FEATURES OF ADAPTATION OF DIFFERENT FORMS OF SCOTS PINE UNDER CONDITIONS OF PROLONGED EXCESSIVE SOIL MOISTENING

Abstract

Intrapopulation variability of biochemical traits and cambial growth shows the adaptive ability of pine trees in different growth conditions. There is a genetically determined process of activation of defense systems in pine trees under unfavorable environmental conditions. Structural and functional rearrangement of the assimilating apparatus due to seasonal development ensures increased tree resilience and the passage of ontogenesis under the influence of stress factors within the reaction norm. This work aims at the study of adaptive ability of Pinus sylvestris L., which differs in the apophysis form of seed scales under conditions of prolonged excessive soil moistening in northern taiga. Studies were carried out in shrubby-sphagnum pine forests on boggy upland peat soils in the mouth of the Northern Dvina River. Trees with primary apophysis variations (forms) of seed scales were identified on the sample plots. Samples of 1, 2 and 3-year-old needles were taken in order to determine biochemical traits in 10 trees of each pine form isolated by type of apophysis, in different calendar periods (from May to December, 2016). The content of free proline, water-soluble proteins, and ascorbic acid was determined in the needles by the spectrophotometric method. Wood cores were sampled from 52 trees at a height of 1.3 m and width of the annual layer was determined in each selected form. Relative dendrochronological parameters were calculated along with the absolute value of radial growth. Meteorological parameters at the study sites (air temperature and precipitation) were determined from data of the Arkhangelsk Weather Station. The studies show the similarities and differences of trees of various forms in the seasonal dynamics of stress metabolites content in needles of different ages in relation to meteorological factors and phenological phases of pine vegetative organs in the Northern Dvina mouth. Trees with flat form of apophysis inherent more intensive accumulation of ascorbic acid and proline in 2-year-old needles in late October. This indicates increased activation of their protective reactions before overwintering compared to trees with convex form of apophysis. Patterns of variability in cambial growth of trees of different forms in time series were found. It was observed that trees with flat form of apophysis are more strongly affected by maladaptive (stressful) environmental factors.