Measures of the Health of Rivers and Streams - Hydro-Environmental Analysis: Freshwater Environments - page 199

TABLE 7.3
Example Computation of Species Richness and Diversity

Community 1 Community 2 Community 3 Community 4

Species No. P No. P No. P No. P

Species A 96 0.96 20 0.2 81 0.81 5 0.05

Species B 1 0.01 20 0.2 1 0.01 5 0.05

Species C 1 0.01 20 0.2 1 0.01 5 0.05

Species D 1 0.01 20 0.2 1 0.01 5 0.05

Species E 1 0.01 20 0.2 1 0.01 5 0.05

Species F - - - - 1 0.01 5 0.05

Species G - - - - 1 0.01 5 0.05

Species H - - - - 1 0.01 5 0.05

Species I - - - - 1 0.01 5 0.05

Species J - - - - 1 0.01 5 0.05

Species K - - - - 1 0.01 5 0.05

Species L - - - - 1 0.01 5 0.05

Species M - - - - 1 0.01 5 0.05

Species N - - - - 1 0.01 5 0.05

Species O - - - - 1 0.01 5 0.05

Species P - - - - 1 0.01 5 0.05

Species Q - - - - 1 0.01 5 0.05

Species R - - - - 1 0.01 5 0.05

Species S - - - - 1 0.01 5 0.05

Species T - - - - 1 0.01 5 0.05

Sum 100 1 100 1 100 1 100 1

Total Species 5 5 5 5 20 20 20 20

Relative
Abundance, H

0.22 1.61 1.05 3.00

A variety of species can tolerate
conditions, but none dominate

Strong competitors
monopolize
resources

Only a few tolerant
species can survive
or recolonize

Frequency of disturbance

FIGURE 7.7 Intermediate disturbance hypothesis. (Redrawn from Connell, J.H., Science , 199, 1302-1310,

1978.)