Tropical Forest Community Ecology

Testing Explanations for Species Diversity using FDPs 105

?

3 2 1

(a)

(b)

Veil line

?

Pasoh

0

20

40

60

80

100

120

140

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Log 2 abundance class

No. of species

Figure 7.2 (a) Disagreements over the shape of the distribution of relative species abundances in communities
resulted, in part, from the inability to sample the rarest species. As sample size increases, the “veil line” moves to the
left, and questions (“?”) are eliminated regarding the shape of the distributions of relative species abundances. Going
from (1) to (2) the logseries distribution (Fisheret al. 1943) is distinguished from a lognormal distribution (Preston
1948, 1962), by including a mode. Then, finally, including the left-hand tail, (3) indicates that the distribution is
asymmetrical, as suggested by the zero-sum multinomial distribution of Hubbell (2001). (b) Example of distribution
of species relative abundances from the plot at Pasoh (Manokaranet al. 1992).