EGU22-12387
https://doi.org/10.5194/egusphere-egu22-12387
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Late Holocene permafrost development triggers hydrological and geochemical changes in subarctic peatlands (Abisko, 68ºN)

Olga Margalef1, Oriol Grau2, Hans Joosten3, Aaron Pérez Haase4, Sergi Pla Rabes5, Pere Roc Fernández5, Santiago Giralt6, Marc Sánchez7, Ramon Pérez Obiol7, Joan Manuel Soriano7, Albert Pèlachs7, Sara Campderrós5, Cristina Fernández Alarcón5, and Josep Peñuelas5,8
Olga Margalef et al.
  • 1RISKNAT Research Group, Department of Earth and Ocean Dynamics, University of Barcelona, 08028 Barcelona, Spain
  • 2Research Group Plants and Ecosystems (PLECO), Department of Biology, University of Antwerp, B-2610 Wilrijk, Belgium
  • 3Department of Peatland Studies and Palaeoecology, Institute of Botany and Landscape Ecology, Greifswald University, Partner in the Greifswald Mire Centre, Greifswald, Germany.
  • 4IRBIO, Institut de Recerca de la Biodiversitat. Departament de Biologia evolutiva, Ecologia i Ciències ambientals, University of Barcelona, 08028, Barcelona, Spain
  • 5CREAF, Center for Ecological Research and Forestry Application, 08193 Cerdanyola del Vallès, Catalonia, Spain
  • 6Geosciences Barcelona (Geo3BCN-CSIC), Lluís Solé i Sabarís s/n, 08028 Barcelona, Spain
  • 7Grup de recerca en àrees de muntanya i paisatge (GRAMP), Departament de Geografia, Autonomous University of Barcelona (UAB), 08193 Cerdanyola del Vallès, Catalonia, Spain
  • 8CSIC, Global Ecology Unit CREAF-CSIC-UAB, Cerdanyola del Vallès, 08193 Catalonia, Spain

Palsa mires are a common feature in the Subarctic zone of discontinuous permafrost. In these peatlands, the patchy distribution of frozen soil constrains relief, water regime and vegetation distribution. Because they lie at the edge of permafrost distribution, palsa mires are very sensitive to climate changes and become extremely valuable high-latitude terrestrial records. However, both (1) their origin, including their rapid development towards ombrotrophy because of uplift by ice accretion and (2) the irreversible geochemical effects of collapse and permafrost thaw make them challenging environmental archives. Understanding the Late Holocene evolution of these systems becomes a key framework to decipher potential consequences of the permafrost disappearance observed during the last decades. A 120 cm peat record was recovered on the Storflaket Palsa plateau (Abisko, Sweden, 68ºN) on June 2018.  This register contains more than 9000 years of paleoenvironmental information and was entirely made of peat, with two centimetric layers of volcanic ash interbedded at 74-77 and 46-47cm depth. A multidisciplinary approach using chemical (stoichiometry, stable isotopy and elemental composition) and biological proxies (macrofossil and pollen determination) was used to reconstruct the environmental evolution of the site. Bottom most layers (50-120cm) were characterized by peat made of different types of brown mosses and abundant aquatic fauna indicating that the area was covered by a high and stable water table that promoted organic matter accumulation in a percolation mire system. The very high accumulation rates and the extremely good preservation of macrofossil remains suggest a permafrost free area around 8000 cal yr BP. From 50 to 9 cm the peat is made of highly degraded brown moss, with increasing degradation towards the top. Chemical and macrofossil analyses indicate a strong oxidation processes due to peat exposition. The top layer (9 to 0 cm) is characterized by dry palsa peat and depicts very low accumulation rates, suggesting that this record is capturing the uplift movement of the peat mound by ice accretion and a shift from a minerotrophic and waterlogged mire system towards the development of a palsa plateau. Chemical and biological signals allow us to date the age of permafrost establishment later than 3000 cal. yr BP. The deposition of ash layers is linked to sudden inputs of phosphorus and metals leading to stoichiometric changes in peat composition.

How to cite: Margalef, O., Grau, O., Joosten, H., Pérez Haase, A., Pla Rabes, S., Fernández, P. R., Giralt, S., Sánchez, M., Pérez Obiol, R., Soriano, J. M., Pèlachs, A., Campderrós, S., Fernández Alarcón, C., and Peñuelas, J.: Late Holocene permafrost development triggers hydrological and geochemical changes in subarctic peatlands (Abisko, 68ºN), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12387, https://doi.org/10.5194/egusphere-egu22-12387, 2022.

Displays

Display file