Propagule pressure, not fire or cattle grazing, promotes invasion of buffel grass Cenchrus ciliaris

Fensham, Rod J., Donald, Sam and Dwyer, John M. (2013) Propagule pressure, not fire or cattle grazing, promotes invasion of buffel grass Cenchrus ciliaris. Journal of Applied Ecology, 50 1: 138-146. doi:10.1111/1365-2664.12009

Author Fensham, Rod J.
Donald, Sam
Dwyer, John M.
Title Propagule pressure, not fire or cattle grazing, promotes invasion of buffel grass Cenchrus ciliaris
Formatted title
Propagule pressure, not fire or cattle grazing, promotes invasion of buffel grass Cenchrus ciliaris
Journal name Journal of Applied Ecology   Check publisher's open access policy
ISSN 0021-8901
Publication date 2013-02
Year available 2012
Sub-type Article (original research)
DOI 10.1111/1365-2664.12009
Volume 50
Issue 1
Start page 138
End page 146
Total pages 9
Place of publication Oxford, United Kingdom
Publisher Wiley-Blackwell Publishing
Collection year 2013
Language eng
Formatted abstract
1. The invasion of exotic grasses into savannas is occurring globally. Despite threats to    
processes and biodiversity, few studies have investigated factors that facilitate invasion
2. The abundance of the exotic perennial Cenchrus ciliaris buffel grass was assessed across
woodland clearings at 46 sites in Queensland, Australia. The influence of fire and grazing on
the invasion success were also examined experimentally within 18 sampling stations (including
cattle grazed and ungrazed treatment pairs) with unburnt, low-intensity and high-intensity fire
3. Mixed-effects logistic regressions suggest that the probability of buffel grass occurring in
remnants was predominantly a function of the abundance of buffel grass in adjoining paddocks.
The abundance of buffel grass in remnants was greater where the boundaries with
clearings faced the prevailing wind adjacent to paddocks with high buffel grass abundance.
4. There was a significant positive association between buffel grass and tree canopies at
approximately half of the sites, and the strength of this association was positively related to the
amount of coarse sand in the surface soil. This association was interpreted as nutrient enrichment
from litter fall on sandy infertile soils being a requirement for invasion. The invasion of
buffel grass at the experimental site accelerated with above-average rainfall after a prolonged
drought, and invasion continued even after imposing all combinations of fire and grazing.
5. Cattle grazing modestly enhanced invasion, relative to the absence of grazing, but this difference
was only significant without burning. The occurrence of fire in both the survey and
experiment was not associated with enhanced buffel grass invasion.
6. Invasion of buffel grass may be inevitable over large areas of savanna, especially when
abundant rainfall follows periods of drought. However, invasion will be minimized in areas
where buffel grass has not been planted, areas without cattle grazing and in areas with low
soil fertility.
7. Synthesis and applications. The invasion of buffel grass accelerates during abundant rainfall
after drought and is enhanced by propagule pressure, dispersal trajectories and under trees,
probably as a result of nutrient enrichment. Disturbance had little influence on invasion, and
there is no support for fire-promoted invasion as predicted by the grass–fire cycle theory.
Keyword Cattle grazing
Exotic grass
Grass fire cycle
Wind dispersal
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Published online in December 2012

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2013 Collection
School of Biological Sciences Publications
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Citation counts: TR Web of Science Citation Count  Cited 12 times in Thomson Reuters Web of Science Article | Citations
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Created: Mon, 04 Mar 2013, 15:56:54 EST by Gail Walter on behalf of School of Biological Sciences