ECOLOGY. 357 



Crop Development and Production Studies, by F. E. Clements and J. E. Weaver. 



The development and production of certain crop plants have been 

 studied at the stations at Lincoln, Phillipsburg, and Burlington in 

 connection with the preceding studies. White Kherson oats, Marquis 

 spring wheat, barley, alfalfa, white sweet clover, and sunflowers were 

 used. Areas typically representative of soil and topography at 

 each station were selected, the seed-bed properly prepared, and the 

 cereals and legumes sown at the same rate (that determined by the 

 farm practice for central I^nsas). This was done at the usual time 

 of seeding, on an area approximately one-thirtieth of an acre at the 

 several stations. These areas joined those of native vegetation, where 

 complete records of precipitation, humidity, evaporation, soil, and air 

 temperatures were obtained. Water-content readings to a depth of 

 4 feet were made at frequent intervals among the crop plants. Careful 

 records of the root and shoot development of all the crops were made 

 at each station at regular intervals. For oats and wheat, and in part 

 for alfalfa and sweet clover, drawings of root and shoot development 

 were made to scale in the field at Lincoln, thus giving several stages in 

 the sequence from seedling to matm*e plant. 



When ripe, the cereals were harvested by selecting 25 to 30 meter- 

 quadrats of each species, from each planting, and by cutting the grain 

 near the surface of the soil. The plants from each quadrat were tied 

 in a separate bundle, and all were shipped to the botanical laboratories 

 of the University of Nebraska, where they were thoroughly air-dried 

 and finally v/eighed. At two or three intervals throughout the season, 

 300 to 500 average plants of alfalfa and sweet clover were measured, 

 cut, dried in the laboratory, and finally weighed. Similar data were 

 obtained for sunflowers. In general, climatic conditions for plant 

 growth were unusually favorable, especially at Phillipsburg and Bur- 

 lington. The correlation of crop production with native vegetation was 

 least at Burlington and usually greatest at Lincoln, although certain 

 cuttings of sunflowers and legumes at PhilHpsburg closely approached 

 or even exceeded the yield at Lincoln. 



Plant Production Quadrats, hy J. E. Weaver. 



A study of the effect of climate upon the production of natural vege- 

 tation has been made at several stations through the gi-assland for- 

 mation. These are Nebraska City in the subclimax prairie, Lincoln 

 in the true prairie, Phillipsburg in the mixed prairie, and Burlington 

 in the short-grass plains. This series of stations gives a range of annual 

 precipitation from about 33 inches at Nebraska City to 28 at Lincoln, 

 23 at Phillipsburg, and 17 at Burhngton. The method employed was 

 to select 20 to 30 meter-quadrats in typical undisturbed areas in the 

 climax vegetation. The height and density of the vegetation, the abun- 

 dance of dominant and subdominant species, etc., are recorded, and pho- 



