20th century Betula pubescens subsp. czerepanovii tree- and forest lines in Norway

Abstract

BackgroundGeoreferenced tree- and forest line data has a wide range of applications and are increasingly used for e.g. monitoring of climate change impacts and range shift modelling. As part of a research project, registrations of previously re-mapped tree- and forest lines have been georeferenced. The data described in this paper contains 100 re-mapped registrations of Betula pubescens subsp. czerepanovii throughout Norway. All of the re-mapped tree- and forest line localities are georeferenced, elevation and aspect are given, elevational and spatial uncertainty are provided, and the re-mapping methods are explained. The published data weremapped for the first time between 1819 and 1963. The same sites were re-mapped between 1928 and 1996, but have until now been missing spatial coordinates. The entries contain 40 x 2 tree lines and 60 x 2 forest lines, most likely presenting the regionally highest registered tree- and forest lines at the given time. The entire material is stored and available for download through the GBIF server.New informationPreviously, the entries have been published in journals or reports, partly in Norwegian or German only. Without the provision of the spatial coordinates, the specific locations have been unknown. The material is now available for modelling and monitoring of tree- and forest line range shifts: The recordings are useful for interpretation of climate change impacts on tree- and forest lines, and the locations of re-mapped tree- and forest lines can be implemented in future monitoring projects. Since the recordings most likely provide the highest registered Betula pubescens subsp. czerepanovii locations within their specific regions, they are probably representing the contemporary physiognomic range limits.

Elevational treeline and forest line dynamics in Norwegian mountain areas – a review

“…Thus, knowledge about methods and related uncertainties that were used to identify the original locations and to resample them is needed in order to assess the uncertainty of any measured change. The authors of the publications reviewed for this article used a variety of methods to study TFL changes: for 69% of the remeasured locations their measurements were based on in situ remeasurement, 15% on measurements of the elevational difference between old and young mountain birch forest or between empirical and climatic forest lines, 12% on maps, aerial photographs and satellite images, 3% on oral information, and 1% on other sources (see Online Appendix 2 for locations; additionally, all single point measurements by Aas (1969) are included, see Bryn and Potthoff (2017) for locations).…”

“…For the 100 single locations (see Bryn and Potthoff 2017 for a map) for which we carried out an accuracy assessment, we in general assumed that in situ measurements and comparisons of empirical and climatic forest lines using a barometer would give intermediate elevational precision (± 10 m a.s.l.) (81 locations) (Bryn and Potthoff 2017). Additionally, we assumed that comparison of old and young forests, map comparisons, and comparison with an old photo would result in a low precision (± 25 m a.s.l.)…”