Shoot demography in new England populations of Maianthemum canadense desf

The demography of shoots of eight populations of a herbaceous perennial exhibiting clonal growth, is presented. The study was done along an elevational gradient, from a more open secondary mixed forest to a denser, more mature stand. Most shoots lived one to three years on the average, but shoots as old as twelve years were found. Large variation in formation and mortality of shoots was observed among plots and years. Yearly trends in the mortality rates of site replicates showed a higher correlation than rates of shoot formation. Although the density of shoots was highest in the drier sites, the turnover of shoots was highly variable and apparently uncorrelated with site location. Age structures revealed a tendency of longer-lived and higher reproductive activities among shoots from more mesic sites. It is hypothesized that environmental rather than density controls are primary causes of the population dynamics observed in this species.