A life history of Carex lasiocarpa Ehrh. ramets

Temporal properties of the ramet dynamics of Carex lasiocarpa Ehrh. were studied for 2 years in permanent quadrats established in a fen in south-central New York State, U.S.A. Individual shoots were marked at time of emergence and their height and condition monitored at 2–4-week intervals until death. Shoot flux was high, with shoots emerging and dying throughout the growing season. The timing of births and deaths was not synchronized and patterns of births and deaths varied between the 2 years. Shoot density was highest in October and lowest in late autumn and early spring of both years. Only 1% of the shoots flowered. A large proportion of the annual populations of ramets overwintered and completed their life cycles the following year. The proportion of overwintering shoots in a cohort had a marked effect on patterns of longevity observed among cohorts, cohort survivorship curves and population structure. We develop the concept of effective life span to compare cohorts emerging at different times of the year.