北方4种抗旱造林树种光合特征及固碳释氧和增湿降温研究

Study on Photosynthetic Characteristics,Carbon Fixation and Oxygen Release,Humidification and Cooling of Four Drought-resistant Afforestation Tree Species in Northern China

为探究太行山旱瘠山地造林树种的光合、蒸腾耗水特性及生态效益,以北方常见抗旱造林树种山桃、山杏、黄栌和榆树4种苗木为试验材料,通过盆栽模拟,分析其净光合速率、蒸腾速率、水分利用效率、气孔导度和胞间CO_(2)浓度日变化,并计算其固碳释氧和增湿降温生态效益。结果表明:(1)净光合速率和蒸腾速率日均值山杏最大,与其他树种均存在显著差异;水分利用效率山桃最好,与其他树种均存在显著差异;胞间CO_(2)浓度黄栌最大,4种树种不存在差异;气孔导度日均值排序为山桃>黄栌>榆树>山杏,且山桃与榆树、山杏之间存在显著差异。(2)4种树种的净光合速率与气孔导度、蒸腾速率呈极显著正相关;山桃、黄栌的净光合速率与环境CO_(2)浓度、大气温度呈显著正相关;山杏的净光合速率与大气湿度呈显著负相关。(3)单位叶面积的日固碳释氧量排序为山桃>榆树>黄栌>山杏,山桃与其他树种均存在显著差异;单位叶面积的增湿降温量排序为山桃>黄栌>山杏>榆树,山桃与其他树种的日蒸腾总量、增湿量、降温量差异均显著。综合看,山桃固碳释氧和增湿降温能力最强,其次为黄栌,试验结果可为当地生态建设中优先树种选择提供依据。

In order to explore the photosynthetic,transpiration water consumption characteristics and ecological benefits of afforestation tree species in arid and barren mountainous areas of Taihang Mountains,four kinds of seedlings of common drought-resistant afforestation tree species in northern China,Prunus davidiana,Prunus sibirica,Cotinus coggygria and Ulmus pumila,were taken as the research objects.The diurnal changes of net photosynthetic rate,transpiration rate,water use efficiency,stomatal conductance and intercellular CO_(2)concentration were analyzed by pot simulation,and the ecological benefits of carbon fixation and oxygen release,humidification and cooling were calculated.The results showed as the following three aspects.(1)The daily mean values of net photosynthetic rate and transpiration rate of Prunus sibirica were the largest,which were significantly different from those of other tree species.The water use efficiency of Prunus davidiana was the best,which was significantly different from other tree species.The intercellular CO_(2)concentration of Cotinus coggygria was the highest,and there was no difference among the four tree species.The order of daily mean value of stomatal conductance was:Prunus davidiana>Cotinus coggygria>Ulmus pumila>Prunus sibirica,and there were significant differences among Prunus davidiana,Ulmus pumila and Prunus sibirica.(2)The net photosynthetic rate of the four tree species was significantly positively correlated with stomatal conductance and transpiration rate.The net photosynthetic rate of Prunus davidiana and Cotinus coggygria was significantly positively correlated with environmental CO_(2)concentration and atmospheric temperature.There was a significant negative correlation between net photosynthetic rate and atmospheric humidity of Prunus sibirica.(3)The order of daily carbon fixation and oxygen release per unit leaf area was:Prunus davidiana>Ulmus pumila>Cotinus coggygria>Prunus sibirica,and there were significant differences between Prunus davidiana and other tree species.The order of humidification and cooling per unit leaf area was:Prunus davidiana>Cotinus coggygria>Prunus sibirica>Ulmus pumila.The differences of daily transpiration,humidification and cooling between Prunus davidiana and other tree species were significant.The comprehensive results showed that the ability of carbon fixation,oxygen release,humidification and cooling of Prunus davidiana was the strongest,followed by Cotinus coggygria.The test results could provide a basis for the selection of priority tree species in local ecological construction.