Spatially varying peatland initiation, Holocene development, carbon accumulation patterns and radiative forcing within a subarctic fen

QUATERNARY SCIENCE REVIEWS

卷:248

Article

Piilo, Sanna R.^1,2  Korhola, Atte^1,2  Heiskanen, Lauri³  Tuovinen, Juha-Pekka³  Aurela, Mika³  Juutinen, Sari^1,2  Marttila, Hannu⁴  Saari, Markus⁴  Tuittila, Eeva-Stiina⁵  Turunen, Jukka⁶  Valiranta, Minna M.^1,2 

[1] Univ Helsinki, Fac Biol & Environm Sci, Ecosyst & Environm Res Programme, ECRU, POB 65, Helsinki 00014, Finland

[2] Helsinki Inst Sustainabil Sci HELSUS, Helsinki, Finland

[3] Finnish Meteorol Inst, Erik Palmenin Aukio 1, Helsinki 00560, Finland

[4] Univ Oulu, Energy & Environm Engn Res Unit, POB 4300, Oulu 90014, Finland

[5] Univ Eastern Finland, Sch Forest Sci, POB 111, Joensuu, Finland

[6] Geol Survey Finland, Environm Solut Peatland Use & Resource Econ, POB 96, Espoo 02151, Finland

关键词: Aapa mire;    Carbon dynamics;    Lateral expansion;    Autogenic succession;    Paleoecology;    Vegetation dynamics;    Climate variation;    High latitudes;   

DOI  :  10.1016/j.quascirev.2020.106596

来源: Elsevier

【 摘 要 】

High latitude peatlands act as globally important carbon (C) sinks and are in constant interaction with the atmosphere. Their C storage formed during the Holocene. In the course of time, the aggregate effect of the C fluxes on radiative forcing (RF) typically changes from warming to cooling, but the timing of this shift varies among different peatlands. Here we investigated Holocene peatland development, including vegetation history, vertical peat growth and the lateral expansion of a patterned subarctic fen in northern Finland by means of multiple sampling points. We modelled the Holocene RF by combining knowledge on past vegetation communities based on plant macrofossil stratigraphies and present in situ C flux measurements. The peatland initiated at ca. 9500 calibrated years Before Present (cal yr BP), and its lateral expansion was greatest between ca. 9000 and 7000 cal yr BP. After the early expansion, vertical peat growth proceeded very differently in different parts of the peatland, regulated by internal and external factors. The pronounced surface microtopography, with high strings and wet (larks, started to form only after ca. 1000 cal yr BP. C accumulation within the peatland recorded a high degree of spatial variability throughout its history, including the recent past. We applied two flux scenarios with different interpretation of the initial peatland development phases to estimate the RF induced by C fluxes of the fen. After ca. 4000 cal yr BP, at the latest, the peatland RF has been negative (cooling), mainly driven by C uptake and biomass production, while methane emissions had a lesser role in the total RF. Interestingly, these scenarios suggest that the greatest cooling effect took place around ca. 1000 cal yr BP, after which the surface microtopography established. The study demonstrated that despite the high spatial heterogeneity and idiosyncratic behaviour of the peatland, the RF of the studied fen followed the general development pattern of more southern peatlands. Holocene climate variations and warm phases did not seem to induce any distinctive and consistent peatland-scale patterns in C accumulation, whereas our data suggests that the changes in vegetation related to autogenic succession were reflected in the C accumulation patterns and RF more clearly. (C) 2020 Elsevier Ltd. All rights reserved.

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