Understanding the climates experienced by Australia’s biota

Weather stations record data with instruments that are not obstructed from the sun by topography or vegetation at any time of the day. However, these are not the conditions that plants and animals are experiencing on the ground. Most of us would have walked into a forest on a hot day and found that it was much more pleasant under the canopy of trees than out in the open. We also know that plants, such as mosses in Swedish forests, may require the cooler and more humid microclimates to establish or survive. Similarly, animals, such as birds, have been shown to seek out locations that provide the most suitable climatic conditions in their habitat.

Unfortunately most of the predictions about the likely effects of climate change on the Australian biota are based on species distribution models based on coarse-scale data that does not take into account the moderating effects of vegetation. Studies have found that canopy cover can significantly effect the distribution of plant species, such as Ornduffia marchantii in the Porongorups Range in Western Australia. As a result, although likely to pick up major trends, most predictions of the likely responses of biodiversity to climate change are of limited accuracy.

Masters student Sean Sparrow installing a microsensor (contained in the white radiation shield and attached to a wooden stake)

We therefore need to understand the prevalent conditions experienced by organisms on the ground – i.e. below the canopy and on slopes facing the equator or the north or south pole.  While past research has provided us with a good understanding about the effects of topography, our knowledge about the impact of vegetation cover remains rudimentary. This is of concern because predictions of the responses of biota to ongoing and future anthropogenic climate change are generally made based on data collected from climate stations that are corrected for moderation by topography, but not vegetation. For example, we have found canopy cover to significantly reduce maximum temperatures in the Fleurieu Peninsula in South Australia.

The first three sensors at the Barossa Valley site, which borders on a vineyard.

We have started to establish a network of transects that investigates how vegetation could buffer global warming by monitoring on-the-ground temperature and humidity under forest canopy. With support from the University of South Australia, three sites have already been established in vegetation remnants in the Barossa Valley, Monarto and the Fleurieu Peninsula. To facilitate far-reaching comparisons, we have followed the methodology of the European Forest Microclimate Assessment (FORMICA) project, which surveys microclimates along 100 meter long transects from the forest edge.

Hopefully, this project will be the first step towards improving our knowledge of how vegetation is moderating microclimate. This will provide us with a more realistic understanding of the on-the-ground climate conditions experienced by our biota. In the long-term, this should lay the foundation for better management of Australia’s biodiversity under anthropogenic climate change.

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