EFFECTS OF DIFFERENT SYSTEMS OF GRAZING. 



23 



was also set aside in one division of the rotation pasture in 1918. 

 When the experiment was started the value of these transects was 

 underestimated. It was not until 1919 that their real worth was ap- 

 preciated. In Figure 9 is shown a diagram of one of these transects. 

 The transect is 300 feet long; the units are each 20 feet square. One 

 of the units in series A is opened to grazing each year, 19 while one 

 of the units in series C is closed to grazing at the same time. Series 

 B is not subject to grazing at any time, nor is the vegetation removed 

 in any manner. 



In the 30-acre pasture the isolation transect 

 shows the points of most interest and signifi- 

 cance in regard to the development of Ar- 

 temisia frigida. In series A it is becoming 

 thicker in the unit opened to grazing in 1918. 

 The growth of this species in series B is no 

 different from that in the 100-acre pasture. 

 The maximum development of A. frigida is 

 shown in series C. the units closed to grazing 

 annually. The plants in the unit closed in 

 1918 are not greatly different from those in 

 series B. The 1919 unit shows a slight in- 

 crease in the number of plants, but they are 

 about normal in size. The units closed in 

 1920 and 1921 show a greater increase in the 

 number of plants and a pronounced increase 

 in the vigor of the individual plants. Plates 

 IV and V illustrate the difference in the 

 thickness of the plants and their vigor. 

 The photographs of the isolation transect 

 in the 30-acre pasture, reproduced in these 

 plates, show the effects of intense grazing 

 for varying periods upon the native vegeta- 

 tion better than it can be recorded in any F] 

 other wav. 



A 



B 



C 



i 



/I XP/<5 



1 





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1 

 3\/&20 



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/&^o 



i 

 i 



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6 









7 









a 









s> 







1 



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(IS) 1 



'V 



LIST QUADRATS. 



ig. 9. — Diagram showing 

 plan, of isolation tran- 

 sects : A, Grazing series, 

 one unit opened to graz- 

 ing each year ; B, per- 

 manent series, units 

 never grazed ; €, regen- 

 eration series,, one unit 

 closed to grazing each 

 year. Solid lines show 

 fences, dotted lines 

 where fences formerly 

 stood, and dash lines 

 where fences will ulti- 

 mately be built 



List quadrats, square-meter areas in which 

 the plants are counted and the numbers re- 

 corded, are of value in keeping a record of 

 the number of plants of individual species. 

 Their value is increased, since it is possible 

 to include a comparatively large number of 

 square-meter quadrats. These quadrats are located in the open pas- 

 tures and in the isolation transects. They are permanently located 

 by means of a single stake. There are 40 of these quadrat's in each 

 pasture. The highly important species are also recorded in an equal 

 number of duplicate quadrats cornering the originals. It is possible 

 to keep a record of individual species which appear as single plants 

 or as single distinct bunches, such as Aristida longiseta or Koeleria 

 cristata. Not all of the species that appear in the quadrats are 

 recorded. The species that are regularly listed have been reduced 



u Units were opened on the north end and closed on the south end in 1917. 

 they were placed across from each other. 



In 191S 



