The ecological consequences of Buffel Grass Cenchrus ciliaris establishment within remnant vegetation of Queensland

Abstract

The effects of Buffel Grass Cenchrus ciliaris presence and dominance in 78 Poplar Box Eucalyptus populnea woodland remnants of south central Queensland are documented, Buffel Grass was recorded from the majority of sites sampled, As the relative cover of Buffel Grass increased at both the quadrat and site level, the number of native ground cover species declined significantly. Most commonly recorded ground cover species displayed significant changes in frequency as Buffel Grass cover increased, Only two species increased with increased Buffel Grass cover: Desert Goosefoot Chenopodium desertorum subsp. anidiophyllum and Galvanised Burr Sclerolaena birchii. The average cover of Buffel Grass decreased significantly from the edge of remnants towards the core areas. The foliage projected cover of the sub-canopy layers appeared to be an important factor affecting the relative cover of Buffel Grass at any one site indicating that shading and competition with the woody layers are important determinants in the structure and composition of the ground cover layer. A number of sub-canopy species were found to produce leachates that were capable of significantly reducing the germination or growth of Buffel Grass seeds, alluding that allelopathy may play a minor role in determining ground cover species assemblages. However, this result can only be interpreted conservatively in relation to its ecological relevance with effects related to competition with overstorey woody species being of greater importance. This study quantifies the long observed effect that the exotic perennial Buffel Grass excludes other ground cover species, which may have detrimental ramifications on the functioning of remnant native vegetation over much of the state. With the recent introduction of regulations controlling broad scale tree clearing on both freehold and leasehold lands in Queensland, it is now important to identify a range of issues pertaining to the effective on ground management of remnant vegetation located outside the existing nature refuge network.