252 ILLINOIS ACADEMY OF SCIENCE 



TABLE II 



Soil temperatures at depth of twelve inches. 



Date Upland Bottomland Difference 



June 21 65.0 62.4 2.6 



June 24 63.2 59.8 3.4 



July 5 67.4 64.0 3.4 



July 6 66.5 62.2 4.3 



July 12 61.5 60.2 1.3 



July 13 62.5 60.9 1.6 



Aug. 12 73.0 70.2 2.8 



Aug. 27 69.5 68.3 1.2 



Sept. 25 55.8 54.0 1.8 



Average 64.9 62.4 2.5 



An inspection of these tables shows that the soil in the 

 bottomland forest is constantly colder than that in the 

 upland forest, the average difference at three inches 

 being 2.4 degrees and at twelve inches 2.5 degrees. The 

 greatest difference found at three inches was 3.5 degrees 

 on June twenty-fourth and at twelve inches the greatest 

 difference was 4.3 degrees on July sixth. The smallest 

 difference recorded at three inches was 1.5 degrees on 

 July twelfth and at twelve inches 1.2 degrees on August 

 twenty-seventh. These various facts are shown graphi- 

 cally by figures 1 and 2. 



Measurements of air temperature were made on only 

 three different days as shown in table III. 



TABLE III 



Air temperatures in degrees Fahrenheit 



Date Upland Bottomland Difference 



July 6 80.5 74.6 5.9 



July 12 70.8 67.2 3,6 



Sept. 25 64.0 61.0 3.0 



Average 71.7 67.6 4.1 



This table indicates that there is an even greater dif- 

 ference in air temperatures than in soil temperatures in 

 upland and lowland forests, the average difference in air 

 temperature for the three readings taken being 4.1 de- 

 grees. 



