ridge slopes. The largest populations observed occur in the 

 latter situation. 



E. Population biology and biological interactions 



1. Population size and condition: Populations are generally 

 small and highly localized. Most consist of one to six 

 clumps, a few range from 20 to 50 or 60. The largest 

 populations generally occur within areas of sparser 

 vegetation. The plants usually occupy an area of less than an 

 acre. The plants appeared healthy, even vigorous in some 

 locals. It is probable that more individuals are present in 

 the area around the extreme small populations of one or two 

 plants observed at some sites. 



2. Reproduction: Expansion of the populations are by seed, 

 while the clumps can expand vegetatively by new basal shoots. 

 Members of this genus have two seed crops each year, produced 

 from early-season monoecious outcrossing flowers that do not 

 consistently produce seed, and from cleistogamous late-season 

 flowers that regularly produce seed. 



3. Competition: Its presence in bluegrass pasture indicates 

 some ability to survive competition from shorter grasses. It 

 occurs with Andropoqon scoparius only sparingly, and within 

 areas opened by grazing. Two of the larger populations exist 

 on sparsely vegetated sandy or rocky, gravelly slopes, 

 indicating a colonizer status for the species. Some 

 populations are within areas heavily burned by the 1988 Brewer 

 Fire in the Long Pines, and locally common. 



4. Herbivory: No signs of grazing were found. The habit of 

 short, sharp, pubescent leaves and short stature limit its 

 use. Moderate grazing on some sites has decreased taller 

 grass cover and may have enhanced the population of 

 Dichanthelium through restriction competition and in opening 

 up areas of soil for colonization. On the other hand, several 

 of the smallest populations occur in heavily grazed bluegrass 

 pasture, suggesting that replacement of native grasses by the 

 sod-forming Poa pratensis may limit the populations through 

 competition, rather than direct grazing. 



F. Assessment and management recommendations: The number of 

 populations and the neutral or positive response to disturbance 

 provides the basis for recommending that it be deleted from further 

 consideration by the U.S. Forest Service and by the Montana Natural 

 Heritage Program. 



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