G. POPULATION ECOLOGY 



1. BIOLOGICAL INTERACTIONS 



a. COMPETITION: In Montana Astragalus 



convallarius var. convallarius occurs in 

 various types of bunchgrass grasslands. 

 Although most Astragalus species are 

 intolerant of direct competition with other 

 herbs, and even more will not grow under the 

 shade cast by overhanging shrubs or trees 

 (Barneby 1964) , A. convallarius var. 

 convallarius may find openings between the 

 grasses to colonize. Competition by noxious 

 species is a threat in much of its potential 

 habitat. Around the South Hills of Helena, 

 large areas of potential habitat for this 

 species have been invaded by Linaria 

 dalmatica, rendering it unsuitable. Its 

 habitat is also potentially invaded by 

 Centaurea maculosa . The Helena National 

 Forest site was in an area which had burned 

 recently, and had 90% vegetative cover. 



b. HERBIVORY: Several species of Astragalus are 



known to be poisonous to livestock. The 



toxicity of A. convallarius var. convallarius 



is unknown. There are no reports of 

 herbivory . 



II. ASSESSMENT AND MANAGEMENT RECOMMENDATIONS 



A. THREATS TO CURRENTLY KNOWN POPULATIONS: No known threats 



are currently known for the Helena National Forest 

 population. However possible potential threats could 

 include overgrazing and mining. Although Astragalus 

 convallarius var. convallarius might not be a preferred 

 food plant, extremely heavy grazing might lead to a 

 decline in the population. Mining in the immediate 

 area of the site would severely impact the population. 



B. MANAGEMENT PRACTICES AND RESPONSE: Not known. 



C. RECOMMENDATIONS FOR MAINTAINING VIABLE POPULATIONS: 



Although Astragalus convallarius var. convallarius on 

 the Helena National Forest appears at present to be 

 self-maintaining, any change in management practices in 

 this area should be carefully evaluated to avoid or 

 minimize any harmful effects to A. convallarius var, 

 convallarius. 



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