Perennial Primula Veris Research Articles

Immediate and lag effects of hydrological change on floodplain grassland plants

Hydrological alteration due to climate change events such as floods and drought is a significant threat to globally important wetlands, including floodplain wet grasslands. This research incorporated two field experiments with the aim to assess immediate and longer-term functional responses of floodplain plants to hydrological change. Plant introductions and transplants between a wetter riparian and a drier site in southern England were used to simulate hydrological change. Species showed immediate and differential responses to contrasting hydrologies. Rhinanthus minor, a hemi-parasitic annual species with ruderal traits, was lost from the riparian grassland within four weeks. The survival and production of a leguminous perennial, Lathyrus pratensis, in high groundwater levels soon decreased. However, the perennial Primula veris mostly functioned well in contrasting hydrological regimes, possibly because it can tolerate stress. The perennial wetland species Caltha palustris showed lag effects, over three years, when its hydrology was altered to a sub-optimal drier scenario by transplantation, with declining survival and a sustained reduction in leaf production and flowering. Disturbance caused by transplantation and weather conditions also affected its performance. Thus, this study shows that some functionally important floodplain species may succumb within weeks to a hydrological event facilitated by climate change, unless they are able to tolerate the challenging conditions, while the performance of other characteristic species could decline and continue to show constrained performance for years as a consequence of altered hydrology.

Rapid response to habitat restoration by the perennial Primula veris as revealed by demographic monitoring

The demography of Primula veris, a typical species of the species-rich Mesobromion grasslands, was investigated at two contrasting habitats in Eastern Belgium. Both a forested site and a clear-cut parcel were part of formerly larger calcareous grassland areas. By monitoring the demographic response of the target species, this study attempts to clarify the differences in fecundity, growth and survival between a restored and degraded calcareous grassland site. A study of plant traits showed a decrease in number of flowers, inflorescence stalks and plant size under a closing tree canopy. We surveyed individuals in permanent plots between 1999 and 2001. At the forested site, a first sign of decline included lower proportions of flowering individuals and afterwards an increase in mortality was found. Alternatively, removing canopy resulted in an immediate flowering response and both increased growth and seedling recruitment the year after. At both sites, survival rates strongly depended on the initial state, location and year. Projection matrix analysis revealed large differences in modelled population growth rates between sites and years. Under closing canopy the species showed only slow population decline, but the decrease was larger in the last survey year when higher mortality affected the number of reproductive individuals. Transitions between stages with the highest impact on population growth rate were identified by elasticity analysis. If calcareous grassland is forested, survival of reproductive adults is predicted to be very important for conservation of P. veris populations. However, seedling recruitment needs to be raised to guarantee long-term persistence of the populations. On the other hand, clear-felling of a site for restoration of species-rich calcareous grasslands may result in a rapid recovery of certain species.