2.27.97
Dipersal
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Soil Seed Bank Notes
Seed bank ecological strategies and adaptations
A. Optimal dynamics of the seed bank
1. modelling the soil seed bank has revealed several important parameters
that affect the size of the seed bank (Cohen (1966) J Theor Biol 12:119):
a. S=number of seeds present
b. Y=number of seeds produced per germinating seedling
c. G=fraction of the total seeds present in the bank that germinate in each
year
d. D=fraction of the seed bank that decays each year
e. P=probability of successful reproduction
2. conclusions reached, ecological strategies of seeds indicated:
a. if there is a high probability (P=0.8) of successful reproduction (Y=500)
the optimal strategy is for a high fraction of the seeds to germinate each
year and the proportion decaying is almost irrelevant
b. if there is a high probability (P=0.8) of low reproduction (Y=5), the
rate of seed decay is irrelevant if there is dormancy
c. if there is a low probability of reproduction (P=0.1) (either at a high
[Y=500] or low [Y=5] rate) a high germination percentage, and a high decay
rate, is disastrous
d. the fraction of seeds that germinate (G) strongly correlated with fraction
of ungerminated seeds that decays (D)
e. the fraction that does not germinate in any given year (1 - G ?) correlated
with the probability of the germinating seed crop to have a total, or near
total, failure (P =/ 0)
