4种园林树木树冠微环境与增湿降温的关系

通过对大花水桠木、红瑞木、山杏、桃叶卫矛树冠东、南、西、北4个方位以及表层、外层、中层和内层4个部位的单位叶面积增湿、降温量和树冠微环境变化的研究,探讨园林树木增湿降温生态功能评价的合理取样部位以及增湿、降温量与树冠微环境的关系。结果表明:4个树种树冠不同方位(部位)单位叶面积增湿、降温量由大到小均呈现为南侧(表层)、东侧(外层)、西侧(中层)、北侧(内层),树冠西侧和外层与增湿、降温量的平均值接近。树冠内微环境呈现为空气CO2摩尔分数在树冠内的变化不明显;细胞间隙CO2摩尔分数和空气相对湿度南侧→东侧→西侧→北侧及表层至内层呈逐渐升高的趋势,蒸腾速率、气孔导度、空气温度、叶面温度和风速呈下降的趋势;树冠西侧和外层的微环境与树冠内的平均值更接近。蒸腾速率、气孔导度和风速与增湿、降温量呈极显著的正相关,细胞间隙CO2摩尔分数和空气相对湿度与增湿、降温量之间分别呈显著和极显著的负相关,空气CO2摩尔分数、空气温度和叶面温度与增湿、降温量之间的相关性不明显。

Rleationship of Four Landsacpe Trees Canopy Microenv ironment with Humidity Increase and Tempe rature Re-duction

We selected four species of landscape trees to investigate reasonable sampling positions to evaluate the landscape trees ecological effects in terms of humidity increase and temperature reduction , and determine the relationship between land-scape 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 of surface layer, outer layer , middle layer and inner layer .We studied the change of humidity increase and tempera-ture reduction values of unit leaf area and the microenvironment of tree canopy in each layer and each direction .The hu-midity increase and temperature reduction values of unit leaf area were in descending of south side , eastern side , west side, and north side between different directions (layers) of four trees.Outer layer of west tree canopy was closer to the average of the humidity increase and temperature reduction values of unit leaf area .The change of air CO 2 concentration was not significant, intercellular CO 2 concentration and air relative humidity increased from south to east to west to north and from surface layer to inner layer , and light intensity , stomatal conductance , leaf temperature and wind speed were counter .The microenvironment in the outer layer of west tree canopy was closer to the average .Light intensity , stomatal conductance and wind speed and humidity increase and temperature reduction with notable positive correlation ;Intercellu-lar CO2 concentration and air relative humidity , and humidity increase and temperature reduction were with significantly negative correlation , and the correlation between air CO 2 concentration , air temperature , leaf temperature and humidity in-crease and temperature reduction was not significant .