The Relationship Between Landscape Trees Canopy Microenvironment And The Ecological Benefits Which Included Carbon Fixation And Oxygen Release, Humidity Increase And Temperature Reduction

Ecological functions of landscape plants plays an indispensable role in the greening of the urban environment, landscape plants can effectively improve the quality of the environment and provide a better living environment fore the people in modern society by fixate carbon and release oxygen, increase humidity and reduce temperature, absorb harmful gases, reduce noise and clean up dust and so on. Canopy is the main place where landscape plants fixated carbon and released oxygen, increased humidity and reduced temperature.Four species of landscape trees were selected to investigate reasonable sampling positions for evaluating the landscape trees ecological effects in terms of humidity increase and temperature reduction and determine the relationship between landscape trees canopy microenvironment and humidity increase and temperature reduction. The canopy of each variety of tree was divided into four directions(south, east, west, north) in the horizontal direction; Each direction was divided into four layers: surface layer(part A), outer layer(part B), middle layer(part C) and inner layer(part D). Research the change of humidity increase and temperature reduction values of unit leaf area and the microenvironment of tree canopy in each layer and each direction. The results show that:(1)From a different point of view of tree, two shrub crown C layer and the light intensity at each time point D layer is significantly less than the two trees, the air relative humidity is significantly greater than the two trees; two micro Overall shrub layer and the D layer C environment Day is less than the diurnal variation of the amplitude variation of two layers of tree C and D layers. By the average of four kinds of trees, the air CO2 concentration changes in canopy layers of value and at the same time points or less. Diurnal variation of intercellular CO2 concentration and air relative humidity in the canopy layer, the layers showed part A> part B > part C > part D, each time point values part A < part B < part C < part D. Diurnal variation of canopy stomatal conductance part A significantly greater than the other three, the crown from outside to inside layers corresponding time point value becomes smaller. Light intensity and wind speed variations in the performance of daily canopy layers of part A > part B > part C > part D, each time point values part A > part B > part C > part D. Air temperature and leaf temperature in diurnal variation A canopy layer, and temperature values at each time point was significantly larger than the other three, part B and part C temperature values at each time point part D less, but still showing the part B> part D > part C. Photosynthesis, transpiration rate in the canopy layers showed a single peak curve, crown layers from outside to inside the diurnal variation curves of the more obvious each time point rate values decreased.(2)The humidity increase and temperature reduction values of unit leaf area appeared south side(part A)> eastern side(part B)> west side(part C)> north side(part D) between different directions(layers) of four trees; part B of west tree canopy is closer to the average of the humidity increase and temperature reduction values of unit leaf area. The change of air CO2 concentration(CR) is not notable, intercellular CO2 concentration(CI) and air relative humidity(RH) increased from south to east to west to north and from part A to part D, Light intensity(G), stomatal conductance(GS), leaf temperature(TC) and wind speed(WS) are counter. The microenvironment in the part B of west tree canopy is closer to the average. Light intensity(G), stomatal conductance(GS) and wind speed(WS) and humidity increase and temperature reduction with notable positive correlation; Intercellular CO2 concentration(CI) and air relative humidity(RH) and humidity increase and temperature reduction with notable negative correlation; the correlation between air CO2 concentration(CR), air temperature(TI), leaf temperature(TC) and humidity increase and temperature reduction is not notable.(3)The carbon fixation and oxygen release values of unit leaf area appeared south side(part A)> eastern side(part B)> west side(part C)> north side(part D) between different directions(layers) of four trees; part B of west tree canopy is closer to the average of the carbon fixation and oxygen release values of unit leaf area. The change of air CO2 concentration(CR) is not notable, intercellular CO2 concentration(CI) and air relative humidity(RH) increased from south to east to west to north and from part A to part D, Light intensity(G), stomatal conductance(GS), leaf temperature(TC) and wind speed(WS) are counter. The microenvironment in the part B of west tree canopy is closer to the average. Light intensity(G), stomatal conductance(GS), leaf temperature(TC) and wind speed(WS) and carbon fixation and oxygen release with notable positive correlation; Intercellular CO2 concentration(CI) and air relative humidity(RH) and carbon fixation and oxygen release with notable negative correlation; the correlation between air CO2 concentration(CR), air temperature(TI) and carbon fixation and oxygen release is not notable. The reasonable sampling positions should be part B of west tree canopy, Light intensity(G), stomatal conductance(GS) and wind speed(WS) have a positive effect to improve the landscape trees ecological effects in terms of carbon fixation and oxygen release.