WA’s land clearing exacerbates drought. In drought-stricken south-west WA, rainfall tends to be restricted to areas of native vegetation.
(This is an article from the Australian Financial Review in May, 2013)
Land clearing in the state’s south-west for agricultural and urban development has coincided with a significant decline in rainfall.Tom Lyons, an experimental micro-meteorologist at Perth’s Murdoch University, said it was remarkable how distinct rainfall was between areas of native vegetation and cleared land in the area. “We’ve witnessed cloud bands over the native vegetation and absolutely nothing over the agricultural areas,” said Professor Lyons, who has been studying the region for more than 20years. “The wettest paddocks are always the paddocks that back onto native vegetation.”
In the early 1900s, the south-west experienced a year that could be classified as a “wet year” about one in every two. That has diminished significantly since the 1960s, to the extent that there hasn’t been a wet year for two decades. The region had its driest year on record in 2010, and the two years of 2010-11 were the driest on record in some parts, the Bureau of Meteorology said.
Experts tend to blame a combination of climate change, land clearing and normal cyclical factors for the drying climate. While there is still debate over how land clearing affects precipitation and how forests “attract” rain, it is widely accepted that felling trees reduces rainfall.
Mark Andrich, an honorary research fellow at the University of Western Australia’s centre for water research, said it appeared that in some locations in WA, more than half the winter rainfall decline observed from the 1960s had been caused by deforestation.
Plant more trees – big ones
“The key is to simply reforest with native vegetation and, where possible, with tall trees that are allowed to reach full maturity,” he said. “The larger the tree, the [greater] impact on the local climate.“ He said further research, such as running reforestation trials and measuring the effect on local climate, should be undertaken.
The rainfall findings and possible solutions raise questions over the effectiveness of short-term financial measures to help farmers stay on the land.
WA Farmers Federation director of policy Trevor Lovelle said the long-term issue didn’t take away from the immediate need of farmers in the region, who had also been hit by unfavourable economic conditions.
“It’s something we are mindful of,” Mr Lovelle said. “There needs to be more research but, for the moment, at top of mind is getting the next crop in.”
The difficult conditions have been exacerbated by a high Australian dollar and increasing input costs for WA’s export-oriented farmers.
The federal government has released a $420million package to help struggling farmers climb out of debt, while WA has a modest package that includes financial help directed at those leaving the sector.