Can a fence change weather patterns? Professor Tom Lyons from Murdoch’s Environmental Science believes the rabbit fence stretching from Esperance to Geraldton has made quite an impact.

“The fence was initially built at the turn of the nineteenth century to protect Western Australian agricultural lands from an impending plague of rabbits,” said Professor Lyons.

“The fence failed to keep rabbits out, but has acted as a barrier protecting agricultural lands from other vermin.”

With native plants to the east and wheatfields to the south-west, the vegetation division along the fence is clear enough to spot from space.

Professor Lyons explained that such distinct demarcations are relatively rare, and his research team have taken the opportunity to study large scale clearing effects.

He said that vegetation divisions were normally caused by changes in soil type or topography, but ground conditions are fairly uniform along the rabbit fence.

Working with Airborne Research Australia, Flinders University, CSIRO, Agriculture WA and the WA Department of Land Administration, Professor Lyons and other Murdoch researchers have compared satellite information to aircraft and ground level data over the past decade.

The researchers flew in laps over the wheatfields and the native bushland, recording climate data including temperature, relative humidity and reflected radiation.

Professor Lyons said that research results from this “exciting field laboratory” were unexpected.

“Satellites average data from a kilometre area, while you can pinpoint changes to a 2m radius by aircraft,” said Professor Lyons.

“We were trying to use this data to work out robust models to characterise the Earth’s surface, but it also told us a lot about the weather patterns.”

Professor Lyons explained that the fence marks a line of clouds that are regularly seen by locals and air travellers alike, hovering over the native vegetation.

“Australian native vegetation is very conservative of water whereas agricultural crops grow through transpiration.”

The curious aspect is that although wheat crops lose significant moisture content to the atmosphere while growing to maturity, clouds form over the native vegetation instead.

The answer, says Professor Lyons, is in the colour of the vegetation.

“Native vegetation is much darker and therefore absorbs more heat from the sun. This makes the air hotter and the convective turbulence is strong enough to raise moisture to a height where clouds are formed.

“The rabbit fence illustrates that convective clouds form preferentially over native vegetation. It is interesting to speculate whether the large scale replacement of native vegetation by agricultural crops has contributed to the decreased rainfall in Western Australia.”

Professor Lyons and his researchers are continuing to examine this relationship.