The importance of urban greening

Abstract The importance of urban greening, including to improve the city's health conditions, with good economic, health and well and so on, highlighting the development of urban greening in the city's important role.

Keywords: urban green; reduce pollution; landscaping

With the development of modern Industry, urban population growth, environmental deterioration and ecological under serious threat. In this case, one can not passively wait for the gift of nature, must take the initiative to improve and create a good living environment. Therefore, the control environment pollution and improve the quality of the environment is placed in front of people a difficult task. And by grow flowers and grass, building green treasure house, a complete system and the beautiful green landscape effect, can effectively prevent and mitigate pollution and beautify the environment. To this end, the following discusses urban greening in order to promote its role in urban development.

1 urban greening can improve health conditions in the city
1.1 Clean air
Various types of urban green space, with its large leaf area, dense branches, blocking, filtering, adsorption air of dust, pArticulates, while also serving as retention, dispersion, absorption of air, the role of toxic gases, which Air can be purified. woods is a special air purification "filter." For example, planting two rows at a cement plant in parallel with a large poplar, the amount of dust in the air can reduce 33% ~ 52%. can be seen, the town planting a variety of green plants, on the regulation of air flow, clean the air has a very important role [1].

1.2 The climate regulation
First of all, garden plants can adjust the temperature. Landscaping can adjust the temperature, plays the role of cool. In the hot summer months, trees can shade a large leaf area, reflects solar radiation effectively, greatly reducing the direct sunlight on the ground . trees evaporate water through the leaves, can reduce its temperature, increase air humidity around. so green in summer the temperature inside the low temperature than non-green 3 ~ 5 ��, lower than the temperature in the building area is about 10 ��. Therefore, urban green space area, high coverage can improve the microclimate of the living area. In Green a good place, people will feel fresh air in summer, you can enjoy the cool air refreshing, summer cooling. winter, trees can reduce wind speed, reduced the intrusion of cold air, woods and back in the side, the temperature can increase 1 ~ 2 ��. Second, the landscape plants can adjust the air flow. As green areas and non-green areas there are differences between the temperature, the temperature than the adjacent green space green space temperature to the non- low. in accordance with the laws of the temperature spread movements, and the air region to the hot air flow, flow speed and sometimes up to 1m / s, which can form a slight wind, and makes people feel cool. Finally, the garden plants can adjust the humidity, the temperature of the " regulator. "water by plants through leaf transpiration, so that the land of the large amounts of water were released into the air, the air humidity increased. According to the Research, because the roots absorb almost all the water evaporates, so the humidity in the air than in the forest about 30% higher in cities [2]. As a strong tree transpiration, so that more water vapor, the air moist, and therefore, green areas than non-green areas humidity is 10% to 20%, so as to people in the production, creation of life a cool, comfortable climate and environment.

Reduced noise 1.3
More serious noise pollution of modern cities, the noise not only affects the people's normal life, serious harm people's health can also affect the central nervous system and spirit of people's reactions, lead to there lack of energy, fatigue, blood pressure and other symptoms [ 3]. use of large canopy trees and branches, you can absorb and isolate noise. According to the determination in the absence of trees, tall buildings lined the streets, the noise intensity ratio of both sides of the street trees planted more than 5 times a large, visible, Urban greening is important to reduce noise pollution.

1.4 landscape
Garden plants are an important pArt of the urban landscape. Plants varied and beautiful shape, rich spatial variation of the environment. The level of scattered trees, tree of the variety, the size difference between the crown, breaking the flat monotony of buildings become a lively, vibrant, urban environment and thus deepened the sense of space and layering. all kinds of plants change with the seasons, showing a different seasonal colors, such as Acer mono, triangle Maple, autumn leaves of red Swiss wood species such as red, maackii, chicken and other tree species Viburnum Article persistent ear branches in winter, a cold winter's unique landscape. colorful flower color is, therefore, reasonable for the city green, can make the city become colorful, life abundant, beautiful people pleasant living environment [4].

1.5 Disaster Prevention and Mitigation
Many landscape trees with a strong fire resistance, with outstanding fire safety features. For example: dense and homogeneous pine and cypress leaves can block 95% of radiant heat through, coral trees can block 83% ~ 93% of the heat through, its role can be comparable with the firewall to avoid. shore planting trees and grass in the rivers and lakes, you can conserve water, water purification, due to soil embankment, reduce soil erosion, reducing pollution, silt deposition.

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The response of plants to air pollution, many sensitive than humans, pollution, toxic substances on the plant will be in various forms. Plants, environmental pollution, this reaction is the apparent "signal." Plants that people can send the "signal" to analyze the identification of environmental pollution. use of plants for environmental monitoring, a wide range of simple, low cost, conducive environment to carry out police work of the masses, increasingly relevant depArtments.

2 has a good economic urban greening
2.1 The production value of landscape plants
Many garden plants have multiple uses, both economic plants, have a high ornamental value, but also integrated a lot of products. Therefore, the development of organic gardening and production together, both the considerable economic income, but also play greening and beautifying effect, so as to realize the value of landscaping Industry.

2.2 landscape plants can provide industrial raw materials
Reed garden plants, bamboo, poplar can be used for papermaking raw materials; Rose can provide natural spices, prepared flavors; Saw Palmetto leaves can be used for fan; garden plants in the walnut, forsythia, honeysuckle, peony, chrysanthemum Dengjun important medicinal plants. Metasequoia garden plants, pine, tulip tree, are both excellent materials and ornamental garden plants. garden plants can provide industrial raw materials, can also provide a variety of business sources; also garden plants can be used as bonsai trees and root carving root processing and so on, the development of Arts Industry.

3 urban greening the health and well
3.1 The plant has a bactericidal
Green can reduce the bacterial content of air, many garden plants can inhibit the spread in the air to kill bacteria in a variety of functions. These roots, stems, leaves, flowers and other organs, can secrete a variety of microorganisms or germs to kill or inhibit the development of volatile substances, it is this substance called "phytoncide.", such as pine, cypress, poplar, honeysuckle, may all contain some of spinosad. trees of Prunus secretions of mosquitoes have a strong lethal effect. residential and non-green environment green environment control, sterilization of green areas in the summer can reach 20% to 59%. shows a variety of urban green benefits for humanity, to promote the role of human beings have a good physical and mental health .

3.2 The plant can purify water
Green plants can purify the air, protect water quality, prevent soil and water pollution downstream. If the sewage contains E. coli, from the 30 ~ 40m wide flow through the pine forests, the number of bacteria can be reduced to the original 1 / 8; from oak, ash, and mixed forest of acacia out of water, E. coli, only the control value of 1 / 23; water if the three decades from a 50m wide poplar and birch mixed forest after the passage of bacteria can reduce the 9 / 10 or more. sewage into the soil After absorption by green plants, soil degradation and soil adsorption, precipitation, ion exchange, fixed and other clay minerals, can largely be purified.

3.3 plants help to carry out horticulture therapy
Horticultural therapy is through the "green" to regulate their own natural environment pressure, and promote normal circulation of the endocrine system, increase their immunity as a therapy. Of particular note is the "forest bath", "aroma therapy" has been widely recognized by the Industry After medical verify these behaviors do for your health. Today, forest gardening method therapy quietly rising in the world, many countries have established forest horticultural therapy hospital, can be effective in treating people suffering from certain diseases. In the hospital, do not take medicine , no injections, do not need medical treatment, with the environment, through the cultivation of fruit trees, flowers, vegetables and other horticultural activities, so that people in the green environment in the treatment of disease and restore health. horticultural plants using a variety of colors treatment of disease, is horticultural therapy the important content. studies have shown that patients with light blue flowers on the fever has a good sedative effect, the red flowers can increase the patient's appetite, purple flowers can make women feel quiet, red with red flowers on a large blood pressure in patients with hypotension benefit. living green environment, their pulse, breathing frequency was significantly reduced, blood flow will slow down, become soothing frayed nerves, hearing and thinking activities, sensitivity is enhanced. China's Hubei Province Province Su Temple National Forest Park has become an economic, ecological and social benefits of forest bathing win.

3.4 plants can reduce soil pollution
With pesticides and pollutants will eventually wind down most of the dust on the ground, the soil will produce pollution. Garden plants due to soil and slope protection, reduce surface runoff, soil and water, regulating climate, reducing wind erosion dust, can reduce further contamination of soil .

4 References
[1] High-hole clearance. Garden Dendrology [M]. Beijing: China Meteorological Press, 2001.

[2] Zhang Jun Hua, Liu Wei. Horticultural therapy [J]. Chinese garden, 2009 (7) :19-23.

[3] ZHAO Jing-linked. Introduction to Environmental Science [M]. Beijing: Mechanical Industry Press, 2005.

[4] Qian East. Of urban greening [J]. Coastal Enterprises and Technology, 2009 (10) :93-96.

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