苏州市夏季园林植物光合特性及固碳释氧、降温增湿效益研究

Summertime Photosynthesis,Carbon-fixation,Oxygen-release,Atmosphere-cooling,and Humidifying Effect of Landscape Plants in Suzhou

【目的】探究苏州市常见园林树种固碳释氧、降温增湿的能力。【方法】以苏州市白鹭园13种园林植物为研究对象,通过测定其光合生理指标,分析植物固碳释氧、降温增湿的综合效率及其影响因素。【结果】(1)13种植物净光合速率日变化主要呈单峰型和双峰型2种,蒸腾速率日变化主要呈单峰型。(2)单位叶面积日固碳量和释氧量最高的是榔榆(Ulmus parvifolia),分别为12.08、8.78 g·m^(-2)·d^(-1),最低的是红枫(Acer palmatum’Atropurpureum’),分别为3.50、2.54 g·m^(-2)·d^(-1)。单位叶面积日降温量和增湿量最高的是木槿(Hibiscus syriacus),分别为0.38℃和2 376.15 g·m^(-2)·d^(-1),红枫最低,分别为0.14℃和848.01 g·m^(-2)·d^(-1)。(3)园林植物固碳增湿量与净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、大气湿度(RH)、光合有效辐射(PAR)呈显著正相关,与叶面水气压亏缺(Vpdl)呈显著负相关。【结论】基于提高城市绿地碳汇功能和缓解热岛效应,在苏州地区乔木中可优选榔榆、朴树(Celtis sinensis)、香樟(Cinnamomum camphora)、垂柳(Salix babylonica)、枫香树(Liquidambar formosana)、重阳木(Bischofia polycarpa)等树种。桂花(Osmanthus fragrans)、珊瑚树(Viburnum odoratissimum)和木槿单位土地面积日固碳释氧、降温增湿效益差距不大。

【Objective】Beneficial effects of landscape plants in Suzhou on carbon-fixation,oxygen-release,atmosphere-cool,and humidity-increase during summer season were studied.【Method】Physiologically,the photosynthetic indicators of 13 varieties of plants at Bailu Garden in in Suzhou were monitored during the summer to determine their effects on the surrounding atmospheric carbon,oxygen,temperature,and humidity.【Result】(1)The diurnal variation on the net photosynthetic rate of the plants was mainly unimodal and bimodal,while that of the transpiration rate basically unimodal.(2)The greatest per leaf area daily carbon-fixation of 12.08 g·m^(-2)·d^(-1) and oxygen-release of 8.78 g·m^(-2)·d^(-1) were found on Ulmus parvifolia,while the lowest 3.50 g·m^(-2)·d^(-1) and 2.54 g·m^(-2)·d^(-1),respectively,on Acer palmatum Atropurpureum.The highest per leaf area daily cooling and humidifying effects of 0.38℃and 2376.15 g·m^(-2)·d^(-1),respectively,were rendered by Hibiscus syriacus,whereas the lowest 0.14℃and 848.01 g·m^(-2)·d^(-1),respectively,by A.palmatum Atropurpureum.And(3)the carbon sequestration and humidification of the plants correlated positively with the net photosynthetic rate(Pn),stomatal conductance(Gs),transpiration rate(Tr),atmospheric humidity(RH),and photosynthetically active radiation(PAR)but negatively with the leaf water vapor pressure deficit(Vpdl).【Conclusion】Through increasing carbon sink and mitigating hot-island effect in the surroundings with plants such as U.parvifolia,Celtis sinensis,Cinnamomum camphora,Salix babylonica,Liquidambar formosana,and Bischofia polycarpa,urban Suzhou could be environmentally improved.On the other hand,Osmanthus fragrans,Viburnum odoratissimum,and H.syriacus did not seem to offer significant benefits in that regard.