A comparative life history study of six species of Apiaceae of the eastern North American deciduous forests, with particular reference to biomass allocation.

摘要

Life cycles and biomass allocation were compared in three monocarpic and three polycarpic species of Apiaceae of the North American eastern deciduous forest. Sanicula canadensis is an obligate biennial and S. trifoliata a facultative biennial. Cryptotaenia canadensis is monocarpic and reproduces by both seeds and monocarpic ramets; seed-derived plants are biennials and ramet-derived plants annuals. Sanicula gregaria and T. barbinode reproduce by seeds and short rhizomes and O. claytonii by seeds only. Seed weight was positively correlated with seedling weight but not with potential to form a persistent soil seed bank.;Root:shoot biomass in the six species increased during the first growing season and decreased between the spring juvenile and flowering stages in the second growing season. At flowering, biomass allocation to roots was higher in the polycarpic (≥46%) than in the monocarpic (≤20%) species. Changes in biomass allocation between flowering and late-fruiting occurred only in above-ground structures in the monocarpic species but in both above- and below-ground structures in the polycarpic species. In both life-cycle types, biomass allocation during reproduction was constrained by ontogeny.;Life cycle phenology, sexual reproductive allocation (RA), sexual reproductive output (RO), and plant dry weight were compared for plants of each species grown under two light levels in a nontemperature-controlled greenhouse and the data compared to those from plants in natural populations. Regardless of growing conditions, RA was greater in monocarpic than in polycarpic species. In monocarpic species, RO was strongly correlated with vegetative dry weight, and larger plants had greater RO than smaller plants. The relationship between RO and vegetative dry weight was weaker for polycarpic than for monocarpic species. In the polycarpic species, variation in RO was a function of both plant size and RA. Greater mean total plant dry weight at late-fruiting resulted in greater RO for all six species.;Within these six ecologically and phylogenetically related species, biomass allocation differed both among species of Sanicula and among genera of Apiaceae. However, as the six species progressed from seedling to adult, the influence of ontogeny on biomass allocation rapidly became more apparent and that of phylogeny less apparent.