Dispersal potential in two restricted and five wide-ranging Senecio (Asteraceae) taxa from central eastern New South Wales, Australia

Abstract

Knowledge on how life history traits affect distribution in range-restricted and endemic plants is paramount for conservation and management, particularly for threatened species. Traits relating to dispersal ability are important in the ongoing persistence of range restricted species and may present a pathway to extinction or invasion. This is evident in the highly diverse and cosmopolitan genus Senecio (Asteraceae), where both threatened and invasive species occur within Australia. In this study, propagule geometry, settling velocity and dispersal potential for two range-restricted and threatened native taxa (S. linearifolious var. dangarensis Belcher ex I.Thomps., S. spathulatus var. attenuatus I.Thomps.) are contrasted with four native taxa that occupy wider ranges (S. amygdalifolius F.Muell., S. l. var. arachnoideus I.Thomps., S. l. var. macrodontus (DC.) I.Thomps., S. pinnatifolius A.Rich. var. pinnatifolius) and one introduced, wide-ranging species (S. madagascariensis Poir.). Differences were found in settling velocity and propagule morphology across all taxa. Based on propagule morphology, S. amygdalifolius has the greatest dispersal potential, S. spathulatus var. attenuatus the smallest, whereas all other taxa were similar. Although useful, dispersal potential alone does not fully explain distributional differences between all range-restricted and widespread taxa, and close assessment of habitat attributes may be required to further elucidate dispersal limitations in some taxa.