Solos com influência ornitogênica na Ilha Greenwich, Antártica

Abstract

Ice-free areas are limited to a small percentage of the entire Antarctic region, where thousands of birds nest during the austral summer. Antarctic terrestrial ecosystems are generally nutrient poor; however, the input of guano, promoted by ornithogenesis, can progressively enrich these environments with organic matter and elements such as phosphorus. In the ice-free areas of maritime Antarctica, penguin colonies predominate, but flying seabirds, such as petrels, have a strong influence in specific areas. The impact of these birds on soil properties is still poorly understood compared to that of penguins, which are more extensively documented in the literature. Therefore, to investigate the influence of petrel activity on soil formation and evolution, samples from eight soil profiles and topsoil samples were collected on Greenwich Island. Physical, chemical, mineralogical, and statistical analyses were conducted. The results showed that the soils are generally poorly developed, with a predominance of primary minerals in the <2 mm fractions. Soils currently influenced by ornithogenesis showed higher concentrations of phosphorus, nitrogen, and organic carbon. On the other hand, soils without current influence showed higher levels of calcium and magnesium. Despite the higher levels of P, N, and organic carbon, it was found that giant petrels do not contribute to guano input equivalent to that promoted by penguins. Nevertheless, the influence of giant petrels is sufficient to modify soil properties and contributes to the formation of weakly ornithogenic soils.