Masters Theses

Date of Award

6-1983

Degree Type

Thesis

Degree Name

Master of Science

Major

Ecology and Evolutionary Biology

Major Professor

Hal R. DeSelm

Committee Members

D. A. Lietzke, J. R. Carter

Abstract

A study of the vegetation of House Mountain in Knox County, Tennessee was carried out in the field from June to October, 1980. The objectives were to classify vegetation types and relate them ecologically to their environments. Ninety-seven circular 0.04 hectare plots were placed in the second growth forests covering House Mountain. Trees greater than ten cm. dbh were counted by taxon and placed into two cm. dbh classes. Saplings between one and ten cm. dbh were only counted by taxon. Seedlings and the shrub layer were noted and recorded. Environmental factors were determined in the field from direct measurement and from maps. These factors include slope angle, aspect, slope position, slope shape, and the soil characteristics, depth to rock, coarse fragment content and horizon thickness. Soil pH and texture were determined in the laboratory. Statistical analysis consisted of correlation among soil and site factors and species importance values (IV). Linear stepwise regression with maximum r-square improvement was performed using species importance value (IV), absolute density (AD), absolute basal area (ABA), relative density (RD), and relative basal area (RB) as the dependent variables and site and soil factors as the independent variables. Slope position affects more soil variables than any other site factor. Aspect and slope position are the site factors most often correlated with species importance values. Of the soil variables, sand content of both the A and B horizons correlate with the most site factors. However, both sand and silt in the A and B horizons most often correlate significantly with importance values. In the regression equations, the xerophytes are predicted mainly by site and soil variables which are correlated with top slope positions (shallow soils, steeper slope angles and increased sand in the soil). Mesophytes characteristically are predicted by those variables correlated with bottom slope positions such as increased coarse fragments, higher pH, and lesser slope angles. Seven community types were defined on House Mountain. Three of them were dominated by chestnut oak (one with much pine), and one by black oak. On top was the pine-oak community while on the lower slopes was the white oak dominated community and in the draws the tulip poplar types. Future trends indicate the stability of the chestnut oak dominated communities on House Mountain. The pine-oak community likewise appears to be unchanging. However, the white oak-northern red oak and tulip cove communities are not reproducing as well, leaving their futures uncertain. Precipitation data was correlated with soil moisture, which in turn was related to mean radial tree growth. Measured soil moisture correlated highest with four day precipitation periods terminating two days before each soil collection date. Both aspect and slope position demonstrated an influence on available soil moisture. Attempts to relate moisture data to mean radial tree growth resulted in a coefficient of determination of 0.35.

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