Baseline data for the first year of a two-year study to assess the current status of ponderosa pine stands in southeastern Montana relative to coal-fired electric power development are presented. Sixteen permanent plots in pine stands were established in eastern Montana, South Dakota, and Wyoming. Several characteristics believed to be sensitive to future sulfur dioxide and fluoride pollution from the power complex were measured on ten trees from each site. Average fluoride concentration in foliage was 1.48 parts per million (ppm), and total sulfur was 483 ppm. Total chlorophyll was .657 mg/gm (fresh wt.) in current needles, .930 mg/gm in year-old needles, 1.016 mg/gm in 2-year old needles, and 1.016 mg/gm in 3-year old foliage. Average foliar water content was 48.9 percent, and mean needle length was 125.3 mm. Needle retention varied between 97-84 percent, depending on internode age. Average fascicular cross-sectional area was 2.1 sq. mm. A number of different insects, fungi, and abiotic factors contributed to slight yellowing and browning of needles, including elegans pine weevil, basal side, various defoliators, and weather factors. Average total necrosis (tissue death) due to the sum of all these factors was less than 7 percent. Measurements of airborne reactive sulfur and fluoride by static plate techniques were negative. This, combined with the very low foliar concentration of sulfur and fluoride, establish the study area as virtually pollution free as of 1975. Additionally, comparisons between the baseline study area and known polluted sites throughout the United States indicate that the polluted sites differ significantly in regard to then pine characteristics measured, and that the degraded pine conditions in the polluted areas are due to airborne sulfur and fluoride concentrations similar to those expected in the near future from the Colstrip power generating facilities. It is anticipated that the ponderosa pine in the study area will be affected. This baseline study will be a convenient, if not necessary, document with which to compare future data in order to detect pollution insults on the pine forests in southeastern Montana.
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