34.2 percent in 1983, 22.1 percent in 1984, 19.5 per- 

 cent in 1986, and 46 percent in 1991 (fig. 1). 



Glyphosate: False hellebore stem density averaged 

 14.8/m^ before treatment. Stem density was reduced 

 55.8 percent in 1983, 73.2 percent in 1984, 62.3 per- 

 cent in 1986, and 28.5 percent in 1991 (fig. 1). 



Triclopyr: False hellebore stem density averaged 

 22.3/m^ before treatment. Stem density was reduced 

 45.4 percent in 1983, 63.8 percent in 1984, 40.6 per- 

 cent in 1986, and 26.0 percent in 1991 (fig. 1). 



2,4-D early: The 1991 data indicated a 37 percent 

 reduction in estimated pretreatment false hellebore 

 stem density (fig. 1). 



2,4-D late: The 1991 data indicated a 25.5 percent 

 reduction in estimated pretreatment stem density 

 (fig. 1). 



Mechanical Treatments 



Hand cutting: False hellebore stem density averaged 

 14.2/m^ before treatment. Stem density was reduced 

 19.7 percent in 1983, 27.3 percent in 1984, 21.2 per- 

 cent in 1986, and increased 43 percent in 1991 (fig. 1). 

 The overall average height of false hellebore plants in 

 this study plot in 1991 was less than that of the initial 

 population. Before treatment, stem heights averaged 

 between 75 and 100 cm; 1 year after treatment, stem 

 heights averaged only 35 to 50 cm. No flowers were 

 produced the year after treatment, but about 50 per- 

 cent of the plants produced flowers the second year 

 after treatment. Four years after cutting, the average 

 plant height was between 50 and 75 cm (plants inside 

 the plot were noticeably shorter than those outside). 



RototilHng: False hellebore stem density averaged 

 21.7/m^ before treatment. Stem density was reduced 



79.2 percent in 1983, 78.2 percent in 1984, 73.3 per- 

 cent in 1986, and 87 percent in 1991 (fig. 1). 



Disc chaining: The 1991 data indicated a 48 percent 

 reduction in false hellebore pretreatment stem densi- 

 ties as estimated fi-om composite baseline stem den- 

 sity (fig. 1). 



By 1991 all treatments were statistically more effec- 

 tive than the hand cutting, the herbicides were not 

 significantly diffierent from each other, and the roto- 

 tilhng was significantly more effective than all other 

 treatments except for disc chaining and picloram 

 (p < 0.001). 



Community Response Based on Nested 

 Frequency and Species Richness 



For the majority of the treatments (2,4-D early, 2,4-D 

 late, amitrole, triclopyr, glyphosate, and hand cutting) 

 the community response was similar. The pattern 

 seemed to be a high score for desirable species, an in- 

 termediate to high score for intermediate species, and 

 a low score for less desirable species (table 3; fig. 2). 

 The picloram treatment had the highest score for de- 

 sirable species and low scores for intermediate and 

 less desirable species. The rototill treatment had a 

 low score for desirable species, a relatively high score 

 for intermediate species, and an intermediate score 

 for less desirable species. The disc chain treatment 

 had an intermediate score for desirable species, a low 

 score for intermediate species, and an intermediate 

 score for less desirable species. 



Species richness (nvunber of species occurring in 

 the treatment) was lowest in the 2,4-D and rototill 

 treatments and highest in the triclopyr treatment 

 (table 3). 



Table 3 — Cumulative nested frequency scores, stem density reduction, and species richness for the early 1980's 

 false hellebore treatments in Boulger Canyon. Values preceded by the same letter are not significantly 

 different within a row; values followed by the same letter are not significantly different within a column 



Cumulative nested frequency scores 

 for recovered community 









Less 



Percent stem 



Species 



Treatment 



Desirable 



Intermediate 



desirable 



reduction 



richness 



Amitrole 



a 38.0 c 



ab 24.3 bed 



b 10.3 a 



32.5 b 



15.8 abc 



Picloram 



a 42.0 c 



b 14.5 ab 



b 12.5 a 



46.0 be 



15.0 abc 



Glyphosate 



a 39.5 c 



b 22.0 be 



b 10.0 a 



28.5 b 



14.3 abc 



Triclopyr 



a 34.0 be 



a 29.3 cd 



b 16.0 ab 



26.0 b 



17.0 e 



2,4-D early 



a 33.3 be 



b 23.0 be 



c 11.3 a 



37.0 b 



14.0 ab 



2,4-D late 



a 26.0 ab 



ab 20.5 abc 



b 13.3 a 



25.5 b 



13.0 a 



Cutting 



a 32.5 be 



ab 22.5 be 



b 12.0 a 



-43.0 a 



16.0 be 



Rototilling 



a 15.5 a 



b 33.3 d 



ab 24.0 e 



87.0 e 



13.0 a 



Disc chaining 



a 21.0 a 



a 12.0 a 



a 22.8 be 



48.0 be 



15.8 abe 



4 



