Recharge beneath a Banksia woodland and a Pinus pinaster plantation on coastal deep sands in south Western Australia

Abstract

Recharge was estimated using three methods during a three-year period (1985–1988) in a Banksia woodland and a dense Pinus pinaster plantation growing on deep sandy soils in the northern Swan Coastal Plain. The methods of estimating recharge were water balance, chloride balance and ground-water-table rise. Substantially less rainwater infiltrated into the shallow groundwater (about 6 m deep) beneath the pine plantation compared with the Banksia woodland. The relative difference in recharge between the two vegetation types increased during years of below average rainfall. When averaged over the three methods of recharge estimation during the three years, recharge beneath the pine plantation was 114 mm (equivalent to 15% of annual rainfall), and beneath Banksia woodland was 173 mm (equivalent to 22% of annual rainfall). Reduced recharge under pines and the merits of the methods of recharge estimation are discussed.