Island turned into a Noah's ark for animals inhabiting the plains of northern Beringia during the Pleistocene. Mammoths that died out in the Arctic in the late Ice Age were still there. In fact, they lived on as late as the Holocene. The holdover mammoths that shrank to dwarfish creatures were still roaming there about 3.5 thousand years ago.
Today Wrangel Island is more than twice superior to arctic regions of the same size in the taxonomic diversity of its plant and animal kingdoms. Many endemic, native species are still there, along with relict species once widespread on the dry oceanic shelf connecting Asia and America into one continent. Actually Wrangel Island is the largest refugium* of Beringia's ecosystems extant during the Pleistocene. Plants and animals were migrating by this bridge from Asia to America and back, thus contributing to the ecodiversity of the two continents. The old land routes between Asia and America are responsible for the unusual mix of arctic and southern taxa
* Refugium (refuge), a place providing shelter, protection, or safety; haven. Here, a land sheltering species in geological periods most unfavorable for life elsewhere.---Ed.
in the island's biota, which is of the American, Asian and Central Asian origin.
The Wrangel Island of today boasts of all arctic landscapes save glaciers. Its central part is formed by three mountain ridges stretching latitudinally from the western to the eastern shore and divided by wide river valleys bounded seawards by tall cliffs. The island's north is under an extensive plain of low hills that Georgi Ushakov, a prominent arctic explorer, dubbed an "Academy of Sciences Tundra". Southwards the island is also under a plain, not as wide, though, as that of the north.
The climate on and about Wrangel Island is quite diverse and variable. Situated in the arctic regions close to the Bering Strait, the island is acted upon by warm Pacific cyclones and ice-cold subpolar air. Gale-force winds are common out there as well as fierce blizzards in autumn, winter and spring; thick fogs and showers visit the island in summertime. Violent ice drifts and hummocking roughen the adjacent sea waters and make open water patches; the icescape is staggering in a great variety of its forms.
The island has as many as 1,400 rivers creeks and brooks, 1 km and longer. Five rivers are above 50 km in length each. And there are about 900 lakes, 80 km2 in area. The diverse topography, the many plains, rivers and lakes account for the great variety and the mosaic pattern of habitats that are optimal for the propagation of many arctic animal species.
LIFE IN THE ARCTIC
The island's plant kingdom is extraordinary in the diversity of its species and communities. On warm summer days large expanses are carpeted with nice fragrant flowers. The inland valleys look like southern steppes rather than barren Arctic expanses. As many as 417 higher vascular plant species and sub-
species have been identified, with 23 endemic among them, home to the island. We can also spot native combinations of species not found elsewhere. Relict plant communities, too, occur here and there---once quite common in the northern districts of Beringia during the Pleistocene. Today they form landscapes in places taking the island back to the Pleistocene period dozens of thousands of years ago.
The world of lower plants is likewise varied; we know of 331 moss and 310 lichen species, and this is not the full list. There is also a great variety of insects: 31 spider, 58 bettle and 42 butterfly species. Relict Pleistocene insects are found as well. The very low presence of gnats and other blood-suckers is a godsend to field workers.
Both the evolutionary history of the two isles and their location in he heart of the high-productivity shallow-water zone are favorable to present-day higher arctic vertebrates. The Wrangel and Harold Islands are the home of many arctic animal species, rare and protected species including.
Thus far more than 170 bird species have been registered on the two islands, with 63 species (eight sea species among them) nesting there; their colonies are the largest in the eastern Arctic. A big nesting colony of the white goose (Anser albus) is also on Wrangel Island, in its northwestern part, in the upper reaches of the Tundrovaya, the only one in Asia. The population of this bird was shrinking rapidly in the 1970s because of rampant hunting and strong progress made by reindeer breeding. Urgent steps were needed to save the Anser albus population, a key argument for setting up a wildlife sanctuary.
Wrangel Island is also the breeding place of other endangered avian species entered in Russia's Red Book. The brant (brent) goose (Branta bernicla) of the Pacific subspecies flies in to shed feathers; it is also the reproduction place of the gull (Xema)--its nesting pairs are found on many lakes of the "Tundra of the Academy" sanctuary. The population of the snowy owl (Nyctea scandiaca) is fairly large, too.
The species makeup of land mammalians is rather small (only eight species are home to the sanctuary as well as the common, or red fox [Vulpes vulpes] that visits Wrangel Island on a regular basis); however, the number of arctic animals is higher than elsewhere in the region. Among the resident species are the white polar bear, the polar (Arctic) fox, the lemming (an endemic species and a subspecies), the volverine (glutton), the wolf, musk ox and the northern deer. Lemmings are the core element of the tundra plains. The density of their colonies on Wrangel Island is
very high, and heir population cycle is longer than in land tundras.
The northern deer and the musk ox were imported with the establishment of permanent wildlife colonies there--the deer were brought in the late 1940s and early 1950s, and the musk oxen, in 1975. Since both species once inhabited Beringia, they could not be foreign to the local ecosystems. The northern deer, first a domesticated animal, ran wild after the local state farm had gone out of existence; now it is back to its wild phenotype and free of man-imposed behavioral ways. The ungulates were followed by large tundra beasts of prey, the glutton (wolverine) and the wolf, they came back of their own free will. Today the insular ecosystem has all essential components and is of great interest to researchers.
Inhabiting the coastal waters are three pinniped species, the ringed nerpa (seal), the bearded seal, the walrus, and two baleen whales, the gray and the Greenland right whale.
POLAR BEAR KINGDOM
The white polar bears are quite at home in the sanctuary due to favorable natural conditions, such as ice cracks and ice-free water patches--an excellent hunting space. The leftovers of their meals are a good feed for the community of polar foxes, wolverines, ravens, ivory gulls, silver owls and burgomasters (large polar gulls, the Larus hyperboreus).
Wrangel Island is world famous as the White Bear Kingdom--the population of white polar bears is the highest out there, both on ice and in coastal waters. When the sea ice in the offshore waters melts away, these ice-living beasts of prey get on shore--their population numbers are the greatest on dry land, in the arctic regions at any rate.
This is also true of accouchement (maternity) dens of white she-bears (Ursae albae)--the number of such lairs is the highest in the Arctic. In the late 1980s and early 1990s, when the population of white polar bears attained an all-time high, the number of accouchement lairs on Wrangel and Harold Islands approached 400. On Harold Island we have registered the highest density of such maternity dens, with as many as twelve per square kilometer. In these last ten years the white bear population has contracted somewhat, and the overall number of maternity dens is now 60 to 70; and yet Wrangel Island is still the lead "maternity home" for the Chukotka-Alaska ursine population. What with the progressing contraction of sea ice, the significance of the island for the survival of polar bears keeps growing.
The ice cover off Chukotka shrinks greatly in summertime, and, given the ongoing global warming, the island is a good shelter for bears seeking refuge from the high sea elements. In its coastal ecosystems these beasts find food when they are unable to hunt for their main prey, the ringed seals, on ice.
In summer and winter periods walrus herds swim into the island's coastal waters, mostly females with their cubs. Big shore rookeries spring up here and there; not so long ago 50 to 60 thousand walruses landed at once. But over the past ten years, due to changes in the ice cover, most of the Pacific walruses prefer the northern coast of Chukotka for their breeding grounds and rookeries. But they are still found on Wrangel Island, albeit in smaller numbers.
Once there, white bears get active as hunters for walruses both on ice and in breeding rookeries. On dry land they form temporary communities; they become more tolerant and less aggressive in their relationships than out on sea ice.
WORLD NATURAL HERITAGE
Biological explorations on Wrangel and Harold Islands began soon after the founding of a permanent settlement there in 1926. Russian ecologists were quick to see the significance of the two islands as a model territory for studying the natural processes in arctic ecosystems. Consequently, it became important to preclude damages that could be caused by nascent industries (rock crystal mining, exploitation of natural resources) and house-building. And thus in 1976 both isles got a protected sanctuary status.
At first this status was accorded to the dry land and the 5 km strip of coastal waters around both isles. Then, the government decision of 1997 expanded the preserves area--the 12 mile marine zone around became protected. Wrangel and Harold Islands came under special protection as part of an arctic natural complex where the insular land and the adjacent sea were to be conserved. Rigorous standards were enforced in keeping with category 1(a) of the classification of the International Nature Conservation Union. This off-limits zone was further extended in 1999 with the addition of a protective belt 24 nautical miles wide. Thus, a protected natural complex emerged in the eastern part of the Russian Arctic that took in the two islands and the surrounding water area 36 nautical miles wide. This was a major contribution to nature conservation in the arctic regions. Today the wildlife preserve is 56,616 miles2 large, with 7,620 km2 of dry land and 48,996 km2 of water area.
In 2004 the Wrangel Island sanctuary was entered into the UNESCO World Heritage list. This status was granted to both islands and the water area around them as a model example of the evolutionary development of arctic natural complexes all through the Cenozoic both in periodic isolation and in periodic contacts between the two continents, Eurasia and North America. Another consideration: it is an area noted for extraordinary biological diversity---in the arctic regions anyway---with good conservation prospects. This is the living space of rare and endangered species protected as objects of global value. So the UNESCO status accorded to the Wrangel preserve attests to the global significance of this natural complex and Russia's contribution to the conservation and research of the arctic natural environment in its primordial state. In fact, the Wrangel preserve is the first arctic object to get into this list of honor.
Scientific explorations at the Wrangel sanctuary have a long record involving many research institutes and scientists. But systematic studies of the arctic biota began only in 1981 when Leonid Staszkewicz, an enthusiastic environmentalist, became the sanctuary's head.
The plant and animal kingdoms of Wrangel Island have been studied better than on other arctic islands. Several exploration projects have been pursued for decades. In scope and in the wealth of material these research efforts are without peer. Take the 40-year monitoring of the white geese colony; or more than thirty years of observations over the population setup and behavioral ways of the polar fox and the snowy owl, the petty miophage predators; or more than 20 years of studies into the population and behavioral ecology of the white polar bear. There was no break in such explorations even in the hard period in arctic research during the latter half of the 1990s and the early zeroes. All in all, we have collected a bounty of data on core objects of the arctic animal kingdom; thus we are able to watch local fauna species and their response to global climate and environment changes; we do that on a long-term basis, for short, now-and-then studies make no sense.
As a natural complex with most strict protection standards the Wrangel Island preserve is of exceptional value as a research and information source and a model territory shedding light on the dynamics of ongoing processes in the local animal kingdom and
ecosystems. In fact, it has been Russia's only permanent research base in the arctic regions. Thereby Russian scientists are making a substantial contribution to global ecology studies.
Drastic changes are taking place in the Arctic with the present global climate warming. Such changes are most conspicuous on Wrangel Island as a model example. They can be detected only in meticulous longterm studies into the key animal species and biota components. Today yearly monitoring comprises 61 parameters for seven groups of objects. Global warming has been shown to have a negative effect on obligate arctic predators, such as the polar bear, polar fox and snowy owl; however, it has a positive effect on the white goose population--the geese nest on Wrangel Island in conditions otherwise harsh for their species elsewhere. Lately their numbers have been on the uptrend after it became warmer there.
Longterm population-related studies are especially important given the dramatic changes in the arctic environment. Such changes are the acid test of the adaptive possibilities of autochthonous animals and can be approached as an experiment designed to uncover the cause-and-effect interplay not noticeable in the steady state of the environment. Let me stress it once again: the reservation regime ensures a natural course of events in insular arctic ecosystems and provides conditions---with no time constraints either--for studying processes within a model territory in the interests of nature conservation and in the absence of human meddling.
Photos by courtesy of the author and Irina Menyushina, a degree-holding (Doctoral Candidate) biologist
Опубликовано на Порталусе 18 ноября 2021 года
Ваше мнение ?