不同朝向的五叶地锦对墙体的降温效果及生理机制

研究攀缘植物对墙体的降温作用及生理学机制，为垂直绿化的植物选择及生态效应的定量化研究提供依据，以不同朝向的五叶地锦Parthenocissus quinquefolia为材料，对墙体温度，蒸腾速率，冠层温度，叶片对入射光的反射、透射及以叶绿素荧光参数表示的潜在光能利用能力等指标进行分析。结果表明，不同朝向的五叶地锦对墙体的降温效果存在显著差异，东、南、西、北4个朝向日平均降温值依次为（5.4 ± 0.61），（3.3 ± 0.48），（3.1 ± 0.47）和（0.48 ± 0.07） ℃。降温值除受墙体温度（r = 0.879 4）影响外，和蒸腾速率（r = 0.770 3）、冠层温度（r = 0.645 8）和透射率（r = 0.504 4）及叶绿素荧光参数F₀（r = 0.475 8）等生理生态指标存在显著的正相关关系。同时表明，五叶地锦不适于北向墙体绿化。因此，在垂直绿化选择植物种时，应同时考虑植物的蒸腾速率及其对光的反射、透射及利用能力。图1表5参20

Cooling and physiology with Parthenocissus quinquefolia on walls oriented in cardinal directions

To determine differences in cooling as well as physiological characteristics from Parthenocissus quinquefolia covering four walls facing north, east, south, and west, a non-contact infrared temperature thermometer （Optris Minisight ms＋）, an Li-1600 steady state porometer, and a hand-held OS-30p chlorophyll fluorometer were employed to examine temperatures of a bare wall, a plant-covered wall, a canopy, and a leaf as well as determine ambient air temperature, transpiration and stomatal resistance, leaf albedo and transmission, and basic parameters of P. quinquefolia chlorophyll fluorescence： Fo, Fm, and Fv /Fm, and a correlation analysis were also utilized. Results of day temperature deviations showed plant-covered walls had significantly greater mean cooling values for east （P0.05）, south （P0.05）, and west （P 0.05） orientations compared to bare walls. There were also significant positive correlations between cooler wall temperatures and bare wall temperatures （r = 0.879 4, P0.000 1）, transpiration （r = 0.770 3, P 0.01）, canopy temperature （r = 0.645 8, P0.01）, leaf transmission （r = 0.504 4, P0.05）, and Fm （r = 0.475 8, P0.05）. Thus, plants covering east-, south-, and west-facing walls would be beneficial. Additionally, transpiration, leaf albedo, leaf transmission, Fm, and Fv /Fm could be used as selection indexes.