The Use of a Wet-Surface Weighing Lysimeter System in Rainfall Interception Studies of Heather (Calluna vulgaris)

A portable, wet-surface lysimeter system, for measuring the in situ interception characteristics of short to medium height vegetation is described. The system, comprising an electronic balance and meteorological sensors linked to a microcomputer, has been used successfully at a number of U.K. sites of widely varying topography. In this paper, results are presented from two heather sites near Killin in Scotland. The aerodynamic resistance (rv) to the transport of water vapor from a canopy of wet heather was found, from solution of the Penman-Monteith equation, to be rv = (20.0 ± 2.0)ū−(0.60±0.06), where ū is the mean windspeed, and the canopy capacity of intercepted water was found to be (1.4 ± 0.2) mm. A review of methods of determining aerodynamic resistance is also given.