ECOLOGY. 355 



typical dominance, and it is expected that these wdll aid in the solution 

 of the rhythm. 



A third type of periodicity occurs in the case of such secondary 

 species as Calypso borealis and Botrychium lunularia. Ten years ago 

 these plants were so rare in the vicinity of the Alpine Laboratory as 

 to be known by actual count. The present summer they are a hundred 

 times more abundant. The cause for this is obscure, though it prob- 

 ably is related to the greater rainfall of the past three years, as Pike's 

 Peak has passed through the drought period of 1917-1919 with more 

 than the normal rainfall. Quadrats have been installed in these 

 communities and their behavior will be followed in detail. 



The fourth type of periodicity involves the life-form of certain 

 grasses and herbs in the desert plains. During dry periods there is a 

 marked increase in the annual forms. Bouteloua rothrockii appears to 

 turn into the annual B. polystachya, and the perennial Franseria tenui- 

 folia becomes annual, and thus through a number of species. With the 

 return of vv^et years the perennial forms predominate. 



Transplant Quadrats and Areas, by F. E. Clements and J. E. Weaver. 



Studies in the application of the methods and principles of experi- 

 mental vegetation by the estabhshment of transplant and seeded 

 quadrats were begun in 1918 and greatly extended during 1919. 

 During the past season they have been continued on a very extensive 

 scale. In addition to the former stations at Lincoln (Nebraska) and 

 Colorado Springs, other permanent stations have been estabUshed at 

 Nebraska City, Phillipsburg (Kansas), and Burlington (Colorado). 

 These stations are equipped with instruments for the determination of 

 air and soil temperatures, humidity, and evaporation, while deter- 

 minations of water-content are made to a depth of 4 feet. 



Dominants are transplanted by cutting out and removing blocks 

 of soil, 12 to 18 inches square and about 8 inches deep, and inserting 

 these blocks in areas of similar dimensions excavated in the new habi- 

 tat. This is usually done in duplicate, the soil being carefully com- 

 pacted about the sides of the transplants and at least one series watered 

 until established, as well as at critical periods throughout the first 

 growing-season. In this manner reciprocal transplants of the following 

 dominants have been made at Lincoln in high and low prahie, gravel- 

 knoll, wet meadow, and salt flat: Agropyrum spicatum, Andropogon 

 furcatus, A. nutans, A. scoparius, Bouteloua gracilis, B. curtipendula, 

 Bulbilis dadyloides, Distichlis spicata, Elymus canadensis, Kceleria 

 cristata, Panicum virgatum, Poa pratensis, Spartina cynosuroides, and 

 Stipa spariea. Practically all of these have been transplanted mto 

 the short-grass area at Burlington and the mixed prairie at Colorado 

 Springs. Several of them have likewise been planted in the desert 

 plains at Sonora, Texas, and Tucson, Arizona, and in the montane 

 zone at the Alpine Laboratory. Transplants of Stipa setigera and 



