Index of Quality and Yield

an indicator of the productivity of a forest which depends upon the soil and ground and climatic conditions (site). The index is determined by the average height of the trees of the dominant variety in a stand, with their age being taken into account. In Soviet surveying practice the scale of the quality classes compiled in 1911 by Professor M. M. Orlov is used. According to the quality scale, the stands are divided into five quality classes designated by Roman numerals. Class I includes the stands which are most productive, and class V those which are least productive. The number of quality classes is often increased. For example, the designation Ia is used for stands with a productivity above class I and Va for stands below class V. The general quality scale is used for all tree varieties, and special scales have been established for seed and sucker stands.