EFFECTS OF REPRODUCTION AND ARTIFICIAL HERBIVORY ON VEGETATIVE GROWTHAND RESOURCE LEVELS IN DECIDUOUS AND EVERGREEN DWARF SHRUBS

Effects of reproduction (production of flowers and berries) and artifi cial herbivory of different phenological stages on deciduous bilberry (Vaccinium myrtillus L.) and evergreen lingonberry (Vaccinium vitis-id aea L.) were investigated to determine differences in allocation patte rns and recovery ability between these species. Vegetative growth and concentration of sugars, starch, and nitrogen were measured in ramets at the end of the growing season. Statistical comparisons were made be tween the treatments and damage times, but not between the species, as these were manipulated at different sites within the same forest. Rep roduction reduced the vegetative growth significantly in lingonberry, whereas the fertile bilberry ramets grew even more than the sterile on es. The bilberry produced new shoots as a response to simulated herbiv ory, which significantly decreased carbohydrate levels in tissues. The evergreen lingonberry produced less shoots, and carbohydrate levels i ncreased significantly. Nitrogen concentration either remained unchang ed or increased in both species. For both species, time of damage affe cted the carbon and nitrogen levels as well as the ability to regrow. The species have developed different strategies to overcome the costs of sexual reproduction and herbivory damage, apparently as a result of the different resource allocation patterns and different architectura l constraints for shoot development. The evergreen lingonberry grows s lowly and conserves resources, whereas the deciduous bilberry allocate s resources to increase the photosynthesizing biomass, which increases the potential of future survival, growth, and reproduction.