冬季郑州市12个常绿树种的光合特性及滞尘能力

Tibetan soil and effects on growth of local grass

关键词:  常绿树种, 冬季光合, 滞尘, 环境污染, 生态调节, 植物生态

Key words:  evergreen tree species, winter photosynthesis, dust retention, environmental pollution, ecoregulation, plant ecology

摘要:

为筛选出北方城市冬季生态效益突出的常绿树种,以缓解大气CO₂和粉尘颗粒物污染,并为这些树种的园林应用提供科学支持,该文选取郑州市园林绿化应用广泛的12个常绿树种,利用LI-6400便携式光合测定仪和洗脱-质量差值法,并对其光合特性及滞尘能力进行测定,计算出其光合参数[叶片的净光合速率(P_n)、蒸腾速率(T_r)、气孔导度(G_s)、胞间CO₂浓度(C_i)]和滞尘参数(单位叶面积滞尘量、单叶滞尘量、单位面积树冠滞尘量),并分别进行聚类分析。结果表明:(1)大叶女贞、黄杨、海桐、枇杷叶片P_n、T_r、G_s值均极显著高于其他树种(P<0.01); 香樟、银木、黄杨、枇杷叶片C_i值极显著高于其他树种(P<0.01)。大叶女贞、海桐、石楠叶肉细胞保持着较高的光合活性,而香樟、银木叶片光合活性较弱,低温抑制明显。(2)洗淋后7 d和14 d,枇杷、广玉兰、桂花各滞尘参数均极显著高于其他树种(P<0.01)。洗淋后14 d,枇杷、广玉兰、桂花单位面积树冠的滞尘量累积在6.65 g·m^-2·crown^-1以上,滞尘能力强; 石楠、银木、大叶女贞、法国冬青、黄杨单位面积树冠的滞尘量在3.99 g·m^-2·crown^-1以上。(3)聚类分析结果表明,黄杨、大叶女贞和海桐光合特性优势明显,其次为法国冬青、广玉兰、枇杷、石楠和乐东拟单性木兰; 广玉兰、桂花、枇杷滞尘能力最强,其次为大叶女贞、法国冬青、石楠和银木。综上所述,大叶女贞、广玉兰、枇杷、法国冬青、黄杨、石楠对改善北方城市冬季空气质量及滞尘均有重要贡献,生态调节能力强,可作为园林绿化优先选用树种。

Abstract:

In this study, 12 evergreen tree species were selected in Zhengzhou City, and their photosynthetic characteristics and dust retention capacity in winter were determined and analyzed differentially to select the evergreen tree species with outstanding ecological benefits for alleviating atmospheric CO₂ and particulate pollution, and to provide scientific support for the application of these trees in gardens. The photosynthetic parameters including the net photosynthetic rate(P_n), transcription rate(T_r), stomatal conductance(G_s), intercellular CO₂ concentration(C_i)and dust retention parameters(dust retention per unit leaf area, dust retention capacity of single leaf and dust rentention in crown per unit area)of each tree species in January were measured by LI-6400 portable photosynthesis analyzer could with the elution-mass method, and the results of each parameter were analyzed by cluster analysis. The results were as follows:(1)The P_n, T_r and G_s values of leaves from Ligustrum lucidum, Buxus sinica, Pittosporum tobira and Eriobotrya japonica were significantly higher than those of other eight species(P<0.01), and the C_i values of leaves from Cinnamomum camphora, C. septentrionale, Buxus sinica and Eriobotrya japonica were extremely significant(P<0.01)higher than those of other eight species. The mesophyll cells of Ligustrum lucidum, Pittosporum tobira and Photinia serratifolia maintained higher photosynthetic activities, but the activities of mesophyll cells of Cinnamomum camphora, C. septentrionale were significantly inhibited by low temperature and were weaker than those of other species.(2)7 d and 14 d after washing, the dust retention parameters of Eriobotrya japonica, Magnolia grandiflora and Osmanthus fragrans were significantly higher than those of other species(P<0.01). 14 d after washing, the dust retention amount of Eriobotrya japonica, Magnolia grandiflora and Osmanthus fragrans accumulated to more than 6.65 g·m^-2· crown^-1, and showed a strong dust retention capacity. In addition, the amount of Photinia serratifolia, Cinnamomum septentrionale, Ligustrum lucidum, Viburnum odoratissimum and Buxus sinica accumulated to more than 3.99 g·m^-2· crown^-1.(3)The result of cluster analysis indicated that Buxus sinica, Ligustrum lucidum and Pittosporum tobira had the strongest leaf photosynthetic properties, followed by Viburnum odoratissimum, Magnolia grandiflora, Eriobotrya japonica, Photinia serratifolia and Parakmeria lotungensis; Magnolia grandiflora, Osmanthus fragrans and Eriobotrya japonica had strong dust retention abilities, followed by Ligustrum lucidum, Viburnum odoratissimum, Photinia serratifolia and Cinnamomum septentrionale. Therefore, the six evergreen tree species including Ligustrum lucidum, Magnolia grandiflora, Eriobotrya japonica, Viburnum odoratissimum, Buxus sinica, and Photinia serratifolia, could be used as the priority tree species for greening because they have strong capacity on ecological regulation through improving the air quality and dust retention in northern cities in winter.