250 ILLINOIS ACADEMY OF SCIENCE 



The measurements were made at two stations located 

 east of the Middle Fork of the Vermilion River and be- 

 tween the C. C. C. & St. L. and I. T. S. railroads. The 

 river at this place is bordered on the east by a strip of 

 typical bottomland forest 300 to 500 feet wide. The 

 dominant trees here are American elm (Uhmis ameri- 

 cana), sycamore {Platanu's occidentalis) and soft maple 

 (Acer saccharinum). Common secondary trees are the 

 hackberry (Celtis occidentalis), box elder (Acer ne- 

 gundo), green ash (Fraxinns pennsylvanica var. lanceo- 

 lata), bur oak (Qitercus macrocarpa) , walnut (Juglcms 

 nigra), honey locust (Gleditsia triacanthos), black maple 

 {Acer saccharum var. nigrum) and cottonwood {Populus 

 deltoides). The dominant species of the herbaceous 

 layer are the wood nettle {Laportea canadensis) and the 

 pale touch-me-not {Impatiens palida) both of which grow 

 very vigorously, reaching heights of four feet or more, 

 and often occupying the soil over considerable areas to 

 the almost total exclusion of other herbaceous plants. 



At the eastern edge of the bottomland forest the land 

 rises by a steep slope to the upland plain about 70 feet 

 above. The slope itself is clothed with a transitional 

 mixed hillside forest in which the dominant trees vary 

 from those characteristic of the bottomland forest at 

 the base, through the most mesophytic species of the 

 region, namely hard maple (Acer saccharum) , red oak 

 (Quercus rubra) and beech (Fagus grandifolia) which 

 are found part way up the slope, to the more xerophytic 

 species of upland forest types such as the white and black 

 oaks (Quercus alba and Q. velutina), and the shag-bark 

 and pig-nut hickories (Carya ovata and C. cordiformis). 

 At the top and adjacent to the slope the soil was formerly 

 occupied by the ordinary oak-hickory mesoxerophytic 

 association. Most of this adjacent land, however, has 

 been cleared and is under cultivation. 



The upland station selected for making soil tempera- 

 ture readings was just at the top of the slope where the 

 land begins slanting to the west. The particular place 

 chosen was near a cluster of raspberry bushes where the 

 other undergrowth was also abundant and the instru- 



