GBAZING AND FORAGE PRODUCTION ON NATIONAL FORESTS 27 



EXPERIMENTAL PROCEDURE 



ESTABLISHMENT OF PLOTS 



Four plots each of mountain brome (Bromus polyanthus), com- 

 mon brome (B. inermis), and violet wheat grass (Agropyron vio- 

 laceum) were planted in the forage nursery located in the aspen-fir 

 type at an elevation of 8,700 feet. Each plot contained 30 specimens, 

 which were uniformly spaced 1 foot apart. In order that all the 

 specimens might be as nearly alike as possible with respect to size, 

 age, and vigor, the plants were developed from seed sown in a seed 

 bed a year prior to their being carefully transplanted in the regular 

 plots. 



In 1919, when the first experimental series was well under way, 

 the investigation was expanded by the planting of a large number 

 of additional plots in the nursery to native forage species. (PL III, 

 fig. 1). Following the more extensive plot work of the nursery, it 

 was deemed advisable to approach range conditions more nearly than 

 was possible on cultivated ground. With this in view, in the spring 

 of 1920 a large number of new plots were established on the range 

 where the plants were growing naturally in association with many 

 species and had been subjected to normal annual grazing. These 

 were located in the oak-brush type at an elevation of 7,200 feet 

 and in the spruce-fir association at an elevation of about 10,000 

 feet. Approximately 1,000 plant specimens for experimental work 

 were contained in these series of plots and an unusual opportunity 

 was afforded for comparative study, especially as to (1) possible 

 variations in the response of plants of the same species to a given 

 method of treatment, and (2) the combined effects of widely differ- 

 ent climatic conditions and methods of harvesting. All the more 

 important types of forage plants had a representative in the test, 

 Although most of the work dealt with plants of the " bunch " or 

 tufted habit of growth, such as are found commonly on high moun- 

 tain range, typical turf -forming species (those which reproduce 

 asexually or vegetatively, as from rootstocks) were also included. 



METHODS OF TREATMENT 



In order to procure the most accurate data possible, the forage 

 removed from all the plots was harvested with shears in a way to 

 resemble grazing, the season and closeness of the harvesting (the 

 latter approximately 1 inch from the surface of the ground in most 

 instances) representing as nearly as practicable that of certain graz- 

 ing practices. In harvesting the various forage plots in one or more 

 of the grazing types 24 methods differing as to date, frequency, 

 and closeness of cutting were used. 



During the period of experimentation on a " plant plot " basis for 

 the purpose of ascertaining the cumulative effect of different methods 

 of cropping on the yield of herbage, extensive observations were 

 also made over a wide range of forage, soil, and climatic conditions 

 where the methods of cropping were known. These observations 

 have proved helpful, not only in checking, but also in interpreting 

 the results of the detailed studies. 



For the purpose of determining the comparative food value, 

 pound for pound, of forage harvested at different times in the 



