| Abstract: | The dispersal and spatial patterning of sweet briar (Rosa rubiginosa) by pied currawongs (Strepera graculina) and horses (Equus caballus) on the southern tablelands of New South Wales was investigated. These two vertebrate species eat the sweet briar fruits and disperse them in a viable condition. The spatial patterns of horse faeces and pied currawong pellets were shown to correspond to the patterns of sweet briar in paddocks which had one of these vertebrate species present. Paddocks with a history of horse grazing but with no large roosting trees had sweet briar populations which were distributed almost randomly; in paddocks never grazed by horses but with roosting trees there was a strong aggregation of sweet briar under trees. These spatial patterns were additive in paddocks with a history of both horse grazing and large trees. Such structuring of vegetation by vertebrates is discussed as an alternative hypothesis to be considered when interpreting ecological processes from spatial patterns. |
