Selective herbivory by mammals on 19 species planted at two densities

The impact of mammalian herbivory, particularly macropods, upon seedling establishment in a post-fire environment was studied experimentally at Whiteman Park Reserve, Perth, Western Australia. Nineteen plant species of contrasting morphology and chemistry were established at low and high densities in protective exclosures, and half of the plants later exposed to herbivores. After one year of exposure, 16 species showed evidence of greater mortality and/or reduced shoot mass due to mammal herbivory. Two species had reduced shoot mass at high density (competition) and two had the reverse (facilitation), both annulled in the presence of herbivores due to poor growth at both densities. There was no preference by herbivores for high over low density plots. A general preference (high percentage plants eaten, large difference between biomass inside and outside exclosures) for species high in K, N or P and leaf mass: area, and low in initial shoot mass, spinescence, moisture and height was evident from principal components and canonical variates analyses. Grass-like species were more vulnerable to herbivory than seedlings of shrubs.