Field measurements of carbon leaching from leaves in beech and alder forests of northern Germany

Carbon compounds were measured in solutes from crown drip and stem flow collected by rain gauges in a beech and an alder stand in northern Germany. The amount of leachate was calculated by using the concept of a canopy deposition model. Under this aspect leaching rate is the difference between canopy and bulk deposition. The calculations comprise direct leaching from leaves as well as carbon loss to honey-suckling insects and carbon loss used to compensate loss of inorganic substances. Leaching of organic carbon depends mainly on the amount of rainfall, the activity of phytophages and on the water repellance of the leaf cuticles. The annual loss of organic carbon by leaching was about 300 kg.ha(-1) per year in the alder forest, that was 1,4% of the annual gross carbon production. The loss in the beech forest was lower with about 60 kg C.ha(-1) year(-1), corresponding to 0,8%.