55 



2. POPULATION SIZE AND CONDITION: Population sizes in the 

 study area ranged from tens () to ten thousands () ; two of 

 the three being very large. 



3. REPRODUCTIVE BIOLOGY: Unknown. 



POPULATION ECOLOGY 



1. BIOLOGICAL INTERACTIONS 



a. COMPETITION: Graceful arrowgrass 



b. HERBIVORY: The two largest populations are in areas grazed 

 by livestock. No signs of browse were observed. 



LAND OWNERSHIP: The ten known sites are evenly split between 

 public and private lands. Two of the three study area 

 populations are on BLM lands and the third is on State School 

 Lands. One of the largest populations is on the Pine Butte 

 Preserve owned by The Nature Conservancy. 



ASSESSMENT AND MANAGEMENT RECOMMENDATIONS 



1. THREATS TO CURRENTLY KNOWN POPULATIONS: The population 

 documented near Circle was in an abandoned oxbow of the . . 

 One end of the oxbow meander had been dredged apparently to 

 develop waterfowl habitat. The species is absent from this 

 segment. 



2. MANAGEMENT PRACTICES AND RESPONSE: There is no evidence to 

 suggest that the species decreases under grazing or its 

 indirect affects. 



J. SUMMARY: Graceful arrowgrass is no longer being tracked as a 

 Montana species of special concern, based on its wide 

 distribution, range of habitats, and low vulnerability. While it 

 is not common in the study area, it is recurrent, and locally 

 abundant in places. 



