Control of carbon and nitrogen accumulation by vegetation in pristine bogs of southern Patagonia.

SCHUSTER MÜNCHBERGER, WIEBKE; KNORR, KLAUS-HOLGER; BLODAU C,; GAłKA, M.; BORKEN W; PANCOTTO V. A,; KLEINEBECKER T

SCIENCE OF THE TOTAL ENVIRONMENT

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2022

0048-9697

Peatlands are long-term sinks of carbon (C) and nitrogen (N) that are exposed to anthropogenic pressure. This has often induced a vegetation shift from peat mosses towards increasing presence of vascular plants. However, the impact of this vegetation shift on the sink function of peatlands remains unclear. To address this research gap, we studied C and N accumulation in a Patagonian cushion bog where a shift to the predominance of vascular cushion plants is a natural phenomenon since millennia. For comparison, long-term accumulation and decomposition patterns in a pristine Patagonian Sphagnum bog were studied. Thereto, we determined recent and long term rates of C and N accumulation, their within-site variability, and studied plant-macrofossils. These results were related to decomposition indicators (C/N ratio, humification index, stable isotopes) of the bog types. Despite differences in decomposition indicators, long-termrates of C accumulation were of similar magnitude in the Sphagnum (21.9 g Cm−2 yr−1) and in the cushion bog (22.2 g Cm−2 yr−1). N accumulationwas significantly lower in the Sphagnum bog (0.35 g N m−2 yr−1) compared to the surprisingly high accumulation in the cushion bog (0.55 g N m−2 yr−1). Tephra depositions in the cushion bog about 1600 cal. Years ago presumably triggered the vegetation shift towards dominance of cushion plants by a fertilization effect. C accumulation rates during past decades in the upper decimeters of peatwere four times higher in the cushion bog (245 g Cm−2 yr−1) compared to the Sphagnum bog (64 g C m−2 yr−1), but substantially decreased since the appearance of cushion