Permafrost Biases Climate Signals in δ<sup>18</sup>O<sub>tree-ring</sub> Series from a Sub-Alpine Tree Stand in Val Bever/Switzerland
During recent decades, stable oxygen isotopes derived from tree-ring cellulose (δ<sup>18</sup>O<sub>TRC</sub>) have been frequently utilised as the baseline for palaeoclimatic reconstructions. In this context, numerous studies take advantage of the high sensitivity of trees c...
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MDPI AG
2021-06-01
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| Series: | Atmosphere |
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| Online Access: | https://www.mdpi.com/2073-4433/12/7/836 |
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| author | Jussi Grießinger Wolfgang Jens-Henrik Meier Alexander Bast Annette Debel Isabelle Gärtner-Roer Holger Gärtner |
| author_facet | Jussi Grießinger Wolfgang Jens-Henrik Meier Alexander Bast Annette Debel Isabelle Gärtner-Roer Holger Gärtner |
| author_sort | Jussi Grießinger |
| collection | DOAJ |
| description | During recent decades, stable oxygen isotopes derived from tree-ring cellulose (δ<sup>18</sup>O<sub>TRC</sub>) have been frequently utilised as the baseline for palaeoclimatic reconstructions. In this context, numerous studies take advantage of the high sensitivity of trees close to their ecological distribution limit (high elevation or high latitudes). However, this increases the chance that indirect climatic forces such as cold ground induced by permafrost can distort the climate-proxy relationship. In this study, a tree stand of sub-alpine larch trees (<i>Larix decidua</i> Mill.) located in an inner alpine dry valley (Val Bever), Switzerland, was analysed for its δ<sup>18</sup>O<sub>TRC</sub> variations during the last 180 years. A total of eight <i>L. decidua</i> trees were analysed on an individual base, half of which are located on verified sporadic permafrost lenses approximately 500 m below the expected lower limit of discontinuous permafrost. The derived isotope time series are strongly dependent on variations in summer temperature, precipitation and large-scale circulation patterns (geopotential height fields). The results demonstrate that trees growing outside of the permafrost distribution provide a significantly stronger and more consistent climate-proxy relationship over time than permafrost-affected tree stands. The climate sensitivity of permafrost-affected trees is analogical to the permafrost-free tree stands (positive and negative correlations with temperature and precipitation, respectively) but attenuated partly leading to a complete loss of significance. In particular, decadal summer temperature variations are well reflected in δ<sup>18</sup>O<sub>TRC</sub> from permafrost-free sites (r = 0.62, <i>p</i> < 0.01), while permafrost-affected sites demonstrate a full lack of this dependency (r = 0.30, <i>p</i> > 0.05). Since both tree stands are located just a few meters away from one another and are subject to the same climatic influences, discrepancies in the isotope time series can only be attributed to variations in the trees’ source water that constraints the climatic fingerprints on δ<sup>18</sup>O<sub>TRC</sub>. If the two individual time series are merged to one local mean chronology, the climatic sensitivity reflects an intermediate between the permafrost-free and –affected δ<sup>18</sup>O<sub>TRC</sub> time series. It can be deduced, that a significant loss of information on past climate variations arises by simply averaging both tree stands without prior knowledge of differing subsurface conditions. |
| first_indexed | 2024-03-10T09:59:03Z |
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| language | English |
| last_indexed | 2024-03-10T09:59:03Z |
| publishDate | 2021-06-01 |
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| spelling | doaj.art-d0d944765cec46c2a7f85be21b6310ec2023-11-22T02:06:02ZengMDPI AGAtmosphere2073-44332021-06-0112783610.3390/atmos12070836Permafrost Biases Climate Signals in δ<sup>18</sup>O<sub>tree-ring</sub> Series from a Sub-Alpine Tree Stand in Val Bever/SwitzerlandJussi Grießinger0Wolfgang Jens-Henrik Meier1Alexander Bast2Annette Debel3Isabelle Gärtner-Roer4Holger Gärtner5Institute of Geography, Friedrich-Alexander-University Erlangen-Nürnberg, 91058 Erlangen, GermanyInstitute of Geography, Friedrich-Alexander-University Erlangen-Nürnberg, 91058 Erlangen, GermanyWSL Institute for Snow and Avalanche Research SLF, 7260 Davos Dorf, SwitzerlandInstitute of Geography, Friedrich-Alexander-University Erlangen-Nürnberg, 91058 Erlangen, GermanyDepartment of Geography, University of Zürich, 8057 Zürich, SwitzerlandSwiss Federal Research Institut WSL, Forest Dynamics, Dendrosciences, 8903 Birmensdorf, SwitzerlandDuring recent decades, stable oxygen isotopes derived from tree-ring cellulose (δ<sup>18</sup>O<sub>TRC</sub>) have been frequently utilised as the baseline for palaeoclimatic reconstructions. In this context, numerous studies take advantage of the high sensitivity of trees close to their ecological distribution limit (high elevation or high latitudes). However, this increases the chance that indirect climatic forces such as cold ground induced by permafrost can distort the climate-proxy relationship. In this study, a tree stand of sub-alpine larch trees (<i>Larix decidua</i> Mill.) located in an inner alpine dry valley (Val Bever), Switzerland, was analysed for its δ<sup>18</sup>O<sub>TRC</sub> variations during the last 180 years. A total of eight <i>L. decidua</i> trees were analysed on an individual base, half of which are located on verified sporadic permafrost lenses approximately 500 m below the expected lower limit of discontinuous permafrost. The derived isotope time series are strongly dependent on variations in summer temperature, precipitation and large-scale circulation patterns (geopotential height fields). The results demonstrate that trees growing outside of the permafrost distribution provide a significantly stronger and more consistent climate-proxy relationship over time than permafrost-affected tree stands. The climate sensitivity of permafrost-affected trees is analogical to the permafrost-free tree stands (positive and negative correlations with temperature and precipitation, respectively) but attenuated partly leading to a complete loss of significance. In particular, decadal summer temperature variations are well reflected in δ<sup>18</sup>O<sub>TRC</sub> from permafrost-free sites (r = 0.62, <i>p</i> < 0.01), while permafrost-affected sites demonstrate a full lack of this dependency (r = 0.30, <i>p</i> > 0.05). Since both tree stands are located just a few meters away from one another and are subject to the same climatic influences, discrepancies in the isotope time series can only be attributed to variations in the trees’ source water that constraints the climatic fingerprints on δ<sup>18</sup>O<sub>TRC</sub>. If the two individual time series are merged to one local mean chronology, the climatic sensitivity reflects an intermediate between the permafrost-free and –affected δ<sup>18</sup>O<sub>TRC</sub> time series. It can be deduced, that a significant loss of information on past climate variations arises by simply averaging both tree stands without prior knowledge of differing subsurface conditions.https://www.mdpi.com/2073-4433/12/7/836tree-ring δ<sup>18</sup>Osignal biassporadic mountain permafrost<i>Larix decidua</i> Mill.Upper EngadinSwiss Alps |
| spellingShingle | Jussi Grießinger Wolfgang Jens-Henrik Meier Alexander Bast Annette Debel Isabelle Gärtner-Roer Holger Gärtner Permafrost Biases Climate Signals in δ<sup>18</sup>O<sub>tree-ring</sub> Series from a Sub-Alpine Tree Stand in Val Bever/Switzerland Atmosphere tree-ring δ<sup>18</sup>O signal bias sporadic mountain permafrost <i>Larix decidua</i> Mill. Upper Engadin Swiss Alps |
| title | Permafrost Biases Climate Signals in δ<sup>18</sup>O<sub>tree-ring</sub> Series from a Sub-Alpine Tree Stand in Val Bever/Switzerland |
| title_full | Permafrost Biases Climate Signals in δ<sup>18</sup>O<sub>tree-ring</sub> Series from a Sub-Alpine Tree Stand in Val Bever/Switzerland |
| title_fullStr | Permafrost Biases Climate Signals in δ<sup>18</sup>O<sub>tree-ring</sub> Series from a Sub-Alpine Tree Stand in Val Bever/Switzerland |
| title_full_unstemmed | Permafrost Biases Climate Signals in δ<sup>18</sup>O<sub>tree-ring</sub> Series from a Sub-Alpine Tree Stand in Val Bever/Switzerland |
| title_short | Permafrost Biases Climate Signals in δ<sup>18</sup>O<sub>tree-ring</sub> Series from a Sub-Alpine Tree Stand in Val Bever/Switzerland |
| title_sort | permafrost biases climate signals in δ sup 18 sup o sub tree ring sub series from a sub alpine tree stand in val bever switzerland |
| topic | tree-ring δ<sup>18</sup>O signal bias sporadic mountain permafrost <i>Larix decidua</i> Mill. Upper Engadin Swiss Alps |
| url | https://www.mdpi.com/2073-4433/12/7/836 |
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