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145-406: In the mid to late 1800s, European and American explorers discovered its natural resources and began settling in the region. The Yukon River Basin remains a relatively intact ecosystem , known for its density of salmon , which are used as both food for the villagers and a growing industry for the community. Some of the oldest known humans who inhabited North America are thought to have lived around

290-409: A cell wall . Newly dead animals may be covered by an exoskeleton . Fragmentation processes, which break through these protective layers, accelerate the rate of microbial decomposition. Animals fragment detritus as they hunt for food, as does passage through the gut. Freeze-thaw cycles and cycles of wetting and drying also fragment dead material. The chemical alteration of the dead organic matter

435-495: A food chain . Real systems are much more complex than this—organisms will generally feed on more than one form of food, and may feed at more than one trophic level. Carnivores may capture some prey that is part of a plant-based trophic system and others that are part of a detritus-based trophic system (a bird that feeds both on herbivorous grasshoppers and earthworms, which consume detritus). Real systems, with all these complexities, form food webs rather than food chains which present

580-619: A habitat . Ecosystem ecology is the "study of the interactions between organisms and their environment as an integrated system". The size of ecosystems can range up to ten orders of magnitude , from the surface layers of rocks to the surface of the planet. The Hubbard Brook Ecosystem Study started in 1963 to study the White Mountains in New Hampshire . It was the first successful attempt to study an entire watershed as an ecosystem. The study used stream chemistry as

725-458: A moment magnitude of 9.2 (more than a thousand times as powerful as the 1989 San Francisco earthquake ). The time of day (5:36 pm), time of year (spring) and location of the epicenter were all cited as factors in potentially sparing thousands of lives, particularly in Anchorage. Alaska suffered a more severe megathrust earthquake on July 11, 1585, estimated at magnitude 9.25, which remains

870-409: A territory on May 11, 1912. It was admitted as the 49th state of the U.S. on January 3, 1959. Abundant natural resources have enabled Alaska— with one of the smallest state economies—to have one of the highest per capita incomes , with commercial fishing , and the extraction of natural gas and oil, dominating Alaska's economy . U.S. Armed Forces bases and tourism also contribute to

1015-609: A central role over a wide range, for example, in the slow development of soil from bare rock and the faster recovery of a community from disturbance . Disturbance also plays an important role in ecological processes. F. Stuart Chapin and coauthors define disturbance as "a relatively discrete event in time that removes plant biomass". This can range from herbivore outbreaks, treefalls, fires, hurricanes, floods, glacial advances , to volcanic eruptions . Such disturbances can cause large changes in plant, animal and microbe populations, as well as soil organic matter content. Disturbance

1160-399: A convoy to Valdez. On the advice of military and civilian leaders, President Lyndon B. Johnson declared all of Alaska a major disaster area the day after the quake. The U.S. Navy and U.S. Coast Guard deployed ships to isolated coastal communities to assist with immediate needs. Bad weather and poor visibility hampered air rescue and observation efforts the day after the quake, but on Sunday

1305-507: A critical role in global nutrient cycling and ecosystem function. Phosphorus enters ecosystems through weathering . As ecosystems age this supply diminishes, making phosphorus-limitation more common in older landscapes (especially in the tropics). Calcium and sulfur are also produced by weathering, but acid deposition is an important source of sulfur in many ecosystems. Although magnesium and manganese are produced by weathering, exchanges between soil organic matter and living cells account for

1450-517: A faster recovery. More severe and more frequent disturbance result in longer recovery times. From one year to another, ecosystems experience variation in their biotic and abiotic environments. A drought , a colder than usual winter, and a pest outbreak all are short-term variability in environmental conditions. Animal populations vary from year to year, building up during resource-rich periods and crashing as they overshoot their food supply. Longer-term changes also shape ecosystem processes. For example,

1595-427: A function-based typology has been proposed to leverage the strengths of these different approaches into a unified system. Human activities are important in almost all ecosystems. Although humans exist and operate within ecosystems, their cumulative effects are large enough to influence external factors like climate. Ecosystems provide a variety of goods and services upon which people depend. Ecosystem goods include

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1740-698: A general level, for example, tropical forests , temperate grasslands , and arctic tundra . There can be any degree of subcategories among ecosystem types that comprise a biome, e.g., needle-leafed boreal forests or wet tropical forests. Although ecosystems are most commonly categorized by their structure and geography, there are also other ways to categorize and classify ecosystems such as by their level of human impact (see anthropogenic biome ), or by their integration with social processes or technological processes or their novelty (e.g. novel ecosystem ). Each of these taxonomies of ecosystems tends to emphasize different structural or functional properties. None of these

1885-469: A longer coastline than all the other U.S. states combined. At 663,268 square miles (1,717,856 km ) in total area, Alaska is by far the largest state in the United States. Alaska is more than twice the size of the second-largest U.S. state (Texas), and it is larger than the next three largest states (Texas, California, and Montana) combined. Alaska is the seventh largest subnational division in

2030-813: A massive underwater landslide, resulting in the deaths of 32 people between the collapse of the Valdez city harbor and docks, and inside the ship that was docked there at the time. Nearby, a 27-foot (8.2 m) tsunami destroyed the village of Chenega , killing 23 of the 68 people who lived there; survivors out-ran the wave, climbing to high ground. Post-quake tsunamis severely affected Whittier , Seward , Kodiak, and other Alaskan communities, as well as people and property in British Columbia, Washington , Oregon , and California . Tsunamis also caused damage in Hawaii and Japan . Evidence of motion directly related to

2175-672: A means of monitoring ecosystem properties, and developed a detailed biogeochemical model of the ecosystem. Long-term research at the site led to the discovery of acid rain in North America in 1972. Researchers documented the depletion of soil cations (especially calcium) over the next several decades. Ecosystems can be studied through a variety of approaches—theoretical studies, studies monitoring specific ecosystems over long periods of time, those that look at differences between ecosystems to elucidate how they work and direct manipulative experimentation. Studies can be carried out at

2320-528: A more important role in moving nutrients around. This can be especially important as the soil thaws in the spring, creating a pulse of nutrients that become available. Decomposition rates are low under very wet or very dry conditions. Decomposition rates are highest in wet, moist conditions with adequate levels of oxygen. Wet soils tend to become deficient in oxygen (this is especially true in wetlands ), which slows microbial growth. In dry soils, decomposition slows as well, but bacteria continue to grow (albeit at

2465-406: A number of common, non random properties in the topology of their network. The carbon and nutrients in dead organic matter are broken down by a group of processes known as decomposition. This releases nutrients that can then be re-used for plant and microbial production and returns carbon dioxide to the atmosphere (or water) where it can be used for photosynthesis. In the absence of decomposition,

2610-670: A population that was genetically separate from other native groups present elsewhere in the New World at the end of the Pleistocene . Ben Potter, the University of Alaska Fairbanks archaeologist who unearthed the remains at the Upward Sun River site in 2013, named this new group Ancient Beringian . The Tlingit people developed a society with a matrilineal kinship system of property inheritance and descent in what

2755-421: A process known as denitrification . Mycorrhizal fungi which are symbiotic with plant roots, use carbohydrates supplied by the plants and in return transfer phosphorus and nitrogen compounds back to the plant roots. This is an important pathway of organic nitrogen transfer from dead organic matter to plants. This mechanism may contribute to more than 70 Tg of annually assimilated plant nitrogen, thereby playing

2900-474: A relatively intact ecosystem . It is a quality habitat for birds, mammal, fish, invertebrates, and one amphibian. The wood frog is the only amphibian able to survive in the ecosystem. This is due to its increased level of glucose in its cells. This addition acts as an antifreeze. It allows the frogs to survive the extremely cold winters. The basin consists of thousands of lakes, ponds, sloughs, wetlands, and rivers/streams to provide habitats for these animals. Within

3045-696: A significant portion of ecosystem fluxes. Potassium is primarily cycled between living cells and soil organic matter. Biodiversity plays an important role in ecosystem functioning. Ecosystem processes are driven by the species in an ecosystem, the nature of the individual species, and the relative abundance of organisms among these species. Ecosystem processes are the net effect of the actions of individual organisms as they interact with their environment. Ecological theory suggests that in order to coexist, species must have some level of limiting similarity —they must be different from one another in some fundamental way, otherwise, one species would competitively exclude

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3190-408: A slower rate) even after soils become too dry to support plant growth. Ecosystems are dynamic entities. They are subject to periodic disturbances and are always in the process of recovering from past disturbances. When a perturbation occurs, an ecosystem responds by moving away from its initial state. The tendency of an ecosystem to remain close to its equilibrium state, despite that disturbance,

3335-464: A small effect on ecosystem function. Ecologically distinct species, on the other hand, have a much larger effect. Similarly, dominant species have a large effect on ecosystem function, while rare species tend to have a small effect. Keystone species tend to have an effect on ecosystem function that is disproportionate to their abundance in an ecosystem. An ecosystem engineer is any organism that creates, significantly modifies, maintains or destroys

3480-522: A toll on the Yukon River basin, such as flooding in 2009 due to the above average snow and ice levels, followed by and abnormal high spring temperatures. Rapid melting of the ice and snow flooding, erosion, and damage from debris along the river. Not only has the climate change affected the Yukon river and the Yukon river basin but, it has also affected the watershed as a whole. The Yukon River Basin has

3625-649: A total of 50 Aleut civilians and eight sailors were interned in Japan. About half of the Aleuts died during the period of internment. Unalaska / Dutch Harbor and Adak became significant bases for the United States Army , United States Army Air Forces and United States Navy. The United States Lend-Lease program involved flying American warplanes through Canada to Fairbanks and then Nome ; Soviet pilots took possession of these aircraft, ferrying them to fight

3770-468: A variety of approaches—theoretical studies, studies monitoring specific ecosystems over long periods of time, those that look at differences between ecosystems to elucidate how they work and direct manipulative experimentation. Biomes are general classes or categories of ecosystems. However, there is no clear distinction between biomes and ecosystems. Ecosystem classifications are specific kinds of ecological classifications that consider all four elements of

3915-443: A variety of goods and services upon which people depend, and may be part of. Ecosystem goods include the "tangible, material products" of ecosystem processes such as water, food, fuel, construction material, and medicinal plants . Ecosystem services , on the other hand, are generally "improvements in the condition or location of things of value". These include things like the maintenance of hydrological cycles , cleaning air and water,

4060-522: A variety of scales, ranging from whole-ecosystem studies to studying microcosms or mesocosms (simplified representations of ecosystems). American ecologist Stephen R. Carpenter has argued that microcosm experiments can be "irrelevant and diversionary" if they are not carried out in conjunction with field studies done at the ecosystem scale. In such cases, microcosm experiments may fail to accurately predict ecosystem-level dynamics. Biomes are general classes or categories of ecosystems. However, there

4205-489: A year and others receive up to 50 inches (1,300 mm). With that being said, annual rainfall is greater on tall, rugged mountains than on flat lowland areas of the whole region. The average temperature now for the Yukon River Basin is approximately 30 °C (86 °F) in the summer and −40 °C (−40 °F) in the winter. However, the region has some of the most extreme temperature changes for an area that

4350-624: Is a non-contiguous U.S. state on the northwest extremity of North America . Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii . Alaska is also considered to be the northernmost, westernmost, and easternmost (the Aleutian Islands cross the 180th meridian into the eastern hemisphere) state in the United States. It borders the Canadian territory of Yukon and

4495-431: Is a system that environments and their organisms form through their interaction. The biotic and abiotic components are linked together through nutrient cycles and energy flows. Ecosystems are controlled by external and internal factors . External factors such as climate , parent material which forms the soil and topography , control the overall structure of an ecosystem but are not themselves influenced by

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4640-458: Is an international synthesis by over 1000 of the world's leading biological scientists that analyzes the state of the Earth's ecosystems and provides summaries and guidelines for decision-makers. The report identified four major categories of ecosystem services: provisioning, regulating, cultural and supporting services. It concludes that human activity is having a significant and escalating impact on

4785-797: Is based on the testimony of Chukchi geographer Nikolai Daurkin, who had visited Alaska in 1764–1765 and who had reported on a village on the Kheuveren River, populated by "bearded men" who "pray to the icons ". Some modern researchers associate Kheuveren with Koyuk River . The first European vessel to reach Alaska is generally held to be the St. Gabriel under the authority of the surveyor M. S. Gvozdev and assistant navigator I. Fyodorov on August 21, 1732, during an expedition of Siberian Cossack A. F. Shestakov and Russian explorer Dmitry Pavlutsky (1729–1735). Another European contact with Alaska occurred in 1741, when Vitus Bering led an expedition for

4930-884: Is bordered by Canada's Yukon and British Columbia to the east (making it the only state to border only a Canadian territory ); the Gulf of Alaska and the Pacific Ocean to the south and southwest; the Bering Sea , Bering Strait , and Chukchi Sea to the west; and the Arctic Ocean to the north. Alaska's territorial waters touch Russia's territorial waters in the Bering Strait, as the Russian Big Diomede Island and Alaskan Little Diomede Island are only 3 miles (4.8 km) apart. Alaska has

5075-442: Is consumed by animals while still alive and enters the plant-based trophic system. After plants and animals die, the organic matter contained in them enters the detritus-based trophic system. Ecosystem respiration is the sum of respiration by all living organisms (plants, animals, and decomposers) in the ecosystem. Net ecosystem production is the difference between gross primary production (GPP) and ecosystem respiration. In

5220-492: Is divided into boroughs . Delegates to the Alaska Constitutional Convention wanted to avoid the pitfalls of the traditional county system and adopted their own unique model. Many of the more densely populated parts of the state are part of Alaska's 16 boroughs, which function somewhat similarly to counties in other states. Unlike county-equivalents in the other states, the boroughs do not cover

5365-569: Is followed by succession, a "directional change in ecosystem structure and functioning resulting from biotically driven changes in resource supply." The frequency and severity of disturbance determine the way it affects ecosystem function. A major disturbance like a volcanic eruption or glacial advance and retreat leave behind soils that lack plants, animals or organic matter. Ecosystems that experience such disturbances undergo primary succession . A less severe disturbance like forest fires, hurricanes or cultivation result in secondary succession and

5510-554: Is governed by three sets of factors—the physical environment (temperature, moisture, and soil properties), the quantity and quality of the dead material available to decomposers, and the nature of the microbial community itself. Temperature controls the rate of microbial respiration; the higher the temperature, the faster the microbial decomposition occurs. Temperature also affects soil moisture, which affects decomposition. Freeze-thaw cycles also affect decomposition—freezing temperatures kill soil microorganisms, which allows leaching to play

5655-569: Is home to Mount Shishaldin , which is an occasionally smoldering volcano that rises to 10,000 feet (3,000 m) above the North Pacific. The chain of volcanoes extends to Mount Spurr , west of Anchorage on the mainland. Geologists have identified Alaska as part of Wrangellia , a large region consisting of multiple states and Canadian provinces in the Pacific Northwest , which is actively undergoing continent building . One of

5800-412: Is home to the longest salmon runs in history. Salmon from this area are prized for their rich oily meat. This is due to the large fat reserves that they must build up in order to make the long journey up the Yukon River. A few examples of these prized salmon would be of the chinook, coho and chum salmon species. Not only are the salmon prized for their meat, but also as an economic resource for villages in

5945-629: Is known for its massive reserves of crude oil and contains both the National Petroleum Reserve–Alaska and the Prudhoe Bay Oil Field . The city of Utqiaġvik , formerly known as Barrow, is the northernmost city in the United States and is located here. The Northwest Arctic area , anchored by Kotzebue and also containing the Kobuk River valley, is often considered part of this region. The respective Inupiat of

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6090-860: Is located between the Rocky Mountains in the north and the Pacific Mountain system to the south. The Basin spans across Canada in the Yukon Territory and the US state of Alaska. The Yukon Flats basin is south of the Yukon River Basin and it drains deposits and reworked materials into the Flats. It is within the Arctic Complex of the Arctic-Atlantic Bioregion, therefore has freshwater. The Yukon River Basin

6235-428: Is located in a continental zone. Recent studies indicate that temperatures have been steadily rising throughout the region since the 1840s. Climate change has been a serious, on-going issue throughout the Yukon River Basin and other surrounding areas. With drier, hotter temperatures, there have been more forest fires and melting permafrost, which leads to changes in water flows. The recent change in climate has also taken

6380-787: Is made up of 13 other individual basins and stretches across two countries: the United States of America and Canada . The topography of the Yukon Basin is diverse with different elevations. While there are 13 individual basins within the Basin, there are also 5 physio-graphic regions. They include Alaska Range (6,000–9,000 feet or 1,800–2,700 metres), Central and Eastern Brooks Range (7,000–8,000 feet or 2,100–2,400 metres), Indian River Uplands (1,500–2,000 feet or 460–610 metres), Innoko Lowlands (flat flood plains), and Kolkrine-Hodzana Highlands (2,000–4,000 feet or 610–1,220 metres). Half of

6525-455: Is maintained by the Office of History and Archaeology. The survey's inventory of cultural resources includes objects, structures, buildings, sites, districts, and travel ways, with a general provision that they are more than fifty years old. As of 31 January 2012 , more than 35,000 sites have been reported. Alaska is not divided into counties , as most of the other U.S. states, but it

6670-405: Is no clear distinction between biomes and ecosystems. Biomes are always defined at a very general level. Ecosystems can be described at levels that range from very general (in which case the names are sometimes the same as those of biomes) to very specific, such as "wet coastal needle-leafed forests". Biomes vary due to global variations in climate . Biomes are often defined by their structure: at

6815-516: Is now Southeast Alaska , became the capital of Russian America . It remained the capital after the colony was transferred to the United States. The Russians never fully colonized Alaska, and the colony was never very profitable. Evidence of Russian settlement in names and churches survives throughout southeastern Alaska. In 1867, William H. Seward , the United States Secretary of State under President Andrew Johnson , negotiated

6960-617: Is owned and managed by the U.S. federal government as public lands, including a multitude of national forests , national parks, and national wildlife refuges . Of these, the Bureau of Land Management manages 87 million acres (35 million hectares), or 23.8% of the state. The Arctic National Wildlife Refuge is managed by the United States Fish and Wildlife Service . It is the world's largest wildlife refuge, comprising 16 million acres (6.5 million hectares). Of

7105-531: Is primarily achieved through bacterial and fungal action. Fungal hyphae produce enzymes that can break through the tough outer structures surrounding dead plant material. They also produce enzymes that break down lignin , which allows them access to both cell contents and the nitrogen in the lignin. Fungi can transfer carbon and nitrogen through their hyphal networks and thus, unlike bacteria, are not dependent solely on locally available resources. Decomposition rates vary among ecosystems. The rate of decomposition

7250-532: Is proportionally the second highest of any U.S. state, at over 15 percent, after only Hawaii. The name "Alaska" ( Russian : Аля́ска , romanized :  Aljáska ) was introduced during the Russian colonial period when it was used to refer to the Alaska Peninsula . It was derived from an Aleut-language idiom , alaxsxaq , meaning "the mainland" or, more literally, "the object towards which

7395-580: Is technically part of the continental U.S. , but is not usually included in the colloquial use of the term; Alaska is not part of the contiguous U.S. , often called " the Lower 48 ". The capital city, Juneau , is situated on the mainland of the North American continent but is not connected by road to the rest of the North American highway system. The largest lake in Alaska is Lake Illiamna . The state

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7540-485: Is termed its resistance . The capacity of a system to absorb disturbance and reorganize while undergoing change so as to retain essentially the same function, structure, identity, and feedbacks is termed its ecological resilience . Resilience thinking also includes humanity as an integral part of the biosphere where we are dependent on ecosystem services for our survival and must build and maintain their natural capacities to withstand shocks and disturbances. Time plays

7685-422: Is the "best" classification. Ecosystem classifications are specific kinds of ecological classifications that consider all four elements of the definition of ecosystems : a biotic component, an abiotic complex, the interactions between and within them, and the physical space they occupy. Different approaches to ecological classifications have been developed in terrestrial, freshwater and marine disciplines, and

7830-555: Is the largest glacier in North America, covering 2,008 square miles (5,200 km ) alone. There are no officially defined borders demarcating the various regions of Alaska, but there are five/six regions that the state is most commonly broken up into: The most populous region of Alaska contains Anchorage , the Matanuska-Susitna Valley and the Kenai Peninsula . Rural, mostly unpopulated areas south of

7975-596: Is the northernmost and westernmost state in the United States, but also has the most easterly longitude in the United States because the Aleutian Islands extend into the Eastern Hemisphere . Alaska is the only non- contiguous U.S. state on continental North America; about 500 miles (800 km) of Canadian territory consisting of British Columbia (in Canada ) separates Alaska from Washington . It

8120-614: Is today Southeast Alaska, along with parts of British Columbia and the Yukon . Also in Southeast were the Haida , now well known for their unique arts. The Tsimshian people came to Alaska from British Columbia in 1887, when President Grover Cleveland , and later the U.S. Congress, granted them permission to settle on Annette Island and found the town of Metlakatla, Alaska . All three of these peoples, as well as other indigenous peoples of

8265-650: The Exxon Valdez hit a reef in the Prince William Sound, spilling more than 11 million gallons (42 megalitres) of crude oil over 1,100 miles (1,800 km) of coastline. Today, the battle between philosophies of development and conservation is seen in the contentious debate over oil drilling in the Arctic National Wildlife Refuge and the proposed Pebble Mine . Located at the northwest corner of North America , Alaska

8410-583: The Alaska Peninsula are considered part of the Southwest, with the Aleutian Islands often (but not always) being grouped in as well. While primarily part of Southwest Alaska when grouped economically, the Aleutian islands are sometimes recognized as an alternate group from the rest of the region due to the geographic separation from the continent. More than 300 small volcanic islands make up this chain, which stretches more than 1,200 miles (1,900 km) into

8555-755: The Alaska Purchase (referred to pejoratively as Seward's Folly) with the Russians for $ 7.2 million. Russia's contemporary ruler Tsar Alexander II , the Emperor of the Russian Empire , King of Poland and Grand Duke of Finland , also planned the sale; the purchase was made on March 30, 1867. Six months later the commissioners arrived in Sitka and the formal transfer was arranged; the formal flag-raising took place at Fort Sitka on October 18, 1867. In

8700-631: The Alaska Purchase . The region is dominated by the Alexander Archipelago as well as the Tongass National Forest , the largest national forest in the United States. It contains the state capital Juneau , the former capital Sitka , and Ketchikan , at one time Alaska's largest city. The Alaska Marine Highway provides a vital surface transportation link throughout the area and country, as only three communities ( Haines , Hyder and Skagway ) enjoy direct connections to

8845-669: The Alaska Range and west of the Wrangell Mountains also fall within the definition of South Central, as do the Prince William Sound area and the communities of Cordova and Valdez . Also referred to as the Panhandle or Inside Passage , this is the region of Alaska closest to the contiguous states. As such, this was where most of the initial non-indigenous settlement occurred in the years following

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8990-581: The Bering land bridge . The Russian Empire was the first to actively colonize the area beginning in the 18th century, eventually establishing Russian America , which spanned most of the current state and promoted and maintained a native Alaskan Creole population. The expense and logistical difficulty of maintaining this distant possession prompted its sale to the U.S. in 1867 for US$ 7.2 million (equivalent to $ 157 million in 2023). The area went through several administrative changes before becoming organized as

9135-667: The National Wildlife Refuge system , parts of 25 rivers to the National Wild and Scenic Rivers system , 3.3 million acres (13,000 km ) to National Forest lands , and 43.6 million acres (176,000 km ) to National Park land . Because of the Act, Alaska now contains two-thirds of all American national parklands. Today, more than half of Alaskan land is owned by the Federal Government . In 1989,

9280-622: The province of British Columbia to the east. It shares a western maritime border, in the Bering Strait , with Russia's Chukotka Autonomous Okrug . The Chukchi and Beaufort Seas of the Arctic Ocean lie to the north, and the Pacific Ocean lies to the south. Technically, it is a semi-exclave of the U.S., and is the largest exclave in the world. Alaska is the largest U.S. state by area, comprising more total area than

9425-418: The public record in Alaska. The state is divided into 34 recording districts which are centrally administered under a state recorder . All recording districts use the same acceptance criteria, fee schedule, etc., for accepting documents into the public record. Whereas many U.S. states use a three-tiered system of decentralization—state/county/township—most of Alaska uses only two tiers—state/borough. Owing to

9570-555: The resource inputs are generally controlled by external processes like climate and parent material, the availability of these resources within the ecosystem is controlled by internal factors like decomposition, root competition or shading. Other factors like disturbance, succession or the types of species present are also internal factors. Primary production is the production of organic matter from inorganic carbon sources. This mainly occurs through photosynthesis . The energy incorporated through this process supports life on earth, while

9715-435: The "tangible, material products" of ecosystem processes such as water, food, fuel, construction material, and medicinal plants . They also include less tangible items like tourism and recreation, and genes from wild plants and animals that can be used to improve domestic species. Ecosystem services , on the other hand, are generally "improvements in the condition or location of things of value". These include things like

9860-469: The 29th the situation improved and rescue helicopters and observation aircraft were deployed. A military airlift immediately began shipping relief supplies to Alaska, eventually delivering 2,570,000 pounds (1,170,000 kg) of food and other supplies. Broadcast journalist, Genie Chance , assisted in recovery and relief efforts, staying on the KENI air waves over Anchorage for more than 24 continuous hours as

10005-675: The Alaska Division of Emergency Services to respond to any future disasters. The 1968 discovery of oil at Prudhoe Bay and the 1977 completion of the Trans-Alaska Pipeline System led to an oil boom. Royalty revenues from oil have funded large state budgets from 1980 onward. Oil production was not the only economic value of Alaska's land. In the second half of the 20th century, Alaska discovered tourism as an important source of revenue. Tourism became popular after World War II when military personnel stationed in

10150-671: The German invasion of the Soviet Union . The construction of military bases contributed to the population growth of some Alaskan cities. Statehood for Alaska was an important cause of James Wickersham early in his tenure as a congressional delegate. Decades later, the statehood movement gained its first real momentum following a territorial referendum in 1946. The Alaska Statehood Committee and Alaska's Constitutional Convention would soon follow. Statehood supporters also found themselves fighting major battles against political foes, mostly in

10295-593: The North Slope and of the Northwest Arctic seldom consider themselves to be one people. Southwest Alaska is a sparsely inhabited region stretching some 500 miles (800 km) inland from the Bering Sea. Most of the population lives along the coast. Kodiak Island is also located in the Southwest. The massive Yukon–Kuskokwim Delta , one of the largest river deltas in the world, is here. Portions of

10440-583: The Pacific Northwest Coast , experienced smallpox outbreaks from the late 18th through the mid- 19th century , with the most devastating epidemics occurring in the 1830s and 1860s, resulting in high fatalities and social disruption. Some researchers believe the first Russian settlement in Alaska was established in the 17th century. According to this hypothesis, in 1648 several koches of Semyon Dezhnyov 's expedition came ashore in Alaska by storm and founded this settlement. This hypothesis

10585-619: The Pacific Northwest. In 1789, a Spanish settlement and fort were built in Nootka Sound . These expeditions gave names to places such as Valdez , Bucareli Sound , and Cordova . Later, the Russian-American Company carried out an expanded colonization program during the early-to-mid-19th century. Sitka , renamed New Archangel from 1804 to 1867, on Baranof Island in the Alexander Archipelago in what

10730-654: The Pacific Ocean. Some of these islands fall in the Eastern Hemisphere, but the International Date Line was drawn west of 180° to keep the whole state, and thus the entire North American continent, within the same legal day. Two of the islands, Attu and Kiska , were occupied by Japanese forces during World War II. According to an October 1998 report by the United States Bureau of Land Management , approximately 65% of Alaska

10875-462: The Russian Navy aboard the St. Peter . After his crew returned to Russia with sea otter pelts judged to be the finest fur in the world, small associations of fur traders began to sail from the shores of Siberia toward the Aleutian Islands. The first permanent European settlement was founded in 1784. Between 1774 and 1800, Spain sent several expeditions to Alaska to assert its claim over

11020-436: The U.S. Congress but also within Alaska. Statehood was approved by the U.S. Congress on July 7, 1958; Alaska was officially proclaimed a state on January 3, 1959. On March 27, 1964, the massive Good Friday earthquake killed 133 people and destroyed several villages and portions of large coastal communities, mainly by the resultant tsunamis and landslides. It was the fourth-most-powerful earthquake in recorded history, with

11165-507: The Yukon River Basin is frozen over for nearly 8 months out of the year. The climate around the Yukon River Basin varies because of factors like its topography and large size. This large area covers land from Alaska and from parts of the Yukon Territory in Canada . The precipitation over the entire basin is approximately 19 inches (480 mm) per year. With the diverse topography certain places receive more rain than others. Some areas receive less than 10 inches (250 mm) of rainfall

11310-463: The Yukon River Basin lies in Canada, with the other half occupying space in Alaska. The Yukon River Basin is made up of many different geological terrains, with a variety of different rocks that make up the basin itself. These include various types of sedimentary , igneous , and metamorphic rocks There are several different land types that make up the entirety of the Yukon River Basin. These include

11455-456: The Yukon River Basin. Because of the level of permafrost in the basin, the basin itself is far more prone to flash floods. The melting of permafrost is believed to be one of the reasons that the Yukon River Basin's flow has increased over the years, causing erosion of the basin. The Yukon River Basin drains from east to west, with the temperature of the water increasing as the water flows down stream. The water, fish, and other animals throughout

11600-532: The Yukon river and Yukon River basin was with minerals. Their mining ventures grew and spread until they reached the Stewart River , where they found gold, starting the Klondike Gold Rush . The Yukon River Basin is approximately 330,000 square miles (850,000 km) in area and 1,980 miles (3,190 km) in length. This makes the Yukon River Basin the fourth largest basin in North America. It

11745-505: The Yukon river. The Yukon River Basin has 4 towns/cities and 43 villages, with approximately 126,000 currently inhabitants. Of those, 10 percent still rely solely on the land and 83 percent are indigenous . In the towns of Dawson and Faro, there are 1,000-2,000 residents. The city Whitehorse has over 23,000 residents, while Fairbanks had around 84,000 residents. Villages around the basin hold anywhere from 30 to 800 people. Ecosystem An ecosystem (or ecological system )

11890-481: The absence of disturbance, net ecosystem production is equivalent to the net carbon accumulation in the ecosystem. Energy can also be released from an ecosystem through disturbances such as wildfire or transferred to other ecosystems (e.g., from a forest to a stream to a lake) by erosion . In aquatic systems , the proportion of plant biomass that gets consumed by herbivores is much higher than in terrestrial systems. In trophic systems, photosynthetic organisms are

12035-574: The action of the sea is directed". Numerous indigenous peoples occupied Alaska for thousands of years before the arrival of European peoples to the area. Linguistic and DNA studies done here have provided evidence for the settlement of North America by way of the Bering land bridge . At the Upward Sun River site in the Tanana Valley in Alaska, remains of a six-week-old infant were found. The baby's DNA showed that she belonged to

12180-402: The amount of energy available to the ecosystem. Parent material determines the nature of the soil in an ecosystem, and influences the supply of mineral nutrients. Topography also controls ecosystem processes by affecting things like microclimate , soil development and the movement of water through a system. For example, ecosystems can be quite different if situated in a small depression on

12325-504: The amount of light available, the amount of leaf area a plant has to capture light (shading by other plants is a major limitation of photosynthesis), the rate at which carbon dioxide can be supplied to the chloroplasts to support photosynthesis, the availability of water, and the availability of suitable temperatures for carrying out photosynthesis. Energy and carbon enter ecosystems through photosynthesis, are incorporated into living tissue, transferred to other organisms that feed on

12470-476: The area. In these areas the salmon are typically dried, smoked, and frozen. Without these salmon runs it is possible that the ecosystem might not thrive. Therefore, the fisheries are managed by the Alaska Department of Fish and Game along with other national and international treaties. Many studies have been done to watch the migratory patterns of the salmon. In one particular study researchers studied

12615-414: The basin are used by local inhabitants for various reasons, which is why it is very important that the quality of the water be checked often and be healthy. Water quality varies from site to site throughout the Yukon River Basin, for example the density throughout the eastern and southern sites of the basin is much more prominent than that of the western and northern cites. Because of its northern location,

12760-412: The basin there are more than 150 bird species, 40 mammals, and 18 fish species. There is an estimated 1.5 million ducks that breed here annually. It is also home to the longest salmon runs in history. Plant life includes white spruce, paper birch, and quaking aspen forests, willow and alder thickets, grasslands, and meows. In these areas are where the animals of the ecosystem thrive. The Yukon River Basin

12905-491: The biodiversity of the world ecosystems, reducing both their resilience and biocapacity . The report refers to natural systems as humanity's "life-support system", providing essential ecosystem services. The assessment measures 24 ecosystem services and concludes that only four have shown improvement over the last 50 years, 15 are in serious decline, and five are in a precarious condition. Alaska Alaska ( / ə ˈ l æ s k ə / ə- LASS -kə )

13050-408: The carbon makes up much of the organic matter in living and dead biomass, soil carbon and fossil fuels . It also drives the carbon cycle , which influences global climate via the greenhouse effect . Through the process of photosynthesis, plants capture energy from light and use it to combine carbon dioxide and water to produce carbohydrates and oxygen . The photosynthesis carried out by all

13195-494: The ceremony, 250 uniformed U.S. soldiers marched to the governor's house at "Castle Hill", where the Russian troops lowered the Russian flag and the U.S. flag was raised. This event is celebrated as Alaska Day , a legal holiday on October 18. Alaska was loosely governed by the military initially and was administered as a district starting in 1884, with a governor appointed by the United States president. A federal district court

13340-555: The city proper and the communities of Eagle River, Chugiak, Peters Creek, Girdwood, Bird, and Indian. Fairbanks has a separate borough (the Fairbanks North Star Borough ) and municipality (the City of Fairbanks). The state's most populous city is Anchorage , home to 291,247 people in 2020. The richest location in Alaska by per capita income is Denali ($ 42,245). Yakutat City , Sitka, Juneau, and Anchorage are

13485-432: The combustion of fossil fuels, ammonia gas which evaporates from agricultural fields which have had fertilizers applied to them, and dust. Anthropogenic nitrogen inputs account for about 80% of all nitrogen fluxes in ecosystems. When plant tissues are shed or are eaten, the nitrogen in those tissues becomes available to animals and microbes. Microbial decomposition releases nitrogen compounds from dead organic matter in

13630-429: The community, disseminating information about shelters and prepared food rations, passing messages of well-being between loved ones, and helping to reunite families. In the longer term, the U.S. Army Corps of Engineers led the effort to rebuild roads, clear debris, and establish new townsites for communities that had been completely destroyed, at a cost of $ 110 million. The West Coast and Alaska Tsunami Warning Center

13775-418: The concept to draw attention to the importance of transfers of materials between organisms and their environment. He later refined the term, describing it as "The whole system, ... including not only the organism-complex, but also the whole complex of physical factors forming what we call the environment". Tansley regarded ecosystems not simply as natural units, but as "mental isolates". Tansley later defined

13920-410: The contiguous North American road system. The Interior is the largest region of Alaska; much of it is uninhabited wilderness. Fairbanks is the only large city in the region. Denali National Park and Preserve is located here. Denali , formerly Mount McKinley, is the highest mountain in North America and is also located here. The North Slope is mostly tundra peppered with small villages. The area

14065-462: The damage done by the earthquake to the city. The team, called the Engineering and Geological Evaluation Group, was headed by Ruth A. M. Schmidt , a geology professor at the University of Alaska Anchorage . The team of scientists came into conflict with local developers and downtown business owners who wanted to immediately rebuild; the scientists wanted to identify future dangers to ensure that

14210-403: The dead organic matter would accumulate in an ecosystem, and nutrients and atmospheric carbon dioxide would be depleted. Decomposition processes can be separated into three categories— leaching , fragmentation and chemical alteration of dead material. As water moves through dead organic matter, it dissolves and carries with it the water-soluble components. These are then taken up by organisms in

14355-447: The definition of ecosystems : a biotic component, an abiotic complex, the interactions between and within them, and the physical space they occupy. Biotic factors of the ecosystem are living things; such as plants, animals, and bacteria, while abiotic are non-living components; such as water, soil and atmosphere. Plants allow energy to enter the system through photosynthesis , building up plant tissue. Animals play an important role in

14500-524: The earthquake was also reported from Florida and Texas . Alaska had never experienced a major disaster in a highly populated area before and had very limited resources for dealing with the effects of such an event. In Anchorage, at the urging of geologist Lidia Selkregg , the City of Anchorage and the Alaska State Housing Authority appointed a team of 40 scientists, including geologists, soil scientists, and engineers, to assess

14645-466: The economy; more than half of the state is federally-owned land containing national forests , national parks , and wildlife refuges . It is among the most irreligious states , one of the first to legalize recreational marijuana , and is known for its libertarian-leaning political culture, generally supporting the Republican Party in national elections. The Indigenous population of Alaska

14790-655: The ecosystem or to gradual disruption of biotic processes and degradation of abiotic conditions of the ecosystem. Once the original ecosystem has lost its defining features, it is considered "collapsed ". Ecosystem restoration can contribute to achieving the Sustainable Development Goals . An ecosystem (or ecological system) consists of all the organisms and the abiotic pools (or physical environment) with which they interact. The biotic and abiotic components are linked together through nutrient cycles and energy flows. "Ecosystem processes" are

14935-528: The ecosystem. Internal factors are controlled, for example, by decomposition , root competition, shading, disturbance, succession, and the types of species present. While the resource inputs are generally controlled by external processes, the availability of these resources within the ecosystem is controlled by internal factors. Therefore, internal factors not only control ecosystem processes but are also controlled by them. Ecosystems are dynamic entities—they are subject to periodic disturbances and are always in

15080-421: The flow of energy through a lake was the primary driver of the ecosystem. Hutchinson's students, brothers Howard T. Odum and Eugene P. Odum , further developed a "systems approach" to the study of ecosystems. This allowed them to study the flow of energy and material through ecological systems. Ecosystems are controlled by both external and internal factors. External factors, also called state factors, control

15225-467: The following three largest states of Texas , California , and Montana combined, and is the seventh-largest subnational division in the world . It is the third-least populous and most sparsely populated U.S. state, but is, with a population of 736,081 as of 2020 , the continent's most populous territory located mostly north of the 60th parallel , with more than quadruple the combined populations of Northern Canada and Greenland . The state contains

15370-399: The forests of eastern North America still show legacies of cultivation which ceased in 1850 when large areas were reverted to forests. Another example is the methane production in eastern Siberian lakes that is controlled by organic matter which accumulated during the Pleistocene . Ecosystems continually exchange energy and carbon with the wider environment . Mineral nutrients, on

15515-481: The four largest cities in the U.S. by area . As reflected in the 2020 United States census , Alaska has a total of 355 incorporated cities and census-designated places (CDPs). The tally of cities includes four unified municipalities, essentially the equivalent of a consolidated city–county . The majority of these communities are located in the rural expanse of Alaska known as " The Bush " and are unconnected to that contiguous North American road network. The table at

15660-416: The four largest cities in the United States by area , including the state capital of Juneau . The state's most populous city is Anchorage , and approximately half of Alaska's residents live within its metropolitan area . Indigenous people have lived in Alaska for thousands of years, and it is widely believed that the region served as the entry point for the initial settlement of North America by way of

15805-691: The landscape, versus one present on an adjacent steep hillside. Other external factors that play an important role in ecosystem functioning include time and potential biota , the organisms that are present in a region and could potentially occupy a particular site. Ecosystems in similar environments that are located in different parts of the world can end up doing things very differently simply because they have different pools of species present. The introduction of non-native species can cause substantial shifts in ecosystem function. Unlike external factors, internal factors in ecosystems not only control ecosystem processes but are also controlled by them. While

15950-432: The largest private landowner in Alaska in advertisements and other communications. Provisions of ANCSA allowing the corporations' land holdings to be sold on the open market starting in 1991 were repealed before they could take effect. Effectively, the corporations hold title (including subsurface title in many cases, a privilege denied to individual Alaskans) but cannot sell the land. Individual Native allotments are sold on

16095-423: The living and dead plant matter, and eventually released through respiration. The carbon and energy incorporated into plant tissues (net primary production) is either consumed by animals while the plant is alive, or it remains uneaten when the plant tissue dies and becomes detritus . In terrestrial ecosystems , the vast majority of the net primary production ends up being broken down by decomposers . The remainder

16240-637: The low population density, most of the land is located in the Unorganized Borough . As the name implies, it has no intermediate borough government but is administered directly by the state government. In 2000, 57.71% of Alaska's area has this status, with 13.05% of the population. Anchorage merged the city government with the Greater Anchorage Area Borough in 1975 to form the Municipality of Anchorage, containing

16385-408: The maintenance of hydrological cycles, cleaning air and water, the maintenance of oxygen in the atmosphere, crop pollination and even things like beauty, inspiration and opportunities for research. While material from the ecosystem had traditionally been recognized as being the basis for things of economic value, ecosystem services tend to be taken for granted. The Millennium Ecosystem Assessment

16530-405: The maintenance of oxygen in the atmosphere, crop pollination and even things like beauty, inspiration and opportunities for research. Many ecosystems become degraded through human impacts, such as soil loss , air and water pollution , habitat fragmentation , water diversion , fire suppression , and introduced species and invasive species . These threats can lead to abrupt transformation of

16675-411: The migratory patterns of wild chinook salmon . They did this by capturing and tagging adult chinook salmon from June to mid July in the lower Yukon river. The tagged fish had radio transmitters, which were used to track the salmon and their migration patterns throughout the Yukon river. This data was then used to monitor the salmon in the river system. This is data regarding Chinook salmon migration in

16820-808: The most powerful earthquake recorded in North American history, and the second most powerful earthquake recorded in world history. The Good Friday earthquake lasted 4 minutes and 38 seconds. Six hundred miles (970 km) of fault ruptured at once and moved up to 60 ft (18 m), releasing about 500 years of stress buildup. Soil liquefaction , fissures, landslides, and other ground failures caused major structural damage in several communities and much damage to property. Anchorage sustained great destruction or damage to many inadequately earthquake-engineered houses, buildings, and infrastructure (paved streets, sidewalks, water and sewer mains, electrical systems, and other human-made equipment), particularly in

16965-433: The movement of matter and energy through the system, by feeding on plants and on one another. They also influence the quantity of plant and microbial biomass present. By breaking down dead organic matter , decomposers release carbon back to the atmosphere and facilitate nutrient cycling by converting nutrients stored in dead biomass back to a form that can be readily used by plants and microbes. Ecosystems provide

17110-415: The needleleaf forest, tall and low shrublands, broadleaf forest, lichens, barren, wet herbaceous, dwarf shrublands, dry herbaceous, ice/snow, and rivers, streams, and lakes. There are also many different types of soils that make up the Yukon River Basin. These soils include Entisols , Gelisols , Inceptisols , Inceptisols/Gelisols, Mollisols, Spodosols , and Rough Mountainous Land. Permafrost dominates

17255-522: The often remote and roadless locations. The University of Alaska , as a land grant university , also owns substantial acreage which it manages independently. Another 44 million acres (18 million hectares) are owned by 12 regional, and scores of local, Native corporations created under the Alaska Native Claims Settlement Act (ANCSA) of 1971. Regional Native corporation Doyon, Limited often promotes itself as

17400-412: The open market. Various private interests own the remaining land, totaling about one percent of the state. Alaska is, by a large margin, the state with the smallest percentage of private land ownership when Native corporation holdings are excluded. The Alaska Heritage Resources Survey (AHRS) is a restricted inventory of all reported historic and prehistoric sites within the U.S. state of Alaska; it

17545-537: The other hand, are mostly cycled back and forth between plants, animals, microbes and the soil. Most nitrogen enters ecosystems through biological nitrogen fixation , is deposited through precipitation, dust, gases or is applied as fertilizer . Most terrestrial ecosystems are nitrogen-limited in the short term making nitrogen cycling an important control on ecosystem production. Over the long term, phosphorus availability can also be critical. Macronutrients which are required by all plants in large quantities include

17690-509: The other. Despite this, the cumulative effect of additional species in an ecosystem is not linear: additional species may enhance nitrogen retention, for example. However, beyond some level of species richness, additional species may have little additive effect unless they differ substantially from species already present. This is the case for example for exotic species . The addition (or loss) of species that are ecologically similar to those already present in an ecosystem tends to only have

17835-403: The overall structure of an ecosystem and the way things work within it, but are not themselves influenced by the ecosystem. On broad geographic scales, climate is the factor that "most strongly determines ecosystem processes and structure". Climate determines the biome in which the ecosystem is embedded. Rainfall patterns and seasonal temperatures influence photosynthesis and thereby determine

17980-405: The plants in an ecosystem is called the gross primary production (GPP). About half of the gross GPP is respired by plants in order to provide the energy that supports their growth and maintenance. The remainder, that portion of GPP that is not used up by respiration, is known as the net primary production (NPP). Total photosynthesis is limited by a range of environmental factors. These include

18125-585: The primary nutrients (which are most limiting as they are used in largest amounts): Nitrogen, phosphorus, potassium. Secondary major nutrients (less often limiting) include: Calcium, magnesium, sulfur. Micronutrients required by all plants in small quantities include boron, chloride, copper, iron, manganese, molybdenum, zinc. Finally, there are also beneficial nutrients which may be required by certain plants or by plants under specific environmental conditions: aluminum, cobalt, iodine, nickel, selenium, silicon, sodium, vanadium. Until modern times, nitrogen fixation

18270-413: The primary producers. The organisms that consume their tissues are called primary consumers or secondary producers — herbivores . Organisms which feed on microbes ( bacteria and fungi ) are termed microbivores . Animals that feed on primary consumers— carnivores —are secondary consumers. Each of these constitutes a trophic level. The sequence of consumption—from plant to herbivore, to carnivore—forms

18415-419: The process of recovering from some past disturbance. The tendency of an ecosystem to remain close to its equilibrium state, despite that disturbance, is termed its resistance . The capacity of a system to absorb disturbance and reorganize while undergoing change so as to retain essentially the same function, structure, identity, and feedbacks is termed its ecological resilience . Ecosystems can be studied through

18560-428: The rebuilt infrastructure would be safe. The team produced a report on May 8, 1964, just a little more than a month after the earthquake. The United States military, which has a large active presence in Alaska, also stepped in to assist within moments of the end of the quake. The U.S. Army rapidly re-established communications with the lower 48 states, deployed troops to assist the citizens of Anchorage, and dispatched

18705-602: The region returned home praising its natural splendor. The Alcan Highway , built during the war, and the Alaska Marine Highway System , completed in 1963, made the state more accessible than before. Tourism has become increasingly important in Alaska, and today over 1.4 million people visit the state each year. With tourism more vital to the economy, environmentalism also rose in importance. The Alaska National Interest Lands Conservation Act (ANILCA) of 1980 added 53.7 million acres (217,000 km ) to

18850-514: The remaining land area, the state of Alaska owns 101 million acres (41 million hectares), its entitlement under the Alaska Statehood Act . A portion of that acreage is occasionally ceded to the organized boroughs presented above, under the statutory provisions pertaining to newly formed boroughs. Smaller portions are set aside for rural subdivisions and other homesteading-related opportunities. These are not very popular due to

18995-555: The several landslide zones along Knik Arm . Two hundred miles (320 km) southwest, some areas near Kodiak were permanently raised by 30 feet (9 m). Southeast of Anchorage, areas around the head of Turnagain Arm near Girdwood and Portage dropped as much as 8 feet (2.4 m), requiring reconstruction and fill to raise the Seward Highway above the new high tide mark. In Prince William Sound , Port Valdez suffered

19140-611: The soil, react with mineral soil, or are transported beyond the confines of the ecosystem (and are considered lost to it). Newly shed leaves and newly dead animals have high concentrations of water-soluble components and include sugars , amino acids and mineral nutrients. Leaching is more important in wet environments and less important in dry ones. Fragmentation processes break organic material into smaller pieces, exposing new surfaces for colonization by microbes. Freshly shed leaf litter may be inaccessible due to an outer layer of cuticle or bark , and cell contents are protected by

19285-511: The soil, where plants, fungi, and bacteria compete for it. Some soil bacteria use organic nitrogen-containing compounds as a source of carbon, and release ammonium ions into the soil. This process is known as nitrogen mineralization . Others convert ammonium to nitrite and nitrate ions, a process known as nitrification . Nitric oxide and nitrous oxide are also produced during nitrification. Under nitrogen-rich and oxygen-poor conditions, nitrates and nitrites are converted to nitrogen gas ,

19430-483: The spatial extent of ecosystems using the term " ecotope ". G. Evelyn Hutchinson , a limnologist who was a contemporary of Tansley's, combined Charles Elton 's ideas about trophic ecology with those of Russian geochemist Vladimir Vernadsky . As a result, he suggested that mineral nutrient availability in a lake limited algal production . This would, in turn, limit the abundance of animals that feed on algae. Raymond Lindeman took these ideas further to suggest that

19575-470: The state's entire land area. The area not part of any borough is referred to as the Unorganized Borough . The Unorganized Borough has no government of its own, but the U.S. Census Bureau in cooperation with the state divided the Unorganized Borough into 11 census areas solely for the purposes of statistical analysis and presentation. A recording district is a mechanism for management of

19720-421: The transfers of energy and materials from one pool to another. Ecosystem processes are known to "take place at a wide range of scales". Therefore, the correct scale of study depends on the question asked. The term "ecosystem" was first used in 1935 in a publication by British ecologist Arthur Tansley . The term was coined by Arthur Roy Clapham , who came up with the word at Tansley's request. Tansley devised

19865-522: The voice of calm from her temporary post within the Anchorage Public Safety Building. She was effectively designated as the public safety officer by the city's police chief. Chance provided breaking news of the catastrophic events that continued to develop following the magnitude 9.2 earthquake, and she served as the voice of the public safety office, coordinating response efforts, connecting available resources to needs around

20010-430: The western part of the Yukon Basin. They migrated across the land bridge, Beringia , living without influence from other cultures for hundreds of years. The earliest exploration and European settlement in the Yukon River Basin was by Robert Campbell in 1840. Early explorers like Campbell came not for gold but for furs. In the 1870s, explorers like Leroy McQuesten, Arthur Harper , and Alfred Mayo discovered how plentiful

20155-476: The world . If it was an independent nation, it would be the 18th largest country in the world; almost the same size as Iran . With its myriad of islands, Alaska has nearly 34,000 miles (55,000 km) of tidal shoreline. The Aleutian Islands chain extends west from the southern tip of the Alaska Peninsula . Many active volcanoes are found in the Aleutians and in coastal regions. Unimak Island , for example,

20300-520: The world's largest tides occurs in Turnagain Arm , just south of Anchorage, where tidal differences can be more than 35 feet (10.7 m). Alaska has more than 409,000 natural lakes at least one hectare or bigger. Marshlands and wetland permafrost cover 188,320 square miles (487,700 km ) (mostly in northern, western and southwest flatlands). Glacier ice covers about 28,957 square miles (75,000 km ) of Alaska. The Bering Glacier

20445-512: Was extremely limited or unavailable until statehood took effect in 1959. Starting in the 1890s and stretching in some places to the early 1910s, gold rushes in Alaska and the nearby Yukon Territory brought thousands of miners and settlers to Alaska. From 1879 to 1920, Alaska produced a cumulative total of over $ 460,000,000 ($ 6,691,927,500 inflation-adjusted) of mineral production. Alaska was officially incorporated as an organized territory in 1912. Alaska's capital, which had been in Sitka until 1906,

20590-492: Was formed as a direct response to the disaster. Federal disaster relief funds paid for reconstruction as well as financially supporting the devastated infrastructure of Alaska's government, spending hundreds of millions of dollars that helped keep Alaska financially solvent until the discovery of massive oil deposits at Prudhoe Bay . At the order of the U.S. Defense Department , the Alaska National Guard founded

20735-408: Was headquartered in Sitka. For most of Alaska's first decade under the United States flag, Sitka was the only community inhabited by American settlers. They organized a "provisional city government", which was Alaska's first municipal government, but not in a legal sense. Legislation allowing Alaskan communities to legally incorporate as cities did not come about until 1900, and home rule for cities

20880-779: Was moved north to Juneau . Construction of the Alaska Governor's Mansion began that same year. European immigrants from Norway and Sweden also settled in southeast Alaska, where they entered the fishing and logging industries. During World War II , the Aleutian Islands Campaign focused on Attu , Agattu and Kiska , all of which were occupied by the Empire of Japan . During the Japanese occupation, an American civilian and two United States Navy personnel were killed at Attu and Kiska respectively, and nearly

21025-679: Was the major source of nitrogen for ecosystems. Nitrogen-fixing bacteria either live symbiotically with plants or live freely in the soil. The energetic cost is high for plants that support nitrogen-fixing symbionts—as much as 25% of gross primary production when measured in controlled conditions. Many members of the legume plant family support nitrogen-fixing symbionts. Some cyanobacteria are also capable of nitrogen fixation. These are phototrophs , which carry out photosynthesis. Like other nitrogen-fixing bacteria, they can either be free-living or have symbiotic relationships with plants. Other sources of nitrogen include acid deposition produced through

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