Abstract
Trees growing at their altitudinal or latitudinal distribution in Fennoscandia have been widelyused to reconstruct warm season temperatures, and the region hosts some of the world’slongest tree-ring chronologies. These multi-millennial long chronologies have mainly beenbuilt from tree remains found in lakes (subfossil wood from lake-shore trees). We used aunique dataset of Scots pine tree-ring data collected from wood remains found on a mountainslope in the central Scandinavian Mountains, yielding a chronology spanning over much ofthe last 1200 years. This data was compared with a local subfossil wood chronology with theaim to 1) describe growth variability in two environments during the Medieval ClimateAnomaly (MCA) and the early Little Ice Age (LIA), and 2) investigate differences in growthcharacteristics during these contrasting periods. It was shown that the local tree-line duringboth the MCA and early LIA was almost 150 m higher that at present. Based on living pinesfrom the two environments, tree-line pine growth was strongly associated with mid-summertemperatures, while the lake-shore trees showed an additional response to summerprecipitation. During the MCA, regarded to be a period of favourable climate in the region,the tree-ring data from both environments showed strong coherency and moderate growthvariability. In the early LIA, the two chronologies were less coherent, with the tree-linechronology showing more variability, suggesting different growth responses in the twoenvironments during this period of less favourable growing conditions. Our results indicatethat tree-ring width chronologies mainly based on lake-shore trees may need to be reevaluated.
Highlights
With a growing number of climate proxies extending over several centuries, the understanding of past climate variability during the last two millennia has significantly increased in many parts of the world over the last few decades
A good example of the latter is the recent efforts of the PAGES 2K consortium, who utilized a wide range of climate proxies with different time resolution to reconstruct temperature variability over the last two millennia for all the continental regions of the world (Kaufman et al, 2013; PAGES 2k Consortium, 2013), which has significantly increased our understanding of spatiotemporal temperature variability across the world
The other pronounced period, between ca 1300 and 1500 CE corresponds to the early part of the Little Ice Age (LIA, ibid.) After ca 1500, there is a sharp decline in the drywood sample number, until the inclusion of samples from living trees in the 1800s
Summary
With a growing number of climate proxies extending over several centuries, the understanding of past climate variability during the last two millennia has significantly increased in many parts of the world over the last few decades. Tree-ring data are the most utilized proxy for inferring late Holocene high-resolution climate variability, mainly at high-latitudes This is due to the possibility of gaining annually resolved data that can be calibrated against observational records. Several of the world’s longest tree-ring chronologies, widely used in regional to global temperature reconstructions, come from Fennoscandia (Linderholm et al, 2010) In this region there are good possibilities to find long-lived trees (up to 700 years old) without too much human impact on their growth environments, and trees that have been preserved in peat bogs and lakes, so called subfossil wood, for centuries to millennia (Gunnarson, 2001). Snags (i.e., deadwood found on standing or lying on the ground) may be found, but this is quite rare since it is a source for fire wood and has been depleted over the centuries, even in the more remote parts of the region
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
