A comparison of evaporation from stands of Scots pine and Corsican pine in Thetford Chase, East Anglia.
Transpiration and interception were compared for a Scots pine stand and a Corsican pine stand in Thetford Chase, East Anglia. The Scots pine stand had an open tree canopy below which a bracken understorey grew in summer. The Corsican pine stand consisted only of trees: they had a dense canopy with no understorey. Similar transpiration was measured in both stands with differences not exceeding 0.2 mm day-1. Interception was also similar, differing in total over 21 months by only 10 mm. Transpiration from the Corsican pine trees was up to 28% greater than from the Scots pine trees. The difference was explained by the 27% greater leaf area index in Corsican pine trees than in Scots pine trees, and by the greater proportion of foliage in Corsican pine trees which was distributed in the upper parts of the crowns, where radiation is greater. The difference in transpiration between the tree species was compensated for by transpiration from the bracken understorey in the Scots pine stand. Previous studies in Thetford Forest have shown that transpiration from bracken is normally about 25% of the forest total in summer.