Abstract
Through the evaluation of a detailed experimental description of the population biology of Gentianella praecox subsp. bohemica on four localities from the centre of the species area, we were able: (i) to examine the effects of different management regimes on the survival of the biennial G. praecox subsp. bohemica; (ii) to determine factors influencing the individual phases of the plant's life cycle; (iii) to quantify the size and germination of the plant's seed bank; (iv) to suggest appropriate management for the localities with G. praecox subsp. bohemica. Populations of G. praecox subsp. bohemica clearly show the best viability at the experimental sites managed by the combination of grass mowing and disturbance of vegetation by raking, lower viability at the sites managed by grass mowing only, and the worst viability on the control sites without any management.
Seedling emergence is proven to be the phase of the plant's life cycle most affected by the type of management. The first summer period of the biennial plant's life cycle, the seedlings at the experimental sites managed by mowing survive best; plants at sites managed by mowing and disturbances slightly worse and those on the control sites show the worst survival rate.
This trend could be affected by extreme conditions like the 2003 droughts in our case. There is evidence of a long-lasting viable seed bank of G. praecox subsp. bohemica.
Each year, the amount of viable seeds buried in the seed bank dropped by one half, however, we proved that the seeds are able to emerge even after eight years. Under optimal conditions (experimental site 15 x 15 cm, grass mowed and vegetation disturbed by raking before sowing) the mean number of seeds emerging during the first year is around 15.7%.
Among the rest of the seeds remaining in the seed bank, around 1.6% emerge over the next three years.