Shoot and leaf demography of Carex curvula ssp. Curvula and Carex curvula ssp. rosae in the Central Alps

Abstract. Populations of Carex curvula ssp. curvula, C. curvula ssp. rosae and their intermediate form were investigated in the Central Alps over a three-year period. The closely related taxa showed a different dominance behaviour in their respective communities. This may be caused by different growth strategies and a different reproduction biology. Therefore, the main aim of the study was to compare the demography of the three taxa. Shoot and leaf turnover, flower and seed production and population half-lives were determined. Differences in growth dynamics were less pronounced between the two species of Carex curvula than between these taxa and their intermediate form which showed the highest shoot turnover, highest number of fertile inflorescences and highest number of seeds per inflorescence. Carex curvula ssp. rosae showed a slightly higher shoot and leaf production but a lower reproduction capacity than Carex curvula ssp. curvula. Recruitment of populations of the three Carex-forms was only by vegetative shoots. Flowering had a striking effect on the shoot dynamics of the species grown in the grassland sites: up to about 70 % of all dead shoots could be identified as dead flowering shoots from the previous year. The different dominance behaviour of the three taxa could not be explained by their demographical features. Interspecific interactions and the occurrence of microniches might affect the growth and reproduction processes of the taxa.