Buffel grass (Cenchrus ciliaris) eradication in arid central Australia enhances native plant diversity and increases seed resources for granivores

Abstract

<p><b>Questions:</b> Buffel grass (<i>Cenchrus ciliaris</i> L.) is a drought-adapted invasive plant that has become a serious environmental weed in many arid and semi-arid systems. This paper examined whether eradication of buffel grass infestations: (i) increases frequency, richness and diversity of native vegetation and seed bank pools; and (ii) improves availability of seed resources for granivores.<br/><b>Location:</b> Alluvial ironwood/corkwood woodlands in arid central Australia.</br><br/><b>Methods: </b> We assessed differences in floristic and seed bank composition between buffel-infested sites and sites where buffel grass had been eradicated ca. 12 years previously. Plant species frequency data from nested-quadrat sampling were amalgamated into plant functional groups to examine their relationship to buffel treatment. A seed flotation method was employed to: (i) assess seed bank composition of functional groups at eradicated vs. infested sites; and (ii) test whether the mass of seeds available for granivores was higher at buffel-free sites.</br><br/><b>Results:</b> Buffel-eradicated sites supported richer and more diverse vegetation and seed banks across all functional groups except perennial grasses. The effect was strongest for perennial forbs, annual/short-lived forbs, and annual/short-lived grasses. The overall mass of seeds of non-buffel grass species was ca. 10-fold higher at buffel-removed sites. Numbers of seeds of species in the 0.001-0.009 9 g and 0.000 1-0.000 99 g size classes, both of which contain species with seeds consumed by granivores, were ca. 20- and 14-fold higher respectively at buffel-removed sites.</br><br/><b>Conclusions:</b> Buffel grass removal at localised scales provides islands of habitat with improved opportunities for native plant re-establishment and abundant foraging resources for granivores. Future research must disentangle the relative importance of dispersal vs. residual seed banks for community restoration after buffel grass invasion. Extended delays in eradication could allow seed bank reserves to deteriorate to a state that no longer permits regeneration.</br></p>