Determination of Aluminum, Calcium, and Magnesium in Fraser Fir (Abies fraseri) Foliage from Five Native Sites by Atomic Absorption Spectrometry: The Effect of Elevation upon Nutritional Status

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The Fraser fir (Abies fraseri) is a conifer native to high elevation sites in the southern Appalachians that has recently suffered severe mortality because of an exotic insect, the balsam woolly adelgid (BWA). The companion tree of the Fraser fir, the red spruce (Piceae rubens) has suffered relatively mild decline induced by acidic deposition, due to reduction of extractable calcium and magnesium levels in the soil, while causing an increase in extractable aluminum. We hypothesized that acidic deposition may be involved, along with the BWA, in inducing Fraser fir decline. Our hypothesis was tested by collecting Fraser fir foliage and soil from five sites on Clingman's Dome, NC/TN, Roan Mountain, NC/TN, and Mount Rogers, VA, and determining foliar and extractable soil aluminum, calcium, and magnesium. Foliar aluminum was done by graphite furnace atomic absorption (GFAAS) with continuum source background correction, while all other analyses were done by flame AAS. The analysis of composite samples was shown to provide improved precision by a factor of 2–4 for elemental analysis of a class of conifers compared to averaging individual analyses. Although aluminum levels were larger and calcium/aluminum ratios were smaller at the high elevation sites at two mountains, calcium levels were statistically the same at the high and low elevation sites. Consequently, it is difficult to definitively conclude that acidic deposition has contributed to Fraser fir decline.