6. What are the ecological functions of garden plants in ecological gardens?

Adjusting Microclimate L.J.Batten believes that microclimate mainly refers to the climate from the ground to the height of 10m ~ 100m, which is the area and space for human life and plant growth. The production and living activities of human beings and the growth and development of plants have a profound influence on the microclimate. Transpiration of plant leaves can adjust temperature and humidity and absorb solar radiation heat, which has a positive effect on improving urban microclimate. The research data show that when the urban temperature is 27.5℃ in summer, the surface temperature of lawn is 20℃ ~ 24.5℃, which is 6℃ ~ 7℃ lower than that of bare land and 8℃ ~ 20.5℃ lower than that of asphalt pavement. In winter, the surface temperature of football field covered with lawn is about 4℃ higher than that of bare ground. Because green plants have strong transpiration and constantly transport water vapor into the air, air humidity can be improved. It is observed that the relative humidity of green space is higher than that of non-green space 10% ~ 20%, and street trees can also increase the relative humidity 10% ~ 20%. Urban belt-shaped green space such as road greening and riverside green space is a green ventilation corridor of the city, which can introduce natural airflow from the suburbs of the city into the city and create good conditions for urban ventilation in summer. In winter, the wind speed can be reduced and the wind can be prevented. Improve environmental quality 1 absorb carbon dioxide, release oxygen and maintain carbon-oxygen balance. Relevant data show that each hectare of green space can absorb 900 kgo 2 and produce 600kgO2 every day, and each hectare of broad-leaved forest can absorb 1000 kgo 2 and produce 750kgO2 every day in the growing season, which can be used by 1000 people to breathe. A well-grown lawn can absorb CO2 15kg CO2 per hectare per hour, while the CO2 exhaled by each person per hour is about 38g, so if there is a 25m2 lawn or a l0m2 forest during the day, the CO2 exhaled by one person can be basically absorbed. It can be seen that in a general city, everyone should have at least 25m2 lawn or10m2 forest, so as to adjust the proportion balance of CO2 and O2 in the air and keep the air fresh. If the influence of industrial production on the proportion balance of urban CO2 and O2 is considered, the index of green space should be greater than the above requirements. There are many kinds of toxic and harmful gases that pollute the air and endanger human health, including SO2, NOx, Cl2, HF, NH3, Hg and Pb. At a certain concentration, many plants have the ability to absorb and purify. The research shows that the concentration of SO2 decreases obviously when it passes through the forest, and Cryptomeria fortunei forest absorbs 720kgSO2 every year. Ailanthus altissima, oleander, Podocarpus, Ginkgo biloba, Ligustrum lucidum, Magnolia grandiflora and cypress all have strong absorption capacity. Dust plants, especially trees, have obvious blocking, filtering and adsorption effects on dust. Because the crown of the tree is very strong, the leaves are wrapped and secrete viscous oil, which makes the tree have a dust retention effect. 4 sterilization because there is less dust over the green space, the bacteria attached to it are reduced; In addition, because many plants themselves can secrete a bactericide, they have bactericidal ability. According to the measurement in France, there are as many as 4 million bacteria per cubic meter of air in department stores, 580,000 in boulevards, 1 0,000 in parks and only 55 in forest areas. The difference of bacterial content in the air between forest areas and department stores is 70,000 times. Noise-reducing plants, especially forest belts, have certain effects on noise prevention and control. According to the calculation, the noise can be reduced by 40m wide forest belt 10 ~ 15 dB, 30m wide forest belt/4.4m wide hedge/6 dB. Trees can reduce noise because sound energy is projected on branches and leaves and reflected in all directions, which makes the leaves vibrate slightly and reduces the consumption of sound energy. Beautifying the landscape and enriching the outline of building groups is an effective hunting and application to beautify the city appearance, increase the artistic effect of urban architecture, enrich the city landscape, make the architecture "icing on the cake" and make the city closely linked with nature.