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Title: Sulfur to nitrogen ratios in Ponderosa pine as bioindicators of foliar sulfur loading from air pollution

The objective of the research was to investigate the potential of foliar S:N ratios in Ponderosa pine as bioindicators of foliar sulfur loading in areas of long-term exposure to low levels of sulfurous air pollutants. First it was necessary to document seasonal variation in S:N ratios in trees not exposed to air pollution. Fifteen Ponderosa pines were selected at a site remote from urban and industrial sources of air pollution and the trees sampled at 18 intervals over a 15 month study period. Significant differences in sulfur and nitrogen concentrations occurred among the five needle age groups within most collections. One-year-old needles contained significantly more sulfur than other needles. Current-year needles contained more nitrogen than the three and four-year-old needles. Within each foliar age class significant differences in total sulfur content and S:N ratios occurred throughout the season. Sulfur concentrations and S:N r
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Other Information: Thesis (Ph.D.)
Univ. of Montana,Missoula, MT, USA
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United States
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT. 560303* -- Chemicals Metabolism & Toxicology-- Plants-- (-1987)