126 RECOGNIZING AND CORRECTING DECLINING FORAGE 



dandelion, 51 per cent; yarrow, 38 per cent; and slender wheat- 

 grass, 12 per cent. However, the greatest density in four species 

 occurs on the unprotected area. The species concerned are 

 somewhat unpalatable perennials or annuals, such as usually 

 colonize readily on more or less packed soils. 



Further interesting contrasts may be observed if the average 

 height growth of the different species on the fenced and the un- 

 fen-ced areas may be used as an index of their physiological vigor 

 or strength. For instance, the relative height growth of the 

 different species is strikingly in favor of the protected area, the 

 percentage being greater in all but one instance. The exception 

 is m-eadow rue (Thalictrum), a plant which is practically un- 

 touched by any class of stock. Being unmolested by grazing 

 animals, the plant is quite as strong physiologically on the un- 

 protected area as on the protected plot. In general the differ- 

 ence in the height growth is roughly in proportion to the palata- 

 bility of the different species. Moreover, the amount of seed 

 produced, its germination strength, and the height growth of 

 the vegetation are closely correlated. Regardless of whether 

 the vegetation is permitted to regain its vigor by the entire ex- 

 clusion of stock as a result of deferred grazing, complete physio- 

 logical recovery results in about three years. Likewise, the de- 

 cline in the forage yield and seed production of bunchgrass 

 areas, practically to the zero point, is accompHshed in approxi- 

 mately three years of abusive grazing. 



Possibly the most significant fact brought out in the experi- 

 ment is the difference in the density of the various species on the 

 protected and on the grazed area. On yearlong protected areas 

 the plants with running rootstocks, like yarrow, low peavine, 

 and sweet sage, increase at a rapid rate by sprouts as soon as 

 sufficient food is elaborated to stimulate the buds to growth. 

 Reproduction from seed, especially by plants of the large-seeded 

 species, like the bromegrasses and fescues, for instance, is strik- 

 ingly more vigorous on areas where the grazing is deferred until 

 the seed crop has ripened. For good reproduction of plants 

 whose seeds are fairly large, deferred grazing, with the conse- 

 quent planting of the seed crop by the trampHng of stock, is a 



