Life Histories in Clonal Plants of the Carex Flava Group

SUMMARY (1) Life histories of genets and modules were compared in several taxa in the Carex flava group. Demographic data were obtained from plants grown under controlled conditions and from natural populations in Switzerland. (2) Seeds of all studied taxa have an innate dormancy of about 9 months during which lipids are converted to starch. Germination requires varying temperatures. (3) Seedlings rarely become adults but are long-lived with Deevey type I survivorship curves. Seedlings grown in cultivation show high within-species competition. Carex viridula ssp. viridula seedlings survive at higher density and mature more quickly than C. flava seedlings. (4) Clones of C. flava develop less rapidly but form older and bigger tussocks than clones of C. viridula ssp. viridula. Size and density of tiller populations with time are highly variable in C. viridula ssp. viridula and less variable in C.flava. (5) Most emerging tillers become adult, fruit in their first or second year, and die thereafter. Carex viridula ssp. oedocarpa and C. viridula ssp. viridula have a shorter tiller life-span than C. flava and C. viridula ssp. brachyrrhyncha and their populations produce more than one complete tiller generation per year. (6) Seed set is high (c. 90%) due to self-compatibility. the C. flava group, C. viridula ssp. viridula populations have the highest seed output. Post-floral growth of the stem in C.flava (var.flava) and C. viridula ssp. brachyrrhyncha enables plants to deposit their seeds outside the tussock. Carex viridula ssp. viridula is probably a dispersal generalist. (7) The life cycles of genets and tillers of the different taxa within the C.flava group are compared. They are placed along the r-K-continuum in the order C. viridula ssp. viridula, C. viridula ssp. oedocarpa, C. viridula ssp. brachyrrhyncha, C. flava. Similar trends in life-history patterns are found at both the genet and the tiller level.