The terrestrial vertebrate fauna of Litchfield National Park, Northern Territory: monitoring over a 6-year period and response to fire history
J. C. Z. Woinarski A , M. Armstrong A , O. Price A , J. McCartney B , A. D. Griffiths C and A. Fisher AA Biodiversity Unit, Department of Infrastructure Planning and Environment, PO Box 496, Palmerston, NT 0831, Australia.
B Litchfield National Park, Batchelor, NT 0845, Australia.
C Key Centre for Tropical Wildlife Management, Charles Darwin University, Darwin, NT 0909, Australia.
Wildlife Research 31(6) 587-596 https://doi.org/10.1071/WR03077
Submitted: 25 August 2003 Accepted: 9 July 2004 Published: 23 December 2004
Abstract
Forty-seven 50 m × 50 m quadrats were sampled systematically for vertebrates at Litchfield National Park, northern Australia, in both 1995–96 and 2001–02. A total of 184 vertebrate species was recorded from this sampling, of which 92 species were recorded from five or more quadrats. There was substantial change in the reported species composition of these quadrats between these two periods: the mean Bray–Curtis index for similarity in species composition from the baseline to subsequent sampling of a quadrat was only 22.1 (for an index that varies from 0 for complete turnover in species to 100 for unchanged composition). For individual species, correlations across quadrats in the abundance scores from baseline to resampling varied from –0.12 to 0.85. Matched-pairs testing showed that there was significant change in abundance for 18 species from the baseline to repeat sampling, and significant increase in total bird species richness and total native mammal abundance, but significant decrease in reptile species richness.
Fire history was recorded biannually for 40 of the 47 quadrats. Fire was very frequent, with quadrats being burnt in an average of 3.65 years of the six years between fauna samples. Three aspects of this fire history (total number of years of fires, number of fires in the late dry season, and interval from the last fire to the date of resampling) were related to change in the fauna composition of quadrats. Neither the similarity in species composition, nor change in richness or total abundance of all vertebrates or of the four taxonomic classes considered (frogs, reptiles, birds and mammals) were significantly correlated with these components of the fire history of sampled quadrats. This lack of association was possibly because the monitoring period was too short to show pronounced directional change, because the system was responding to many factors other than fire, because the variations in abundance were too large and the number of samples too small to detect true associations, or because fire histories preceding baseline sampling were not considered.
The apparent instability of fauna species and communities in this system provides a considerable challenge for broad-brush (that is, vertebrate community–wide) monitoring. Power analysis demonstrated that, for most species, more than 1000 sample sites are needed to be 90% certain of detecting a 20% change in abundance, and with a 10% chance of accepting a Type I error. This level of sampling effort is commensurate with the current level of vertebrate sampling in this region. Broad-brush monitoring approaches such as described here are valuable, but need also to be complemented by more targetted monitoring for individual threatened species or species of particular management interest.
Acknowledgments
We thank the Tropical Savannas Cooperative Research Centre for some support in this study. For assistance with fieldwork, we thank Paul Horner, Damian Milne, Louise Kean, Cameron Sharpe, Phil Wise, Matt Connelly, Philip Goodman, Paul O’Leary, Darren Schunke, Michael Horton, Rebecca Hermel, Katrina McMahon, Noel Hogan and Margaret Fuller. Fire-history mapping and reporting was provided by Andrew Edwards. We thank Mark Burgman and an anonymous referee for especially helpful feedback on an earlier draft.
Barnard, C. A. (1925). A review of the bird life on Coomooboolaroo Station, Duaringa district, Queensland, during the past fifty years. Emu 24, 252–265.
Braithwaite, R. W. , and Muller, W. J. (1997). Rainfall, groundwater and refuges: predicting extinctions of Australian tropical mammal species. Australian Journal of Ecology 22, 57–67.
Cabin, R. J. , and Mitchell, R. J. (2000). To Bonferroni or not to Bonferroni: when and how are the questions. Bulletin of the Ecological Society of America 81, 246–248.
Clarke, R. H. , Oliver, D. L. , Boulton, R. L. , Casey, P. , and Clarke, M. F. (2003). Assessing programs for monitoring threatened species – a tale of three honeyeaters (Meliphagidae). Wildlife Research 30, 427–435.
| Crossref | GoogleScholarGoogle Scholar |
Edwards, A. , Hauser, P. , Anderson, M. , McCartney, J. , Armstrong, M. , Thackway, R. , Allan, G. E. , Hempel, C. , and Russell-Smith, J. (2001). A tale of two parks: contemporary fire regimes of Litchfield and Nitmiluk National Parks, monsoonal northern Australia. International Journal of Wildland Fire 10, 79–89.
| Crossref | GoogleScholarGoogle Scholar |
Fairweather, P. G. (1991). Statistical power and design requirements for environmental monitoring. Australian Journal of Marine and Freshwater Research 42, 555–567.
Kerle, J. A. (1985). Habitat preference and diet of the northern brushtail possum Trichosurus arnhemensis in the Alligator Rivers Region, N.T. Proceedings of the Ecological Society of Australia 13, 161–176.
Osenberg, C. W. , Schmitt, R. J. , Holbrook, S. J. , Abu-Saba, K. F. , and Flegal, A. R. (1994). Detection of environmental impacts: natural variability, effect size and power analysis. Ecological Applications 4, 16–30.
Woinarski, J. C. Z. (1990). Effects of fire on bird communities of tropical woodlands and open forests in northern Australia. Australian Journal of Ecology 15, 1–22.
Woinarski, J. C. Z. , and Catterall, C. P. (2004). Historical changes in the bird fauna at Coomooboolaroo, northeastern Australia, from the early years of pastoral settlement (1873) to 1999. Biological Conservation 116, 379–401.
| Crossref | GoogleScholarGoogle Scholar |
Woinarski, J. C. Z. , and Tidemann, S. C. (1991). The bird fauna of a deciduous woodland in the wet–dry tropics of northern Australia. Wildlife Research 18, 479–500.
Woinarski, J. C. Z. , Brock, C. , Armstrong, M. , Hempel, C. , Cheal, D. , and Brennan, K. (2000). Bird distribution in riparian vegetation of an Australian tropical savanna: a broad-scale survey and analysis of distributional data base. Journal of Biogeography 27, 843–868.
| Crossref | GoogleScholarGoogle Scholar |
Woinarski, J. C. Z. , Armstrong, M. , Brennan, K. , Connors, G. , Milne, D. , McKenzie, G. , and Edwards, K. (2000). A different fauna?: captures of vertebrates in a pipeline trench, compared with conventional survey techniques; and a consideration of mortality patterns in a pipeline trench. Australian Zoologist 31, 421–431.
Woinarski, J. C. Z. , Franklin, D. , and Connors, G. (2000). Thinking honeyeater: nectar maps for the Northern Territory, Australia, showing spatial and temporal variation in nectar availability. Pacific Conservation Biology 6, 61–80.
Woinarski, J. C. Z. , Milne, D. J. , and Wanganeen, G. (2001). Changes in mammal populations in relatively intact landscapes of Kakadu National Park, Northern Territory, Australia. Austral Ecology 26, 360–370.
| Crossref | GoogleScholarGoogle Scholar |
Woinarski, J. C. Z. , Risler, J. , and Kean, L. (2004). The response of vegetation and vertebrate fauna to 23 years of fire exclusion in a tropical Eucalyptus open forest, Northern Territory, Australia. Austral Ecology 29, 156–176.
| Crossref | GoogleScholarGoogle Scholar |
Woinarski, J. C. Z. , Williams, R. J. , Price, O. , and Rankmore, B. (2005). Landscapes without boundaries: wildlife and their environments in northern Australia. Wildlife Research ,in press