from steep to moderate slopes, and at the junction of side 

 drainages enhances seasonal moisture, but the soils are 

 typically fairly dry. 



E. Population biology and biological interactions 



1. Population size and condition: Populations range in size 

 from 20 to app. 70 plants. Identification of individual 

 plants is difficult due to the loosely cespitose growth form. 

 Areas occupied are from 2 to 3 acres, but the plants are 

 concentrated in patches within this area, the largest patch 

 being about 15 x 20 m (16 x 22 yd) in size. 



2. Reproduction: Outcrossing by wind pollination is common 

 in the genus. Carex torrevi also reproduces vegetatively by 

 rootstock offshoots on the perimeter of cespitose clumps. 



3. Competition: Carex torrevi co-exists with the highly 

 competitive Poa pratensis at one locality, but it is not known 

 if the species is holding its own or if it is on the decline. 



4. Herbivory: In most sites, within pine forests, grazing 

 intensity is not high and does not affect the species. At the 

 subpopulation at Maverick Spring intensity is high, and Poa 

 pratensis and Cj. sprenqellii are heavily grazed, but C^ 

 torreyi was apparently avoided. Trampling of populations near 

 water sources is indirect impact. 



F. Assessment of management recommendations: Information is 

 incomplete for evaluating threats to and trends of Carex torreyi ; 

 therefore watch status is recommended at this time. Grazing has 

 probably decreased the Maverick Spring subpopulation, either 

 through direct impact, or more likely through enhancement of highly 

 competitive non-native grass cover. This subpopulation contains 

 only a couple of plants; the other subpopulations here are not 

 affected, and might be made site of monitoring studies if the 

 species becomes sensitive. 



The sites within the Long Pines were relatively untouched by the 

 1988 Brewer Fire, with possibly only light ground fires that did 

 not remove canopy cover. 



Probably the greatest potential threat to the species is logging, 

 which would stress its mesic environment and promote encroachment 

 of exotic species or native species that are better suited to 

 competition under altered conditions. It does not appear to be 

 present in the South Dakota units of the District, and may warrant 

 further consideration as a watch species based on limited numbers 

 and potential threats. 



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