Ecological Studies of the Vegetation of the Great Smoky Mountains of North Carolina and Tennessee. I. Soil Reaction and Plant Distribution

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Abstract
Soil samples (289), taken at the surface and 6 in. depth, from 11 forest types scattered over an altitudinal range of 1,000-6,600 ft., were tested for pH. The total range was pH 2.8-82. Each forest type showed considerable range in pH; contiguous communities overlapped in range but were separable on averages derived from 10 to 60 tests each. When arranged in altitudinal sequence, the forest types were progressively more acid with increasing altitude. This is also true for different stands of the same forest type. Triplicate tests on each soil sample averaged about 0.1 pH deviation from the mean; this demonstrates that 1 test per sample is sufficient, but more numerous samples are of greater value. Emphasis is placed on broad sclerophyll scrub communities, post climax to the spruce-fir, at high elevations because of their extreme acidity, surface soils averaging pH 3.2 and 3.6, while samples at 6 in. depths averaged 3.8 and 4.0 at 6,600 and 5,000 ft., respectively. This community, dominated by ericaceous sp. and accompanied by extensive upland peat formation is here described for the first time. The general problem of high soil acidity is discussed in relation to climatic, edaphic, and biotic factors, coordinated largely with high altitude.