The impact of drought on tree water use was investigated in
remnant forest in the Liverpool Plains NSW. Tree water use was
measured using commercial sap flow testers from December 2002 to
September 2004 which corresponded with a period of drought and a
period of higher rainfall. Understorey evapotranspiration and
soil moisture were also measured. Water use of the stand of
trees was a larger proportion of annual total rainfall (87%)
during the drought period than during the post-drought period
(50% water use) when rainfall was higher. Understorey water use
was about 20% of rainfall, suggesting that the understorey
evapotranspiration component of the water balance can make a
significant contribution to water use and the availability of
water for groundwater recharge. The results indicate that the
remnant forest was able to survive during the drought because of
deep roots. The findings also demonstrate the valuable role
forests play in maintaining the hydrological balance and in
ameliorating the development of d