■ The total value of ecological services is 10 trillion yuan per year.
"The total ecological service value of China's forest ecosystem is 10 trillion yuan per year, which is roughly equivalent to 1/3 of the current GDP of 30 trillion yuan." Zhang Fengshou, president of Chinese Academy of Forestry Science, introduced that this is the first time that China has evaluated the quality and value of forest ecological services, including six functions: water conservation, soil conservation, carbon fixation and oxygen release, nutrient accumulation, atmospheric environment purification and biodiversity protection.
The value of saving water, that is, regulating water quantity and purifying water quality, reaches 4.06 trillion yuan every year. The annual water conservation capacity of forest ecosystem in China is 494.766 billion cubic meters, which is equivalent to the storage capacity of 12 Three Gorges reservoirs after the water level reached 175 meters in 2009.
The annual value of soil conservation is 0.99 trillion yuan. The annual soil consolidation of forest ecosystem in China reaches 7.035 billion tons, which is equivalent to reducing soil loss by 730 tons per square kilometer in China. If the soil depth is 40 cm, the forest can reduce land loss by 35 1.75 million hectares per year. The annual fertilizer conservation capacity of the forest is 364 million tons. If the nitrogen content is 14%, it is equivalent to 2.6 billion tons of nitrogen fertilizer.
Carbon fixation and oxygen release, that is, the annual value of forest carbon fixation and oxygen release reaches 1.56 trillion yuan. The annual carbon sequestration of forest ecosystem in China is 359 million tons, and the annual oxygen release is 654.38+22.4 million tons.
Accumulate nutrients, that is, forest plants absorb nitrogen, phosphorus, potassium and other nutrients in the atmosphere, soil and precipitation through biochemical reactions, and store them in various organs in the body. The annual value is 0.2 1 trillion yuan. The annual accumulated nutrient quality of trees in China forest ecosystem is 65.438+0.7 billion tons, which plays an important role in reducing downstream non-point source pollution and water eutrophication.
Purifying the atmospheric environment, that is, the value of forests providing negative ions, absorbing pollutants and stagnant dust every year is 0.79 trillion yuan. China's forests absorb 32 million tons of air pollutants every year, and the annual dust retention is 500 1 100 million tons, which is equivalent to hundreds of millions of air purification equipment.
Biodiversity protection, that is, forest ecosystem provides living and breeding places for biological species, and its annual protection value is 2.40 trillion yuan. China forest ecosystem provides places for tens of thousands of animals and plants to survive and multiply, which has strong biodiversity conservation value.
People often only pay attention to the economic and social benefits of forests, but ignore the ecological benefits of forests. Forest resources are one of the most important resources on the earth and the basis of biodiversity. They can not only provide a variety of valuable wood and raw materials for production and life, but also provide a variety of food for human economic life. More importantly, forests can regulate climate, conserve water and soil, and prevent and mitigate natural disasters such as droughts and floods, sandstorms and hail. It also has the functions of purifying air and eliminating noise.
Forests have great functions of water conservation and soil and water conservation.
Soil erosion is a natural disaster, which has adverse effects on industrial and agricultural production, water conservancy and people's lives. Forests prevent surface soil erosion and play a role in water storage and precipitation. According to research, if the forest land has only one centimeter of litter layer, the sediment loss can be reduced by 94%. The forested land can store 2× 1 04 kg more water than forested land (1hectare). Forests are natural reservoirs. When the root system of trees in the soil reaches 1 m depth, each hectare of forest can store 500-2000 cubic meters of water, and each square kilometer of forest can absorb 20-40 tons of rainwater per hour, which is about 20 times that of non-forest land. When there is more rain, the forest can store water, and when there is less rain, the forest can slowly release water. It is simply a huge natural reservoir.
Forests are also a barrier against sandstorms. The sediment transport per hectare of forested land is 0.05 tons, and that of forested land is 2.22 tons, with a difference of 44 times. 1 hectare shelterbelt can protect 100 hectares of farmland from wind disasters. Its windproof benefits are shown in two aspects: reducing wind speed and changing wind direction. A shelterbelt with porous structure has a windproof range of 3-5 times the height of the windward shelterbelt and 25 times the height of the leeward shelterbelt. In the windproof range, the wind speed is reduced by 20%-50%. If the shelter belt and forest net are properly configured, disastrous strong winds can be turned into small winds or breezes. The roots of trees, shrubs and grass can fix soil particles to prevent desertification, or change fixed sand into soil with certain fertility through biology.
Forests play an important role in regulating climate, purifying air and protecting environment.
Forests are buffers to control global warming. Due to the recent extensive use of fossil fuels, forests have been reduced on a large scale, and the concentration of atmospheric carbon dioxide has increased rapidly, resulting in a "greenhouse effect" and a global warming trend. The results show that the reduction of forest area accounts for about 30%-50% of the total effect of all factors in the current increase of atmospheric carbon dioxide concentration. The consequences of the greenhouse effect are amazing. First of all, it will cause changes in rainfall patterns. Compared with non-forest areas, the frequency and quantity of rainfall in forest areas are 20% more. Second, it will lead to sea level rise. Third, it will cause many plant communities growing on land to die because of temperature changes. Such changes will further promote the temperature rise and form a vicious circle of ecosystems on a global scale.
Forests are "big factories" for making oxygen. Forests absorb carbon dioxide and release oxygen. 1 hectare of broad-leaved forest can absorb 1 ton of carbon dioxide and release 0.73 ton of oxygen a day. 1 hectare of oxygen released by the forest can be used by 1000 people to breathe (an adult consumes 0.75 kg of oxygen and emits 0.90 kg of carbon dioxide every day).
The forest can block and filter dust and is a natural vacuum cleaner. Dense canopy can reduce wind speed. When the airflow with large dust content passes through trees, with the decrease of wind speed, the dust with large particles in the air falls rapidly. In addition, the leaves of some trees have rough surfaces, fluff or can secrete oil or mucus, which can absorb a lot of floating dust in the air, and the content of airflow through the forest will be greatly reduced. 1 hectare forest can absorb all kinds of dust 3.3× 105~9× 105 kg per year. Forests can absorb harmful gases in the atmosphere. It is estimated that the pine forest can absorb 20 mg of sulfur dioxide from the air of 1 m3 every day, and the Cryptomeria fortunei forest of 1 hectare can absorb 720 kg of sulfur dioxide every year. Through a French phoenix tree belt with a height of 15m and a width of 15m, the concentration of sulfur dioxide can be reduced by 25%~75%. It can also reduce the bacterial content in the air. Many trees can secrete fungicides during their growth, killing all kinds of germs brought by dust. It only takes 5-6 minutes for Lagerstroemia indica, conifer and orange tree, 3 minutes for Platanus acerifolia, 2 minutes for eucalyptus citriodora and 0/minute for Sanguisorba root to kill pathogenic bacteria. 667 square meters of pine forest can secrete 2 kilograms of bactericide one day and one night, which can kill bacteria such as tuberculosis, diphtheria and dysentery; 1 ha Berlin can secrete 30 kilograms of bactericide one day and night, which can kill bacteria in a small city. It also has the function of reducing noise. Noise 10~ 15 decibels can be reduced by 40 m forest belt. People's "walking in the forest" is called "a good medicine for urbanites to relieve anxiety and promote health"