CADIC   02618
CENTRO AUSTRAL DE INVESTIGACIONES CIENTIFICAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Patterns of below ground carbon cycling in contrasting pristine bogs in southern Patagonia (Tierra del Fuego, Argentina
Autor/es:
MÜNCHBERGER, WIEBKE; MARIUSZ GAłKA; PANCOTTO V. A,; NINA REIMANN ; WERNER BORKEN; KLEINEBECKER, TILL; KNORR, KLAUS-HOLGER; CHRISTIAN BLODAU
Lugar:
Viena
Reunión:
Congreso; European Geosciences Union General Assembly 2018; 2018
Resumen:
South Patagonianpeatlands cover a wide range of the southern terrestrial area and have beenaccumulating organic material since the last deglaciation. These ecosystems are? in contrast to many northern hemisphere bogs ? virtually unaffected by humanactivities. Therefore, they provide excellent examples to study the functioning of undisturbed bog ecosystems. So far, little attention has been given to thesegreat carbon reservoirs. We aimed to investigate the below ground carboncycling patterns in two contrasting bog ecosystems in southern Patagonia,Tierra del Fuego.Sphagnum-dominated bogecosystems in Tierra del Fuego are similar to those on the northern hemisphere,while cushion plant-dominated (e.g. Astelia pumila, Donatia fascicularis) bogsare unique features of southern Patagonia. These cushion plant-dominated bogs arepredominantly located close to the coast while with increasing distance fromthe coast peatlands gradually change into Sphagnum-dominatedbogs. On the basis of 14C dates, up to 10000-year records from differentmicrosites in each bog type are presented. In order to understand the temporaland spatial variations in carbon cycling, we determined peat and carbonaccumulation rates by age-depth modelling and reconstructed the vegetationdevelopment from analyzed plant macrofossils. Further peat properties such as humificationindices obtained from FTIR spectra as well as carbon and nitrogen isotopic signalswere evaluated. While long-term peat accumulation rates werehighly different between both bog types, overall carbon accumulation rates weresimilar due to higher peat density under cushion forming vegetation. Initially,the cushion bog accumulated peat in similar rates compared to the Sphagnum bog,but accumulation rates dropped when the vegetation composition changed about3000 years ago from Sphagnum-dominated to cushion-dominated. Accordingly, thecushion peat was much more decomposed and humification indices were highercompared to the Sphagnum peat. Changes in carbon accumulation rates might beexplained by more labile litter and a dense, deep and aerenchymatic rootbiomass of A. pumila enhancing (secondary) decomposition even in deeper Sphagnumpeat layers. Our results demonstrate that vegetation composition stronglycontrols carbon cycling not only of current surface peat layers but can alsomask past dynamics in buried peat layers composed of a different vegetationtype. These results may help to improve our understanding of ecosystemfunctioning in northern bogs that are heavily disturbed by human impacts.