Introduction

Vegetation remnants in the eastern Darling Downs are highly fragmented and greatly reduced in size. Since 1975 there has been up to a 60% reduction in native vegetation in the region. Little is known about habitat quality and condition of remnant and re-growth vegetation, including endangered ecosystems such as bluegrass grasslands & semi-evergreen vine thickets.

The objective of this research was to compare plant species richness, condition and habitat complexity in remnant vegetation in the study area.

Results & Discussion

• richness =31-83 spp./500m2; habitat complexity = 6-17; condition = 23-31.

• significant patterns in species richness, complexity and condition across vegetation types (Fig. 2).

• grasslands - low complexity, fewer species, high condition.

• Mt Coolibah & Ironbark/Mt Coolibah woodlands - low condition, intermediate richness and complexity.

• richness-complexity strongly correlated (RS= 0.54 P<0.001); richness-condition poorly related (RS= -0. 20 P>0.05).

References

1. Newsome A.E., & Catling P.C. (1979) Habitat preferences of mammals inhabiting heathlands of warm temperate coastal, montane and alpine regions of southeastern Australia. In ‘Ecosystems of the World. Vol. 9A. Heathlands and Related Shrublands of the World’. (Ed. R.L. Specht.) Elsevier, Amsterdam.

2. Ludwig J.A. & Tongway D.J. (1997) A Landscape approach to Rangeland Ecology, In 'Landscape Ecology Function and Management: Principles from Australia's Rangelands.' ( Eds J. Ludwig, D. Tongway, D. Freudenberger, J.C. Noble & K. Hodgkinson) CSIRO, Melbourne.

3. Parkes D., Newell G. & Cheal D. (2003) Assessing the quality of native vegetation: the 'habitat hectares' approach. Ecological Management & Restoration 4: 529-538.

Conclusions

There is a need for simple, robust and meaningful on-ground indicators of the impacts of human activities in remnants.

Methods for habitat complexity have been developed for some time and have been rigorously tested over a range of ecosystems.

However, the notion of habitat condition remains rather vague and largely untested. This is despite a growing acceptance of this attribute as a decision tool by land managers.

Clearly, further development of methods for the accurate quantification of condition is necessary.

Richness, complexity & condition of remnants in the eastern Darling Downs, Queensland Andy Le Brocque, Charlie Zammit & Kate Reardon-Smith Land Use Research Centre, University of Southern Queensland, Toowoomba, Qld email: landuse@usq.edu.au Andy Charlie Kate

www.usq.edu.au/lurc

Methods

• 43 sites were sampled across 11 vegetation types in the study area in southern Queensland (Fig. 1).

• Plant species richness was determined in a single 500 m2 quadrat at each site.

• Habitat complexity1 was derived from vegetation structure (FPC of strata, cover of litter, logs etc) and other biophysical attributes (e.g. hollows, stags etc).

• A measure of vegetation condition was derived from the summation of scores for range of attributes (Table 1).

• One-way anova compared attributes across vegetation types; Spearman Rank correlations examined relationships between attributes.

While species richness alone is not a definitive attribute of vegetation, current theory would suggest that richness would be related to condition.

Table 1: Components of Condition Index

Figure 2: Comparison of Species Richness, Habitat Complexity and Condition across vegetation types

Figure 1: Map of north eastern Murray-Darling Basin showing location of study area

Acknowledgements

This project is part of the Land Use Change Project by the Land Use Research Centre and supported by a USQ Project Team Research grant. We thank the many landowners in the eastern Darling Downs for allowing access to properties. Further information: landuse@usq.edu.au

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