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European Journal of Applied Sciences – Vol. 12, No. 1

Publication Date: February 25, 2024

DOI:10.14738/aivp.121.16320

Kullman, L., & Öberg, L. (2024). Mt. Åreskutan Nunatak: An Arboreal “Roadmap” to the Paleobiogeograpy of the Swedish Scandes

and a Possible Pointer Towards a Future Revival of a Richer and More Biodiverse Mountainscape. European Journal of Applied

Sciences, Vol - 12(1). 219-242.

Services for Science and Education – United Kingdom

Mt. Åreskutan Nunatak: An Arboreal “Roadmap” to the

Paleobiogeograpy of the Swedish Scandes and a Possible

Pointer Towards a Future Revival of a Richer and More

Biodiverse Mountainscape

Leif Kullman

Department of Ecology and Environmental Science

Umeå University, SE-901 87 Umeå, Sweden

Lisa Öberg

oldTjikko Photo Art & Science

Handöl 544, SE-837 71 Duved, Sweden

ABSTRACT

In the context of proposed future anthropogenic climate warming, the present

study accounts for arboreal responses to recent temperature rise, viewed in the

perspective of Lateglacial and early Holocene climate and ecosystem variability. As

an analogue to a future warmer world, the focus is on an early deglaciated nunatak

in the southern Swedish Scandes, Mt. Åreskutan, with a well-researched arboreal

history, embracing periods of climate warming of present-day extent. New research

from this and adjacent localities challenges traditional historical narratives, which

fail to provide a true picture of deglaciation and vegetation history. It is increasingly

evident that common boreal tree species grew close to this summit in a climate, 2-3

°C warmer than at present, during the Lateglacial and early Holocene periods

16 800- 6000 years ago. Based on minimal temperature requirements for tree

growth, future warming of the same magnitude would be sufficient for trees to

reclaim their lost ground close to this peak. Recent observations of tree saplings

and the emergence of genuine “forest plants” at these high elevations, indicate that

dispersal mechanisms will not constrain this progressive process. Conceivably, it

will not manifest as advancement of a broad forest front. History suggests that

pockets of trees, with a ground cover of boreal plant species, will establish in local

favourable niches, e. g. sites of vanished glaciers and perennial snow beds. Much of

the present-day alpine tundra may be more conservative and resilient to tree

invasion, as evident from insignificant upslope movement of forest limits in

response to modern climate warming. By and large, continued warming is no

imminent threat to alpine biodiversity. An open and diverse high-mountain

landscape is likely to prevail.

Keywords: Treeline, nunatak, climate change, megafossils, paleobiogeography, Holocene,

Swedish Scandes

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European Journal of Applied Sciences (EJAS) Vol. 12, Issue 1, February-2024

INTRODUCTION

Global warming since more the 100 years is a meteorological reality, particularly amplified in

northern and high-altitude regions already by the 1920s -1930s. This course of change is

associated with large and predominantly progressive repercussions for biota, physical

landscape and human society. However, the common and widespread perception of this

development is that it represents a serious and imminent threat to man and planet Earth. This

alarmistic and dystopic view is purported to the public and media by the prestigious

International Council of Climate Change (IPCC) and its followers, which downgrade natural

climate history and rely more on immature and unvalidated numerical models. The latter fail

to reproduce recurrent natural climate changes in the long-term past (e.g., Karlén 1988;

Hormes et al. 2001; Bengtsson et al. 2004) and to deliver reliable and useful climate

projections for the future. In fact, modern warming is within natural Holocene climate

variability (Vinós 2022).

Alpine and subalpine regions are supposed to display early signal and account of

profound geoecological and phytogeographical changes attributable to putative

anthropogenic and unprecedented climate warming (Moen et al. 2004; ACIA 2005; Kaplan &

New 2006; Gottfried et al. 2012). This alarmistic climate view has prompted some scientists to

ventilate doubt as to the realism and strength of these model projections, often based on

“worst-case” climate change scenarios and neglecting robust paleoperspectives on climate

and vegetation (cf. Idso 1998; Bengtsson, Semenov & Johannessen 2004; Walther, Beissner

& Burga 2005; Karlén, 2008; Ljungqvist 2009: Humlum et al. 2011; Hausfather & Peters

2020).

With this general background, our objective is to provide the best available view of past and

recent climate-driven landscape change in the high-altitude Swedish Scandes and to

complement projective biogeographic models with robust observational and paleecological

data. As focus object, we chose Mt. Åreskutan, an iconic object in Scandinavian paleogeograhy,

also displaying detailed data on arboreal and general vegetation responses to recent climate

change (Kullman 2002a, b). In addition, an independent model has projected the future

treeline rise by 600 m, in the case of a 3 °C warming, on this specific mountain (Boer et al.

1990).

Moreover, Mt. Åreskutan has been in the centre of a controversy concerning the date of

deglaciation and late-glacial arboreal performance. Kullman (2000, 2002) presented robust

megafossil data, showing unequivocal presence of mountain birch (Betula pubescens ssp.

czerepanovii), spruce (Picea abies) and pine (Pinus sylvestris), as early as about 16 000 cal. a

BP, close to the summit 300-400 m higher than present-day treelines. This is about 6000 and

more years earlier than previous estimates of local deglaciation. These megafossil

dates also represent the first presence of tree growth in the Scandes, in conflict with

inferences by less precise methods, e.g., pollen analysis and terrestrial cosmogenic

nuclide (TCN) analysis (Tallantire 1977; Kleman et al. 1997; Johnsen 2010; Stroeven et al.

2016).

Not surprisingly, these new and unorthodox results were heavily attacked by defenders of the

old paradigm with the simple and negative argument that they deviated from established

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Kullman, L., & Öberg, L. (2024). Mt. Åreskutan Nunatak: An Arboreal “Roadmap” to the Paleobiogeograpy of the Swedish Scandes and a Possible

Pointer Towards a Future Revival of a Richer and More Biodiverse Mountainscape. European Journal of Applied Sciences, Vol - 12(1). 219-242.

URL: http://dx.doi.org/10.14738/aivp.121.16320

truth (Birks, Larsen & Birks 2005, 2006; Johnsen 2010). These opinions were viewed in a

wider perspective and refuted by some authors (Kullman 2005, 2006, 2008; Parducci et al.

2012; Nota, Klaminder, Milesi 2022). To make doubly likely, late-glacial tree remains have

been recovered at widely distributed sites along the Swedish Scandes (Kullman 2002a, 2017b;

Öberg & Kullman 2011; Kullman & Öberg 2015, 2020). Taken together, these paleo-arboreal

results, based on megafossils, provide profound implications for the comprehension of

Lateglacial climate and paleogeography of the Scandes. In addition, the precision of some

traditional paleoenvironmental research approaches and biogeographical histories are

challenged in general. It needs to be realized that positive records of megafossils do

trump most other approaches concerning presence of species and deglaciation (cf. Paus

& Haugland 2017; Kullman 2018b; Odland & Paus 2021). The presented early dates of

arboreal presence represent a “roadmap” of fixed points, that future students of high- mountain paleogeography have to relate to. The main objective of the present study is to add

detail to previous late-glacial records of megafossil tree remnants, recovered at high

elevations on Mt. Åreskutan (Kullman 2002a, b) and questioned by some authors (see above).

In analogy, and based on these data, the likely course of change in a putative warmer future

climate will be tentatively outlined. For that purpose, recent trends in treeline positions and

plant cover in general are highlighted and considered.

Radiocarbon dates are given as calibrated years BP (cal. a BP; present1950 calibrated in CALIB

8.20 (Stuiver et al. 2021) using the Intcal20 data set (Reimer et al. 2020). In the text, the

intercept values of radiocarbon age with the calibration curve are used for simplicity. Original

data are derived from Kullman (2002).

STUDY AREA

Mt. Åreskutan (1420 m a.s.l.), is an isolated massif, located somewhat to the east of the main

Scandes mountain change in central Sweden, 63° 26 ́N, 13° 06 ́E (Fig.1). The relief, built by

schists and highly fissured Seve amphibolite, is alpine in its upper parts. Adjacent valley

bottoms are about 1000 m below the summit. Proximity to the Norwegian Sea and low passes

to the west support a local maritime and humid macroclimate (Raab & Vedin 1995). The nearest

official weather station Storlien/Visjövalen (642 m a.s.l.) displays mean temperatures

(1991-2020) for the summer and winter periods; June-August, December-February and the

year, 12.3, -5.5 and 2.0 °C, respectively. During the years 1980-1998 an automatic weather

station was operated about 1 km to the west of the main study site, 1280 m a.s.l. Mean

temperatures for June-August, December-February and the year were 5.8, -8.2 and -2.2 °C,

respectively. The last-mentioned figures match temperatures extrapolated from the Storlien/

Visjövalen station and a lapse rate of 0.6 °C per 100 m altitude (Laaksonen 1976). Summer

(J.J.A.) and winter (D.J.F.) temperature evolution 1901-2023 displays regional warming by 1.4

°C and 1.9 °C, respectively (Kullman & Öberg 2023). Here concerned megafossils were

retrieved from a site, close to the summit, 1360-1370 m a.s.l. This locality is a flat surface at the

base of a steep south-facing slope, characterized as a minor glacier/ice patch cirque

(Borgström 1989). A rock wall provides protection from prevailing westerly winds and

enables accumulation of a huge and late-lying snowdrift, occupying a topographic niche in the

steep slope (1360-1400 m a.s.l.), and adjacent parts of the flat area below (Figs. 2-4). At the

present time, snow prevails here well into mid-July or early August. The melting snow feeds

two small pools, interconnected by a wet moss carpet area, predominantly, Warnstorfia