Structural features in the bark of the annual stem Betula e rmanii Cham, exposed to the Baransky volcano hydrothermal gases and fluids

The authors studied structural changes in the tissues of bark of annual stem Betula ermanii Cham. (Betulaceae Gray) under various environmental conditions. They collected the Betula ermanii samples in typical for this species conditions, characteristic of the Sakhalin Island, Krasnaya Mountain, Starozavodsky solfatara field, Baransky Volcano on the island of Iturup, and the Blue Lakes thermal springs area. A comparative quantitative analysis of the anatomical features of bark of annual stem made it possible to identify unidirectional structural changes in the conditions of gas-hydrothermal outcrops of Baransky Volcano, both upward and downward. These parameters include a number of crystals in cortex and phloem parenchyma, sieve tube diameters, the total number of ph loem rays and the uniseriate rays’ quantity, and the length of uniseriate phloem rays. The rest of bark tissue parameters of annual stem Betula ermanii from the studied habitats either showed no significant change, or changed in only one of the habitats with unfavorable conditions. The phellem width, the number of phellem cells in the radial row, and width of secondary phloem are modified in the Starozavodskoye solfatara field. The specific area of protophloem fibers and sclereids is changed under the conditions of thermal Blue Lakes. Thus, the structural response of annual stem Betula ermanii bark under extreme conditions of gas-hydrothermal springs associates mainly with a change of secondary phloem traits - sieve tubes and ray parenchyma parameters.