Table 2 — Species assignment to desirability class based on serai placement and forage potential 



Desirability class 



Desirable 



Intermediate 



Less desirable 



Agropyron trachycaulum 

 Bromus carinatus 

 Poa reflexa 

 Stipa Columbiana 

 Thalictrum fendleri 



Galium boreale 

 Hackelia floribunda 

 Phacelia hastata 

 Polemonium foliosissimum 

 RudbeMa occidentalis 

 Stipa lettermani 

 Viola purpurea 



Descurainia pinnata 

 Helenium hoopesii 

 Madia glomerata 



Grouping species into classes of plants (desirable, 

 intermediate, and less desirable) and summing their 

 nested frequency scores (cumxilative nested frequency) 

 allowed for a more useful analysis determining treat- 

 ment effects on community structure. Assignment 

 to these classes was based on a combination of spe- 

 cies' serai placement and their potential forage utility 

 (table 2). Since commimity baseline data were not re- 

 corded, only differences among treatments may be 

 assessed. This comparison is valid with the assump- 

 tion that the baseline commimity was similar through- 

 out the study area. 



Standard analysis of variance and Fisher's least 

 significant difference (LSD) mean separation proce- 

 dures were employed to distinguish treatment differ- 

 ences in stem density and nested frequency scores. 



RESULTS 



The level of control achieved by the various chemi- 

 cal and mechanical treatments was quantified only 

 by stem density counts. However, there were notice- 

 able, apparent differences in stem heights and diam- 

 eters between treatments. 



Herbicides 



Amitrole: False hellebore stem density averaged 

 11. 5/m^ before treatment. Stem density was reduced 

 21.5 percent in 1983, 44 percent in 1984, 30 percent 

 in 1986, and 32.5 percent in 1991 (fig. 1). 



Picloram: False hellebore stem density averaged 

 16.0/m^ before treatment. Stem density was reduced 



0) 



c 

 o 

 Q 



E 



c 

 c 



o 



3 



a> 

 QC 



c 



o 

 L_ 



0) 

 Q. 



100 

 80 H 

 60 

 40 ^ 

 20 

 



-20 

 -40-1 

 -60 



|1983 □1984 IOl986 i I 1991 



i 



Amitrole Picloram Glyphosate Triclopyr 2,4-D 2,4-D 



early late 



Rototilling Disc 

 chaining 



Cutting 



False Hellebore Treatment and Year 



Figure 1 — Percent reduction of false hellebore stem density from 1982 to 1983, 

 1984, 1986, and 1991 by treatment. 



3 



