Reproductive strategies and liming responses in forest field-layer flora

Abstract: Liming increased species richness, in accordance with the species pool hypothesis, and number of plants of individual species in beech forest field-layer vegetation, by increasing establishment by seedlings and vegetative offspring. Turnover rates also increased, suggesting the explanatory value of the carousel model. Plant size, absolute measures of reproduction, and poportional measures of sexual (SRE) and vegetative (VRE) reproduction were unaffected by liming in the clonal, stoloniferous herb Lamiastrum galeobdolon. Absolute measures of sexual and vegetative reproduction were positively related to L. galeobdolon size, both in a population of unmanipulated plants growing on limed and unlimed plots, and in plants in which plant size was increased after flower buds were cut off. Neither SRE nor VRE showed any changes after flowering was prevented. Both measures were negatively related to plant size in the unmanipulated plants. Forest liming and wood-ash application seem to have positive rather than negative effects on the field-layer vegetation. When forest thinning occurs in limed areas the effects of liming on the field-layer vegetation are accelerated and possibly also magnified. Liming is not likely to restore forest ecosystems to a pre-acidified state, however, and liming could not be taken as an argument against decreasing acidifying emissions.