Remote probing of plant photosynthetic apparatus by measuring laser-induced fluorescence

Laser-induced fluorescence of birch, pine, and aspen trees was studied. The fluorescence of birch leaves, excited with a Xe-Cl laser at a wavelength o f 308 nm, was measured under laboratory conditions. A persistent directly p roportional dependence was found between the measured fluorescence signals and the chlorophyll content. An apparatus for measuring laser-induced fluor escence under field conditions was designed. Deciduous trees were found to have a wider range of fluorescence variability when compared to conifers, w ith the fluorescence intensity increasing in the leaves of deciduous trees before the autumn fall of leaves, during leaf yellowing. It is concluded th at the method of lidar probing can be used for identifying tree species and assessing the condition of leaf and needle canopies.