The investigation results on the concentration dependence of birch leaf chlorophyll fluorescence are presented. It is established that variation of the F682/F734 parameter during the vegetation process is described by two parabolas. One parabola refers to the period of the chlorophyll concentration increase up to its maximum and the second one - to the leaf aging. Minimum of the first parabola is observed during the birch flowering while of the second one - before coloring leaves. Red and far-red fluorescence parameters of birch leaf chlorophyll have been determined, which are more informative for early diagnostics of their state under different environmental conditions.