Seedling Responses of Five Species of Western Conifers to Simulated Ambient Sulfur Dioxide Exposures

Authors: Leininger, Theodor D.; Miller, Paul R.; Schilling, Susan L.; Dunn, Paul H.

Source: Forest Science, Volume 37, Number 6, 1 December 1991 , pp. 1538-1549(12)

Publisher: Society of American Foresters

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Abstract:

Seedlings of ponderosa pine, Douglas-fir, white fir, Engelmann spruce, and subalpine fir were exposed continuously to charcoal-filtered (CF) air or one of three levels of a simulated ambient exposure typical of SO₂ pollution near smelters in the western United States. Seedlings were exposed during winter-spring experiments for 60 days to hourly means of 17, 38, and 54 ppb in 1988 and 35, 57, and 99 ppb in 1989. Sensitivities of species to SO₂ were determined from height growth, diameter growth, root, stem, and needle weights, and from foliar injury. Ponderosa pine in all SO₂ treatments in 1989 had decreased diameter growth and decreased needle weights compared with those in CF air. In 1989, average diameter growth of Douglas-fir in all SO₂ treatments was less than those in CF air. Diameter growth and needle weights of ponderosa pine were correlated in all SO₂ treatments and CF air. Diameter growth and needle weights of Douglas-fir were correlated in all SO₂ treatments. Tip necrosis of needles occurred on a larger proportion of seedlings of all species in high SO₂ than on those in CF air. Ponderosa pine and Douglas-fir were about equally sensitive to SO₂ and both were more sensitive than white fir. White fir was more sensitive to SO₂ than Engelmann spruce and subalpine fir which were equally unresponsive to SO₂. For. Sci. 37(6):1538-1549.

Keywords: Ponderosa pine; Douglas-fir; white fir; Engelmann spruce; subalpine fir

Document Type: Journal article

Affiliations: 1: USDA Forest Service, Forest Environment Research, South Building, 12th and Independence Ave. SW, Washington, DC 20250

Publication date: 1991-12-01

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