(340) 



Temperature 



The temperature readings for the season at all stations have 

 been averaged, and the results are presented in Table I. The 

 weekly records themselves are too voluminous to include.^ In 

 order to bring out the relationships between the stations, which 

 could not be found without a great deal of poring over the figures, 

 some of the values are shown graphically in Figures 2 to 4. 



It is impracticable to reproduce all of the 18 charts which were 

 plotted to compare the weekly readings of the different stations 

 throughout the season. Three charts, the mean soil temperature 

 at 6 inches for the New York stations, the mean soil temperature 

 at 6 inches for the cooperating stations and New York hemlock, 

 and the mean soil temperature at 18 inches for the other stations 

 and New York hemlock, are shown as Figures 2 to 4 In 

 general, the charts on which the New York stations alone appear 

 are clear and have comparatively little crossing of the lines. The 

 mean 6-inch soil temperature for the New York stations, Figure 

 2, is a good example. With the other stations and New York 

 hemlock there is a good deal of crossing back and forth, making it 

 difficult to follow out the different stations. The 6-inch mean 

 soil temperature for all cooperating stations and New York, 

 Figure 3, is a fair example of this. As would be expected, the 

 criss-crossing is most with the air temperatures, and least at 18 

 inches in the soil. 



The air temperature records show, among other things, the 

 influence of the forest canopy in moderating extremes. On the 

 maximum chart the open station was consistently highest 

 throughout, and on the minimum chart it was consistently the 

 lowest. The higher maxima and lower minima at the open sta- 

 tion offset each other, so that the mean temperature for the 

 season was only very slightly above that under the forest. This 

 illustrates the importance of obtaining maximum and minimum 

 readings in studies of plant habitats. In this case the mean 

 fails to show the severer temperature stresses to which the 

 plants are subjected in the open as compared with those under 

 the shelter of the forest. 



The maximum air temperatures at New York show that the 

 hemlock forest was noticeably and consistently warmer than the 



• As with the evaporation records (see footnote 6), copies can be obtained by 

 qualified persons at the cost of reproducing. 



