1. Overview
Zhang Jianping's book "Ecotourism" proposed the type of "landscape ecological restoration ecotourism resources" among artificial natural ecotourism resources. According to this point of view, We propose the concept of "ecological park for restoration and improvement of natural or artificial ecology". Ecosystems are not good or bad for the earth itself. Deserts, wetlands, forests, and fertile agricultural areas are all landscapes on its surface and have no impact on its existence or development. But for humans, the support of these ecosystems for human survival is very different. Humans must rely on agricultural areas, grasslands, wetlands, etc. to survive. Deserts, Gobis, rock deserts, saline-alkali lands, etc. cannot become spaces for human survival. Therefore, starting from the needs of human beings, various types of ecosystems are distinguished by their advantages and disadvantages, thus giving rise to the concepts of ecosystem deterioration, restoration or improvement. The so-called restoration of the ecosystem refers to an excellent ecosystem that was originally very beneficial to human survival, but has degraded into an ecosystem that is detrimental to human survival for some reason. For example, grassland or cultivated land has turned into a desert, fertile cultivated land has turned into an unproductive salt crust, and good cultivated land has turned into a rocky desert due to erosion. This is the deterioration of the ecosystem. However, these harsh ecosystems can be transformed into ecosystems that are beneficial to human survival. This is the ecosystem restoration area. Before the construction of Dujiangyan, the western Sichuan plain was threatened by the Minjiang River and suffered frequent floods. After the construction of Dujiangyan, it became a land of abundance.
The deterioration, restoration and improvement of ecosystems have both natural and man-made causes. The Taihu Lake Basin, the western Sichuan Plain, the desert transformation in the Yulin area, and the greening of the Loess Plateau in northern Shaanxi are all caused by man-made causes. Natural causes have a wide range of effects on the deterioration, restoration and improvement of ecology, such as climate changes such as drought and humidity, glacial and interglacial periods, and rise and fall of ground and sea levels. However, changes caused by natural causes last for a long time and are difficult to observe in a short human life. Therefore, changes to the ecosystem will mainly rely on human efforts and human efforts to prevent and improve the deterioration of the ecological environment. For this reason, it is necessary to further explore the various factors that lead to the quality and badness of the ecological environment.
The quality of the ecological environment is determined by three factors:
1) Water is the foundation, and its abundance directly determines the type of ecological environment. Wetlands are the most prone areas to floods. The series of changes in deserts such as - rainforest - forest - sparse steppe - grassland - desert steppe - desert Gobi are caused by the change in water resources from more to less.
2) Land is also the foundation. There are two directions of change from high-quality land to land extinction: ① Changes caused by soil loss and erosion from plains to mountainous areas, that is, vast, thick, and fertile plain land— Large sloping land - barren and sporadic sloping land - rocky desert areas with exposed rocks; ② The zoning caused by the change in water resources, namely flood-prone areas - wetlands - saline-alkali land - fertile land - arid and desertified land - wasteland - desert Gobi Waiting for the desert.
3) Temperature (energy) (when rainfall is abundant) causes vegetation zoning: tropical rain forest-broadleaf forest-coniferous forest-shrub-grassland-ice and snowfield.
It is difficult and unclear to use three-dimensional space diagrams to express the effects of the three factors of water, soil, and temperature. To this end, the temperature and altitude are used as the abscissa, and the abundance of water resources is used as the ordinate. The land availability, scale, and ability to support vegetation are divided into different types in this coordinate system to show the ecological relationship.*** It is divided into 16 categories (Figure 7-1): ① Plain land areas with abundant water resources; ② Salinization-prone land areas; ③ Wetland and rice planting land areas; ④ Flood-prone areas; ⑤ Large-area slope areas; ⑥ Severe water and soil Loss areas; ⑦ barren and scattered land areas; ⑧ rocky desert areas where land disappears; ⑨ ice and snow areas with or without land; arid and water-scarce land areas; grasslands; land desertification areas; desert steppes; deserts, Gobi and other soilless deserts ; coastal land; ocean. Among them, the land desertification area is superimposed on several types of land and is not divided into independent areas. Its range is marked with broken lines in Figure 7-1.
Figure 7-1 Schematic diagram of the relationship between ecological types
See text for ecological zones shown by numbers
Among the 9 categories of nature reserves in my country, the first 5 categories can represent Ecosystem area, its relationship with the ecological area represented by land in this book is shown in Figure 7-2. The order of priority of these five types of ecological zones according to their ability to support human survival is: wetland > forest > grassland > ocean coast > desert. The remaining animal and plant protected areas can appear in any of the five categories shown in Figure 7-2. However, geological relics and paleontological relics do not belong to the ecological category, so only five categories are listed in Figure 7-2. In the above order, forest is actually an area suitable for forest growth. In our country, it is mainly cultivated land, so it is better than grassland.
Figure 7-2 Schematic diagram of the location of 5 types of nature reserves
The 5 types of ecological areas divided by nature reserves are not all ecological areas, because they only represent the areas that need to be protected. 5 ecological types to protect. The 16 ecological types shown in Figure 7-1 can basically represent the current ecological status of our country, but there is no forest ecological type among them, because forests can appear in 11 types other than the 5 ecological types such as ice and snow areas, grasslands, desert steppes, and oceans. Among the types, good cultivated land is even more suitable for forest growth. Because of the shortage of arable land in our country, all arable land should not be afforestation. Therefore, our country's forest ecosystems are mainly located in severe soil erosion areas, barren and scattered land areas, rocky deserts and other types. This is also our country's reality. Therefore, after adding the forest system, there are 17 ecological types.
Food is extremely important to human society, so these 17 ecological types are sorted according to their ability to provide food for humans: wetlands and rice planting areas > plain farmland with rich water sources > coastal land > large areas of sloping land > floods Disaster-prone areas > Saline-alkali land areas > Severe water and soil erosion areas > Dry and water-deficient lands > Grassland > Desertification areas > Forests > Scattered land areas > Oceans > Desert grasslands > Stony desert areas > Ice and snow areas > Deserts and other arid deserts. In the above ranking, those who can move from the rear position to the front position are ecological restoration or improvement areas; those who retreat from the front position are ecological deterioration areas. For example, saline-alkali soil areas and areas with severe soil erosion can be replanted with rice, such as Yuanyang in Henan and Ailao Mountain in Yunnan; stony desert areas can be transformed into forests, such as Qianling Mountain in Guiyang, Jiyuan in Henan, and Yulin in Shaanxi to green the desert... These are all substantial improvements to the ecosystem. The lower reaches of the Tarim River in the Tarim Basin have stopped flowing, Lop Nur has dried up, and Populus euphratica forests have died, which is a sign of the deterioration of the ecological environment.
In the above ranking, grasslands are placed before forests and oceans because the latter does not provide as much food per unit area as grasslands. However, if edible fruit tree species such as chestnuts and walnuts are planted, forests can be transformed into Perennial agricultural area. If a large number of edible plants and edible animals are cultivated in the ocean, it can be developed into a marine farm and pasture, and its ecological position will be elevated to that of grassland.
It can also be seen from the relationship shown in Figure 7-1 that among the three factors that determine the type of ecosystem, if any one factor deteriorates to a certain extent, it can cause the ecosystem to deteriorate, or a factor The deterioration of factors will lead to the deterioration of other factors, simultaneously causing the deterioration of the ecological environment; sometimes, multiple factors can also deteriorate at the same time, causing the deterioration of the ecological environment. On the contrary, when restoring or improving the ecosystem, the ecological environment can also be improved by improving one factor. For example, drought in farmland or pasture can be solved by water diversion and irrigation. When the temperature in the North China Plain is low, greenhouses can be built to grow vegetables. Sometimes two factors must be solved at the same time. For example, transforming a desert requires covering the soil layer to solve the mobility of the desert, and diverting water for irrigation to solve the aridity of the desert. The Hani terraces in Ailao Mountain, Yunnan, not only transform the hillside into terraced flat land, but also combine it with water diversion to transform the entire hillside into an artificial wetland. There are many terraces in Sichuan and dry farming terraces in the north, but the effect is far less than the former because it is not integrated with water conservancy construction. Some ecological problems cannot be solved directly, such as rocky desertification in mountainous areas. Local small areas can be filled with soil to restore their original appearance, but large-scale restoration is impossible. However, strengthening water resources can afforestation on rocky mountains to make up for the lack of land, and then build desert-type perennial agriculture; another example is planting rice on saline-alkaline land, which can discharge saline-alkali water into the sea.
Several factors in some ecological environments can also interact with each other, forming a vicious cycle or a virtuous cycle. For example, droughts in the Tarim Basin and the northern edge of the Tibetan Plateau are generally believed to be caused by the Himalayas blocking the northward movement of water vapor from the Indian Ocean. This is certainly one of the reasons, but the current extreme drought is the result of the interaction between the plateau and the basin, a vicious cycle. Because the Tarim River had a large amount of water during the Qin and Han Dynasties, it was the desertification of the Tarim Basin that reduced precipitation on the northern edge of the plateau, which in turn caused a reduction in the flow of rivers entering the basin. This in turn accelerated the desertification process in the basin, and the results of their interaction accelerated process of drought. If this vicious cycle is cut off, the entire ecosystem will be radically improved. For example, based on the South-to-North Water Diversion and East-to-West Water Diversion, building a forest belt (desert-type perennial agricultural area) about 2,500km long from the Tengger Desert through the Central Gobi and the Gobi in front of the Kunlun Mountains can improve the entire northwest region, including Qinghai-Tibet The current drought situation on the northern edge of the plateau can at least return to the state of the Qin and Han Dynasties, and the precipitation can even reach the precipitation in North China. The factors that determine ecological quality are as polar as the beauty factors. If the temperature is too low, it will become an ice and snowfield. If the temperature is too high, it will not be suitable for human habitation, but will also bring about a series of problems such as rising sea levels. The ground will rise quickly, and the land will become less and rocky deserts will appear. The decline of the ground will expand the area of ??the plains, but it will also cause Threatened by seawater intrusion, such as the land subsidence problem in the North China Plain; too much water will cause floods, and too little water will cause the land to lose its production capacity and die through desertification. It is precisely because of this polarity that water that causes disasters must be transferred to water-scarce areas to play the dual role of eliminating harm and creating benefits. Ecology is a large system, and there must be a unified plan that comprehensively solves various problems at the same time. In this way, our country's ecological outlook can be completely improved. The land area of ??960×104km2 and the sea area of ??473×104km2 can provide daily necessities, forming a unified large land and resources. If this can be achieved, the contribution of ecotourism will be extremely huge.
Restored and improved ecological areas also have two types: complex with scenic areas and pure ecological areas. For example, Dujiangyan is a famous scenic tourist area and an area for ecological improvement due to human factors; Henan Wangwushan Rock Desert The forest on the Maolan karst landform in Guizhou is not only a famous scenic spot, but also an area where natural factors have improved the ecology. However, the improvement of ecological restoration in most areas does not have great tourism value. For example, the transformation of the desert in Yulin area, the afforestation of Dagouhe Forest Farm in Jiyuan City, Henan Province and the stone mountains to the west, and the afforestation of the hot dry valley of the Jinsha River... are all artificial ecological changes. However, they only have scientific value for scientific research, scientific investigation, and exchange of production experience, and have no tourism value. Therefore, they are purely ecological parks, not ecological parks combined with scenic spots.
2. Ecosystem Deterioration Areas
Sudden forest loss, land desertification, water and soil erosion, etc. are currently the most prominent problems in the deterioration of my country's ecosystem. Since the severe floods in the Yangtze River, the country has attached great importance to the protection of forests, and has provided subsidies and incentives for returning farmland to forests and artificial afforestation. The sharp decline in forests is no longer a serious problem. On the contrary, the ecosystems in some areas have been restored and improved.
1. Desertification
(1) The drying up of Lop Nur
There are Taitema Lake, Karaheshun Lake and Lop Nur in the east of the Tarim Basin, and between the three lakes there are The rivers communicate with each other and are collectively called the Lop Nur Depression. The area of ??Lop Nur once reached 5350km2, and it was the terminal lake of the Tarim River and Kongque River. Due to the increasing drought in the Tarim Basin and the increase in water consumption in the upper reaches of the Tarim River and along the way, the area gradually shrank, reaching 3006km2 in 1942; The river mouth was dammed, and only the Kongque River flowed into Lop Nur alone; in 1962, the area was only 660km2, and the water surface disappeared in 1975. After the dam was built in 1952, the Tarim River and Dongerchen Lake flowed into Taitema Lake, covering an area of ??150km2; in 1962, the area was only 88km2; the main part dried up in 1981; in 1987, the Lop Nur area completely dried up and became completely desertified.
(2) The disappearance of Juyanze and Juyan Oasis
The Heihe River is the largest river in the central part of the Hexi Corridor. Its tail end forms Juyanze, covering an area of ??726km2, and the Juyan Oasis is along the coast. , during the Han Dynasty, heavy troops were stationed in it and it was called Juyansai. The Tang, Xixia and Yuan Dynasties set up Jinaicheng here. Wang Wei's famous sentence "The solitary smoke in the desert is straight, and the sun is setting in the long river" shows that the Heihe River was still a big river at that time. In the fifth year of Hongwu's reign in the Ming Dynasty, Zhu Yuanzhang ordered Feng Ren to march to the west. The defender of Ji Nai City refused to surrender, so Feng cut off the water source. From then on, the river flowed north, Juyanze dried up, and the oasis became part of the Badain Jaran Desert.
2. Stony desertification
In mountainous areas and hills where the ground rises or the altitude is slightly higher, flowing water will cause soil erosion. Further erosion will take away all the soil, leaving the remaining Rocky desert with exposed rocks. my country is a mountainous country, so rocky desertification is one of the serious problems faced by my country's ecological environment, especially in the southwest region. The rocky desertification area in the five provinces (autonomous regions and municipalities) of Sichuan, Chongqing, Yunnan, Guizhou and Guangxi exceeds 100 million acres, and the rocky desert area in Guizhou accounts for one-third of the province's area.
3. Ecosystem restoration and improvement area
1. Artificial wetland area
Wetland is an important ecosystem, known as the kidney of the earth. Wetland protection has has become a hot issue around the world. In fact, rice fields (including terraces) are typical artificial wetlands. Building terraces means building artificial wetlands. In addition to having all the functions of wetlands, rice fields also have many other ecological values, the most important of which are the following four aspects:
1) Resist the erosion of land by running water and reduce the siltation of rivers. The ability of running water to erode land depends on the amount and velocity of runoff formed during rainfall. The runoff formed by rainfall on slopes will carry sediment, causing soil erosion and land erosion. However, after the runoff enters the paddy field, it will become still water, and the flow rate will be close to zero. The sediment carried will be deposited in the paddy field, reducing the amount of sediment entering the river. The annual sediment transport of the Yellow River is about 3 times that of the Yangtze River, and the annual runoff of the Yangtze River is about 12.5 times that of the Yellow River. Therefore, the sediment transport per cubic meter of the Yellow River is about 37.5 times that of the Yangtze River. In addition to the loess in the Loess Plateau, the ability to resist erosion is relatively low. In addition, the widespread rice fields in the source areas of the Yangtze River system should be a more important reason. Therefore, combined with water conservancy construction, extensive construction of rice terraces around the Loess Plateau may reduce the sediment content of the Yellow River to the level of the Yangtze River.
2) Detain floods, stagger flood peaks, regulate river flow, and reduce flood disasters. When it rains, rainwater is accumulated in paddy fields and then gradually enters rivers, which can stagger flood peaks and stabilize river flows. In the past, people only paid attention to the storage capacity of lakes. In fact, paddy fields also have this function. my country's existing rice fields are about 38×104km2. If the water storage depth is 0.5m, its water storage capacity will exceed the total water storage capacity of lakes in southeastern my country and the Yunnan-Guizhou Plateau. Its regulating function will exceed that of lakes, and it can solve or alleviate floods in many areas. .
3) Rice fields have the dual functions of water storage and agricultural production, which can solve the conflict between water storage and planting for land.
4) Developing terraces upstream of the reservoir can not only slow down the siltation of the reservoir, but also expand the storage capacity.
The Yuanyang Rice Terraces can be taken as an example. There is no flat river in Yuanyang County. The terraces are all embedded in the ravines and mountains of 400 to 2000 meters. The mountains and valleys here are connected to the slopes and the ravines are embedded in each other. They are all terraced fields. Therefore, the Hani people live here, and the terraces are also called Hani terraces.
The unified construction of water conservancy and terraces is the essence of Yuanyang terrace technology. Many places where terraced fields were developed in Yuanyang have very dangerous terrain. There are cliffs beside the highway and layers of terraced fields under the cliffs. In Bada, the Hani people carved out 5,000 terraces. As far as the eye can see, they look like ladders hanging down from heaven. During the busy farming season, in order to save time on the road, local people live in field sheds, which are like small boats floating on the vast sea.
2. The Dujiangyan Project that benefits both disaster reduction and irrigation
Diversion of water can eliminate flood disasters in the transferred area and increase water resources in the transferred area, which has a dual ecological improvement effect , is a measure that simultaneously reduces disasters and promotes benefits. Dujiangyan is not only a world-renowned water conservancy project, but also a favorite tourist attraction. Dujiangyan was originally built to relieve flooding in the Chengdu Plain.
Because of the large flow of the Min River, the Chengdu Plain would be flooded when the water rose. The prime minister of Shu opened the mouth of the treasure bottle and built a canal to divert part of the river water into the Tuo River. This eliminated the floods in the Chengdu Plain. Later, after the Qin State destroyed Shu, the governor Li Bing developed irrigation on the original basis of Dujiangyan. The economic benefits of irrigation were high, making Shu (Sichuan) a land of abundance. It can be seen that the construction of Dujiangyan has simultaneously improved the ecological level of the water resources transfer area and the transfer area.
Since floods occur at different times in various river basins in our country, this time difference can be used to promote the experience of Dujiangyan diversion to the whole country, connect the river basins for mutual benefit, and divert the floods that cause floods during floods to Other watersheds become water resources introduced into the area. For example, it is easy to communicate between the Yangtze River, the Yellow River, and the Huaihe River, and between the Songhua River and the Liaohe River.
The fundamental factor that determines the quality of ecology is water. The fundamental direction of solving water problems is to guide the excess water that causes floods to where it is needed. Therefore, as long as sufficient water sources from outside enter the desert, the ecological level will be improved and it will become an oasis.
3. Rice planting can transform saline-alkali land into artificial wetland
Many of the technologies of the Dujiangyan Irrigation Project are beyond the reach of modern water conservancy projects. However, irrigation to prevent the land from becoming saline-alkali is the key to Dujiangyan Irrigation Project. The essence of engineering.
Between 6,000 and 7,000 years ago, in the Tigris and Euphrates plains, people knew how to divert river water to farmland, so the Mesopotamia region in the Mesopotamian plains became the oldest in the world. of irrigation areas. But irrigation did not turn this area into fertile land, but instead formed a thick, white salt crust. On the surface, the Dujiangyan Irrigation System has not taken any measures to solve salinization, but it has been operating for more than 2,000 years without any signs of salinization. The reason is that it uses easily soluble elements (salt-alkali components) separated from rocks during weathering. Sent into the ocean. When rice is grown in the Dujiangyan Irrigation Area, saline and alkaline water enters the sea with the water. Many places in the country use this method to transform saline-alkali land. For example, in the 1970s, more than 1.5 million acres of rice were planted on saline-alkali land in Panjin and Yingkou, Liaoning, with a yield of 400kg per unit and desalination in 3 to 5 years, which improved the level of the local ecosystem. Yuanyang was once the hardest-hit area by salinization in Henan Province, with saline-alkali land accounting for 80% of the cultivated land. However, it has achieved great success in switching to rice cultivation. This method of irrigation should be used wherever large amounts of water can be diverted.
4. Underground water storage can improve the level of the ecosystem
In landscape classification, we regard spring scenery as the source of rivers, because each spring must have a corresponding A stream or small ditch, even if it cannot become the main source of a river due to its unfavorable location, must still be a supply water source for the river. Precipitation on the surface is short-lived, but rivers flow all year round. The reason is that precipitation seeps into the ground and forms a huge reservoir, which supplies rivers evenly over time. The fact that precipitation accumulates underground can be directly seen in many scenic spots. For example, in Guizhou Longgong Scenic Area, there are swirling ponds where surface water enters the underground in the upstream of Dragon Palace; in karst scenic areas, sinkholes where precipitation enters the ground can be seen everywhere; In the rural areas of Sanmenxia City, Henan, there are still many patio kiln courtyards. The patio kiln courtyard is a pit dug 6 to 7 meters deep on the ground. The bottom of the pit is open on the four walls. All rainfall water and daily domestic water enter the ground through the seepage well in the courtyard. A well can be dug to collect water in the patio kiln courtyard, indicating that there is a small underground reservoir underneath. When it rains, rainwater seeps into the ground and is stored underground for daily use of water drawn from the well. Therefore, water shortages can be solved by building rainwater harvesting projects on the Loess Plateau and other water-scarce lands, and by building seepage wells extensively to store most of the precipitation underground, and then dig wells to draw water for irrigation and living. problem. Precipitation mainly supplies the Yellow River in the form of spring water (clear water), and can also solve the sediment problem in the Yellow River.
The annual allowable water extraction volume of the Dawu Water Source in Zibo City, Shandong Province is 1.42 × 108 m3, and the actual average annual water extraction volume is 1.9 × 108 m3. The groundwater level drops to -10m during the dry season. Later, the Taihe Reservoir Yufeng During the flood season, water is released to the Zihe River beach, and the annual water supply is nearly 1.3 × 108 m3, which meets the water supply needs for local industrial and agricultural production.
Storing water underground is a world trend.
For example, Berlin in Germany uses groundwater as drinking water, and the groundwater supplemented through river bank filtration accounts for 40 to 70% of the total water volume. In the Ganges River Basin in India, floods in the rainy season are widespread, but floods in the dry season cannot meet the needs. Scholars from Harvard University in the United States suggest that large amounts of groundwater should be extracted and utilized during the dry season to free up underground water storage space and store excess river water in underground aquifers. Realize the recycling of groundwater and surface water.
As mentioned above, underground water storage can improve the ecological level of dry and water-deficient land to the level of water-rich land.
5. Stony desert can be converted into forest
Maolan Nature Reserve is located in Libo County, southern Guizhou Province. It is a typical karst landform (karst landform). In all karst areas in the world, including most of our country's karst areas, the forests have long since disappeared, leaving only bare limestone and dolomite barren mountains. However, within the 2×104 hm2 area of ??Maolan Nature Reserve, 1.937×104 hm2 is dense forest, accounting for 92% of the total land area. Compared with the desolate scenes in karst areas around the world, this relatively stable forest ecosystem cannot but become a rare treasure. It points out the direction for humans to use "rocky deserts" and conquer barren mountains.
The karst forest in the reserve includes various types of funnel forest, depression forest, basin forest and canyon forest. It is a dense subtropical primeval forest, lush and green, and is completely a wilderness primeval forest, extending 80km and 20km wide. It is the only karst forest area on earth. Whether it is steep conical peaks, peak clusters and peak forests, or swamps and wetlands, they are all covered with lush evergreen forests. Viewed from the air, it looks like a vast green ocean with rough waves. The forest blocks the sky and almost no sunlight reaches the ground through the thick canopy.
The funnel forest is composed of 30-40m tall trees. These trees are distributed on the bottom of a funnel-shaped pit with a depth of 100-200m and a diameter of 100-200m, and grow from the steep cliff to the top of the cliff. The karst depressions are large and flat and can be used as farmland, and forests grow on the karst cone peaks surrounding the depressions. Basin forests grow in open and flat basins, and lush woods also grow in valleys, turning them into green corridors.
The rocks here are rugged and steep, with different shapes, but all the rocks are covered with green plants. Trees grow along the cracks in the rocks, and their well-developed root systems can penetrate deeply into the cracks. Some trees have The roots developed into a dense root network around the rocks, and some penetrated into the caves. Ferns and moss covered the damp ground, creating a green patchwork. The reason why the Maolan karst area can be covered with forests is that there are abundant water resources here, high and low, above and below ground, and everywhere. Streams, springs, ponds... provide water sources that nourish the forest, ensuring that plants can grow on rocks.
Maolan Nature Reserve and Guiyang Qianlingshan Park are limestone rocky deserts. Henan Wangwushan Global Geopark is a granite and quartzite rocky desert. Henan Madao Lithogenic Forest Park is a granite rocky desert. Henan Jiyuan Dagouhe Forest Farm and the small hills in the suburbs of Zhuzhou, Hunan are sandy shale rocky deserts, with dense forests growing on them. This proves that under moderate water conditions, rocky deserts of various types can become forests, that is, It is said that it can be developed into a desert-type perennial agricultural area, that is, a new type of agriculture that grows chestnuts, walnuts, etc. and harvests it for many years.
The rock types in the rocky desert are different, and the methods of solving water sources are different. The karst underground reservoir in Longshan County, Hunan is formed by damming the underground river outlet in the limestone area, using the cave space to store water. The cave outlet is small, the dam construction cost is low, the reservoir does not flood the ground, and there is no evaporation loss; the water in the reservoir flows to Penetration all around can raise the diving surface close to the surface, ensuring the water needs of the rock desert forest. If Guizhou can promote this measure, most rocky desert areas can be developed into perennial agricultural areas, which will greatly improve Guizhou's ecological level and economic benefits.
6. Human efforts can improve the level of the ecosystem
Generally, when the ground altitude rises to a certain height, the forest belt will be replaced by the grassland belt, but the upper limit of the forest belt can be raised through human measures .
People in Daocheng County, Ganzi Tibetan Autonomous Prefecture, Sichuan, have cultivated 10,000 acres of poplar forest that stretches for more than 20 kilometers and covers an area of ??32,000 acres on the Qinghai-Tibet Plateau at an altitude of more than 3,800 meters. On average, each man-made forest is more than one acre, and all poplar trees are planted in On the pebbles on the river beach, what was originally a gray-yellow wasteland has turned into a life zone in the restricted area of ??life. The international forestry community agrees that successful afforestation in high-altitude areas has great scientific value. The hot and dry valley at the confluence of the Heishui River and the Jinsha River in Ningnan County, Liangshan Prefecture, Sichuan, is known as the Death Valley. The maximum temperature reaches over 42°C and the surface temperature reaches 78°C. It is the biggest obstacle to the construction of an ecological barrier in the upper reaches of the Yangtze River. In 1964, the Ministry of Forestry experimented with seedling afforestation here. After screening and comparing dozens of tree species, Casuarina was found to have the best effect. Later, Leucaena leucaena was introduced from Australia. Through the joint efforts of the people of the county, the river beaches and barren hillsides were restored. Dressed in green, "This is really a miracle of mankind's victory over drought." Forests are the main body of terrestrial ecosystems, storing more than 80% of the carbon in global terrestrial ecosystems. Needless to say, its importance is not high, but my country's forest coverage rate is not high. There is a shortage of land in our country and there is not enough land for afforestation. Therefore, afforestation in harsh environments has opened up a new direction to improve the level of our country's ecosystem and forest coverage.