Valley reforestation to lower saline groundwater tables - Results from Stene Farm, Western-Australia

Abstract

Dense planting of selected trees in salt-affected valley floors and non-saline adjacent slopes has been evaluated as one strategy for controlling rising saline groundwater under agriculture. Of the 127 ha experimental catchment, 44% had been cleared of native forest in the 1950s. Valley reforestation covering 35% of the cleared area took place in 1979, by which time a groundwater of 5300 mg L-1 TSS had risen to within 0.5 m of the soil surface. The eucalypt reforestation was successful in lowering the groundwater table by 1.5 m by 1989, whilst groundwater levels under nearby pasture had risen by 1.8 m. The groundwater salinity beneath reforestation decreased by 30% over the study period, allaying fears of a detrimental groundwater salinity increase brought about by transpirative concentration. Measures such as replanting failed areas, implementing agricultural recharge control or selecting higher water using tree species would improve the performance of the valley reforestation strategy.