What is a "salt marsh"? How is the "salt marsh" formed?
The formation is similar to that of ordinary swamps.
Formation of swamps:
Lake evolution
Let's see how the lake evolved into a swamp. In wet areas, rivers and swamps
Water carries sediments into the lake. Due to the sudden widening of the water surface, the current speed slows down, the sediment carrying capacity weakens, and the sediment deposits on the lake, forming a shoal. There are also some tiny substances that drift to the wide part of the lake with the current and deposit at the bottom of the lake. As time goes on, the lake becomes shallower and shallower. However, in different positions of the depth of the lake, various aquatic plants gradually proliferate. In the depths of the lake, there are various algae such as POTAMOGETON. In the deeper zone, duckweed, water lily and water lily grow. In the shallow waters along the coast, reeds and cattails grow. They keep growing and dying, and a large number of rotten residues keep accumulating at the bottom of the lake, eventually forming peat. As the bottom of the lake gradually becomes shallow, new plants reappear and develop from the center of the lake around, and the lake becomes shallower and smaller. In the end, the lake with wide water surface became a shallow swamp with weeds.
Other ways
In addition to the evolution from lakes to swamps, there are the following situations: in forest areas, litter keeps accumulating under the forest, just like covering the ground with a thick quilt, which can not only accumulate a lot of rain, but also reduce the evaporation of soil moisture, making it in an excessively humid state. In the process of carbonization, most mineral nutrients in the soil are lost, which leads to the death of vegetation and replaced by lush bryophytes. Bryophytes can retain a lot of water, slow down the decomposition process of plant residues, and peat gradually accumulates to form swamps. The swamps in the forests of Daxing 'anling and Xiaoxing 'anling in China were formed in this way. In some too humid areas, weeds can multiply in large numbers and form thick grass layers, soil aeration becomes worse, and carbon content gradually decreases, which makes the original plants gradually decline and grow wet-loving plants such as sphagnum, which are very swampy.
Strong water storage capacity further strengthens soil moisture, and meadow swamping can develop rapidly. This is how some grasslands in western Sichuan were formed. In some plateaus and mountainous areas, the ground is covered with snow in winter, and the snow melts in the spring and summer of the following year, which makes the ground accumulate water, which makes the short grass and bryophytes mix and form a swamp. Low-lying plains along the river, the river is shallow, the flow rate is slow, aquatic plants can grow, and gradually form a swamp. Coastal lowlands are repeatedly submerged by seawater, and reeds and weeds are overgrown on the beach, which can also form salt marshes. Swamp refers to the area where the surface is too wet, swamp plants grow and peat forms and accumulates. Among the marsh materials, water accounts for 85% ~ 95%, dry matter? Cave mainly refers to peat? Snow accounts for 5% ~ 10%. The global swamp area is about112.2 million hectares, accounting for 0.8% of the land area. The formation of swamp mainly depends on hydrothermal conditions and landforms. Among them, water condition is the dominant factor in the formation of swamp, because the excessively wet surface will cause the invasion of hygrophilic plants, which will lead to the change of soil aeration and the accumulation of peat under biological action. The formation of swamp can be divided into water swamp and land swamp. In humid areas, rivers carry a lot of sediments into lakes. In the lakeside or estuary area, due to the sudden widening of the water surface, the speed of water flow suddenly slows down, and sediment is deposited on the lakeside, forming shoals, and some tiny substances drift to the open area of the lake with the water flow and precipitate to the bottom of the lake. As time goes on, the lake becomes shallower and shallower. With the different depths of the lake, various aquatic plants are gradually multiplying. These plants keep growing and dying, and a large number of rotting plant residues keep piling up at the bottom of the lake, gradually forming peat. With the gradual deposition of the lake bottom, new plants appear and develop from the center of the lake around, making the lake smaller and shallower. When the sediment in the lake increases to a certain limit, the lake with wide water surface becomes a shallow swamp with weeds. This is the drowning of water.
Swamp: that is, soil swamp. Due to the influence of long-term or seasonal ground water and groundwater immersion, the soil is too wet for a long time, and the process of organic matter biological accumulation and mineral elements reduction under the action of wet plants and anaerobic conditions.
Do you know where the grassland that the Chinese Red Army walked on was? In the west of Sichuan, China, there is a vast grassland with endless water plants. Under the thick grass stems and rotten grass, there is black water with a soft surface. If people walk on it, they will worry about their lives. This is a swamp.