ON THE CONCEPT SAVANNA

The term ''savanna'' defines a wide complex of plant groups from the t ree-grass grous to the purely grass ones occurring in the tropical and subtropical areas under the conditions of excessive humidaty and form ing a transitional zone from the tropical (rain) forests to semidesert s and deserts. Grass communities with the presence of trees or shrubs in the upper layer, the density of which does not exceed 0.1, are comm only referred to savannes per se (typical savannas). In order to make the concept of ''savanna'' more precise it is necessary to take into s ccount specific structural features of these plant grous, besides the floristic and ecological-biological features.