The number (S_n) and weight (Sw) of seeds produced by plants of successional dominants were studied. The relationships between S_n and plant height (H cm), diameter at stem base of plant (D cm) and their derivates (DH and D^2H) were described by the power function S_n=gX^n (X=D, H, DH or D^2H) for each species, except Miscanthus sinensis. The relationship between Sw and X was obtained by multiplying S_n by the seed weight of each species. The constants g and h in the equation of S_n=g (DH)^n were as follows : 4.76 and 1.69 for Polygonum persicaria, 1.38 and 1.78 for Chenopodium albunm (dominants of summer annual stage), 327.0 and 1.11 for Erigeron annuus, 706.3 and 1.11 for E. canadensis and 32.96 and 1.47 for Oenothera parviflora (dominants of winter annual stage), 1.21 and 2.02 for Artemisia princeps (dominant of perennial herb stage). The pioneer species produced a relatively small number of heavy seeds. Whereas dominants of the winter annual stage produced a vast number of light anemochore seeds. Total seed number m^<-2> produced by the stands were 144,222 for P. persicaria, 2,744,010 for E. annuus and 223,408 for A. princeps-Oe. parviflora. The weight of seed biomass to total biomass of the stands decreased from pioneer to final stages of succession of herbaceous communities. The seed production is discussed in relation to the type of life history of each species.
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