Figure 4.— Isolated aspen stand treated with 

 herbicide with no regeneration of aspen 

 because of heavy grazing by deer and cattle. 



(less than 1 acre [0.4 ha]), isolated, and grazed heavily 

 by livestock or big game (fig. 4). 



The understory composition had more grass and fewer 

 forbs in the sprayed than in the unsprayed stands 

 (table 3). Grass and total vegetation production was 

 higher in the sprayed than in the unsprayed stands. 

 Shrub numbers were slightly lower in the sprayed 

 stands. Vegetation cover was greater on the sprayed 

 plots, but the organic matter was deeper on the 

 unsprayed plots, possibly due to undisturbed litter from 

 aspen and understory categories. These results agree 



with expectations of broadleaf herbicide treatments 

 (Anderson 1977). Forbs and shrubs would sharply 

 decrease early while the grasses would increase after 

 spraying. We found that these effects still show 20 or 

 more years after treatment. 



Based on the results of our observations and related 

 literature, considerations for the use of herbicides on 

 aspen that appear appropriate are: 



1. The purpose for the herbicide treatment should be 

 clearly identified. Aspen regeneration requires less herbi- 

 cide and different timing than conifer site preparation 

 and release. 



2. The use of 2,4-D at a rate of 2 lb/acre (2.2 kg/ha) 

 acid equivalent, low volatile mixed with a water carrier, 

 kills most aspen overstory and initiates aspen regenera- 

 tion. Lower rates of 1 to 1.5 lb/acre (1.1 to 1.6 kg/ha) 

 may be effective in checking the aspen overstory and 

 initiating suckering. However, this needs to be tested. 

 Dicamba and 2,4-D mixtures have been recommended for 

 Populus spp. control (Hamel 1983). These should be used 

 mostly for conifer site preparations. Glyphosate 

 (Roundup 1 ) is being used experimentally in southern 

 Utah in the fall for conifer release in stands with abun- 

 dant aspen suckers, Ribes spp., or both. 



3. Herbicides are most effective for stimulating aspen 

 regeneration and conifer site preparation when applied 

 soon after aspen reaches the full leaf stage. For conifer 

 release, herbicides should be applied 1 to 3 weeks before 

 aspen leaf fall to reduce herbicide damage to the conifer. 



4. Spraying large openings in the aspen canopy 

 should be avoided to reduce damage to shrubs and forbs, 

 especially where aspen regeneration is the goal. Slight to 

 moderate reductions of shrubs and forbs beneath the 

 aspen should be expected when spraying aspen. 



Table 3.— Understory vegetation and soil attributes for 34 sprayed and 22 unsprayed aspen stands 







Sprayed 



Unsprayed 







Range 



Variable 



Units 



x ± s 



x ± s 



t Prob 



Sprayed 



Unsprayed 



Composition 















Shrub 



Percent 



22.5 + 17.7 



23.1 ±14.3 



0.4419 



1.1-73.9 



4.5-56.6 



Grass 



Percent 



47.5 ±21.3 



33.9±15.7 



.0063 



8.8-86.7 



5.8-64.3 



Forb 



Percent 



31.8 + 17.9 



43.0 ±18.0 



.0129 



2.6-58.3 



9.9-76.2 



Weight 















Shrub 



kg/ha 



296.1 +303.1 



284.0 ±255.9 



.4390 



2.5-1,147.9 



29.5-956.0 



Grass 



kg/ha 



585.7±471.3 



400.8 ±449.8 



.0764 



6.4-1,845.1 



17.5-2,018.8 



Forb 



kg/ha 



410.8 ±343.8 



393.4 ±21 7.6 



.4167 



20.8-1,078.9 



70.0-832.5 



Total 



kg/ha 



1,292.9 ±600.6 



1,078.3 ±548.7 



.0925 



241.9-2,351.2 



211.2-2,539.4 



Numbers 















Shrub 



N/0.01 ha 



4.0 + 1.8 



4.9 ±1.4 



.0287 



2-9 



3-8 



Grass 



N/0.01 ha 



5.7±2.0 



5.9±1.8 



.4049 



3-10 



1-8 



Forb 



N/0.01 ha 



11.0 + 4.6 



11.9 + 4.9 



.2354 



2-22 



4-20 



Total 



N/0.01 ha 



20.6±6.1 



22.6 + 5.7 



.1111 



12-31 



12-34 



Cover 















Vegetal 



Percent 



81.0 + 16.8 



73.6 + 19.1 



.0729 



43-100 



30-98 



Litter 



Percent 



18.2 + 16.5 



24.4 + 18.3 



.1052 



0-65 



0-70.0 



Rock 



Percent 



0.6+1.6 



1.7 + 3.3 



.0713 



0-7 



0-11.1 



Bare ground 



Percent 



0.4 + 0.9 



0.8+1.5 



.1558 



0-3.6 



0-5 



Soils 















Organic 



cm 



4.2 + 1.6 



5.8 ±2.8 



.0317 



2-8 



2-12 



A 



cm 



25.1 ±14.8 



23.5 ±11.8 



.3650 



3.8-60 



3.8-53 



B 



cm 



40.1 ±17.4 



32.4 ±12.8 



.1204 



15-70 



15-59 



5 



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