The vegetation of the tundra and forest-tundra, its forms, methods of plant reproduction, adaptability to survival largely depend on the features that characterize these zones.
Geographic location
The location of the tundra zone falls on the subarctic belt of the Earth. On the mainland of Eurasia, it stretches along the entire coast of the seas of the Arctic Ocean for tens of thousands of kilometers. The northern coast of the mainland of North America is also occupied by tundra. The length of the zone from north to south is on average about 500 kilometers. In addition, the tundra occupies some islands near Antarctica. In the mountains, where altitudinal zonality is expressed, mountain tundras are formed. Considering all the territories where the zone is located, its total area on the planet has been calculated. It is about 3 million km2.
Forest-tundra is a zone where small patches of tundra and taiga vegetation are located. The forest-tundra stretches from west to east south of the tundra on the continents of Eurasia and North America. The length of the strip from north to south ranges from 30 to 400 kilometers. On its southern borders, the forest-tundra passes into the forest zone.
Climatic conditions,affecting plant growth
The climate of the tundra and forest-tundra zone is very severe. Winter lasts 6 to 8 months a year. During all this time, a constant snow cover is kept, the air temperature sometimes drops to 50 degrees below zero. The polar night lasts about two months. Strong cold winds and snow storms almost never subside.
Summer in the tundra is short and cool. Frosts and snowfall are possible. Despite the polar day, the surface of the earth does not receive much heat, since the sun does not rise high above the horizon and sends scattered rays to the Earth. To survive in such conditions, the vegetation of the tundra must adapt.
Effect of permafrost on species composition of vegetation
In the warm season in the tundra zone, the soil thaws only to a depth of no more than 50 centimeters. Next comes the layer of permafrost. This factor is one of the decisive factors in the distribution of plants in the tundra zone. The same factor affects their species diversity.
Permafrost has a significant impact on the terrain. Freezing and thawing of rocks leads to their deformation. As a result of the heaving process, surface forms such as bumps appear. Their height is no more than two meters above sea level, but the appearance of such forms also affects the vegetation of the tundra, its settlement in a certain area.
Influence of soil on speciesvariety of vegetation
In the zone of tundra and forest-tundra there is a high waterlogging of soils. It is especially noticeable during the snowmelt period. Water cannot penetrate deeper due to the presence of permafrost. Its evaporation is also not very intense due to the low air temperature. For these reasons, meltwater and precipitation accumulate on the surface, forming large and small swamps.
High waterlogging, the presence of permafrost, the predominance of low temperatures hinder the flow of chemical and biological processes in the soil. It contains little humus, ferrous oxide accumulates. Tundra-gley soils are suitable for the growth of only certain plant species. But the vegetation of the tundra adapts to such living conditions. A person who has visited these parts during the flowering period of plants has indelible impressions for many years - the flowering tundra is so beautiful and attractive!
In the forest-tundra, the natural fertile layer of the earth is also thin. The soil is poor in nutrients, it is characterized by high acidity. When cultivating land, a large amount of mineral and organic fertilizers is introduced into the soil. In the cultivated areas of the forest-tundra, there are more diverse types of herbaceous vegetation, trees and shrubs.
Types
The vegetation of the tundra and forest-tundra largely depends on the type of natural zones. Their landscapes only at first glance seem monotonous.
Bumpy and bumpytundra occupy the largest areas. Among the swamps, plant turf forms mounds and tussocks, on which many plant species take root. A special type of tundra is polygonal. Here you can observe landforms in the form of large polygons, which are broken by depressions and frost cracks.
There are other approaches to the classification of such a natural area as the tundra. What kind of vegetation prevails in a certain area, this will be the type of tundra. For example, the moss-lichen tundra is made up of areas covered with various types of mosses and lichens. There are also shrub tundras, where thickets of polar willow, elfin cedar, and bushy alder are common.
Plants
As mentioned earlier, the vegetation of the tundra and forest-tundra had to adapt to the harsh climatic conditions of the subarctic zone of the Earth. Otherwise, her life and development would be impossible here.
The adaptability of tundra and forest-tundra plants is expressed as follows. Most representatives of the fauna are perennials. Annual plants with a short duration of summer would not be able to complete their life cycle. Only a small part of plants reproduces by seeds. The main way to prolong life is vegetative.
The short stature of tundra plants allows them to hold out during strong winds. This is also facilitated by the creeping nature of the shoots and their ability to intertwine with each other, forming a semblance of a soft pillow. In winter, all parts of plants are undersnow. This saves them from severe frosts. Most tundra and forest tundra plants have a wax coating on their leaves, which contributes to moderate evaporation of moisture from their surface.
Tundra vegetation, photographs of some species of which are available in the article, is represented by perennial frost-resistant herbs: sedge, dominant in lowlands and swamps, buttercup, cotton grass, dandelion, poppy. From the trees grow dwarf birch, polar willow, bushy alder. These tree species in the forest-tundra can already reach a height of three or more meters. Blueberries, cloudberries, bilberries, lingonberries are widespread among shrubs. Mosses and lichens take root in the uplands, many of which are the main food for animals living in these places.
Forest-tundra and taiga
The vegetation of the tundra and taiga is very different from each other. The forest tundra is a transition zone between them. On the territory of the forest-tundra, among the treeless space, you can find islands of thickets of spruce, birch, larch and other tree species.
The forest-tundra zone is unique, since tundra and taiga vegetation are found on its territory, which becomes more noticeable as you move south. Forest areas, consisting of individual species of trees and shrubs, create the most favorable conditions for the growth of herbaceous vegetation. Thanks to trees and shrubs, the wind speed decreases, more snow is retained, which covers the plants, saving them fromfreezing.
Studying the vegetation of the subarctic belt
The vegetation cover of the tundra and forest-tundra has not yet been fully studied. A systematic scientific description of the species growing here began only in the middle of the last century.
To continue this work, special expeditions are being created today. In the course of them, scientists are also trying to establish how the vegetation of the tundra and forest-tundra is influenced by animals living in these zones. They want answers to questions about whether plant species diversity is changing in areas protected from the presence of certain animal species, how long it takes for the complete restoration of the destroyed vegetation cover. So far, scientists have not found answers to all questions regarding natural balance in the zone of the subarctic belt of the planet.
Fauna Conservation
The nature of the tundra and forest-tundra is very vulnerable. It takes more than a dozen years, and in some cases even centuries, to restore the soil layer, the vegetation cover.
Man has long understood that it is he who has a detrimental effect on the nature of the tundra and forest tundra. Trying to atone for their guilt, people have created a number of nature reserves, national parks, wildlife sanctuaries. They are located both on the territory of Russia and other countries of the world.
