What is high-altitude zone? Definition
Since ancient times, many natural scientists and geographers have not ceased to interest the process of changing the soil and vegetation as they ascend the mountains. The first who paid attention to this was the German scientist Alexander von Humboldt. Since that time, it was given a simple definition - high-altitude. What is typical in the mountains, in contrast to the plains, the animal and plant world is much more diverse in relation to various species. At the same time in this area there are several belts. But what is high-altitude zone and what kinds of it exist? We will understand in order.
Definition of term
In another way, it is also called altitudinal zonality. This definition refers to the process of changing the natural conditions and landscape in a natural way as the height above sea level increases. All this is due to climate change relative to the height of the mountain:
- The average air temperature drops by 6 ° C for each kilometer of ascent.
- Reduced pressure level.
- Precipitation and cloudiness are decreasing.
- Solar radiation, on the contrary, becomes stronger.
This is how high-altitude belts are formed, which are a kind of landscape dividing unit in highlands. There is something similar between them and the latitudinal belts. However, not all high-altitude lines have latitudinal analogues. For example, the belt of mountain tundra and the latitudinal band have a significant difference between them. It lies in the absence of polar nights in the mountains, and therefore there are completely different hydroclimatic and soil-biological processes.
Separation of mountain areas
Changing areas of altitudinal zoning in the highlands occurs in almost the same way as in the plain, when viewed from south to north. However, the mountains are characterized by a sharp and contrasting change of belts. And it can be felt at a relatively short distance. Note that all belts are present only in those mountains that are located in the tropics or at the equator. An example of this are the Andes and the Himalayas. However, as the poles get closer, some warm zones disappear. Here, as an example, the Scandinavian mountains, where there are only three belts.
That is, the more south there are mountains, the greater the number of belts they have. And it is best seen in the mountain system in the Urals, where the heights are less than in the northern and polar terrain. Nevertheless, there are much more high-altitude belts here, while in the northern part there is only one - the mountain-tundra strip. The rate of change in the altitudinal zonation of the mountains depends on the nature of the relief and the remoteness of the highlands from the ocean. In other words, for those mountains that are located closest to the sea coast, a mountain-forest landscape is characteristic. The mountains in the center of the mainland are distinguished by a small number of forests.
For some areas characterized by a more contrasting change of altitude belts. A vivid example of this is the Black Sea coast of the Caucasus. If you travel by car, from the subtropics you can get to the subalpine meadows in less than an hour. It does not do without some features. Usually at the foot of the mountain conditions are similar to the climate of the nearby plains. Above is a terrain with colder and more severe conditions. Above all is the tier of eternal snow and ice. And the higher, the lower the temperature. In the Siberian mountains, everything could be different.That is, in some areas the climatic conditions of the foot are more severe than on longlines. This is due to the fact that in the intermontane basins cold air stagnates.
Better understand what the high-altitude zone, will help knowledge of its types. You can clearly distinguish the two main groups of high-altitude.
In the seaside group there are mountain-forest belts in the lowlands, and the alpine stripes are concentrated in the high mountains. In the continental group, the desert-steppe belt is usually located in the foothills, while the mountain-meadow zone is located at the high mountains.
As for the examples, here they are:
- Seaside type - mountain system of the Western Caucasus. Here the mountain forest belt is located at the very foot of the mountain, where there are deciduous and coniferous forests. Above is the alpine zone with the inclusion of subalpine crooked and high grass meadows. Even higher is the nival band.
- The continental type is the mountains of the Urals and Tan-Shan, whose belts change from deserts (foothills) to mountain steppes on the slopes. Mostly mountainous forests, meadows and alpine deserts. And above them is the nival belt.
The formation of types of altitudinal zonation, or altitude zonality, is directly influenced by several factors. About them will be discussed further.
The number of altitudes directly depends on the geographical location of a mountain system in relation to the seas and oceans. And in the course of movement from north to south, the set of lanes increases.
For example, in the north of the Urals forests rise to a height of no more than 700-800 meters. Whereas on the south side the forest belt extends further - up to 1000-1100 meters. In the mountains of the Caucasus and even higher - forests can be found at an altitude of 1800-2000 meters. In this case, the lowermost belt is a continuation of the area that is located at the foot of the mountain.
The relief of the mountains depends on:
- snow distribution;
- humidity level; safety or removal of weathering products;
- development of land cover.
All this leads to a variety of natural landscapes. At the same time, more homogeneous natural complexes can be formed.
What is the altitude zone and how does it depend on the height? The answer is quite simple: the closer the mountains are in relation to the equator, the higher they are. For this reason, there are much more high-altitude belts.Each mountain system, depending on the location, has its own set of belts.
Nature of the mountain slopes
The exposure of the slopes has a significant impact on the distribution of heat, moisture and wind. And therefore, the degree of weathering processes depends on this parameter, which in turn affects the distribution of land cover. As a rule, any mountain on the northern slopes of the high-altitude zones are located lower than on the south side.
Perhaps this is the most important factor that has a direct impact on the formation of altitudinal zonation in the mountains. With increasing height, many parameters change, which was already mentioned at the beginning of the article. Because of the climate, the distribution and intensity of not only plant, but also animal life is determined. What is high-altitude zone? This is a whole variety of complexes created by the efforts of nature itself.
Types of mountain bands
The number of mountain belts (it is more correct to call them belts) depends not only on the height of the terrain, but also on its geographical position.
There are several types of altitude belts:
1. Desert-steppe. A dry climate prevails here, and therefore mostly concentrated desert and steppe vegetation. As a rule, located at the foot or lowlands.With a climb, the mountain-desert landscape is replaced by a mountain-semi-desert, followed by a transition to the mountain-steppe.
2. Mountain and forest. In this zone, the highest level of humidity among all others. As for plants, there are concentrated deciduous, coniferous, mixed forests, grasses and shrubs, which is typical of middle latitudes. Among the wildlife here reigns diversity of herbivorous representatives, predators, insects and birds.
3. Mountain meadow. This zone of high altitude zone unites several belts:
- Subalpine - this belt is characterized by alternation of subalpine meadows with light forests. Also there are both open landscapes and curved forest.
- Alpine - this zone is covered with grass and creeping bushes. In some places there are stone scree. At the same time, a region of high mountains is located above the forest and the ridge. In a number of mountain systems, the Alpine border is located at different heights: the Alps and the Andes - 2.2 km, the mountains of the Eastern Caucasus - 2.8 km, the Tien Shan - 3 km, the Himalayas - above 3.6 km.
4. Mountain tundra. Here, winter has a rather severe character, and summer is short and cold.The average monthly temperature usually does not rise above +8 ° C. At the same time there are strong winds that are waving snow cover in the winter time and dry up the soil in summer. From the vegetation there are mosses, lichens and arctic-alpine shrubs.
5. Nival This is the highest zone of eternal glaciers and snow. Even the term itself, derived from the Latin word nivalis, means "snow", "cold". The area that is free of snow cover is strongly affected by frost weathering. As for plants of high-altitude zones, lichens, as well as isolated flowering herbs, find their shelter in such harsh conditions. In rare cases, birds, insects, some species of rodents and predators wander into this area.
Thanks to such a number of high-altitude belts, a great diversity of nature itself is obtained. As you know, many people love to travel the world, fixing their location using digital cameras or camcorders. But it is especially pleasant to be in the mountains. In one day, you can visit different lanes: starting with green forests and ending with snow-white peaks. There will be plenty of impressions!
Altitudinal zonality of Russia
In our country, high-altitude zones began to form in the early Pleistocene epoch during the interglacial period. At that time, the terrain was subjected to repeated climatic transformations. And as a result - the displacement of the boundaries of the high-altitude zones, and this happened more than once. Scientists have found that the entire mountain system of the Russian Federation was previously located higher by 6 ° than it is now.
Subsequently, whole complexes appeared: the mountains of the Urals, the Caucasus, the Altai, the Baikal ranges, the Sayans. But as for the Ural Mountains, they are certainly the oldest in the world. It is assumed that they began to form a long time ago - in the Archean era. And its beginning was laid about 4 billion years ago.
At that time, the Earth was very hot, there were many volcanoes acting on it, and it was subjected to periodic bombardment of meteorites from space. Thus, in some places of natural altitude zoning, there are many years.