Pääkkönen E, Paasisalo S, Holopainen T, Kärenlamp L
Ecological Laboratory, Department of Environmental Sciences, University of Kuopio, P.O. Box 1627, 70211 Kuopio, Finland.
Botanical Garden, University of Kuopio, P.O. Box 1627, 70211 Kuopio, Finland.
New Phytol. 1993 Nov;125(3):615-623. doi: 10.1111/j.1469-8137.1993.tb03911.x.
It is evident that even outside the classical high ozone areas some plant species are at risk. In this study seedlings of five birch clones (Betula pendula Roth.) were exposed to a slightly elevated ozone level in an open-field experiment over two growing seasons. The ozone doses were 1.2 × (1991) and 15 × (1992) higher than the ambient. The clones were also fumigated with 150 nl I ozone for 24 d (12 h d ) in a chamber experiment. They were found to differ in their susceptibility to ozone: ozone fumigation decreased the height growth and leaf biomass, and increased the amount of advanced visible injury in leaves of the most sensitive clone, but did not affect the height growth or amount of visible injury of the most tolerant clone. The other three clones were intermediate with respect to their sensitivity to ozone. In all clones, elevated O concentrations increased diffusive resistance to water vapour but increased the stomatal density in the emerging leaves. The appearance of autumn colouring was accelerated in the field experiments. The results support the conclusion that birch populations in Finland can be negatively affected by ozone. The effect is most likely in sensitive birch individuals during ozone episodes.
很明显，即使在传统的高臭氧区域之外，一些植物物种也面临风险。在本研究中，五个桦树克隆品种（垂枝桦）的幼苗在两个生长季节的露天试验中暴露于略高的臭氧水平下。1991年的臭氧剂量比环境水平高1.2倍，1992年高15倍。在室内试验中，这些克隆品种还用150 nl/L的臭氧熏蒸24天（每天12小时）。结果发现它们对臭氧的敏感性存在差异：臭氧熏蒸降低了最敏感克隆品种的高度生长和叶片生物量，并增加了其叶片上严重可见损伤的数量，但对最耐受克隆品种的高度生长或可见损伤数量没有影响。其他三个克隆品种对臭氧的敏感性处于中间水平。在所有克隆品种中，升高的臭氧浓度增加了对水蒸气的扩散阻力，但增加了新长出叶片的气孔密度。在田间试验中，秋季变色现象提前出现。这些结果支持了芬兰的桦树种群可能受到臭氧负面影响的结论。这种影响在臭氧事件期间最可能发生在敏感的桦树个体上。
