Density-dependence in a population of Fucus distichus

Regulation of a Fucus djstichus L. emend.Powell population is probably mediated through a density-dependent mortality of the recruits.Blocks seeded with different densities of germlings of E distichusand cleared plots with naturally occurring recruits of different densities and with artificially thinned densities were used to monitor the effect of density on mortality and growth among recruits in a populat~on of F: distjchus in False Creek.Vancouver, British Columbia.Canada.In the first 2 mo of development, germlings on the high density blocks experienced a lower mortality than those on the low density blocks.At later stages (> 2 mo), the effect of density on mortality was reversed.Plants recruited into the cleared plots were > 1 mm in length and they also experienced a positive effect of density on mortality.In both the density blocks and cleared plots, plant mortality eventually became independent of plant density.Plant growth rate was generally not related to density but was related to plant size (length).There was a large variation in the sizes of the plants.All 3 measures of si7c inequality: zero-centered skewness, coefficient of variation, and Gini coefficient are significantly correlated.Plants in both the density blocks and cleared plots showed a slight tendency towards a more normal or positively skewed size distribution from fall 1986 to spring 1987, probably due to an increased mortality of the smaller plants during this time.The mechanism of dominance-suppression and difference in the intrinsic growth rate or timing of settlement probably all contributed to the inequality in size distribution.