408 CARNEGIE INSTITUTION OF WASHINGTON. 



either destroyed the carrying capacity of the range or greatly reduced 

 it, though this has been somewhat counterbalanced by the value of 

 the sagebrush or mesquite as browse, and especially by the extension 

 of the buffalo-grass with its unique value as a resistant sod. 



Definite grazing experiments have been conducted chiefly in Ari- 

 zona. The fenced inclosures at the Grand Canyon, Williams, and 

 Seligman in the northern part of the State have been maintained, as 

 well as the series of exclosures on the Santa Rita Range Reserve at 

 Tucson. In addition to the studies of Dr. Vorhies on the life-history 

 of the kangaroo rat and the relation of its feeding and storage habits 

 to the maintenance of the range, the effect of seasonal rainfall and 

 temperature has received much attention. The winter of 1920-21 

 was nearly rainless and resulted in the almost complete suppression 

 of the cover of winter annuals, as well as in the death of many of the 

 bunches of perennial grasses. The summer of 1921 yielded about 

 the normal rainfall, but this was unable to bring about the usual 

 development of the grasses. In addition to the regular quadrats 

 charted both winter and summer, clip quadrats were employed to 

 determine the utilization of the various grasses and browse shrubs 

 upon the range, and a simple practicable method was devised for 

 estimating the amount of available forage upon it. 



Experiments have been begun to determine the best methods of 

 reseeding overgrazed ranges. Seeds of Bouteloua rothrockii, B. erio- 

 poda, B. racemosa, and Sporobolus cryptandrus were employed, and 

 6 seed-plots were established for each species. The methods used 

 were broadcast seeding, drilling, broadcasting and raking with a 

 harrow, burning followed by broadcasting, planting, and planting 

 with protection. A hydrothermograph was installed to make it 

 possible to determine the relative importance of water and tempera- 

 ture in germination and establishment, as well as in growth. The 

 results indicated that water was the controlling factor, but they can 

 not be regarded as representative, owing to the exceptional dryness 

 of the winter, and observations for a number of years will be necessary 

 to determine the effect of each factor. 



Soil Fauna of Engelmann Canyon, by G. W. Goldsmith. 



The work of the previous season has been continued at representa- 

 tive stations in the transect across Englemann Canyon at the Alpine 

 Laboratory. The methods employed were essentially those already 

 described, in which soil layers of 2.5 cm. were taken successively 

 from soil quadrats 4 dm. square. Greater accuracy in obtaining the 

 sample for each count was obtained by using a steel frame 1 dm. 

 square, one edge of which was sharpened. This was driven into the 

 ground at the place desired, and the soil obtained was carefully re- 

 moved and taken to the laboratory for counting. The accuracy and 



