AIR AND SOIL TEMPERATURES UNDER 3 FOREST CONDITIONS IN EAST TEXAS

Air and soil temperatures on a poorly drained saline soil in the Davy Crockett National Forest near Apple Springs, Texas were monitored week ly under three forest conditions for 2.5 years. These conditions inclu ded undisturbed forest, commercial clearcutting without site preparati on and clearcutting with stumps shreaded and debris windrowed. Soil te mperatures were monitored at 15, 60, 90, and 120 centimeters below the surface. The mean annual air and soil temperatures were lower and the amplitudes of fluctuation were smaller in an undisturbed loblolly-sho rtleaf pine forest than in a sheared plot by 0.5-1.0-degrees-C. Temper atures of the upper soil were warmer in summer and cooler in winter th an that of the subsoils, and there was a time lag of about one month i n maximum temperature between the top and the sub-soils. There were so me inconsistencies in the temperature differences and the temperature amplitudes between the forested and cleared plots due to site characte ristics and data representativeness. Low soil hydraulic conductivity, high water content, and abundant precipitation may have caused the mea n annual temperatures of the saline soil to be two to three degrees-C cooler than mean air temperture, but further tests on more saline soil s are needed. The soil temperatures could be satisfactorily estimated using air temperature and time angle in a periodic regression model. A lthough sites with low water content tended to have high soil temperat ure, the inclusion of soil water content did not significantly improve the accuracy of estimates.