Long-term effects of simulated acid fog on visible injury, growth, chlorophyll and nitrogen content of Japanese cedar [Juniperus virginiana], red pine and beech seedlings
2004
Silwal, S. (Tokyo Univ. of Agriculture and Technology, Fuchu (Japan)) | Aoki, M. | Horie, K.
Seedlings of three tree species, Japanese cedar, red pine and beech, grown in plastic green houses were subjected to a simulated acid fog adjusted to pH values of 2, 3 and 4 and to distilled water (the control), during the growing season from 1998 to 2001, and effects on visible injury, growth, foliage chlorophyll and nitrogen contents were studied. In cedar and pine, an increase in total dry weight (TDW) was accelerated by acid fog of pH 2 and pH 3 with increasing duration of treated years, although a trend of growth inhibition of TDW was observed in beech. The stimulated growth in cedar of pH 2 and pH 3 plots resulted in death of 29 to 45% of plants. Foliage nitrogen and chlorophyll content in beech were severely affected than in cedar and pine. On the other hand, foliar injury in pine and cedar by acid fog exposure was higher in lower pH plots and the injury increased with increasing duration of treated years. In contrast, in beech, the injury increased with the decreasing acid fog pH, but wasn't accelerated by increase in duration of treated years. Thus, response of tree seedlings to simulated acid fog was found to be quite complex depending on species and duration of treated years.
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