Tree-rings are natural archives of the climate variation experienced by trees during their life span. Because trees actively discriminate against 13C versus 12C in atmospheric carbon dioxide due to environmental forcing inducing higher assimilation of 12C in optimal conditions for growth, the ratio between these two isotopes represents a record of climate variability occurring at the time of the wood formation. Therefore, the delta13C can be used to reconstruct palaeoclimate from when the trees sampled were living. As the instrumental period from meteorological methods to measure climate is relatively short (last 150 years), the calibration between delta13C time series and climatic data can be used to improve the understanding of climate variability through longer periods. The main objective of this study is to produce a consistent methodology for the reconstruction of climate and environmental forcing on trees from the high resolution delta13C time series over the period 1997-2009 at three study sites in Europe where extensive eddy covariance measurements have been conducted. This atmospheric measurement technique permits a very fine resolution to observe the exchange of gases between the atmosphere and a land surface with additional applications in meteorology. At Hyytiala, dendrometer and microcore measurements were used to test if a methodology can be developed to predict the occurrence of radial growth during years when dendrological data are missing. The modeling of the intra-annual rate of growth is then performed via the Gompertz equation. Integration of cell life time to match climate information with time delta13C series is also assessed. The delta13C signature from both inter- and intra-annual resolution are tested against three weather variables: photosynthetically active radiation, temperature and precipitation. The results show stronger linear responses from the delta13C time series of the most northern site (Hyytiala, Finland) to the weather variables while the two other study sites (Norunda, Sweden and Loobos, the Netherlands) did not show significant linear relationships at both annual and intra-annual resolution. The approach developed in this study represents a first step in developing a generic method accessible for non-specialists in dendroclimatology for the use of delta13C time series as climate archives.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:678384 |
| Date | January 2015 |
| Creators | Soudant, Alex |
| Publisher | Swansea University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://cronfa.swan.ac.uk/Record/cronfa42353 |
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