Image #BRR-3: Use of a portable photosynthesis system for leaf gas exchange measurements at the Barro Colorado tropical forest site, Panama. (Gerhard Zotz, a German doctoral student, is using a clamp-on leaf chamber and infra-red gas analyser [Heinz Walz, Effettrich, Germany] on leaves of Clusia uvitana. Photograph taken around 1995 by Marcos Guerra, STRI).