Contribution of understorey vegetation to evapotranspiration partitioning in apple orchards under Mediterranean climatic conditions in South Africa

Orchard evapotranspiration (ET) is a complex flux which has been the subject of many studies. It often includes transpiration from trees, cover crops and weeds, evaporation soil, mulches other orchard artefacts. In this study we investigated contribution floor evaporative fluxes to whole ET focusing on dynamics understorey vegetation currently not well known. Data partitioning into its constituent components were collected in apple (Malus Domestica Bork) orchards with varying fractional canopy cover. The prime growing regions South Africa. planted Golden Delicious/Reinders red cultivars (i.e. Cripps’ Pink/ Royal Gala/Fuji). Tree was quantified using heat ratio method thermal dissipation sap flow techniques. Understorey measured at selected intervals micro stem balance gauges calibrated against infrared gas analyser readings. an open path eddy covariance system while microclimate, radiation interception, soil also monitored. accounted for as much 80% young dense that covered most floor. these same order magnitude bare moist suggesting water use by substantial. However, mature high (>55% cover), losses less than 30% ET. rates lower, contributing 10% Significant volumes can be saved, especially orchards, keeping short, reducing area occupied vegetation, wetted ground surface area.