The growth and mass accumulation of Hylocomium splendens in Khibiny mountain forest belt

The annual increment dynamics (linear and mass) of Hylocomium splendens during vegetation periods in the forest belt of Khibiny mountains are examined. The main part of the linear growth (80 %) was formed in summer (with its maximum in mid-July). In autumn, the linear growth slowed down, but the mass of annual increment was actively growing. The growth indicators of moss in different conditions were compared. The linear and mass increments are the largest in the openings found between trees. The average growth of the linear increment in 2013-2015 was 18-28 mm/year, and the average growth of the dry mass amounted to 4-8 mg/year. It was revealed that the growth of H. splendens continued during two years: the length of the annual increment was formed mainly in the first year of its life, and the increase in the masses continued through the next year. A statistical model reflecting dependence of the growth rate of H. splendens in the openings between trees with main environmental factors is presented.