Phytogenic Hillocks as Ecological Indicators of Long‐Term Vegetation Development on Temperate‐Zone Inland Dunes

ABSTRACT Phytogenic hillocks, or nebkhas, are commonly found in arid and semi‐arid regions, but can also form in temperate zones, particularly in areas where forests on sandy soils have been cleared. In such environments, they play a key role in stabilizing and facilitating the regeneration of ecosystems. This study was conducted in the extensive inland sand region known as the Błędowska Desert (southern Poland), which developed as a result of anthropogenic deforestation of pine forests. The development of hillocks in this area is closely tied to the intensity of aeolian activity. Vegetation is frequently buried by sand, and as it re‐establishes, new hillocks form. This results in alternating layers of clean, light‐colored sand and thin, dark‐colored humic streaks. The research focused on the physicochemical, mineralogical, and organic properties of these light and grey layers within phytogenic hillocks. The study indicates that the formation of these landforms begins with colonization by soil‐dwelling algae, followed by the development of psammophilous grasslands, and culminating in the establishment of Salix arenaria . The soils within the hillocks display similar physical and chemical characteristics, with the exception of buried horizons, which show notable differentiation. In the humic layers, preserved traces of photosynthetic filamentous algal cells were observed on the surfaces of sand grains at various depths. The grey layers were found to contain a range of organic compounds, including saccharides (with sucrose, trehalose, α ‐ and β ‐glucose, and α ‐ and β ‐galactose as dominant sugars), n ‐fatty acids, n ‐fatty alcohols, steroids, and terpenoids. These compounds are typically derived from bacteria, fungi, algae, and higher plants. This suggests that the dark‐grey humus layers are linked to the vegetation communities that developed on their surfaces before being repeatedly covered by sand.