As the main body of renewable natural resources and terrestrial ecosystem, forest plays an irreplaceable role in the history of human survival and development.
With the arrival of the new century, the growing economy and population bring more and more pressure to the forest.
People's concern about forest disappearance and forest destruction has become an important aspect of international environmental problems.
Among the green vegetation, the forest is called the lungs of the earth.
This is because forests absorb a lot of carbon dioxide to produce oxygen needed by humans and other living things.
Trees are oxygen factories, dust filters, natural reservoirs and natural air conditioners. ...
Trees bring us endless benefits ... protecting forests and vegetation.
I. The role of forests
The forest is the mother who breeds human beings;
Forest is a treasure house of human resources;
Forests can protect the soil;
Forests can conserve water;
Forests can regulate the climate and produce oxygen;
Forests can purify the air;
Forests can eliminate noise.
Second, the value of a tree.
How much is a tree worth? A professor at Calcutta Agricultural University in India calculated two different accounts for a tree: a tree that has grown normally for 50 years is worth more than 300 dollars at most according to the value of wood in the market, but if it is calculated according to its ecological benefits, its value is far more than that. According to rough calculation, if a tree grows for 50 years, it can produce oxygen worth $365,438 +0.250 and protein worth $2,500 every year. At the same time, it can reduce air pollution (worth $62,500), conserve water (worth $365,438 +0.250) and provide habitats for birds and other animals (worth $365,438 +0.250). Taken together, the value of a tree is not 300 dollars, but 200 thousand dollars.
In recent years, many countries have begun to study the indirect benefits of forests. From 197 1, it took Japan three years to measure the benefits of forests. Japan has 25 million hectares of forests, which can store 22 billion tons of rainwater every year, prevent soil erosion by 5.7 billion cubic meters, inhabit 8 1 10,000 birds and generate 52 million tons of oxygen. The indirect benefits in the following year totaled128 billion RMB, equivalent to the total annual budget of Japan 1972. Finland's forests only produce 654.38+0.7 billion marks of wood every year, and the value generated by the forest's insight into the environment is 5.3 billion marks. The indirect benefit value of American forests is nine times that of wood. China Yunnan Forestry Investigation Team calculated the forest benefits of the whole province, and the results showed that the total forest ecological benefits accounted for 94% of the total forest benefits, and the direct benefits only accounted for 6%. It can be seen that the evaluation of forest function should not only look at how much wood and other forest products it can produce, but also look at its indirect benefits in covering ecological environment and promoting agricultural and animal husbandry production.
Third, the forest crisis
The forest crisis is mainly caused by human beings. With the growth of population, agricultural land has been continuously expanded, and a large number of forests and grasslands have been destroyed. Predation is mining, which makes the world's forests less and less. According to FAO statistics, at present, more than 20 hectares of forests are destroyed every minute on the earth, and the world forest area has been reduced by half from 1950 to 1985 in just over 30 years. Environmental pollution caused by human activities has also brought disasters to plants.
Forest is an important participant in the biosphere process. It is not only the "sink" of some substances and energy in the process of material circulation and energy flow in the near-surface atmosphere, but also the "source" of others. It is also a "reservoir" for producers and an important channel for energy flow and material circulation in the atmosphere-vegetation-soil system. Jiang (1993) divided the ecological functions of forests into five aspects, namely:
① Forest is the most abundant terrestrial ecosystem;
② Forest is a unique biological gene pool;
(3) The forest has a spatio-temporal structure;
④ The forest biomass is the highest;
⑤ Forest is the pillar of biosphere balance.
Forest is also an important part of biosphere, which plays an irreplaceable role in ensuring the balance of biosphere environment, maintaining biodiversity and providing various materials and energy for human beings. Forest is a multi-functional and multi-benefit system, which plays a link role in maintaining the ecological balance of the earth's land, which is embodied in purifying the environment, regulating the climate, preventing soil erosion, protecting animal resources and so on. Forests can purify the environment and are known as "environmental guardians".
The first is to consume CO2 in the air and release O2. At present, humans release about 2x 10 10t CO2 into the atmosphere every year, of which 2/3 are absorbed by the sea and land, and the photosynthesis of forests consumes18 billion tons of CO2 in the air every year. At the same time, the O2 released by forests is 65,438+00 times that of the global population. It is predicted that the average 10 m2 forest can meet the O2 required for breathing, so it is regarded as the standard of urban greening.
The second is to ban smoking and dust removal and purify the atmosphere. About 600 million tons of harmful gases are discharged into the atmosphere every year all over the world, which seriously deteriorates the environment. Forests are natural filters, and many tree species have different degrees of resistance and absorption to air pollutants, such as SO2, CO, NO, NO2, O3, HC compounds and F compounds.
The third is to absorb dust and smoke. Because the leaf area of the tree is 50 times larger than that of the tree, and the leaf surface is uneven and furry, it has the ability to absorb dust. 1 m2 of elm leaves can absorb 3-4 g of dust one day and night.
The fourth is sterilization. Many trees can secrete phytoncide, sandkill diphtheria, tuberculosis, typhoid fever, dysentery and other germs. There are 580,000 bacteria in the air on the boulevard 1 m3, but only 55 bacteria in the forest. In addition, forests play an obvious role in reducing urban noise and tsunami.
Forest photosynthesis absorbs carbon dioxide and releases oxygen, but it also consumes oxygen. An adult tree consumes the same amount of oxygen in photosynthesis. Trees that enter old age consume more oxygen.
In climate, photosynthesis needs to absorb light energy. If forests are cut down more, light energy will be absorbed by other substances, and the climate temperature will rise.
Forests can stop sandstorms and prevent land desertification.
Excessive deforestation has led to disasters such as landslides and mudslides.
It also has a great impact on biological companies
Coastal forests have also reduced the impact of the tsunami on cities.
Forests are the lungs of the earth, and every tree is an oxygen generator and a carbon dioxide absorber. A linden tree can absorb 16 kg of carbon dioxide a day, and 150 hectares of broad-leaved forests such as poplar, willow and locust can produce 100 tons of oxygen a day. If urban residents have an average of 65,438+00 square meters of trees or 25 square meters of grassland, the carbon dioxide they exhale will have a place to go and the oxygen they need will have a source.
Forests have the functions of absorbing carbon dioxide and releasing oxygen, taking medicine, removing dust, sterilizing, purifying sewage, reducing noise, preventing sandstorms, regulating climate, indicating and monitoring toxic substances and so on.
Wind is an important condition to determine the fire area and development direction. It can not only accelerate the evaporation of combustible water, accelerate drying and make it burn mechanically, but also supplement new oxygen and increase combustion conditions. There is an old saying: "The wind helps the fire." The greater the wind speed, the more fires will occur, especially in dry and hot weather. Most major forest fires and characteristic forest fires occur in windy weather conditions above level 5.
Forest is an ecosystem that has an important impact on terrestrial life, and its importance is as follows:
1. Provide habitats, foraging places, mating and breeding places for other animals,
2. Provide a cool place for other plants and save water.
3. Providing oxygen, preventing wind and fixing sand, improving local climate, etc. For the economic purposes of mankind.
If the effect of deforestation is contrary to the above (note: proper deforestation is beneficial to the stability of forest system)
If there is no forest
Many trees can absorb harmful gases, such as camphor tree, oleander, clove, maple, Robinia pseudoacacia, Ailanthus altissima, Sabina vulgaris, Ligustrum lucidum, oak tree, willow tree, hibiscus, elm tree, Pinus massoniana, Platanus acerifolia and other ......................................................................................... These gases usually have 1/4, which can be purified or turned into oxygen when passing through the green belt.
Leaves have a strong adsorption and filtration effect on dust particles through their fluff, secreted mucus and oil. Each hectare of forest can absorb 50 ~ 80 tons of dust every year, and the dust content in the air of urban green space is generally less than half of that of non-green space.
Many trees can secrete fungicides, for example, the fungicides secreted by pine trees can kill pathogenic microorganisms of diphtheria, dysentery and tuberculosis. The content of bacteria in the air in downtown area is 85% higher than that in green area.
Trees can also absorb noise. A 40-meter-wide forest belt can reduce noise 10 ~ 15 decibels.
Forests are so important that FAO has designated "Forests and Life" as the theme of World Food Day in 199 1 year: not for planting trees, but to show how forests can help mankind achieve the goal of sustainable development; What needs to be emphasized is that forests have the function of lasting productivity, that is, while preserving the resource base for future generations, they can also meet the needs of the continuous development of current production; It is necessary to remind people that forests can not only provide food and fuel, but also have the most fundamental value of protecting the environment.
If there is no forest, most of the life on land will be extinct, and most of the water will flow into the ocean; Oxygen in the atmosphere will decrease and carbon dioxide will increase; The temperature will rise obviously, and floods and droughts will occur frequently.
The lush forest covering the earth is a huge and most precious "green wealth" owned by nature.
The preciousness of the forest:
Our ancestors first lived in the forest. They collect wild fruits, catch birds and animals for food, make clothes out of leaves and skins, and build houses on branches. Forest is the hometown of human beings, from which human beings originated and developed.
To this day, forests still provide us with all kinds of materials necessary for production and life. It is estimated that 300 million people in the world depend on forests for their livelihood.
Forests provide all kinds of food, including fruits, seeds, nuts, roots, tubers, fungi and so on. In some forest areas in Thailand, 60% of food comes from forests. Animals in forest bushes also provide people with meat and animal protein.
Wood has a wide range of uses, such as building houses, mining, building railways, building bridges, making paper and making furniture ... Forests provide employment opportunities for millions of people. Other forest products are also rich and colorful, such as turpentine, baking gum, insect wax, spices and so on. Are all raw materials for light industry.
China and India have used medicinal plants for 5000 years. Today, most medicinal materials in the world still depend on plants and forests. In developed countries, the active ingredients in 1/4 drugs come from medicinal plants.
Fuelwood is the main fuel in some developing countries. About 2 billion people in the world cook with firewood and charcoal. In some countries, such as Burundi and Bhutan, more than 90% of energy is provided by forests.
It can be said that the forest is like the "dispatcher" of nature, regulating the circulation of air and water in nature, affecting the climate change, protecting the soil from wind and rain, and reducing the harm brought by environmental pollution to people.
Forests are the real lungs of the earth, and every tree is an oxygen generator and a carbon dioxide absorber. A linden tree can absorb 16 kg of carbon dioxide a day, and 150 hectares of broad-leaved forests such as poplar, willow and locust can produce 100 tons of oxygen a day. If urban residents have an average of 65,438+00 square meters of trees or 25 square meters of grassland, the carbon dioxide they exhale will have a place to go and the oxygen they need will have a source.
Forests can conserve water and play an important role in the natural circulation of water. "Green mountains are always there, and green water is always flowing." Trees are always associated with water. Part of the precipitation rainwater is intercepted by the canopy, most of it falls into the litter under the tree and is stored in the loose and porous forest soil, some of it is absorbed by the roots of plants in the forest, and some of it returns to the atmosphere through evaporation. 1 hectare of forest can evaporate 8000 tons of water a year, which makes the air in the forest area moist, increases precipitation, and makes it warm in winter and cool in summer, thus playing a role in regulating climate.
Forests can prevent sandstorms and prevent soil erosion. As soon as the wind blows, it blocks the way with the crown of the tree, reducing the wind speed, and the roots are long and dense, so hold on to the soil to prevent the wind from blowing away. Heavy rain falls into the forest, seeps into the deep soil and rock crevices, and slowly flows out in the form of groundwater, which can't wash away the soil. According to the records of Kenya, Africa, when the rainfall was 500 mm in that year, the sediment loss of agricultural land was 100 times that of forest area, and that of pasture land was 3000 times that of forest area. Aren't we going to stop desertification and soil erosion? The most effective helper is the forest.
Photosynthesis of green plants can beautify our environment and make our living environment better. Forests can resist sandstorms and protect human beings.
In recent years, due to the consumption of wood and forest products in consumer countries, the global forest area has decreased significantly, and nearly 10 million hectares of forests disappear every year. This is not only an internal problem of a country, but also an international problem.
197 1 The Seventh World Forest Congress decided to designate March 2 1 every year as World Forest Day, in order to arouse the attention of all countries to the green protector of mankind-forest resources, and realize the sustainable utilization of forest resources by coordinating the relationship between people and forests.
Divide two forests with the same size and conditions in the same area, but strictly separate them and prohibit species exchange, and then put the experimental animals into one of the forests, and don't leave any such animals to record every once in a while, which is ok, but no results can be seen for a year or two. With luck, it will take 30-40 years. If you are unlucky, you will wait for hundreds of thousands of years to record it slowly. After several generations, the result came out.