Welles, J.M., LI-COR, Inc., 4421 Superior St., Lincoln, NE 68504, United States
Cohen, S., Dept. of Environ. Phys. and Irrigat., Institute of Soils and Water, Volcani Center, PO Box 6, Bet Dagan, Israel

In the past few years, a number of systems for making indirect canopy structural estimates have become commercially available. These include linear sensors, such as the DEMON, line quantum sensors, and hemispherical sensors, such as the LAI-2000, the Leaf Laser, and the CI-100. The performance of these instruments as reported in the literature is reviewed for forests, row crops, and individual trees.