Eddy flux measurements above a pine forest

Abstract

AbstractEstimates of sensible and latent heat flux measured above a Pinus radiata forest plantation, 11km north of Mt Gambier in South Australia, by eddy‐correlation instrumentation, were found to satisfy the forest energy budget to within 20% provided the mean windspeed was greater than about 2ms−1. In lighter winds these two fluxes were severely underestimated. A study of the higher windspeed data when the forest canopy was externally dry and transpiration the only water loss, gave a Bowen ratio of 0.8 ± 0.1 during the day, with a diurnal trend similar to that for shorter vegetation types. In these conditions the hourly change in canopy heat storage was a significant component of the energy budget. When the canopy was wet from intercepted rainfall, the Bowen ratio was generally less than 0.3 and often negative. Incoming sensible heat and a cooling canopy provided energy for evaporation when the net radiation was low or negative.