■ Relation of 

 Grazing to Aspen 

 Reproduction and 

 Range Condition 



Aspen dominates several million acres of 

 high-elevation summer range in the Rocky 

 Mountain and Intermountain areas, mostly be- 

 tween the mountain brush and subalpine coni- 

 fer zones. When in good condition, the lush 

 undergrowth in aspen furnishes considerable 

 cover and forage for wildlife and livestock. The 

 type also has esthetic value, some commercial 

 value for certain timber products (e.g., ex- 

 celsior), and is valuable for watershed protec- 

 tion. Studies on aspen here actually predated 

 the establishment of the Great Basin Station. 

 One study on the effect of grazing upon aspen 

 reproduction (Sampson 1919a) was started in 

 1902 and dealt with management of grazing on 

 aspen range, particularly on what effect sheep 

 grazing had on reproduction and growth of 

 aspen following clearcutting. The conclusions 

 were that, to avoid destruction of aspen sprouts 

 after cutting, three courses of action were avail- 

 able: (1) entire exclusion of grazing for 3 years; 



(2) exceedingly light grazing by sheep; or 



(3) moderate grazing by cattle. The height of 

 the sprouts was found to be the main factor 

 determining when reproduction was protected 

 from destruction by livestock grazing. A sur- 

 prisingly large proportion of aspen sprouts 

 were killed during the first 3 years by causes 



other than grazing; e.g., frost, and bark con- 

 sumption by gophers, mice, and rabbits. Big 

 game populations were quite low at the time 

 these early studies were conducted; later re- 

 search elsewhere has shown that deer and other 

 game can also browse sprouts too heavily to 

 allow aspen reproduction. Other factors, par- 

 ticularly competition from herbaceous vegeta- 

 tion, may also suppress aspen regeneration. 



Interest in aspen range continued, and some 

 35 years later Jack Major (now at the Univer- 

 sity of California, Davis), Walter Houston (now 

 with the Agricultural Research Service), and 

 Lincoln Ellison, began a study designed to help 

 managers assess the condition of aspen range 

 (Houston 1954; Ellison and Houston 1958). 

 Their study was concerned primarily with 

 openings in aspen forest rather than with the 

 aspen stand itself. They pointed out that open- 

 ings are key areas, that they have more grass 

 and forbs than the aspen stands and conse- 

 quently carry the bulk of the grazing load. If 

 the cover in these openings is kept in good con- 

 dition, understory vegetation in the tree areas 

 will also be good. Comparison of forage pro- 

 duction under aspen canopy and in openings 

 can aid in judging range condition. 



Houston's criteria for judging the condition 

 of aspen range included amount of cover, spe- 

 cies composition, amount of current aspen re- 

 production, current production of all types of 

 forage, and presence or absence of erosion. In 

 evaluating species composition he gave highest 

 rating to species that were tall, succulent, and 

 palatable. 



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