This project was set up to test the hypothesis that treatment with wind will alter pathways for pollutants into the needles of Norway spruce, and will render them more susceptible to air pollution. To test this hypothesis two year old seedlings were treated with either acid mist or ozone in open-top chambers, combined with treatments in a controlled environment wind tunnel. Acid mist was applied at pH = 2.5 and pH = 5.0 as a control. The ozone treatment was designed to fumigate the plants with air containing on average 140 nmol and mol<SUP>-1</SUP> of ozone, and was compared with a charcoal-filtered control. The wind treatments were applied in a controlled environment wind tunnel, at various times during the year, usually for 48 hours at 16 m s<SUP>-1</SUP>, which were compared with a 'no-wind' control. The main measurements made on the Norway spruce seedlings in this project were of gas exchange and frost hardiness. In 1990 two series of gas exchange measurements were made, shortly before and immediately after the wind treatments, during August and September. In 1991 the plants from the acid mist experiment were measured during August, while the plants from the ozone experiment were measured in November, both after the wind treatments. Frost hardiness was assessed from both pollution experiments in November 1990, while in 1991 only the frost hardiness of the seedlings from the ozone experiment was determined, in early October, immediately after the last wind treatment. Measurements of visible injury, whole plant transpiration rates, chlorophyll concentrations and a destructive harvest, were also carried out, to support the findings of the main experiments. This study on Norway spruce showed that synergistic interactions, which would have proved the main hypothesis of this study, were only found for a few of the variables measured, probably a consequence of the tough cuticle on this species. The ozone and wind treatments did not interact significantly to produce effects on any of the parameters measured in this study, and therefore the working hypothesis was not substantiated. This study did suggest that the nutritional status of trees can strongly modify the effects of air pollution. The capacity of trees to absorb and neutralize pollutants is higher when all elements are available in sufficient amounts, compared to deficient growth conditions. This study also demonstrated that high speeds may reduce the effects of pollutants on tree foliage, but this depends on the timing of the high winds.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:663653 |
| Date | January 1994 |
| Creators | Werkman, Ben R. |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/11541 |
Page generated in 0.0211 seconds