Structure, pattern, and diversity of a mallee community in New South Wales

Summary

An intensive sample of Australian mallee included a strip of 100 1 sq. m plots and counts of species numbers in expanding areas (1, 10, 100, and 1000 sq. m) to a full hectare. Reciprocal averaging (RA) produced an effective arrangement of the sq. m plots and their species along an axis of internal pattern from mallee patches to the openings between them. RA scores permitted definition of the patches and transitions and comparisons of relative difference between successive sq. m plots (mean RA score differences of 6.9 in the openings, 11.9 in mallee patches, and 14.7 in transitions). Pattern diversity, measured as degree of species turnover along the first RA axis, was 2.3 half-changes. Groups of species most characteristic of openings, transitions, and mallee patches could be recognized; but many species are of wide amplitude along the pattern axis, and neither RA nor association measurements showed distinct species groups separate from one another. The mallee sample is rich in species (mean of 53/0.1 ha, total of 101/ha) compared with North American samples; it is roughly similar to North American woodlands and shrublands in life-form spectrum but different in growth-form representation. Mean heights of species formed an apparent lognormal distribution with the concentration of species in the 0.2–0.4 m oetave. Species numbers in relation to areas (A, in sq. m), traced from 1 sq. mm to 10⁵ sq. m, were reasonably fitted by either S=5.33 + 15.28 log A or S=8.22A ^0.29 at intermediate quadrat sizes (1–1000 sq. m) but not at smaller sizes. The ten replicate 0.1 ha samples gave coefficients of variation of 7% for species numbers and 9–10% for the regression coefficients (except b=5.33 with a CV of 43%).