Coupled soil-vegetation changes along a topographic gradient on King George Island, maritime Antarctica

Abstract

Studies on the unique terrestrial ecosystems of Antarctica’s ice-free areas have potential to enhance the understanding of the soil/vegetation interplays and ecological relationships of endangered polar environments. Studies that have emphasized the plants distribution and diversity increase the knowledge on the Antarctic vegetation and controlling factors, enabling better conservation strategies for these fragile ecosystems. In this study, we investigated the composition and distribution of plant communities in association with soil characteristics, landscape elements (altitude and geomorphological variations), and local faunal influence. We related these factors to plant species richness along topographic gradient on a typical maritime Antarctica landscape. We hypothesized that plant species distribution responds to soil and topographical variations; further, we postulated greater plant diversity in ornithogenic areas of increasing age and higher organic matter content. Ten plant communities and a bare-soil reference located at Thomas Point, King George Island, were identified, selected and mapped for the study. Plant cover was analyzed using phytosociological data from 132 squares across the area to evaluate frequency, coverage degree, and the ecological significance index. These values determined the type of community observed. We also determined general soil physical and chemical attributes. The microscale variations in sheltering of the different environments directly impacted floristic composition across the landscape. Vegetation composition and floristic characteristics significantly varied along the topographic gradient, according to soil attributes, in which ornithogenesis (phosphatization) and drainage conditions played a key role. Both factors are likely to be greatly affected by recent warming trend in this part of Antarctica.