Question: How do the relative frequencies of plant traits (clonality, growth form, seed weight, diaspore morphology) vary during the life cycle and how does this affect regeneration?
Location: Alpine meadow and heath communities at Kilpisjärvi, sub-Arctic Finland.
Methods: Control plots and three treatments were used to measure relative species abundances for five life cycle stages: standing vegetation, seed rain, seed bank and seedlings emerging in gaps and in closed vegetation.
Results: The relative frequencies of plant traits varied between the life cycle stages. The meadows were dominated by weakly clonal herbs, small or intermediate seeds and unappendaged diaspores, while the heaths were dominated by clonal dwarf shrubs, small seeds and fleshy fruits. In the meadows, species with small seeds dominated during the seed rain and in the seedling stage in gaps, while species with intermediate seeds dominated the seed bank and the seedling stage in closed vegetation. Species with unappendaged diaspores dominated throughout the life cycle. In the heaths, seed bank and seedling stage were practically absent.
Conclusions: The observed differences in plant trait spectra between life cycle stages indicate that important environmental factors differ among the stages. Small seeds are advantageous for dispersal, whereas intermediate seeds have a greater probability of germinating and establishing in closed vegetation. Appendages facilitate dispersal, whereas unappendaged diaspores favour seed burial. Although the plant growth form spectrum largely reflects environmental constraints during the regeneration cycle, information on seed weight and diaspore morphology improves our knowledge of the relative importance of morphological adaptations of sexual structures in different stages during the life cycle.
Nomenclature: Hämet-Ahti et al. (1998).