EXTINCTION DYNAMICS, POPULATION-GROWTH AND SEED BANKS - AN EXAMPLE USING AN AGE-STRUCTURED ANNUAL

The goal of this paper is to test theoretical predictions about the ef fects of seed banks on population dynamics and extinction rates in var iable environments using simulations based on data from a natural popu lation of the winter annual Collinsia verna. In the simulations we var ied the frequency of demographically good and bad years and the autoco rrelation between conditions in consecutive years to examine the impac t of seed dormancy on population growth rate, extinction rate and time to extinction. The existence of a seed bank enhanced population growt h rates under all environmental regimes except when good years were ve ry frequent, but this enhancement was minimal. In addition, the presen ce of the seed bank decreased the likelihood of extinctions and increa sed the time to extinction. The time to extinction was longest when th e environmental conditions were most unpredictable.