A comparison of the effects on Canadian boreal forest lichens of nitric and sulphuric acids as sources of rain acidity

• Published in: The New phytologist Vol. 111; no. 4; pp. 663 - 671
• Main Authors: Scott, Martha G., Hutchinson, T. C., Feth, Marilyn J.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Cambridge University Press 01.04.1989; Blackwell Publishing Ltd; Blackwell
• Subjects: Acid rain; Acidity; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; boreal forest lichens; Boreal forests; bosque boreal; Cladina species; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on plants and fungi; Fertilization; fitotoxicidad; foret boreale; Fundamental and applied biological sciences. Psychology; growth rate; indice de crecimiento; lichen; lichenes; Lichens; liquenes; lluvia acida; nitrate; Nitrates; nitratos; ontario; phytotoxicite; phytotoxicity; pluie acide; Precipitation; Rain; Spraying; sulfate; sulfatos; Sulfur; sulphate; sulphates; taux de croissance; Pollutant; Growth; Acid rain; Lichenes; Nitrates; Sulfates; Sulfur dioxide; Thallophyta; nitrate; Cladina species; boreal forest lichens; sulphate
• ISSN: 0028-646X; 1469-8137
• 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 field 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.