Phosphatization under birds' activity: Ornithogenesis at different scales on Antarctic Soilscapes

Extensive areas of penguins' nesting (Pygoscelis sp.), on ice-free areas, account for vast deposits of organic matter-rich guano in maritime Antarctica. One such area, at Harmony Point, currently houses different penguin colonies with extensive and unique ornithogenic soils, where phosphatization is the key soil-forming process. We sought to enhance the knowledge of phosphatization process, products, cycles, and phosphorus (P) forms in these unusual soils. We compared ornithogenic and non-ornithogenic soils, based on advanced chemical, micromorphological and mineralogical analyses of samples of guano and phosphate biocrusts, complete with P and OM fractionation. Ornithogenic soils have the organic P-pool as the largest phosphorous compartment, followed by varying P-Ca forms. In contrast, soils unaffected by phosphatization showed a high inorganic P-pool. Penguin guano is enriched with P, Ca, K, Cu, Zn, C and N. The phosphatic biocrusts are composed of struvite and hydroxyapatite, forming a gradient of phosphate forms. We recognized three different phosphatization environments, namely (i) present-day marine birds' rookeries, (ii) adjacent zone of rookeries and (iii) abandoned rookeries. Geomorphological evolution of the coastal areas, by Holocene glacier retreat, resulted in the changing location of penguin colonies, resulting in a larger area and varying ages of phosphatization, forming ornithogenic soils with contrasting evolution degrees. Abandoned areas have greater vegetation growth, with higher diversity.

Automated summary

Extensive penguin nesting in ice-free areas of maritime Antarctica leads to the vast deposits of organic-rich guano, forming unique ornithogenic soils where phosphatization is the key soil-forming process. Penguin guano is enriched with various elements, while phosphatic biocrusts are composed of different phosphate forms. The evolution of coastal areas due to Holocene glacier retreat has resulted in varying ages and degrees of phosphatization in abandoned penguin colonies, forming soils with different levels of vegetation growth and diversity.