Studies on the Population Biology of the Genus Viola: III. The Demography of Viola Blanda and Viola Pallens

Abstract

All ramets 1 yr or older of V. blanda and V. pallens were enumerated at regular intervals for up to 4 yr in 2 New England [USA] forest sites. Each seedling was similarly enumerated and each leaf and reproductive structure in 20 plants was marked and their fate recorded at weekly intervals. Calculations were made of population flux, age distribution, survival and life expectancy for ramets 1 yr or older and for seedlings. At 1 site, fluctuation in population size was small compared with the large number of individual ramets gained and lost but at the other site the population declined and eventually disappeared. On average individual ramets lived for 4 1/2 yr. The rate of seed production and the probability that a ramet will survive is a function of ramet size.