Scott Martha G, Hutchinson T C, Feth Marilyn J
Department of Botany and the Institute for Environmental Studies, University of Toronto, Toronto, Ontario, Canada M5S 1A1.
New Phytol. 1989 Apr;111(4):663-671. doi: 10.1111/j.1469-8137.1989.tb02361.x.
The effects of different levels of nitrate and sulphate in acidic precipitation on the growth of the lichens Cladina rangiferina (L.) Wigg. and C. stellaris (Opiz.) Brodo were compared. Permanent Held plots in a Canadian boreal forest ecosystem received two years of spraying with artificial rains of pH 4.2 (ambient), 3.5 or 2.8, each containing one of four molar ratios of sulphate to nitrate, i.e. sulphuric acid alone, nitric acid alone: 2:1 or 1:2. A substantial fertilization effect was observed when C. rangiferina was watered with rain of pH 2.8, derived from nitric acid alone. Compared with before-treatment values, gains in mean dry weight (+ 62%) and mean podetial height (+14%) were obtained for this species, in addition to elevated levels of N in air-dried tissues. Post-treatment values for the mean dry weight of C. rangiferina were significantly reduced for those podetia sprayed with rain of low pH, derived from sulphuric acid alone. Although podetia of C. stellaris were stimulated by rains of pH 4.2, based on a higher concentration of nitric acid, there was no N fertilization following the most acidic sprays. Data from this study support the view that the N content of acidic rain can cause a short-term growth stimulation for those species able to absorb nitrate from solution. However, beneficial effects on growth of prolonged fertilization via acid rain inputs are unlikely.
比较了酸性降水中不同水平的硝酸盐和硫酸盐对石蕊（Cladina rangiferina (L.) Wigg.）和星状石蕊（C. stellaris (Opiz.) Brodo）生长的影响。在加拿大北方森林生态系统的永久性样地中，用pH值为4.2（环境值）、3.5或2.8的人工降雨喷洒两年，每种降雨包含四种硫酸盐与硝酸盐摩尔比之一，即单独的硫酸、单独的硝酸、2:1或1:2。当用仅由硝酸产生的pH值为2.8的雨水浇灌石蕊时，观察到显著的施肥效果。与处理前的值相比，该物种的平均干重增加了（+62%），平均子囊体高度增加了（+14%），此外风干组织中的氮含量也有所升高。对于仅用硫酸产生的低pH值雨水喷洒的子囊体，石蕊的平均干重处理后值显著降低。尽管星状石蕊的子囊体受到pH值为4.2且硝酸浓度较高的雨水的刺激，但在最酸性的喷雾处理后没有氮的施肥效果。本研究的数据支持这样的观点，即酸雨的氮含量可以对那些能够从溶液中吸收硝酸盐的物种产生短期的生长刺激。然而，通过酸雨输入进行长期施肥对生长产生有益影响的可能性不大。
