Site-specific climatic signals in stable isotope records from Swedish pine forests

0494151 - ÚVGZ 2019 RIV DE eng J - Journal Article
Esper, J. - Holzkamper, S. - Büntgen, Ulf - Schöne, B. - Keppler, F. - Hartl, C. - St. George, S. - Riechelmann, D. F. C. - Treydte, K.
Site-specific climatic signals in stable isotope records from Swedish pine forests.
Trees: structure and function. Roč. 32, č. 3 (2018), s. 855-869. ISSN 0931-1890. E-ISSN 1432-2285
Institutional support: RVO:86652079
Keywords : summer temperature-variations * north-atlantic oscillation * lignin methoxyl groups * tree-ring delta-o-18 * water-use efficiency * whole wood * oxygen isotopes * carbon isotopes * past millennium * relative sunshine * delta C-13 * delta O-18 * Pinus sylvestris L. * Microsite * Dendrochronology * Sweden
OECD category: Forestry
Impact factor: 1.799, year: 2018

We produced twentieth century stable isotope data from Pinus sylvestris trees near lakeshores and inland sites in northern Sweden (near Kiruna) and central Sweden (near Stockholm) to evaluate the influence of changing microsite conditions on the climate sensitivity of tree-ring delta C-13 and delta O-18. The data reveal a latitudinal trend towards lower C and O isotope values near the Arctic tree line (-0.8 parts per thousand for delta C-13 and - 2.4 parts per thousand for delta O-18 relative to central Sweden) reflecting widely recognized atmospheric changes. At the microsite scale, delta C-13 decreases from the dry inland to the moist lakeshore sites (- 0.7 parts per thousand in Kiruna and - 1.2 parts per thousand in Stockholm), evidence of the importance of groundwater access to this proxy. While all isotope records from northern and central Sweden correlate significantly against temperature, precipitation, cloud cover and/or drought data, climate signals in the records from moist microsites are consistently stronger, which emphasizes the importance of site selection when producing stable isotope chronologies. Overall strongest correlations are found with summer temperature, except for delta O-18 from Stockholm correlating best with instrumental drought indices. These findings are complemented by significant positive correlations with temperature-sensitive ring width data in Kiruna, and inverse (or absent) correlations with precipitation-sensitive ring width data in Stockholm. A conclusive differentiation between leading and co-varying forcings is challenging based on only the calibration against often defective instrumental climate data, and would require an improved understanding of the physiological processes that control isotope fractionation at varying microsites and joined application of forward modelling.
Permanent Link: http://hdl.handle.net/11104/0287410