Geospatial variability of soil CO2–C exchange in the main terrestrial ecosystems of Keller Peninsula, Maritime Antarctica.

Soils and vegetation play an important role in the carbon exchange in Maritime Antarctica but little is known on the spatial variability of carbon processes in Antarctic terrestrial environments. The objective of the current study was to investigate (i) the soil development and (ii) spatial variability of ecosystem respiration (ER), net ecosystem CO 2 exchange (NEE), gross primary production (GPP), soil temperature (ST) and soil moisture (SM) under four distinct vegetation types and a bare soil in Keller Peninsula, King George Island, Maritime Antarctica, as follows: site 1: moss-turf community; site 2: moss-carpet community; site 3: phanerogamic antarctic community; site 4: moss-carpet community (predominantly colonized by Sanionia uncinata ); site 5: bare soil. Soils were sampled at different layers. A regular 40-point (5 × 8 m) grid, with a minimum separation distance of 1 m, was installed at each site to quantify the spatial variability of carbon exchange, soil moisture and temperature. Vegetation characteristics showed closer relation with soil development across the studied sites. ER reached 2.26 μmol CO 2 m − 2 s − 1 in site 3, where ST was higher (7.53 °C). A greater sink effect was revealed in site 4 (net uptake of 1.54 μmol CO 2 m − 2 s − 1 ) associated with higher SM (0.32 m 3 m − 3 ). Spherical models were fitted to describe all experimental semivariograms. Results indicate that ST and SM are directly related to the spatial variability of CO 2 exchange. Heterogeneous vegetation patches showed smaller range values. Overall, poorly drained terrestrial ecosystems act as CO 2 sink. Conversely, where ER is more pronounced, they are associated with intense soil carbon mineralization. The formations of new ice-free areas, depending on the local soil drainage condition, have an important effect on CO 2 exchange. With increasing ice/snow melting, and resulting widespread waterlogging, increasing CO 2 sink in terrestrial ecosystems is expected for Maritime Antarctica. [ABSTRACT FROM AUTHOR]