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

We report abundance of C-13 and N-15 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 delta C-13 and delta N-15 values between -29.0 and -20.0aEuro degrees and between -15.3 and 22.8aEuro degrees, 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 C-3 photosynthetic pathway. Lichens are characterized by the widest carbon isotope range, from -29.0 to -20.0aEuro degrees. However, the average delta C-13 value of lichens is the highest (-23.6 +/- A 2.8aEuro degrees) among King George Island plants, followed by grasses (-25.6 +/- A 1.7aEuro degrees), mosses (-25.9 +/- A 1.6aEuro degrees), liverworts (-26.3 +/- A 0.5aEuro degrees) and algae (-26.3 +/- A 1.2aEuro degrees), partly related to habitats controlled by water availability. The delta N-15 values of moss samples range widest (-9.0 to 22.8aEuro degrees, with an average of 4.6 +/- A 6.6aEuro degrees). Lichens are on the average most depleted in N-15 (mean = -7.4 +/- A 6.4aEuro degrees), whereas algae are most enriched in N-15 (10.0 +/- A 3.3aEuro degrees). 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.