STUDIES IN LAKE AND STREAMSIDE VEGETATION 



149 



Naturally this zonation depends on edaphic factors of soil texture, amount 

 of humus and moisture content. Some of these points have been dis- 

 cussed in the account of Geology and of the Soil. 



Table IV. Percentage of Soil Moisture in Samples Taken at Depth of 3 dm. 



DURING THE SUMMER OF igo8 



Date 



Sedge 

 Zone 



Shrub 

 Zone 



.Engelmann 

 Spruce 

 Forest 



Dasiphora 

 Assn. 



Arenaria 

 Assn. 



June 11. 

 June 28. 

 July 20. 

 Aug. 10. 

 Sept. 7.. 

 Average . 



64 

 62 



87 

 46 



52 

 62 .2 



3° 

 20 



5i 



36 



9 



29. 



12 

 13 

 3° 

 34 

 15 

 21 .0 



13 



28* 



9 



7 

 5 

 8 

 8* 



* Undoubtedly above normal for this time of year. August was unusually wet in 1908. 



Previous Lake Studies. — The first zonation studies of lake shores 

 made in America were by MacMillan. 1 He distinguished many types of 

 shores on this lake showing various kinds of zonation. His "dry morassic 

 attached shores" show a zonation comparable to what is found at Red- 

 rock Lake. Here he distinguishes four zones: (i) Scirpus zone; (2) 

 Salix zone; (3) Betula zone; (4) Larix zone. Other students of shore 

 vegetation in this country have contributed to a knowledge of the lakes 

 of the eastern and central parts of the United States. Mention may be 

 made of articles by Messrs. John H. SchafTner, Geo. F. Atkinson, 

 S. M. Coulter, Harry N. Whitford, Howard S. Reed, Lewis H. Weld, 

 Otto E. Jennings, LeRoy Harris Harvey. This is not the place to 

 summarize these studies; the writings of these authors with others in 

 America and Europe will be considered in detail in a later paper by the 

 present writers after the publication by them of further studies on the 

 lakes of the Rocky Mountains of Colorado. The only work on shore 

 vegetation in Colorado is that by Professor Frederic E. Clements who 

 has worked so energetically upon the plants of the Pike's Peak region. 

 In his "alpine bog formation" and "alpine lake formation" he names 

 various species characteristic of each formation 2 and in his recent 



1 MacMillan, Conway, "Observations on the Distribution of Plants along Shore at Lake of the Woods," 

 Minn. Bot. Studies, Vol. I, pt. 2, pp. 940-1023, 1897. 



* Clements, Frederic E., "Formation and Succession Herbaria," Univ. oj Nebraska Studies, Vol. IV, 

 PP- 352, 3S3. I9°4- 



