Causes of marshland formation in the Northwest Territories 20

There are many reasons for this, as a result of the movement of the earth's crust.

1) The latitude is high, the solar radiation is weak, and the evaporation is small;

2) The underground permafrost is widely distributed, and it is difficult for the water to penetrate into the ground when the ice and snow melt in summer, and the soil forms a swamp with too much moisture;

3) The terrain of the Great Plain of Western Siberia is flat and low-lying, and the drainage is not smooth;

4) The river flows from low latitude to high latitude, and the flood occurs in spring, and the Arctic Ocean coast is still frozen, and the river water is difficult to discharge into the Arctic Ocean, and a large amount of river water overflows the river, resulting in excessive soil moisture on both sides of the river and the formation of swamps.

First of all, topographic factors, 1. The topography of the Northeast region is mainly the vast Northeast Plain, and the swamps are mainly formed on the plain, which is a prerequisite; 2. The Northeast Plain is surrounded by mountains on three sides, which is not easy to drain, and it is easy to form swamps.

Secondly, climatic factors, 1. The Northeast Plain has abundant annual precipitation, low temperature and low evaporation, resulting in large soil water content and easy to form swamps; 2. There are many rivers in the Northeast Plain, and at the confluence of the rivers, especially the Sanjiang Plain is located at the confluence of the Songhua River, Heilongjiang River and Ussuri River, the water volume is abundant, the drainage is not smooth, and it is easy to form swamps. 3. The temperature in the Northeast Plain is low and the freezing period is long, so it is not easy to drain water, resulting in excessive soil water content and easy to form swamps.

Finally, the Northeast Plain is rich in plant species, and a large number of plants lock in a large amount of water, making the soil water-containing and easy to form swamps.

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The reason for the formation of marshlands in the northeastern part of our country is due to excessive irrigation. In areas where tundra is suitable for the growth of lower plants, seasonal thawing can also contribute to the process of swamping.

In the process of development, in some swamps, because the accumulation rate of dead plant residues is greater than the decomposition rate, a quagmire accumulation layer appears, called peat bogs, and most swamps in the cold temperate zone belong to this category; The rate of accumulation of swamp plant remains is less than or equal to the rate of decomposition, and only a certain thickness of grass root layer appears, as is the case in most swamps in the Northeast China Plain.

In forested areas, litter accumulates under the forest, as if a thick quilt is placed on the ground, which not only stores a lot of rainwater, but also reduces soil evaporation and keeps it overly moist. In addition, due to the carbonization process, most of the mineral nutrients in the soil are leached, causing the death of plants and trees, and replacing them with flourishing bryophytes.

Bryophytes retain a lot of water, slowing down the decomposition process of plant residues, and peat begins to accumulate and gradually form swamps. In the forests of China's large and small Xing'an Mountains, this phenomenon of forest swamping can be seen.

The swamps are perennially waterlogged or the soil is too wet, and most of the plants that grow there have well developed aeration tissues. The roots of the plant are submerged in water or soaked soil, and the stems and leaves protrude from the water. The swamp vegetation is mainly composed of sedges, grasses, mosses and a few woody plants.

Except for the Antarctic, which has not yet been found in swamps, there are swamps everywhere on the earth.

Since the soil of marshland is divided into peat soil and latent soil, swamps can be divided into two categories: peat bogs and latent bogs. The largest peat bog on Earth is in the Western Siberian lowlands, 800 km wide from north to south and 1,800 km long from east to west, and this bog area is home to 40% of the earth's total peat.

1. Northeast China has high latitude, low temperature and weak evaporation.

2. The terrain is flat, there are many depressions, and the drainage is not smooth.

3. There are seasonal and permafrost layers underground, which are not conducive to infiltration.

4. River flooding.

Second, the long-term overwetness of the soil surface is the direct cause of the formation of swamps:

1. Meadows and low-lying lands have poor surface water drainage or difficulty in infiltration due to the gentle slope drop and heavy soil claying;

2. The water balance of the soil layer is destroyed due to the loss of the huge water absorption effect of trees in forest felling areas or burned areas;

3. The groundwater overflow zone is often exposed due to spring water;

4. Irrigation area due to excessive irrigation, etc.

In addition, in places where the tundra is suitable for the growth of lower plants, seasonal thawing can also contribute to the process of swamping.

In the process of development, in some swamps, because the accumulation rate of dead plant residues is greater than the decomposition rate, a quagmire accumulation layer appears, called peat bogs, and most swamps in the cold temperate zone belong to this category;

The accumulation rate of some swamp plant remains is less than or equal to the rate of decomposition, and only a certain thickness of grass root layer appears, which is called latent swamp, and most of the swamps in the Sanjiang Plain in northeast China belong to this category.

The plain terrain is gentle, the water flow is slow, the groundwater is relatively sufficient, the infiltration can not digest most of the precipitation, and it is easy to gather in low-lying places and develop into wetlands and swamps.

Seasonal permafrost, which melts in summer, is rich in water, and in summer there is more precipitation and less evaporation, forming swamps.

In the rainy season, the flood discharge capacity is insufficient, the flood is spreading, the drainage capacity is weak, and swamps will be formed after a long time.

One: Reason:

1. Northeast China has high latitude, low temperature and weak evaporation.

2. The terrain is flat, there are many depressions, and the drainage is not smooth.

3. There are seasonal and permafrost layers underground, which are not conducive to infiltration.

4. River flooding.

Two: Not exactly.

1: The terrain is low and flat, and the drainage is not smooth.

2: The climate is cold, the evaporation is weak, and the annual precipitation will be more.

3: There is a permafrost layer underground, which has the effect of water insulation, and the surface water is not easy to infiltrate.

4: There is a flood phenomenon in the river that flows through it, resulting in the flooding of the river.

5: There are rivers flowing through the area, and there is an abundance of water.

1. The terrain is low-lying, the drainage is not smooth, and the precipitation is not easy to lose;

2. High latitude, low temperature and low evaporation;

3. The permafrost is widely distributed, and the surface water is not easy to infiltrate.

1) The latitude is high, the solar radiation is weak, and the evaporation is small;

2) The underground permafrost is widely distributed, and it is difficult for the water to penetrate into the ground when the ice and snow melt in summer, and the soil forms a swamp with too much moisture;

3) The Siberian Plain is flat and low-lying with poor drainage;

4) The river flows from low latitude to high latitude, and the flood occurs in spring, and the coast of the Arctic Ocean is still frozen, and it is difficult for the river water to be discharged into the Arctic Ocean only at a high level, and a large amount of river water overflows the river, resulting in excessive soil moisture on both sides of the river and the formation of swamps.

First of all, topographic factors, 1. The topography of the Northeast region is mainly the vast Northeast Plain, and the swamps are mainly formed on the plain, which is a prerequisite; 2. The Northeast Plain is surrounded by mountains on three sides, which is not easy to drain and easy to form swamps. Secondly, climatic factors, 1. The Northeast Plain has abundant annual precipitation, low temperature and low evaporation, resulting in large soil water content and easy to form swamps; 2. There are many rivers in the Northeast Plain, and at the confluence of the rivers, especially the Sanjiang Plain is located at the confluence of the Songhua River, Heilongjiang River and Ussuri River, the water volume is abundant, the drainage is not smooth, and it is easy to form swamps. 3. The temperature in the Northeast Plain is low and the freezing period is long, so it is not easy to drain, resulting in excessive soil water content and easy to form swamps.

Finally, the Northeast Plain is rich in plant species, and a large number of plants lock in a large amount of water, making the soil have a large water content and are prone to swamps.

Bogs are characterized by the fact that the surface of the land is often or permanently wet, with special vegetation and soil-forming processes, some with peat accumulation and some without peat.

There are several main types of swamp wetlands:

Moss swamps are dominated by mosses with 100% coverage, some forming moss mosses and a small number of shrubs and herbs. There is generally a thin layer of peat developing.

Herbaceous bogs are dominated by herbaceous plants, including sedge bogs, grass bogs, and weed bogs, with a plant coverage of 30%. There is peat or latent layer development.

The shrub swamp is dominated by shrubs, including birch, willow, meadowsweet, arrow bamboo, pine, rhododendron, rhododendron, etc., with a plant coverage of 30%. There is generally no peat accumulation.

Forest swamps are dominated by woody plants, common such as larch, fir, water pine, metasequoia, red cypress, etc., canopy density. There is generally peat or latent layer development.

Marshy meadows include river, lake, and floodplains, swampy wetlands caused by seasonal and temporary water accumulation. No peat build-up.

Inland salt marshes are dominated by annual or perennial halophytes, such as salina grass, tamarix, Suaeda salsa, alkali grass, lysa grass, roe grass, etc., with a plant coverage of 30% and a water salt content of more than 10%. There is generally no peat formation.

Forest swamps, shrub swamps, moss swamps and some herbaceous swamps are mostly distributed in forest areas and valleys. Herbaceous swamps and swampy meadows are mostly developed in river (lake) floodplains, floodplains, old river channels and alluvial fan margins. In the herbaceous swamps, Songgrass and Songgrass moss swamps are distributed in the wide valleys, floodplains, terraces, and various glacial depressions (paleocirques, valleys, and glacial valley wetlands) in the western plateau of China.

Marsh wetlands are distributed in all provinces (autonomous regions and municipalities directly under the central government) across the country, but in cold temperate and temperate humid areas, the distribution of swamp wetlands is relatively concentrated. The large and small Khing'an Mountains, the Changbai Mountains, the Sanjiang Plain, the Liaohe River Delta, the southern part of the Qinghai-Tibet Plateau and the Zoige Plateau in the east, the source areas of the Yangtze River and the Yellow River, the floodplain areas of rivers and lakes, the deltas of rivers entering the sea and the swamp wetlands in sandy or silty coastal areas are very developed.