Ultrastructure and Amino Acid/Protein Contents of Pinus Strobus Needles: A Potential Monitor for Ozone (O₃)

Abstract

A variety of pine species, including eastern white pine (Pinus strobus L.), are a significant resource in the Southern USA (Dorman, 1976). Ambient levels of ozone beyond the Earth’s background of 0.02 to 0.03 ppm are suspected to adversely affect the quality and growth of various pines (Berry, 1974). Consequently, visible symptoms of ozone damage can appear on eastern white pine below 10 pphm (Taylor, 1984) which is generally regarded as ozone-sensitive (Berry, 1971). Representative average monthly and mean hourly ozone concentrations are shown in Figures 1A and 1B, respectively, for the Coweeta Hydrologic Laboratory which is located in western North Carolina within the southern Appalachian Mountains. The 2200-ha Laboratory is in a rural county and the ozone monitoring station is located at low elevation (685 m). General ozone concentrations for 1986 were lower than concentrations experienced in 1987 and 1988, but are useful to characterize seasonal and diurnal trends. Concentrations are typically highest in spring and early summer months (May-June) and subsequently decrease through the summer into fall (Figure 1A). High concentrations coincide with the initiation and development of new foliage which is a period when forest trees may be most susceptible to oxidant damage.