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Climate, Norway

Seppa H.,University of Helsinki | Schurgers G.,Lund University | Miller P.A.,Lund University | Bjune A.E.,University Research Climate | And 4 more authors.

Palaeoecological records provide a rich source of information to explore how plant distribution ranges respond to climate changes, but their use is complicated by the fact that, especially when based on pollen data, they are often spatially too inaccurate to reliably determine past range limits. To solve this problem, we focus on hazel (Corylus avellana), a tree species with large and heavy fruits (nuts), which provide firm evidence of the local occurrence of species in the past. We combine the fossil nut records of hazel from Fennoscandia, map its maximum distribution range during the Holocene thermal maximum (HTM) and compare the fossil record with the Holocene hazel range shift as simulated by the LPJ-GUESS dynamic vegetation model. The results show that the current northern range limit of hazel in central and eastern Fennoscandia is constrained by too short growing seasons and too long and cold winters and demonstrate that the species responded to the HTM warming of about 2.5°C (relative to the present) by shifting its range limit up to 63–64°N, reached a rough equilibrium with the HTM climatic conditions and retreated from there to about 60°N during the last 4000 years in response to the late-Holocene cooling. Thus, the projected future warming of about 2.5°C would reverse the long-term southward retraction of species’ northern range limit in Europe and is likely to lead to hazel being a common, regeneratively reproductive species up to 63–64°N. In addition to the accuracy of the projected warming, the likelihood of this scenario will depend on inter-specific competition with other tree taxa and the potential of hazel to migrate and its population to grow in balance with the warming. In general, the range dynamics from the HTM to the present suggest a tight climatic control over hazel’s range limit in Fennoscandia. © The Author(s) 2015. Source

Battarbee R.W.,University College London | Lamb H.,Aberystwyth University | Bennett K.,Queens University of Belfast | Edwards M.,University of Southampton | And 9 more authors.

We describe the career of John Birks as a pioneering scientist who has, over a career spanning five decades, transformed palaeoecology from a largely descriptive to a rigorous quantitative science relevant to contemporary questions in ecology and environmental change. We review his influence on students and colleagues not only at Cambridge and Bergen Universities, his places of primary employment, but also on individuals and research groups in Europe and North America. We also introduce the collection of papers that we have assembled in his honour. The papers are written by his former students and close colleagues and span many of the areas of palaeoecology to which John himself has made major contributions. These include the relationship between ecology and palaeoecology, late-glacial and Holocene palaeoecology, ecological succession, climate change and vegetation history, the role of palaeoecological techniques in reconstructing and understanding the impact of human activity on terrestrial and freshwater ecosystems and numerical analysis of multivariate palaeoecological data. © The Author(s) 2015. Source

Bjune A.E.,University Research Climate | Bjune A.E.,University of Bergen | Grytnes J.-A.,University of Bergen | Jenks C.R.,University of Bergen | And 2 more authors.

Palaeoecology and ecology have a lot in common. However, the two disciplines have evolved almost separately, leading to an ongoing debate on how to link them better, as both would undoubtedly benefit from a higher degree of cross-fertilisation of ideas, research insights and questions. In this paper, we explore similarities and differences in the two branches of ecology over the past 40 years by assessing the publication output from an unusually large cohort of ‘academic siblings’ – researchers in ecology and palaeoecology who all share one of the strongest career-shaping influences on researchers; their supervisor. This was made possible by John Birks’ long and active career within ecology and palaeoecology, and his supervision of a large number of students in both fields (n = 12 and 21, respectively). Among them, John Birks’ academic progeny has published 934 papers in the international peer-reviewed literature. We collected information on the year, titles, keywords and journals of all these publications and used these data to assess the extent of, and find potential explanations for, the historical and present-day separation of ecology and palaeoecology. Despite considerable thematic overlap, there is a real and possibly widening division between the two branches that is visible both at the scale of individual research careers, journals and papers. We argue that rather than being unique to the relationship between palaeoecology and ecology, this reflects trends for thematic and methodological specialisation evident across the research landscape. We propose that both individual researchers and journals would benefit from, and can contribute to, closing the gaps developing between various ‘special branches’ in science. A good title, an informative abstract, a careful and thought-through selection of keywords and a focus on readability and avoidance of jargon will likely improve readership and impact both within one’s own ‘special branch’ and beyond. © The Author(s) 2015. Source

Felde V.A.,University Research Climate | Felde V.A.,University of Bergen | Peglar S.M.,University of Bergen | Bjune A.E.,University Research Climate | And 4 more authors.

The relationships between modern pollen and floristic plant richness, diversity and evenness are assessed using pollen assemblages and associated vegetation data from 52 lakes along an elevational and vegetational gradient in the Setesdal valley of south-central Norway. Various data transformations were applied to minimise bias in the vegetation and pollen datasets. Plant species were transformed to their pollen or spore equivalents to reduce taxonomic biases. Pollen counts were transformed using Andersen’s general pollen-representation values for northern European trees and shrubs and the Regional Estimates of Vegetation Abundance from Large Sites (REVEALS) model with pollen-productivity estimates (PPEs) appropriate for Setesdal to minimise pollen-representation bias. Pollen count-size bias (before or after transformation) was eliminated by rarefaction analysis based on bootstrap resampling. Richness and diversity were quantified using Hill numbers (N0, N1, N2), and evenness was estimated as the ratios of N0, N1 and N2. Diversity partitioning was used to estimate β diversity. The strongest correlations between pollen and plant richness and diversity are with pollen counts transformed using Andersen’s representation values and rarefied to a common count size and with plants transformed to their pollen equivalents. However, if sites from the low-alpine zone are excluded where there are high values of far-transported tree pollen, the richness and diversity relationships are also statistically significant for untransformed pollen data and plants transformed into their pollen equivalents. The effects of data transformation on diversity partitioning and estimates of β diversity are explored. We demonstrate that there are statistically significant positive relationships between pollen and plant richness and diversity along the entire elevational gradient after transforming the datasets to minimise biases due to taxonomic differences, differential pollen representation, and pollen-count size, and similar significant positive relationships along the forested parts of the gradient (nemoral, boreonemoral, southern boreal, middle boreal) after transforming the datasets to minimise biases due to taxonomic differences and pollen-count size. © 2015, © The Author(s) 2015. Source

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