In the middle taiga subzone of the Komi Republic, the accumulation of phytomass and the relative growth rate of invasive species – H. mantegazzianum were studied. Ten age classes were identified in the structure of the local populations of this invasive species, where virginal individuals accumulated an order of magnitude less dry phytomass than generative ones. Despite the low relative growth rate (of up to 0.05 g/g dry mass per day), the plants maintained high productivity. Light availability within the local populations was the key factor regulating the relative growth rate. Shading and intraspecific competition limited growth, especially in young plants. Virginal plants showed maximum RGR in the second age class, when their leaves were located in the middle or upper canopy layers of the vegetation. The relative growth rate of generative individuals was 20–60 % higher than that of virginal ones. During ontogenesis (aging), the rate of phytomass accumulation in H. mantegazzianum decreased to 0.004 g/g DW per day.

Dalke I.V., Chadin I.F.