Date of Award

12-1969

Degree Type

Thesis

Degree Name

Master of Science

Major

Botany

Major Professor

E. E. C. Clebsch

Committee Members

H. A. Fribourg, H. R. DeSelm

Abstract

Between January 1, 1947, and December 31, 1950, hourly temperature and relative humidity and daily precipitation and cloud cover data were collected at the 1,460 ft., 3,850 ft., 5,000 ft., and 6,300 ft. elevations in the Great Smoky Mountains National Park. These four years were part of a period of data collection extending from January, 1946, through March, 1951. These data were processed by a digital electronic computer, IBM 7040, under the control of data summary and potential evapotranspiration programs. Selected statistical tests were employed to compare the similarity of variation in some monthly mean values or to determine the degree of variation between some of the climatic elements.

The findings showed that cloud cover increased with elevation and decreased in the warmer part of the year. Temperature decreased with elevation at a curvilinear rate. As altitude increased, the decrease in temperature per 1,000 ft. decreased. Lapse rate increased from a minimum in December-January to a maximum in July. Relative humidity also increased with altitude, except that microclimatic influences were strongly reflected in these data. Wind probably reduced the relative humidity at the 6,300 ft. elevation and lack of wind allowed atmospheric moisture build-up. Distribution of relative humidity had greater range in colder months than in the summer. Vapor pressure deficit decreased with elevation; however, the difference among the means of the three highest stations was small, reflecting the difference in temperature and relative humidity at the different elevations. Precipitation increased with an increase in elevation; however, the two highest stations showed the results of microclimate and precipitation type on amounts collected. The 5,000 ft. station had the highest precipitation in the winter when precipitation was predominantly cyclonic. The 6,300 ft. station had the highest rainfall in the summer when much of the high-elevation precipitation was orographic.

Soil moisture balance, calculated by the Thornthwaite method, reflected only the variation in temperature and precipitation. When the assumptions were made that rooting depth was 6 feet and field capacity was 12.00 inches of water, soil moisture content increased and evapotranspiration decreased with an increase in altitude. Many other research workers have stated that these two climatic elements are not sufficient to calculate water balance and other factors were suggested for use in making such calculations.

The use of climate alone as the parameter for defining species distribution in the Smokies has been omitted because species ranges reflect a complex of environmental factors beyond those analyzed here.

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