Rough agalinis (Agalinis aspera) COSEWIC assessment and status report: chapter 8

Limiting Factors and Threats

Agalinis aspera requires habitats that are open and sunny, where competing plants are sparse. The plants seem to survive well along roadsides where the right combination of soil and sparse vegetation is present. They seem to be able to tolerate soil disturbance; in fact such disturbance may increase the chance of successful germination.

In Manitoba, human impact poses the greatest threat to these populations because most of them are in road allowance areas. Any major disturbance of the road allowance undertaken for road expansion, road straightening, etc., would put these populations at risk. Slight disturbance due to cattle tracks and moderate erosion is probably not a problem. Mowing may be useful to control competing species but should not be done during late summer when flowers and capsules are present. Extensive damage to the seed capsules was observed at Woodlands due to late-season mowing. The A. aspera plants were between 11 and 24 cm tall on August 28. The mowed specimens were still alive on September 10 but, although some capsules were still developing safely, many seed capsules had been destroyed by the mowing.

The impact of burning on this species is presently unknown, but it appears that the extensive burning undertaken at the Grosse Isle prairie has reduced the population of A. aspera there. Canne-Hilliker (2000) noted that “short plants that produce small seeds, such as Skinner’s agalinis, are known to be particularly susceptible to loss in fire-suppressed prairies.”

The impact of grazing is significant at the Poplar Point sites, and cooperation with range management personnel will be important in the prevention of overgrazing.

The population may be reaching a critical level below which the genetic diversity would be too low to ensure survival.

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