STUDIES IN LAKE AND STREAMSIDE VEGETATION 



147 



rainfall than mountain stations in the Appalachian region but there is 

 much more rainfall than in the foothills and plains regions of the Rocky 

 Mountain area. It may be said that the climate of Redrock Lake is 

 highly unfavorable for the growth of plants except such as can exist 

 with a very small amount of total heat for the growing period. It 

 would be quite impossible to grow even the hardiest grains because 

 of the general low summer temperature and the short season. 



III. Soil Temperature and Moisture 



Observations of Soil Temperature. — Readings were made by the 

 authors at different times during the summer of 1908. The various 

 plant formations were studied separately in order to have data of physical 

 factors in the different habitats (see under Zonation, part IV). An 



Table III. Soil Temperatures in Degrees Fahrenheit at Depth of 3 dm. during 



the Summer of 1008 



Date 



Water of 

 Lake 



June 11. . 

 June 28. . 

 July 20. . . 

 Aug. 10*. 

 Aug. 21*. 

 Sept. 7t- • 

 Average. . 



62 

 69 

 68 



59 

 60 



58 

 62.7 



* The month of August was wet, with much cloudy weather, so that temperatures are not as high as would 

 ordinarily be the case. 



t Preceded by a week of unseasonably hot weather; temperatures evidently above normal for the time 

 of year. 



examination of the table shows, what might be expected, that the forest 

 soil is the coldest and the soil of the shrub zone next coldest. In both 

 these cases the soil is shaded. In the forest the readings were taken 

 among large Engelmann spruces. No observations were made in the 

 drier mixed forest of limber pine and lodgepole pine (P. flexilis and P. 

 murrayana). Without doubt the drier soil of this often more open 

 forest is warmer than that of the mesophytic spruce forest. The Are- 

 naria association has the warmest soil and the Dasiphora association 

 the next warmest. Here there is no shade. Very early in the spring 

 these forest openings warm up and there is a development of vernal 



