338 CARNEGIE INSTITUTION OF WASHINGTON. 



Permanent Quadrats, by F. E. Clements, E. S. Clements, and G. V. Loftfield. 



The use of permanent quadrats for the study of changes in cHmatic 

 and successional communities, and of the competition of dominants, 

 especially under grazing conditions, has been much extended during 

 the year. Their ability to afford exact measurements of population 

 changes, and to reveal the degree of equivalence of dominants in terms 

 of physical factors and of competition, gives them essentially an experi- 

 mental value. In fact, they are the means of measuring and recording 

 the vegetation experiments which are constantly being made in nature 

 by shifting climatic cycles or by various disturbing agencies. While 

 every permanent quadrat yields several sets of results, they are usually 

 established for particular purposes. The general installation through- 

 out the West is for the study of changes of climax vegetation in response 

 to climatic cycles, and the serai movement in primary and secondary 

 succession. A large number of quadrats have been established in 

 grassland to disclose the behavior of climax and serai communities 

 under different intensities of grazing, and to measure changes in carry- 

 ing capacity. Unusually complete series of quadrats have been 

 located in the desert plains and short-grass plains to permit tracing 

 the effect of rodents upon grassland in detail. In the former commu- 

 nity, winter and summer series were necessary, owing to the two vegeta- 

 tive periods. In addition to the quadrat-transect at the Alpine Lab- 

 oratory, a number have been installed to trace the effects of competi- 

 tion in fir and aspen communities. Quadrats have likewise been 

 employed for a similar purpose in the transplant areas in Nebraska 

 and Colorado, where dominant grasses are brought into competition 

 with the grasses in possession. The climax quadrats have been visited 

 and recharted and additional ones established at Logan (Utah), Bend, 

 Eugene (Oregon), Berkley, Benton, and La JoUa (Cahfornia), and 

 Seligman, Wilhams, Grand Canyon, and Tucson (Arizona) . The unique 

 value of the permanent quadrat increases with each year's change and 

 the record of it, and it is proposed to sunmiarize the results at intervals 

 of 5 to 10 years. 



Quadrat-Transect for the Study of the Biome, by F. E. Clements, G. V. Loftjield, 



and G. W. Goldsmith. 



A permanent quadrat-transect for the complete study and correla- 

 tion of the habitat with the plant and animal community, or biome, 

 has been established in the montane zone at the Alpine Laboratory. 

 The transect is 860 meters long and 2 meters wide, and includes 6 

 distinct habitats from the gravel-slide to the subclimax pine forest and 

 the climax Douglas fir forest. A series of three quadrats has been 

 installed in each community. One of these is located in the transect 

 and maintained as a permanent chart quadrat. The other two are 

 denuded after charting, and in one of them the soil is replaced with 



