Biomorph indicators of human-induced transformation of soils under early nomad burial mounds in southern Russia

Abstract

Biomorph analysis was utilized to study soils buried under early nomad burial mounds (kurgans) in the Orenburg region (southern Russia). Biomorph analysis is the study of the macro- and micro- remains of biota (biomorphs) in the context of the conditions of their origin. The earliest of the studied kurgans (VI–V centuries B.C.) were constructed in an undisturbed meadow-steppe. The subsequent group (IV–II centuries B.C.) was built on a highly disturbed, eroded landsurface that was largely devoid of vegetation and topsoil. After a prolonged break, kurgans again were built in II–III centuries A.D., on a surface where the vegetation and soil cover had partly recovered from human occupation. Our results definitely show the human-induced transformation of soils before and/or during the course of kurgan construction. The grade of disturbance varies in the different historical epochs and reflects the intensity of anthropogenic impact on ecosystems and landscapes. When buried soils under kurgans are used for paleoclimatic studies, it should be taken into account that anthropogenic soil transformation can modify various parameters such as the thickness of the topsoil horizon and thus the depth to carbonate and salt horizons. These changes documented on the basis of morphological and analytical data could be misinterpreted as indicators of climatic change whereas biomorph analysis allows researchers to avoid this mistake.