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The Thermal Buffering Effect of Australia's Alpine Boulder Fields

Paper Reviewed
Shi, H., Paull, D., Wen, Z. and Broome, L. 2014. Thermal buffering effect of alpine boulder field microhabitats in Australia: Implications for habitat management and conservation. Biological Conservation 180: 278-287.

In light of concerns about potential negative effects of predicted increases in global temperature on various plants and animals, Shi et al. (2014) write that "microhabitats can partially decouple from regional climatic conditions, and species can persist in situ as regional climates become less suitable," citing the studies of Bennie et al. (2008), Ashcroft (2010) and Keppel and Wardell-Johnson (2012), while making special note of the microhabitats of tree hollows, roost cavities, tropical boulder fields and various microhabitats within primary rainforests, citing the additional studies of Isaac et al. (2008), Sedgeley (2001), Shoo et al. (2010) and Scheffers et al. (2014).

Focusing their attention on Australia's alpine boulder fields -- because they provide den and nest sites for a range of endemic small mammals -- the four researchers collected hourly temperature data from 70 sites located within nine boulder field clusters in an area of approximately 60 km x 30 km in New South Wales over a period of slightly more than two years duration. And what did they thereby find?

Shi et al. report that the boulder fields "buffered the surface temperature maxima by 2.91°C at a depth of 50 cm and 4.39°C at a depth of 100 cm, while they buffered the surface temperature minima by 0.54°C at the depth of 50 cm and 1.36°C at the depth of 100 cm." And these effects could well mean the difference between a species surviving or dying out in a gradually warming world, especially if it is unable to migrate either poleward in latitude or upward in altitude.

Ashcroft, M.B. 2010. Identifying refugia from climate change. Journal of Biogeography 37: 1407-1413.

Bennie, J., Huntley, B., Wiltshire, A., Hill, M.O. and Baxter, R. 2008. Slope, aspect and climate: spatially explicit and implicit models of topographic microclimate in chalk grassland. Ecological Modeling 216: 47-59.

Isaac, J., De Gabriel, J. and Goodman, B. 2008. Microclimate of daytime den sites in a tropical possum: Implications for the conservation of tropical arboreal marsupials. Animal Conservation 11: 281-287.

Keppel, G. and Wardell-Johnson, G.W. 2012. Refugia: keys to climate change management. Global Change Biology 18: 2389-2391.

Scheffers, B.R., Edwards, D.P., Diesmos, A., Williams, S.E. and Evans, T.A. 2014. Microhabitats reduce animal's exposure to climate extremes. Global Change Biology 20: 495-503.

Sedgeley, J. 2001. Quality of cavity microclimate as a factor influencing selection of maternity roosts by a tree-dwelling bat, Chalinolobus tuberculatus, in New Zealand. Journal of Applied Ecology 38: 425-438.

Shoo, L., Storlie, C., Williams, Y. and Williams, S. 2010. Potential for mountaintop boulder fields to buffer species against extreme heat stress under climate change. International Journal of Biometeorology 54: 475-478.

Posted 13 April 2015