Original paper

Ecological characterization of northernmost birch forests and treeline ecotones in Norway

Bandekar, Gauri; Odland, Arvid

Phytocoenologia Band 47 Heft 2 (2017), p. 111 - 124

79 references

published: Jul 20, 2017
published online: May 11, 2017
manuscript accepted: Dec 7, 2016
manuscript revision received: Dec 7, 2016
manuscript revision requested: Jul 26, 2016
manuscript received: Jan 23, 2016

DOI: 10.1127/phyto/2017/0111

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Abstract

Abstract Aims: The current paper focuses on quantifying ground vegetation, estimating age, distribution and ecological conditions in 28 birch forest stands. Another key objective of this study was to investigate whether these forests are temperature limited. We also determined if there were any significant differences in ecological conditions between forest, scattered trees and shrub plots. Study area: Sampling was conducted in northernmost birch forests (dominated by Betula pubescens) found along the coast in Finnmark (Norway). These forest limits are used to delimit the boreal biome from the alpine/arctic biome and are assumed to have a bioclimatic characterization. Methods: Soil and air temperatures were measured within selected stands and soil samples and tree cores were collected. Results: The results showed the field layer to be dominated by Empetrum-Cornus-Vaccinium, Polytrichum-Cornus and Cirsium-Viola types; the gradients between these types being explained by pH, July temperatures and thaw days. Based on the tree-ring data, the age of the trees was estimated to be 11−
77 yr. Elevated levels of calcium were evident in some of the study plots. Conclusions: We found no differences in temperature conditions and soil properties between forests, scattered trees and shrubby stands (with the exception of potassium concentration). The overall temperature conditions in present study were warmer than in other northern limit of birch forests. This suggests, that forests are probably not limited by temperature conditions, but more likely limited by strong wind, topography and absence of land further north. However, more data is necessary to confirm this hypothesis.
 Nomenclature: Plant species names follow Lid & Lid (2005). Abbreviations: ATFS = Air temperature frost sum; ATHS = Air temperature heat sum; Avg = Average annual temperature; Avg(Jan) = Average January temperature; Avg(Jul) = Average July temperature; BD = bulk density; CRL = coastal reference line; CV = Cirsium-Viola type; DBH = diameter at breast height; dd = degree days; DOY = day of year; ECV = Empetrum-Cornus-Vaccinium type; GSAT = Average air temperature during the growing season; GSL = Growing season length; GSST = Average soil temperature during the growing season; OM = organic matter; PC = Polytrichum-Cornus type; SF = Soil frozen period; SGS = Start of growing season; SM = soil moisture; Smelt = Snowmelt; SOA = species occurrence and abundance value; STFS = Soil temperature frost sum; STHS = Soil temperature heat sum; ThD = Thaw days


Keywords

air temperatureBetula pubescensbirch forestdistributiongrowing season lengthNorwaysoil propertysoil temperaturetree agetreeline ecotone