Carbon and nitrogen isotope composition of vegetation on King George Island,maritime Antarctic

We report abundance of ¹³C and ¹⁵N contents in terrestrial plants (mosses, lichens, liverworts, algae and grasses) from the area of Barton Peninsula (King George Island, maritime Antarctic). The investigated plants show a wide range of δ¹³C and δ¹⁵N values between −29.0 and −20.0‰ and between −15.3 and 22.8‰, respectively. The King George Island terrestrial plants show species specificity of both carbon and nitrogen isotope compositions, probably due to differences in plant physiology and biochemistry, related to their sources and in part to water availability. Carbon isotope compositions of Antarctic terrestrial plants are typical of the C₃ photosynthetic pathway. Lichens are characterized by the widest carbon isotope range, from −29.0 to −20.0‰. However, the average δ¹³C value of lichens is the highest (−23.6 ± 2.8‰) among King George Island plants, followed by grasses (−25.6 ± 1.7‰), mosses (−25.9 ± 1.6‰), liverworts (−26.3 ± 0.5‰) and algae (−26.3 ± 1.2‰), partly related to habitats controlled by water availability. The δ¹⁵N values of moss samples range widest (−9.0 to 22.8‰, with an average of 4.6 ± 6.6‰). Lichens are on the average most depleted in ¹⁵N (mean = −7.4 ± 6.4‰), whereas algae are most enriched in ¹⁵N (10.0 ± 3.3‰). The broad range of nitrogen isotope compositions suggest that the N source for these Antarctic terrestrial plants is spatially much variable, with the local presence of seabird colonies being particularly significant.