ECOLOGY. 407 



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



Practically all of the permanent quadrat? and transects established 

 have been visited and recharted during the year. In addition, a con- 

 siderable number of new ones has been installed, and much use has 

 been made of the camera-set, or tristat, in determining the progress of 

 vegetative changes. This device supplements the quadrat by record- 

 ing the major changes in structure with the aid of the camera, which is 

 placed each year in the same position by means of permanent stakes 

 on which the tripod legs rest. A new improved form of the Hill 

 pantograph has been devised that can be set up and alined in less 

 than a minute, and permits charting the average quadrat in 15 minutes. 

 By it the personal factor is almost completely eliminated, the accuracy 

 greatly increased, and the time required diminished several times. It 

 has made it possible to greatly extend the scope of the quadrat method, 

 and to transform it from a time-consuming method possible only at 

 base stations to one readily available on field-trips generally. A new 

 type of quadrat sheet has been developed that conforms to the greater 

 accuracy of the pantograph. This is made preferably of tracing-cloth, 

 since its transparence not only permits copies to be made regularly, 

 but also enables the charts for different years to be superimposed and 

 the changes to be determined more accurately than in any other fashion. 

 An endeavor is still being made to perfect the overhead method of 

 quadrating bj^ means of the camera through the use of special lenses 

 and a fixed focus, and it is expected that this method will ultimately 

 replace all others for quadrats of a meter or less. 



A considerable extension has been made of the use of the denuded 

 quadrat, and it is now felt that these should be installed alongside of 

 permanent quadrats wherever a complete analysis of movement or 

 development is required. In fact, it has become evident that experi- 

 mental quadrats of various sorts are indispensable wherever causes 

 or processes are to be analyzed. By their use it is possible to duplicate 

 practically all habitats and serai stages, as well as to follow ecesis and 

 competition in a manner not otherwise possible. The quadrat in all 

 of its modifications seems more than ever the basic method in the 

 quantitative and experimental study of vegetation, and the endeavor 

 is now being made to refine it to the highest degree possible. 



Grazing Research, by F. E. Clements and J. V. G. Loftfield. 



Studies of the effect of grazing on the carrying capacity of ranges, 

 the structure of grassland communities, the competition of grasses and 

 shrubs, and its relation to indicator plants have again been made 

 throughout the West. As already indicated, these have confirmed the 

 view that grazing has profoundly modified the grasslands of arid 

 regions, and has led to their replacement by sagebrush and desert 

 scrub over wide areas. As a rule, overgrazing to this extent has 



