Master's Theses

Date of Award

Spring 1961

Degree Name

Master of Science (MS)

Department

Biology

Advisor

G. W. Tomanek

Abstract

North- and south-facing slopes were studied to determine differences in vegetation and microclimate. Vegetation was analyzed by line transects. The study on microclimate included soil and air temperatures, evaporation, light intensities, and wind velocities. Appropriate instruments were used for each microclimatic factor, and were identical on both slopes. The microclimate on north- facing slopes was less intense and severe than on south-facing slopes, resulting in a difference in vegetation. The protected position of the north-facing slope has provided a habitat which is favorable to more mesophytic plants. In contrast, the exposed position of the south-facing slope has limited the vegetation to more xerophytic species. Big bluestem (Andropogon gerardi) and little bluestem (A. scoparius) were the dominant grasses on the north- facing slope, whereas, buffalo grass (Buchloe dactyloides), blue grama (Bouteloua gracilis), and side-oats grama (B. curtipendula) were dominant on the south-facing slope. Several species of forbs were restricted to, or were much more abundant on one slope or the other. Woody species were common on north-facing slopes, but were seldom found on south-facing slopes. Seasonal averages of microclimatic conditions are as follows: Evaporation rates were 88.51 mI. per week more on the south-facing slope. Wind velocities were 3.33 MPH faster on south exposures and were closely correlated with evaporation. Soil temperatures on the north-facing slope averaged 11.23 deg. F. cooler at 1-inch depth, and 10.20 deg. F. cooler at 6-inch depth. Maximum air temperatures were 88.25 deg. F. for the south-facing slope and 85.77 deg. F. for the north-facing slope. Minimum air temperatures were 61.65 deg. F. for south exposures, and 60.04 deg. F. for north exposures. Light intensities averaged 4068.86 foot candles at ground level, and 4693.15 foot candles above the vegetation on the south-facing slope, compared to 2927.60 foot candles at ground level and 3632.2 foot candles above the vegetation on the north-facing slope. Yields of forage on the north-facing slope were 1,727.7 pounds per acre, compared to 838.1 pounds per acre on the south-facing slope. Mid grasses contributed most to yields on the north-facing slope, whereas, short grasses provided the largest part of the yield on the south-facing slope.

Rights

Copyright 1961 James T. Nichols

Comments

Notice: This material may be protected by copyright law (Title 17 U.S. Code).

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