Holarctic realm
The Holarctic realm is a
These regions are further subdivided into a variety of
Major ecosystems
Within the Holarctic realm, there are a variety of ecosystems. The type of ecosystem found in a given area depends on its latitude and the local geography. In the far north, a band of Arctic
Animal species with a Holarctic distribution
A variety of animal species are distributed across continents, throughout much of the Holarctic realm. These include the brown bear, grey wolf, red fox, wolverine, moose, caribou, golden eagle and common raven.
The brown bear (Ursus arctos) is found in mountainous and semi-open areas distributed throughout the Holarctic. It once occupied much larger areas, but has been driven out by human development and the resulting habitat fragmentation. Today it is only found in remaining wilderness areas.
The
The red fox (Vulpes vulpes) is a highly adaptable predator. It has the widest distribution of any terrestrial carnivore, and is adapted to a wide range of habitats, including areas of intense human development. Like the wolf, it is distributed throughout the majority of the Holarctic, but it has avoided extirpation.
The
The moose (Alces alces) is the largest member of the deer family. It is found throughout most of the boreal forest through continental Eurasia into Scandinavia, eastern North America, and boreal and montane regions of western North America. In some areas it ranges south into the deciduous forest.
The caribou, or reindeer (Rangifer tarandus) is found in boreal forest and tundra in the northern parts of the Holarctic. In Eurasia, it has been domesticated. It is divided into several subspecies, which are adapted to different habitats and geographic areas.
The golden eagle (Aquila chrysaetos) is one of the best-known birds of prey in the Northern Hemisphere. It is the most widely distributed species of eagle. Golden eagles use their agility and speed combined with powerful feet and massive, sharp talons to snatch up a variety of prey (mainly hares, rabbits, marmots and other ground squirrels).
The common raven (Corvus corax) is the most widespread of the corvids, and one of the largest. It is found in a variety of habitats, but primarily wooded northern areas. It has been known to adapt well to areas of human activity. Their distribution also makes up most of the Holarctic realm.
Leptothorax acervorum is a small red Holarctic ant widely distributed across Eurasia, ranging from central Spain and Italy to the northernmost parts of Scandinavia and Siberia.
Zygiella x-notata is a species of orb-weaving spider with a Holarctic distribution, mostly inhabiting urban and suburban regions of Europe and parts of North America.
Hemerobius humulinus is a species of brown lacewing in the family Hemerobiidae. It is found in Europe and Northern Asia (excluding China), North America, and Southern Asia.[2]
Origin
The continuity of the northern parts of the Holarctic results from their shared
Wherever these areas were found, they became source populations during
Another factor contributing to the continuity of Holarctic ecosystems is the movement between continents allowed by the
Threats
As the Holarctic is an enormous area, it is subject to environmental problems of international scale. The primary threats throughout the region result from
Global warming is a threat to all the Earth's ecosystems, but it is a more immediate threat to those found in cold climates. The communities of species found at these latitudes are adapted to the cold, so any significant warming can upset the balance. For instance, insects struggle to survive the cold winters typical of the boreal forest. Many do not make it, especially in harsh winters. However, recently the winters have grown milder, which has had a drastic effect on the forest. Winter mortality of some insect species drastically decreased, allowing the population to build on itself in subsequent years. In some areas the effects have been severe.
In this case a native species has caused massive disturbance of habitat as a result of climate change. Warming temperatures may also allow pest species to enlarge their range, moving into habitats that were previously unsuitable. Studies of potential areas for outbreaks of bark beetles indicate that as the climate shifts, these beetles will expand to the north and to higher elevations than they have previously affected.[10] With warmer temperatures, insect infestation will become a greater problem throughout the northern parts of the Holarctic.
Another potential effect of global warming to northern ecosystems is the melting of permafrost. This can have significant effects on the plant communities that are adapted to the frozen soil, and may also have implications for further climate change. As permafrost melts, any trees growing above it may die, and the land shifts from forest to peatland. In the far north, shrubs may later take over what was formerly tundra. The precise effect depends on whether the water that was locked up is able to drain off. In either case, the habitat will undergo a shift. Melting permafrost may also accelerate climate change in the future. Within the permafrost, vast quantities of carbon are locked up. If this soil melts, the carbon may be released into the air as either carbon dioxide or methane. Both of these are greenhouse gases.[11]
Habitat fragmentation threatens a wide variety of habitats throughout the world, and the Holarctic is no exception. Fragmentation has a variety of negative effects on populations. As populations become cut off, their
Large carnivores are particularly affected by habitat fragmentation. These mammals, such as brown bears and wolves, require large areas of land with relatively intact habitat to survive as individuals. Much larger areas are required to maintain a sustainable population. They may also serve as keystone species, regulating the populations of the species they prey on. Thus, their conservation has direct implications for a wide range of species, and is difficult to accomplish politically due to the large size of the areas they need.[13] With increasing development, these species in particular are at risk, which could have effects that carry down throughout the ecosystem.
Conservation actions
This section needs to be updated.(November 2020) |
The threats to the Holarctic realm are not going unrecognized. Many efforts are being made to mitigate these threats, with the hope of preserving the biodiversity of the region. International agreements to combat global warming may help to lessen the effects of climate change on this region. Efforts are also underway to fight habitat fragmentation, both on local and regional scales.
The most comprehensive effort to combat global warming to date is the
Fighting habitat fragmentation is a major challenge in conserving the wide-ranging species of the Holarctic. Some efforts are limited to a local scale of protection, while others are regional in scope. Local efforts include creating reserves and establishing safe routes for animals to cross roads and other human-made barriers. Regional efforts to combat habitat fragmentation take a broader scope.
One major such effort in the Holarctic is the Yellowstone to Yukon Conservation Initiative. This organization was started in 1997 to help establish a contiguous network of protection for the northern Rocky Mountains, from mid Wyoming to the border between Alaska and Canada's Yukon. It brings together a wide variety of environmental organizations for a shared purpose. The goal of the Initiative is to create a core of protected areas, connected by corridors and surrounded by buffer zones. This will build on the many existing protected areas in this region, with a focus on integrating existing and future human activities into the conservation plan rather than seeking to exclude them (Yellowstone to Yukon). If these efforts are successful, they will be especially beneficial to wide-ranging species such as grizzly bears. If these species can survive, other members of the communities they live in will survive as well.
References
- ISBN 978-3-662-03163-6
- ^ Flint, Oliver S. (2015). "Annotated Checklist of the Neuropterida of Virginia (Arthropoda: Insecta)" (PDF). Banisteria. 45: 3–47.
- ISSN 0169-5347.
- from the original on 2022-01-21. Retrieved 2022-06-30.
- from the original on 2022-03-25. Retrieved 2020-11-02.
- from the original on 2021-08-12. Retrieved 2020-11-02.
- ISSN 0305-1838.
- from the original on 2021-05-25. Retrieved 2020-11-02.
- ISSN 1540-9309.
- S2CID 84848140.
- S2CID 37443830.
- OCLC 209855917.
- from the original on 2022-05-02. Retrieved 2020-11-02.
- United Nations Framework Convention on Climate Change. Available at: http://unfccc.int/2860.php. Accessed December 2007.
- Yellowstone to Yukon Conservation Initiative. Updated 2006. Available at http://www.y2y.net. Accessed December 2007.