Soils of the island bars of the Ola lagoon (Okhotsk sea)

Abstract

The aim of the study. The purpose of the work is investigating soil formation on the island bars of the Ola Lagoon, as soil formation there has a special character due to the severe climate, dynamism and small age of the landscapes, and the influence of marine colonial birds.

Location and time of the study. Field studies were conducted in June-July 2022 in the coastal zone of the Ola Lagoon of Magadan Region; laboratory and desk studies were conducted in 2022 and 2023.

Methods. Methods included route observations with soil profile descriptions, mesomorphological studies; soil physical and chemical analyses: pH, electrical conductivity (TDS), loss on ignition (LOI); satellite photos interpretation and soil mapping.

Results. The bar soils were qualified as dry-peat lithozems, differing in the thickness of the dry peat horizon TJ and the abundance of skeletal material (pebble). The dry-peat horizon is gradually merging into parent rock - dense marine pebbles, which are sometimes found in the dry-peat horizon due to storm "surges" from the sea. The TJ horizon consists of mesophilic plant residues and morphons of dark fine-disperse matter and a large number of semi-decomposed and living roots penetrating into the pebble layer. In the WRB system, soils correspond to Histic Leptosols (if shallow), or to Mawic Fibric Histosols.

Conclusion. Formation of the dry-peat lithozems with the TJ-(TJ/С)-C profile is determined  by the dry marine climate and low plant diversity of the meadows dominated by reed grass and wild rye. The main factors, shaping soil properties, are the island bars dynamics, specific of pebbles a  parent rock material, salt impulverization and marine birds colonies presence. The research expands the knowledge on poorly studied soils of the region, and may contribute to substantiating their position in the classification of soils of Russia; in addition, the data obtained are useful within the framework of sustainable development, as it serves as nesting ground for colonial seabirds.