Io6 RECOGNIZING AND CORRECTING DECLINING FORAGE 



are invariably replaced by certain temporary or short-lived 

 species, corresponding, in a way, to the primitive plant forms, 

 most of which are low or negligible in palatability and nutritious- 

 ness. Accordingly, the incoming species are reliable indicators 

 of small departures in the grazing capacity of the pasture; they 

 tell the true story as to whether the pasture is improving, de- 

 clining, or merely " holding its own " in forage production. 



The rate of the replacement of one set of plants by another is 

 determined essentially by the soil texture, the moisture content 

 of the soil, and the compactness of the soil. If the soil is rich 

 in humus so that it may absorb and retain a large amount of 

 moisture for plant growth, the lands will support a stable per- 

 ennial type of vegetation. The forage yield of such a cover 

 year after year is appreciably larger and less fluctuating than is 

 that of annual or biennial plants, and is therefore the pasture 

 type most desired. 



Conspicuous Signs of Overgrazing. — Overgrazing for an ex- 

 tended period will invariably leave its signs of one kind or an- 

 other.^ The accumulated damage may be recognized by the 

 following conditions: (i) Erosion, barrenness, and deeply cut 

 stock trails where the cover was formerly intact. (2) Remnants 

 of dead shoots of palatable woody plants, such as birchleaf 

 mahogany (Cercocarpus), willow (Salix), snowberry {Sym- 

 phoricarpos), bitterbrush {Purshia), and serviceberry {Amel- 

 anchier). Where such shrub growth has been largely destroyed, 

 most of the palatable grasses and weeds have long been killed 

 out. (3) Damage to tree reproduction, including that of most 

 coniferous species, as well as that of broad-leaved forms like 

 aspens. (4) An increasing abundance of unpalatable or, indeed, 

 poisonous plants, such as certain species of butterweed {Senecio),'^ 

 snakeweed (Gutierrezia) , and sneezeweed (Helenium). Areas 

 upon which an abundance of such vegetation grows need very 

 careful management in order to prevent heavy livestock losses. 

 (5) The predominance of annual weeds and short-lived un- 



' Jardine, James T., and Anderson, Mark, "Ran^e Management on the National 

 Forests." U. S. Dept. of Agr. Bui. 790, pp. 16-23, 1919. 

 * A very few species of Senccio are highly palatable to stock. 



