Postglacial vegetation refers to plants that colonize the newly exposed substrate after a glacial retreat. [1] The term "postglacial" typically refers to processes and events that occur after the departure of glacial ice or glacial climates. [2]
Climate change is the main force behind changes in species distribution and abundance. Repeated changes in climate throughout the Quaternary Period are thought to have had a significant impact on the current vegetation species diversity present today. [3] Functional and phylogenetic diversity are considered to be closely related to changing climatic conditions and this indicates that trait differences are extremely important in long term responses to climate change. During the transition from the last glaciation of the Pleistocene to the Holocene period, climate warming resulted in the expansion of taller plants and larger seed bearing plants which resulted in lower proportions of vegetation regeneration. [4] Hence, low temperatures can be strong environmental filters that prevent tall and large-seeded plants from establishing in postglacial environments. [5] Throughout Europe vegetation dynamics within the first half of the Holocene appear to have been influenced mainly by climate and the reorganization of atmospheric circulation associated with the disappearance of the North American ice sheet. This is evident in the rapid increase of forestation and changing biomes during the postglacial period between 11500ka and 8000ka before the present. [6] [7] Vegetation development periods of post-glacial land forms on Ellesmere Island, Northern Canada, is assumed to have been at least ca. 20,000 years in duration. This slow progression is mostly due to climatic restrictions such as an estimated annual rainfall amount of only 64mm and a mean annual temperature of -19.7 degrees Celsius. The length in time of vegetation development observed on Ellesmere Island is evidence that post glacial vegetation development is much more restricted in the Arctic and colder climates as compared to milder climatic regions such as the boreal, temperate and tropical zones. [8]
As land became exposed following the glaciation of the last ice age, a variety of geographic settings ranging from the tropics to the Arctic and Antarctic became available for the establishment of vegetation. Species that now exist on formerly glaciated terrain must have undergone a change in distribution of hundreds to thousands of kilometers, or have evolved from other taxa that have once done so in the past. [9] In a newly developing environment, plant growth is often strongly influenced by the introduction of new organisms into that environment, where competitive or mutualistic relationships may develop. Often, competitive balances are eventually reached and species abundances remain somewhat constant over a period of generations. Studies done on the Norwegian Island of Svalbard, have been very useful in understanding the behavior of postglacial vegetation. Studies show that many vascular plants that are considered pioneers of vegetation development, eventually become less frequent. For example, the abundance of species such as Braya purpurascens has fallen nearly 30% due to the introduction of new species in the area. [10]
Arctic vegetation has distinct postglacial development characteristics compared to the more temperate zones of lower latitudes. A study of postglacial moraines conducted in the Canadian Arctic on Ellesmere Island have found that dwarf shrubs of Dryas integrifolia and Cassiope tetragona are often good indicators of vegetation development and progression. Dwarf shrubs have been found to increase with the age of the moraine, with Dryas integrifolia becoming the most predominant. As well the cover of vegetation, including lichens and bryophytes showed consistent increase with the moraine age, suggesting directional vegetation development. [11] It is also suggested that part of the high proportions of polypoids occurring in arctic floras is the result of speciation as continental ice-sheets withdrew. [12] Pollen diagrams from northern Quebec, Canada, show advances throughout the Holocene of post-glacial vegetation development. The initial phase of open vegetation began about 6000 years before the present. Following deglaciation, shrub and herbaceous tundra plants dominated for a brief period of time. Plants such as the Larix laricina , Populus and Juniperus , were also important in the initial vegetation development. Some species that followed later include: Alnus crispa , and Betula . Though later vegetation development was mainly dominated by Picea , shortly following deglaciation, they reached their present day limit. Today black spruce is mainly dominant throughout much of northern Quebec. [13] The continental U.S. is considered to have strongly contributed to the re-establishment of postglacial vegetation in Canada following the last ice age. Roughly 300 taxa of vascular plants and mosses that were found to have existed below the extent of the last glacial period within the United States were also found to have migrated to Canada. These patterns are recorded within either pollen or macro fossils. [14]
Studies done by Reitalu, (2015) have found that human impact throughout much of Europe has negatively influenced plant diversity by suppressing the establishment of tall-growing, large seeded taxa. Although human influence has facilitated many ruderal species, this is believed to have led to an overall decrease in phylogenetic diversity. [15]
Many pollen diagrams around the world indicate that major climate changes caused the last continental ice sheets to retreat, leading to dramatic effects on the distribution and abundance of plants. [16] By converting pollen data into plant functional type (PFT) assemblages and interpolating the data, researchers have been able to reconstruct postglacial vegetation patterns around the world. [17] Core sampling and analysis of lake sediments that contain pollen and other plant remains are often used to obtain good records of past pollination cycles. Such paleorecords preserved in lake sediments can be used to reconstruct the history of post glacial vegetation. [18] Lake sediments have an advantage over other core sampling sites, such as fen and bog peats, as they provide no overwhelming local pollen components. As well, lake sediments contain stratigraphic changes in soil character, which are useful for understanding changes in vegetation development over a period of time. [19] Macrofossils that are obtained from sedimentary deposits are also useful for constructing the history of changing postglacial vegetation. [20]
Ellesmere Island is Canada's northernmost and third largest island, and the tenth largest in the world. It comprises an area of 196,236 km2 (75,767 sq mi), slightly smaller than Great Britain, and the total length of the island is 830 km (520 mi).
Prairies are ecosystems considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and a composition of grasses, herbs, and shrubs, rather than trees, as the dominant vegetation type. Temperate grassland regions include the Pampas of Argentina, Brazil and Uruguay, and the steppe of Ukraine, Russia and Kazakhstan. Lands typically referred to as "prairie" tend to be in North America. The term encompasses the area referred to as the Interior Lowlands of Canada, the United States, and Mexico, which includes all of the Great Plains as well as the wetter, hillier land to the east.
Quttinirpaaq National Park is located on the northeastern corner of Ellesmere Island in the Qikiqtaaluk Region of Nunavut, Canada. It is the second most northerly park on Earth after Northeast Greenland National Park. In Inuktitut, Quttinirpaaq means "top of the world". It was established as Ellesmere Island National Park Reserve in 1988, and the name was changed to Quttinirpaaq in 1999, when Nunavut was created, and became a national park in 2000. The reserve covers 37,775 km2 (14,585 sq mi), making it the second largest park in Canada, after Wood Buffalo National Park.
The Last Glacial Period (LGP), also known colloquially as the Last Ice Age or simply Ice Age, occurred from the end of the Eemian to the end of the Younger Dryas, encompassing the period c. 115,000 – c. 11,700 years ago.
Eureka is a small research base on Fosheim Peninsula, Ellesmere Island, Qikiqtaaluk Region, in the Canadian territory of Nunavut. It is located on the north side of Slidre Fiord, which enters Eureka Sound farther west. It is the third-northernmost permanent research community in the world. The only two farther north are Alert, which is also on Ellesmere Island, and Nord, in Greenland. Eureka has the lowest average annual temperature and the lowest amount of precipitation of any weather station in Canada.
Axel Heiberg Island is an uninhabited island in the Qikiqtaaluk Region, Nunavut, Canada. Located in the Arctic Ocean, it is the 32nd largest island in the world and Canada's seventh largest island. According to Statistics Canada, it has an area of 43,178 km2 (16,671 sq mi). It is named after Axel Heiberg.
A glacial lake is a body of water with origins from glacier activity. They are formed when a glacier erodes the land and then melts, filling the depression created by the glacier.
Wapusk National Park (; is Canada's 37th national park, established in 1996. The name comes from the Cree word for polar bear.
A terminal moraine, also called an end moraine, is a type of moraine that forms at the terminal (edge) of a glacier, marking its maximum advance. At this point, debris that has accumulated by plucking and abrasion, has been pushed by the front edge of the ice, is driven no further and instead is deposited in an unsorted pile of sediment. Because the glacier acts very much like a conveyor belt, the longer it stays in one place, the greater the amount of material that will be deposited. The moraine is left as the marking point of the terminal extent of the ice.
The Older Dryas was a stadial (cold) period between the Bølling and Allerød interstadials, about 14,000 years Before Present, towards the end of the Pleistocene. Its date range is not well defined, with estimates varying by 400 years, but its duration is agreed to have been around two centuries.
The Holocene glacial retreat is a geographical phenomenon that involved the global retreat of glaciers (deglaciation) that previously had advanced during the Last Glacial Maximum. Ice sheet retreat initiated ca. 19,000 years ago and accelerated after ca. 15,000 years ago. The Holocene, starting with abrupt warming 11,700 years ago, resulted in rapid melting of the remaining ice sheets of North America and Europe.
The Hudson Bay Lowlands is a vast wetland located between the Canadian Shield and southern shores of Hudson Bay and James Bay. Most of the area lies within the province of Ontario, with smaller portions reaching into Manitoba and Quebec. Many wide and slow-moving rivers flow through this area toward the saltwater of Hudson Bay: these include the Churchill, Nelson and Hayes in Manitoba, Severn, Fawn, Winisk, Asheweig, Ekwan, Attawapiskat, and Albany in Ontario, and the Harricana, Rupert and Eastmain in Quebec. This is the largest wetland in Canada, and one of the largest in the world. The region can be subdivided into three bands running roughly northwest to southeast: the Coastal Hudson Bay Lowland, Hudson Bay Lowland, and James Bay Lowland.
The Weichselian glaciation was the last glacial period and its associated glaciation in northern parts of Europe. In the Alpine region it corresponds to the Würm glaciation. It was characterized by a large ice sheet that spread out from the Scandinavian Mountains and extended as far as the east coast of Schleswig-Holstein, northern Poland and Northwest Russia. This glaciation is also known as the Weichselian ice age, Vistulian glaciation, Weichsel or, less commonly, the Weichsel glaciation, Weichselian cold period (Weichsel-Kaltzeit), Weichselian glacial (Weichsel-Glazial), Weichselian Stage or, rarely, the Weichselian complex (Weichsel-Komplex).
The North American Arctic is composed of the northern polar regions of Alaska (USA), Northern Canada and Greenland. Major bodies of water include the Arctic Ocean, Hudson Bay, the Gulf of Alaska and North Atlantic Ocean. The North American Arctic lies above the Arctic Circle. It is part of the Arctic, which is the northernmost region on Earth. The western limit is the Seward Peninsula and the Bering Strait. The southern limit is the Arctic Circle latitude of 66° 33’N, which is the approximate limit of the midnight sun and the polar night.
Tanquary Fiord is a fjord on the north coast of the Arctic Archipelago's Ellesmere Island, Nunavut, Canada. It is located in the Quttinirpaaq National Park and extends 48 km (30 mi) in a north-westerly direction from Greely Fiord.
Strathcona Fiord is a fiord on the west central coast of Ellesmere Island, the most northern island within the Arctic Archipelago, Nunavut, Canada.
Qausuittuq National Park is a national park located on northwest Bathurst Island in Nunavut. It was established on September 1, 2015, becoming Canada's 45th national park.
Dark diversity is the set of species that are absent from a study site but present in the surrounding region and potentially able to inhabit particular ecological conditions. It can be determined based on species distribution, dispersal potential and ecological needs. The term was introduced in 2011 by three researchers from the University of Tartu and was inspired by the idea of dark matter in physics since dark diversity too cannot be directly observed.
The Canadian Arctic tundra is a biogeographic designation for Northern Canada's terrain generally lying north of the tree line or boreal forest, that corresponds with the Scandinavian Alpine tundra to the east and the Siberian Arctic tundra to the west inside the circumpolar tundra belt of the Northern Hemisphere.
The Canadian High Arctic Tundra ecoregion encompasses most of the northern Arctic archipelago, from much of Baffin Island, Somerset Island, and Prince of Wales Island in the south, through all islands northward to the most northern island in Canada, Ellesmere Island. Much of the northern islands are covered in ice, and the climate is very dry with as little as 50 mm/year in places. The ecoregion has very little human habitation, and most of the non-ice terrain is moss and lichen cover. The region supports viable populations of arctic mammals such as muskox, arctic wolves, arctic foxes, arctic hares, polar bears, and caribou.