Ornithogenic soil genesis by flying birds in Maritime Antarctica: the role of landforms in the nests establishment

This research was conducted to evaluate the contribution of landforms in establishing Giant petrels (G. petrels) and Brown skuas (B. skuas) nesting and the formation of ornithogenic soils by the phosphatization process in Harmony Point, Maritime Antarctic. Ten nests from the coastal domain (marine terrace) and the cryoplanated platform were selected to collect topsoil samples (0-20 cm). The samples were collected from 0 m up to 20 m in each nest, with regular spacing of 2 m. The analysis of the samples included the physical, chemical, mineralogical, and geochemical analyses. The pH acidity found in the topsoils is similar to the phosphatized soils in penguins. Phosphate minerals such as apatite, leucophosphite, and vivianite were identified. The high content of some trace elements, such as Zn, Cu and Sr is associated with the bird’s excrements.  Total-P recorded higher levels in the cryoplanated platform, while higher levels of bioavailable-P were observed in the marine terrace. This result demonstrates the importance of the landforms in the bird’s nesting, as well as in the development of the soil in these soil-forming environment. Phosphatization in these areas is not restricted to the specific location of the nest since high values of P have been identified at distances between 8 and 12m, from de nest’s top. This suggests the transport of P-rich solutions and phosphatized material along with fractures by the freeze-thaw cycles, depositing these materials 20 m away, contributing to increasing the geographical expression of this phenomenon in this ice-free area, consequently the development of soils and the establishment of vegetation.