Productivity and diversity of desert complex environments

Glenda Wardle and Chris Dickman from the Desert Ecology Research Group (DERG), University of Sydney, and LTERN have been collaborating with AusPlots since 2014. Here, Glenda shares some of the details of this collaboration and its benefits for everyone involved.

By co-locating 15 AusPlots within our 8000km2 study site in the Simpson Desert there is an unprecedented opportunity to detect and understand changes in productivity over space and time. Our work combines long-term observations with manipulations to disentangle the multiple drivers of the system, including rainfall, fire, grazing and ferals. We will be remeasuring these AusPlots and synthesising the results with our own data to address pressing issues of increased environmental changes land-managers are facing.

This exciting collaboration brings together work at a national and global scale. Firstly, the desert ecology plot network has been monitoring changes in the flora and fauna for 25 years and this time-depth complements the larger spatial coverage of nearly 500 AusPlots within the rangelands of Australia.

Secondly, since 2013, the desert ecology plot network has been part of the global Nutrient Network and together, with nearly 80 sites around the world, we are conducting an on-going manipulative experiment to identify and test the processes that underpin patterns of diversity and productivity in grasslands by adding different combinations of nutrients and by using fences to exclude large herbivores.

Third, starting in 2015, we will also be undertaking experiments to determine the effects of droughts using the standard experimental protocols of the global Drought-Net. Fourth, if funding is forthcoming, we will be extending this experimental work to encompass the western reaches of the Simpson Desert where there are another suite of AusPlots.

Fifth, we are also part of a Google Earth Engine collaboration with Stuart Phinn and Peter Scarth in TERN’s Auscover Facility and the University of Queensland, to link our plot-level changes to remotely sensed changes in vegetation fractional cover. This is allowing us to extend the spatial resolution of the temporal patterns we track across the study system.

Finally, we have also been able to document the fire and grazing histories of the study site and model the 100- year changes in temperature and rainfall for the Simpson Desert region. Having this historical and contextual environmental data helps to place our results in a broad conceptual framework.

The AusPlots on our study sites are within the Simpson-Strezlecki bioregion and encompass a broad range of vegetation types:

  • Spinifex hummock grasslands (Triodia basedowii) – 3 plots in long unburnt (20+ years)
  • Grevillea stenobotrya sparse shrubland with dense hummock understory – 1 plot
  • Georginae gidgee woodlands (Acacia georginae) – 4 plots
  • Mulga woodlands (Acacia aneura) – 2 plots
  • Blue mallee sparse woodlands (Eucalyptus gamophylla) – 1 plot
  • Eucalyptus coolabah open woodland (Eucalyptus coolabah) – 2 plots
  • Eucalyptus coolabah swamp with emergent Corymbia terminalis – 1 plot
  • Lignum swamp (Muehlenbeckia florulenta) – 1 plot

Why is this project important to both scientists and land managers?
The low productivity dryland ecosystems are poorly known compared to mesic areas but still support substantial pastoral activity and support food production of the world. Further, because coping with increased extreme events while retaining efficient resource use is of great practical importance, this project will help to ensure that inland landscapes are managed productively. The study area also encompasses two of the properties that are managed by Bush Heritage Australia for conservation: Ethabuka Reserve and Cravens Peak Reserve. Both of these were de-stocked and we are monitoring the changes in the biodiversity in response to these changes in land management.

Further reading:

  • Dickman, C. R., Wardle, G. M., Foulkes, J. & de Preu, N. (2014) Desert complex environments. Pp. 379-438 in D. Lindenmayer, E. Burns, N. Thurgate & A. Lowe (eds). Biodiversity and Environmental Change: monitoring, challenges and direction. CSIRO Publishing, Melbourne
  • Frank A.S.K., Dickman C.R., Wardle G.M. and Greenville A.C. (2014) Habitat- and rainfall-dependent biodiversity responses to cattle removal in an arid woodland-grassland environment. Ecological Applications 24:2013–2028
  • Frank A.S.K, Dickman C.R and Wardle G.M. (2012) Habitat use and behaviour of cattle in a heterogeneous desert environment in central Australia. The Rangeland Journal 34: 319-328
  • Greenville A.C., Wardle G.M. and Dickman C.R. (2012) Extreme climatic events drive mammal irruptions: regression analysis of 100-year trends in desert rainfall and temperature.  Ecology and Evolution 2(11): 2645-2658 doi: 10.1002/ece3.37
  • Greenville A.C., Dickman  C.R., Wardle  G.M., Letnic, M. (2009) The fire history of an arid grassland: the influence of antecedent rainfall and ENSO International Journal of Wildland Fire 18: 631-639
  • Wardle G.M. (2010) The story of our land revealed through plants. In Desert Channels: the impulse to conserve. Robin L, Martin, M and Dickman CR (Editors). CSIRO Publishers, Canberra.
  • Wardle, G.M., Pavey, C. R. and Dickman, C. R. (2013) Greening of arid Australia: new insights from extreme years. Austral Ecology 38: 731-740