EFFECTS OF DIFFERENT SYSTEMS OF GRAZING. 



31 



tion transect in the 30-acre pasture show that Stipa is becoming in- 

 creasingly slower in producing seed stalks after protection from the 

 hard grazing. This point was brought out in the past two years, and 

 it is not yet clear how long it will take for this grass to reach a stage 

 of normal seed production after it has been subjected to severe con- 

 tinuous grazing. 



Table 9. — Average quantity of vegetation produced annually by different species 

 and groups of plants on the quadrats clipped at different intervals, in the 

 5-year period from 1917 to 1921, inclusive. 





Weight of vegetation per square-meter quadrat clipped at stated intervals 

 (grams). i 



Species or group. 



10 days. 



20 days. 



30 days. 



40 days. 



Annual. 





Green. 



Dry. 



Green. 



Dry. 



Green. 



Dry. 



Green. 



Dry. 



Green. 



Dry. 



Bouteloua gracilis 



25.9 

 5.3 



14.9 

 3.1 



24.6 



14.7 

 4.2 



27.4 

 13.1 



16.7 



s. 



23.1 



12.8 



15.4 

 8.0 



14.9 

 35.8 



12.7 













Bouteloua gracilis and Stipa 



comata 



Other grasses 



31.2 18.0 



8.8 4.4 



31.4 1 18.9 

 8. 1 4. 4 



40.7 

 11.9 



24.7 

 6.6 



35.9 

 14.0 



23.4 



7.8 



50.7 

 6.4 



42.5 

 5.0 



Total, all grasses 



Carex filifolia and Carex heli- 



ophila 2 



Other plants 



40.0 



34.2 

 31.1 



22.4 



17.1 

 9.9 



39.5 



40.8 

 29.8 



23.3 



21.1 

 9.0 



52.6 



51.6 

 32.6 



31.3 



26.9 

 11.1 



49.9 



45.2 

 47.5 



31.2 



25.2 

 16.5 



57.1 



19.2 

 44.6 



47.5 



16.6 

 22.2 



Total, all species 



105.3 



49.4 



110.1 



.53.4 



136.6 



69.3 



142.6 



72.9 



120.9 



86.3 



1 Grams per q uadrat can be converted to pounds per acre by multiplying by the factor 8.922. 

 * These have been separated since and including 1919. 



The " other grasses " of Table 9 show an apparent reduction in the 

 annual quadrats. A grass that makes up a large percentage of these 

 is Koeleria cristata (prairie June-grass). This species is the earliest 

 grass to mature on the prairie. It is usually mature and starts to 

 dry up before the end of June. It, however, makes some secondary 

 growth in the fall. The grasses of this group that appear in the 

 quadrats in their order of abundance are Koeleria cristata, Aristida 

 longiseta, Muhlenbergia cuspidata, and Agropyron smithii. 



The " other plants " shown in Table 9 are composed of species that 

 appear in the quadrats that do not belong in any other division. 

 The most abundant and important ones are Artemisia gnaphalodes, 

 A. dracunculoides, A. frigida, Solidago pulcherrima, and Psoralea 

 argophylla. Artemisia gnaphalodes makes more rapid and frequent 

 recovery from clipping than the other species, and Psoralea the least. 

 When Psoralea is cut once or twice early in the season it does not 

 usually make much more growth that year. The " other plants " con- 

 tain the highest percentage of water, as may be observed from the 

 weights obtained. 



There is nothing of particular significance in Table 9 in regard to 

 the yield of " other plants." There are indications that the quantity 

 has been reduced in those quadrats that are frequently clipped. This 

 point is confirmed by observation and by the yearly data. It will 

 be noted that the dry weight for " other plants " is much greater in 

 the annual quadrats than in any of the others. This is true for two 

 reasons: (1) Because the plants cut during the early part of the 



