Payson sedge Carex paysonis, dominant in many alpine communities of western USA, is a pioneer coloniser of bare, high altitude, acidic mine spoil. Its strong rhizomatous growth offers potential for revegetating such disturbed rangelands where few other species appear to be able to initially colonise. However, seeding field trials have had poor success with few seedlings observed, suggesting low germination success. Laboratory studies were undertaken to determine germination requirements using seed collected from the McLaren Mine, a disturbed subalpine site (2,950 m elevation) in the Beartooth Mountains about 8 km north of Cooke City, Montana.
Seeds were collected in August 1981 and air dried. About two-thirds of the seeds were either empty or immature. Only ‘filled’ seeds (from which the perigynium was removed) were used in the germination trials.
Treatments (200 seeds each) comprised combinations of: exposure to light vs. darkness flowed by light; temperature constant (25ºC) vs. variable (25/3ºC day/night); and seeds planted on the soil surface vs.buried.
Germination counts were made weekly over 8 weeks. Germination was deemed to have occurred when the cotyledon or radicle had emerged for seeds sown on the soil surface, or when the cotyledon became visible above the surface in buried seed treatments.
Highest germination (average 28.8%) was observed under conditions of darkness followed by exposure to light at variable temperatures. Germination levels were similar under light with variable temperature (21.3%), and darkness followed by light at constant temperature (22.8%). Germination was low (average 10.0%) under light at constant temperature and seeds in darkness at constant temperature (average 1.2%). Germination was low (equal to or less than 2.8%) from buried seeds exposed to both light conditions and both temperature regimes.
Therefore, a requirement for light coupled with low germination levels of buried seeds suggests that currently used Payson sedge seeding techniques (seeds buried), may be inappropriate. The authors recommended autumn surface seeding so that periods of snow cover (low temperature) will promote germination the following spring.
If using or referring to this published study, please read and quote the original paper, this can be viewed at: https://www.uair.arizona.edu/holdings/journal/issue?r=http://jrm.library.arizona.edu/Volume40/Number2/