The contribution of stem flow or trunk flow to the total water fluxes under the canopy can reach a considerable proportion. This means that stemflow represents a significant mineral input to certain areas of the forest floor. Trunk runoff is intercepted by a drainage collar (or flexible drainage channel) attached to the trunk. The height of the drainage channel depends on the shape of the tree trunk and varies between 0.8 m and 1.2 m above the soil.

Structure and functionality

The stem drain measuring kit consists of the following components:

• Covered elastomer collar incl. instep ribbon / band clamp and artificial bark for mounting on trunk
• Tipping counter with adequate sampling (1% per tip), 100ml tipping tray in polycarbonate casing (macrolon), 250 ml - PE collecting flask, REED sensor
• Protective casing for tipping counter and counter module incl. mounting mast
• Electronic counter module with internal lithium battery
• 20 litre PE HD water collecting tank