Dynamics of Mortmass Ash Content and Migration of Elements in Different Moisture Conditions of Midmountain Tropical Forests of Central Vietnam.

This paper presents the results of studying the ash content of twig and leaf debris from forest plants of primary midmountain tropical forests of Central Vietnam (Bidoup Núi Bà National Park) in order to identify and clarify the elements that enter the soil during their decomposition. The difference in the ratio of twig and leaf debris in mortmass samples collected in different landscape conditions is shown. At the same time, the influence of periodical and stagnant moisture conditions on the conduct of migratory soil processes is considered. The sampling points of the twig and leaf debris correspond to the locations of the soil catena within the structural ridge and its top, slope, and foothill. This allows us to relate the results obtained on the elemental composition of the twig and leaf debris to the geochemical migration of chemical elements in different geochemical landscape conditions, from automorphic to accumulative. An attempt has been made to establish the volumes of matter migrating from the mortmass into the soil together with the aqueous solution. Differences in the accumulation of ash elements in the twig and leaf debris depending on the position in different landscape conditions are revealed. The composition of elements entering the soil with twig and leaf debris and involved in geochemical migration is established, and the contribution of leaves and twig debris to the accumulation and migration of elements under different moisture conditions is evaluated. The dependence of geochemical migration processes on the position of the elementary geochemical landscape facies in the catena is pointed out, which manifests itself in a change not only in the total ash content of the twig and leaf debris, but also in the ratio of ash content of twig debris to that of leaf debris. [ABSTRACT FROM AUTHOR]