RELATION BETWEEN EVAPORATION AND PLANT SUCCESSION 1 65 
the pine association ; while a third series leads from open water to the 
Thuja association. In wet soil, seedlings of Thuja are present under 
many conditions. On sandy land, healthy seedlings of Pinus strohus 
and Pinus resinosa occur under a large number of conditions. 
Similarly on the better soil are seedlings of Acer saccharum and 
Fagus grandifolia: On other portions of the lumbered land such 
seedlings have become small trees, with every prospect of reproducing 
the original forest. For the purposes of the present investigation, 
young seedlings, 15 to 25 cm. in height were chosen, as these are in a 
most critical stage. 
Cc. in 
No. Location. 
47-Day 
East Point Series, 
Period. 
27. 
Edge of dune. 
618 
28. 
Dense Thuja Bog. 
330 
29. 
Very dense part of bog. 
225 
30. 
Densest part, no green plants. 
155 
Reese's Bog Series. 
31- 
Clearing. 
587 
32. 
Layered Thuja in opening. 
460 
33- 
Dense, no green plants. 
435 
34- 
Marginal foss. 
391 
35. 
Thuja seedling in dense part. 
345 
36. 
Bog in Aspens. 
335 
Series East of Douglas Lake. 
37- 
Thuja seedling in slashed bog. 
344 
38. 
Thuja seedling in slashed bog. 
307 
Bryant's Bog Series. 
39- 
Edge of Chamaedaphne Assoc. 
590 
40. 
Picea, Pinus and Larix seedlings 
in 555 
Chamaedaphne Assoc. 
Fig. 3. Diagram showing the total evaporation and the rate per day for 47 
days (July 8 to August 24, 191 6) from different bog stations. 
In 191 5 three atmometers were run at the level of Acer saccharum 
seedlings in the dense hardwood forest under three conditions: at- 
mometer No. 11 under ordinary shade (Fig. 6), No. 12 under very 
heavy shade, and No. 9 in an opening caused by the removal of a 
large tree. Atmometers No. 6 and No. 7 were run in a large patch of 
vigorous I to 3 year old seedlings near the edge of the forest. The 
edge was the result of the preceding winter's clean-cut lumbering — 
therefore exposed to light and wind (Fig. 5). Atmometer No. 6 
was placed at the very edge, while No. 7 was run about 90 meters in 
the forest. Atmometers No. i and No. 2 were run alongside of Acer 
