II.— FURTHER STUDIES IN THE ECOTONE BETWEEN 

 PRAIRIE AND WOODLAND 



BY R. J. POOL, J. E. WEAVER AND F. C. JEAN 



A series of intensive investigations of the ecological features of 

 the tension zone between prairie and woodland in the Mississippi 

 valley was begun by Weaver and Thiel in 191 5. These studies 

 were continued for two seasons in Minnesota and were also ex- 

 tended to the prairies of eastern Nebraska in 1916. These inves- 

 tigations represent the first attempt to attack the prairie-forest 

 problem on a comprehensive scale by means of the quantitative 

 methods of modern ecology. 



Some of the results secured from these studies have been pub- 

 lished as the first paper of a series planned to deal with critical 

 investigations in the ecology of the prairie province. The above 

 studies were continued and considerably extended in the Ne- 

 braska area by the authors of the present paper during the year 

 1917. 



The object of the present paper is to record the results and con- 

 clusions derived from another season's investigations of some of 

 the fundamental problems connected with the ecology of the areas 

 lying within the vegetative borderlands between the prairies and 

 the woodlands of the Missouri valley in Nebraska. This con- 

 tribution is a natural sequel to the paper^ by Weaver and Thiel 

 noted in a previous paragraph. 



Results are here recorded from our old stations in the prairie 

 and woodland in the vicinity of Lincoln and also many additional 

 data and materials are presented from a new series of stations 

 established in 191 7 near Peru, on the Missouri River. It has been 

 demonstrated that the latter stations exhibit conditions which are 



1 " Ecological Studies in the Tension Zone between Prairie and Wood- 

 land," J. E. Weaver and A. F. Thiel, The Bot. Surv. Nebr., N. S., No. i, 

 1917. 



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