Influence of micro-organisms on the germination of the monocarpic Cirsium vulgare in relation to disturbance.

Cirsium vulgare is a plant species of disturbed sites. To understand this distribution the effect of micro-organisms on the germination in this species was investigated as the microflora of disturbed and non-disturbed sites shows differences. It was found that micro-organisms from fruitcoat and environment do influence germination. In an environment containing humus, germination is stimulated.Mortality of seedlings is higher in undisturbed sites, resulting in the observed distribution. It is hypothesized that this mortality is the result of germination, forced by microbial activity (break-down of the fruitcoat, exudation of growth-regulating substances) under conditions in which the survival chances of the seedling are low.