Project Details
Projekt
Siberian fire regime shifts during interglacials of the last 3.6 Myrs inferred from sedimentary records of Lake El’gygytgyn (NE Asia)
Applicant
Professorin Dr. Elisabeth Dietze
Subject Area
Geology
Physical Geography
Physical Geography
Term
from 2019 to 2023
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 419058007
Predicting and adapting to the impacts of ongoing and future climate change for society requires a deep understanding of internal natural feedbacks at the Earth surface beyond the influence that humans exert on natural ecosystems. The high-northern boreal and tundra biomes are especially sensitive to climate change and play a fundamental role in global biophysical and biogeochemical cycles, for example via their fire regime. However, the long-term feedbacks between fire, vegetation and climate are largely unknown, especially from Eastern Siberia, although long-term natural variability strongly influences short-term variability. Highly uncertain is, if and how currently increasing temperatures over the Arctic and increasing fire activity are already an indication for shifts in fire regimes and if they will be accompanied by biome shifts. The project studies northeastern Siberian fire regime shifts during multiple Plio-Pleistocene interglacials using the only continuous sedimentary record covering the last 3.6 Myrs, i.e., from Lake El’gygytgyn (ICDP Site 5011-1). Focusing on interglacials of different strengths (maximum temperature), biome configurations (tundra, summergreen boreal or evergreen boreal forest) and global land-ocean-atmosphere boundary conditions, I aim to answer the timely questions on what drove long-term shifts in fire regimes in higher latitudes – climate or vegetation, and which internal fire-permafrost erosion feedbacks stabilized or destabilized vegetation types. Regional fire regimes will be reconstructed using (i) sedimentary charcoal composition and influxes as proxies for high-intensity, stand-replacing fires and associated fuels, common in modern evergreen boreal forest, and, from the same samples, (ii) new sedimentary proxies for low-temperature fires – the molecular markers levoglucosan and its isomers, representing the surface fire regime in modern summergreen boreal larch forests.The project renewal aims to shift the focus in the reconstruction of fire histories to warmer-than-present interglacials and determine source-area specific fire regime shifts for the Early Pleistocene in comparison to the Late Pleistocene. To assess the drivers of fire regime shifts, fire records will be statistically compared with quantitative land cover reconstructions from pollen records and independent climate reconstructions from the same site and global compilations. To assess if frequent fires affected permafrost degradation and sediment erosion, the fire records will be statistically compared with regional and local erosional proxies derived from a re-evaluation of existing grain size data sets using end-member modelling analysis. This will allow to conceptualize time-scale dependent fire-climate-vegetation-permafrost relationships under warmer-than-Holocene climates – suitable for the parametrization of fire-vegetation models required for future predictions of high-northern environmental change.
DFG Programme
Infrastructure Priority Programmes
International Connection
USA
Cooperation Partners
Dr. Isla S. Castañeda; Professor Joe McConnell, Ph.D.
Co-Investigators
Professorin Dr. Ulrike Herzschuh; Dr. Kai Mangelsdorf
