Life History Characteristics and Survivorship of Erythronium Japonicum. The Productive and Reproductive Biology of Flowering Plants V.

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Abstract
The life cycle, energy allocation to reproduction and survivorship of a representative perennial herb of the temperate deciduous forests of Japan, E. japonicum Decne. (Liliaceae-Tulipaeae), were studied in natural populations in Yatsuo, Toyama Prefecture, Honshu. The size class structures of natural populations were studied. For each class, the seasonal growth cycle and dry matter allocation to component organs throughout a year, in relation to the transitions in light and temperature regimes on the forest floor, were critically analyzed. Also examined were the various aspects of sexual reproduction, e.g., number and fertility of male and female gametes, pollinators, breeding system, reproductive allocation (RA), propagule output and dispersal agents. Secondly, based on these data, survivorship and mortality factors for E. japonicum were also analyzed. E. japonicum possess the features typical of very stable, closed woodland elements, showing a rather low but constant reproductive capacity. The mean RA (%) to reproductive structures were as follows: 4.80 .+-. 1.18 (flower), 12.47 .+-. 3.07 (flower + scape), 5.00 .+-. 2.75 (seeds) and 10.87 .+-. 4.12 (seeds + capsule + scape). The mean seed output per plant was 21.92 .+-. 11.03. In both flowering and fruiting stages smaller individuals invested a higher portion of biomass to reproductive structures and propagules, with the rates of allocation much smaller in larger individuals. In response to the increase in the RA, the number of seeds produced per plant clearly increased. An approximate survivorship curve estimated for this species based on the size class structures of natural populations exhibited a distinctive pattern, which is similar to Deevy''s Type 1 with the change in slope occurring at the initial stages (from the 2nd to the 4th size-stages). Niche breadth of this species was also studied. The presence of a bright light environment for at least 1 mo. early spring (late March to late April) was a necessary conditon for the successful establishment of Erythronium population.