# Ice and fire: Norse farming at the edge of the ice cap of the Western settlement in Greenland

Elia Roulé, Natasha Roy, Ludovic Gesset, Camille Picard, Charly Massa,

Emilie Gauthier

► To cite this version:

Elia Roulé, Natasha Roy, Ludovic Gesset, Camille Picard, Charly Massa, et al. Ice and fire: Norse farming at the edge of the ice cap of the Western settlement in Greenland. Quaternary Science Reviews, 2025, 349, pp.109156. 10.1016/j.quascirev.2024.109156. hal-05038030

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# Ice and fire: Norse farming at the edge of the ice cap of the Western settlement in Greenland

Elia Roulé<sup>a,*</sup> <sup>●</sup>, Natasha Roy<sup>b</sup>, Ludovic Gesset<sup>c</sup>, Camille Picard<sup>a</sup>, Charly Massa<sup>a</sup>, Emilie Gauthier<sup>a</sup>

<figure><img src="image_3.png" /></figure>

## ARTICLE INFO

**Keywords:**

Palnology

Micro-charcoals

Greenland

Norse landnám

Western settlement

## ABSTRACT

In the late 10th century, the Norse established settlements in Greenland that lasted until the mid-15th century, driven by more than just climatic factors. These settlers introduced agropastoral practices and engaged in long-distance trade, especially in the highly prized walrus ivory. The Eastern Settlement (Eystribyggd), at 60°N, proved to be the largest and best studied settlement, in contrast to the smaller Western Settlement (Vestribyggd) at 64°N, particularly in the Kapisillit area. The Western Settlement was likely abandoned earlier than the Eastern Settlement, although the exact timing remains debated. The harsher climatic conditions may have pushed the western settlers towards a subsistence strategy focused, in addition to farming activities, on hunting and fishing. High-resolution multi-proxy analyses of lake sediments from Lake Itinera and Lake Pingu at Kapisillit, only 2 km away from the nearest Norse ruins, reveal subtle environmental changes and fire activity between 1000 and 1200 CE. These changes are characterised by a slight clearing of scrubland, including willows and alders, and an increased spread of herbaceous vegetation. Although the presence of coprophilous fungal spores suggests some herbivore activity, the data do not indicate significant grazing pressure. Instead, the declining values of these spores may reflect a decline in domesticated animals or increased hunting of wild herbivores, such as caribou, towards the end of the settlement period. After the mid-13th century, our results suggest a decrease in human influence, coinciding with the onset of the Little Ice Age. However, the reasons for the eventual abandonment of the Western Settlement remain unclear. This study provides evidence from pollen data and records of fire activity and contributes to our understanding of the complex interactions between societies and the environment, highlighting grazing and hunting pressure as key factors in vegetation change at the Western Settlement. The results highlight the complexity of interpreting environmental data, particularly in distinguishing between anthropogenic impacts and natural variability during the Norse period.

## 1. Introduction

At the end of the 10th century, Norse settlers took advantage of a climatic improvement known as the Medieval Warm Period (MWP, approximately 950 ± 300 cal CE) to establish colonies in Greenland, where they remained until the mid-15th century (Dugmore et al., 2001). These settlers imported an Icelandic lifestyle, which included agriculture and pastoralism (Arneborg et al., 2002, 2012). According to sagas and archaeological evidence, they engaged in long-distance trade with European elites, particularly in walrus ivory, a highly valued commodity

at the time (Gulløv, 2008; Lennert, 2012; Frei et al., 2015).

The Norse established two primary settlements in Greenland: the Eastern Settlement (Eystribyggð) at 60°N and the Western Settlement (Vestribyggð) at 64°N, about 450–500 km apart (Fitzhugh et al., 2000; Ogilvie et al., 2000; Sigurðsson, 2008; Massa et al., 2011; 2012; Vésteinsson, 2013; Gauthier et al., 2010; Keller, 2017). They also explored the North American coast as far as L'Anse aux Meadows in Newfoundland (Ingstad et al., 1977; 1985; Ledger et al., 2019; Kuitems et al., 2022). The Eastern Settlement was the largest, featuring numerous buildings, including farms and several churches. This settlement has

<footnote><sup>a</sup> Laboratoire Chrono-Environnement, UMR 6249 CNRS, Université de Bourgogne Franche-Comte, France</footnote>

<footnote><sup>b</sup> Centre de recherche sur la dynamique du système Terre (Geotop), Université du Québec à Montréal, Québec, Canada</footnote>

<footnote><sup>c</sup> Integrative Prehistory and Archaeological Science (IPNA/IPAS), University of Basel, Switzerland</footnote>

<footnote>This article is part of a special issue entitled: Holocene in the sub-Arctic published in Quaternary Science Reviews.</footnote>

<footnote>* Corresponding author.</footnote>

<footnote>E-mail address: elia.roule@univ-fcomte.fr (E. Roulé).</footnote>
been studied by archeologists and paleoenvironmentalists, with a
consensus that the lifestyle was heavily based on farming activities
(Fredskild, 1973; Arneborg et al., 2002; Buckland et al., 2009; Gauthier
et al., 2010, 2015; Schofield and Edwards, 2011; Massa, 2012; Edwards
et al., 2013; Ledger et al., 2014a,b; 2017).

The Western Settlement was strategically located in the sheltered
inner parts of the fjord system, where the climate was somewhat drier
(Barlow et al., 1997; Kuijpers et al., 2014) (Fig. 1a). In addition to the
Norse settlement, it is important to note that the Nuuk region has a long
history of human occupation, with evidence of people living there for
approximately 4000 years (Maxwell, 1985; Grønnow, 1996; Meldgaard,
2004). Reindeer have also been present in the region for at least 3500
years (Meldgaard, 1986), contributing to the complex interactions be-
tween human activities and their environment. The location of the
Western settlement at a more northern latitude posed greater challenges
for farming (Enghoff, 2003; Dugmore et al., 2001, 2012; Arneborg et al.,
2012). Farmsteads were spread over a much larger number of fjords in
the settlement, while areas near glaciers were used as sæters or tem-
porary settlements, with some 90 Norse sites counted (Roussell, 1936,
1941; Dugmore et al., 2012; Lennert, 2012; Madsen, 2014; Madsen and
Lennert, 2022). To reach Sandnes and the farms in the south of the
settlement, for example, you have to travel via Ameralik (also called
Lysefjord). The small part of the settlement that was located in today's

Nuup Kangerlua (Godthåbsfjord) consisted of about 25 farms and other
Norse buildings such as pens and storehouses (McGovern et al., 1996;
Arneborg et al., 2012; Madsen, 2014). This location was closer to the
walrus hunting grounds in Disko Bay, 530 km to the north (Fig. 1a),
known as "Norðursetur," making it a strategic area for resource acquisi-
tion. Archaeological evidence also indicates the presence of domestic
animals and anthrosols have been found whose formation (most prob-
ably) dates back to the early 11th century (McGovern and Jordan, 1982;
McGovern et al., 1996; Panagiotakopulu et al., 2007; Perdikaris and
McGovern, 2007, 2008; Seersholm et al., 2016; Schofield et al., 2022).
The harsh climate likely limited agricultural activities, with long and
cold winters and a relatively short growing season for vegetation,
necessitating a reliance on hunting and fishing from the outset (Barlow
et al., 1997; Panagiotakopulu et al., 2007; Commisso and Nelson, 2010;
Arneborg et al., 2012; Schofield et al., 2022).

While the Sandnes area within the Western Settlement appears to
have been the most densely populated, recent studies by Madsen and
Lennert (2022) suggest that similar farms existed in marginal areas such
as Nunatarsuaq—"the land behind the ice"—about 25 km east of Kapi-
sillit, with occupation extending from ca. 1000 to 1400 CE (Fig. 1b). The
Western Settlement seems to have been abandoned around 1350 CE,
earlier than the Eastern Settlement, according to sources like Ivar Bar-
darson (Fredskild and Humle, 1991; McGovern, 1991; Barlow et al.,

<figure><img src="image_4.png" /><figcaption>**Fig. 1.** Study location in the western settlement. A: Location of the western settlement on the map of Greenland. B: Map of the Western Settlement, showing all norse archaeological sites (black squares); C: Location of Lake Itinera and Lake Pingu in the Kapisillit area, as well as Norse ruins around (black squares). Studied lakes from Fredskild (1973); Weidick et al. (2012) Schofield et al. (2019; 2022). Archaeological sites location can be found in Fredskild (1973), in Madsen and Lennert (2022), and at https://da.nka.gl/. Map courtesy of Asiaq.</figcaption></figure>
1997; Panagiotakopulu et al., 2007; Grove, 2009; Arneborg et al., 2012).

So far, research has provided a detailed understanding of the Sandnes area (Fredskild, 1973; McGovern, 1981; Barlow et al., 1997; Jackson et al., 2018; Schofield et al., 2019). The environmental impact of Norse activities in the Kapisillit area has been less studied (Fredskild, 1973; McGovern and Jordan, 1982). However, former studies have revealed interesting evidence of human activities. For instance, pollen studies performed at Johannes Iversen Sø, a site close to Lake Pingu, provided valuable insights into the past vegetation and environmental changes during the Norse period, in particular an important fire event possibly related to the Norse landnám (Iversen, 1934, 1952, 1954; Fredskild, 1973, 1983; Fredskild and Humle, 1991). Lake Itinera, one of the focus areas of this study, was previously studied by Fredskild (1973), who reported pollen content in the oldest layers, though there was unfortunately a significant hiatus during the Norse period due to taphonomic conditions. In order to better understand the settlement of this area and in particular the possibility of a landnám characterized by a fire episode, we wanted to investigate how the Norse farmers interacted with their environment, especially in terms of agricultural practices. This study conducts high-resolution analyses, including pollen grains, non-pollen palynomorphs, and charcoal, from lacustrine cores in the Kapisillit area. The aim is to gain new insights into the millennia-long history of vegetation changes, the occurrence of wildfires or anthropogenic fire events and human impacts in this part of Greenland.

## 1.1. Study area

### 1.1.1. Geography, climate, and vegetation

The Western Settlement is located in the Kapisillit area, at the end of Nuuk's fjord, known as Godthåbsfjord (Nuup Kangerlua), approximately 75 km east of the capital, Nuuk (64-65° N, 49-51° W) (Fig. 1). This hilly landscape features mountains ranging from 500 to 1480 m above sea level (a.s.l.), with steep valley sides (Bennike, 2000; Mortensen et al., 2015; Pearce et al., 2018). The study area is situated near Kapisillit (Figs. 1c), 20 km north of the well-documented sites in Sandnes, and is characterized by a low Arctic climate (Böcher et al., 1968; Bennike, 2000). Between 1939 and 1956, the Kapisillit weather station recorded mean summer temperatures (June to August) of 9.7 °C and annual precipitation of 344 mm (Fredskild, 1996; Feilberg et al., 1984; Asiaq, 2021; Lennert, 2012, 2017; Schofield et al., 2019). The inner fjord vegetation is characterized by dwarf-shrub heath, with a dense cover of Betula nana, Betula glandulosa, Salix glauca, Alnus crispa, Empetrum nigrum, Vaccinium uliginosum, V. vitis-idaea, Rhododendron groenlandicum, and occasionally Juniperus communis (Rune, 2011).

### 1.1.2. Archaeological and historical background

In the Kapisillit area, archaeological sites from the Saqqaq and Dorset cultures, dating from 2500 BCE to 1000 CE, have been identified (Jensen, 1998; Olsen, 1998). The Thule people, predecessors of the modern Inuit, likely arrived in West Greenland around 1300 CE, entering the Nuuk region during this period (Gulløv, 1997a,b; Arneborg and Gulløv, 1998; Friesen, 2021; Park, 2023). After the Norse abandonment, most of the recent archaeological sites in the area refer to Thule culture (McGhee, 1984; Gulløv, 1997a,b; Appelt, 2005). European Moravian traders later established trading posts for the fur trade in Kapisillit during the 18th century (Appelt, 1996; Gulløv, 1983, 1997; Toft, 2016).

Thus, the majority of archaeological sites around Kapisillit, located within a 2 km radius, belong to both Norse and Thule cultural groups (Bruun, 1908, 1917; McGovern and Jordan, 1982; 1996; Asiaq, 2021). According to Mathers (2009), the Sandnes area, situated 20 km south of Kapisillit (Fig. 1b), was the center of the Western Settlement, evidenced by the presence of a church, cemetery, and blacksmith shop (Fredskild and Humle, 1991; McGovern et al., 1996). Several dating studies have been carried out at this site to refine the chronology of the Western Settlement, focusing on the large farm Sandnes (V51) (Roussell, 1932,

1936; Fredskild and Humle, 1991; McGovern et al., 1996; Arneborg et al., 1999). The archaeological footprint in the Western Settlement, especially at Sandnes, shows similarities with the farmstead in the Eastern Settlement.

So far, few studies have been conducted specifically in Kapisillit area, and the archaeological records present contradictory results, with fewer ruins linked to agropastoralism and more evidences of hunting and fishing activities (Roussell, 1932, 1936; McGovern, 1981; McGovern and Jordan, 1982; Fredskild and Humle, 1991; McGovern et al., 1996; Barlow et al., 1997; Panagiotakopulu et al., 2007; Schofield et al., 2019). Recently, a survey led by Madsen and Lennert (2022) highlighted the adaptability of the Norse, even in marginal areas like Nunatarsuaq near Kapisillit. In addition, Iversen (1934) attributed a charcoal layer in Lake Iversen So to Norse occupation, which Fredskild later found in the Itinera sequence, although taphonomic conditions did not allow it to be linked to Norse (Fredskild, 1973). Furthermore, at Sandnes, analyses by Fredskild and Humle (1991) revealed the impact of local fires on vegetation, which they attributed to human activity. According to their research, the Norse settlers initiated their colonization process, or landnám, by burning vegetation in certain areas (Fredskild and Humle, 1991). For example, Iversen (1934) identified a continuous charcoal layer beneath the Norse church at Ujarassuit (V7), located approximately 60 km north of Sandnes. This charcoal layer was also found beneath a mossy heath at the Umiviarsuk farm (V52), 3 km southeast of Sandnes (Iversen, 1934, 1952; Fredskild, 1972, 1973). These findings suggest that fire was used as a tool for land management during the early phases of Norse settlement in Greenland. Finally, it is essential to consider the possibility of long-distance transport of microscopic charcoal over hundreds of kilometers from the Canadian boreal forests. This potential was explored in studies such as those by Adolf et al. (2018) and Brugger et al. (2023), who directly observed microcharcoal in central Greenland, distant from any local fire sources. Such long-distance transport could potentially influence the charcoal records in Greenland, complicating the interpretation of local fire events.

In that context, Pingu and Itinera's lake sediment core were selected in order to determine if the Norse footprint can be compared to these kinds of previous works. The Kapisillit area, where seven farmsteads were investigated, was likely located away from the main center of the Western Settlement, so the Norse density is very low. Nonetheless, it remains challenging to precisely define the Norse environmental footprint in this part of the Western Settlement (Fredskild, 1973; Schofield et al., 2019).

Today, Kapisillit remains inhabited by a small village (approximately 50 inhabitants in 2019), established in 1927, located just behind Mount Pingu. Nearby, 5 km to the north in the same fjord, lies the modern Neriunaq farm (Dzik, 2016; Mongabay, 2020).

## 2. Material and methods

### 2.1. Coring

In 2018, two lacustrine sequences were collected using a gravity corer in Lake Itinera and Lake Pingu (Table 1). Pingu and Itinera lakes are 6 km apart from each other (Fig. 1c). The nearest Norse sites are less than 2 km away around the lakes (Lennert, 2012; Madsen and Lennert, 2022).

### 2.2. Dates and age-depth modeling

Different dating approaches, including $^{210}$Pb, $^{137}$Cs, and $^{14}$C, were combined to build a composite age-depth model, summarized in Table 2 (Appendix) (Blaauw, 2010). The $^{210}$Pb and $^{137}$Cs measurements were performed on the uppermost 4 cm of the sediment core by the Laboratoire Souterrain of Modane (Grenoble, France) and the Chrono-environment Laboratory (Besançon, France). Where possible, leaf remains were preferred for radiocarbon dating in order to avoid the
<table><caption>**Table 1**
Features of Itinera and Pingu's lakes at Kapisillit (2018–2019).</caption><thead><tr><th>Lake</th><th>Lake surface area (m²)</th><th>Catchment area (m²)</th><th>Elevation (m)</th><th>Max. depth (m)</th><th>Core code</th><th>Core length (cm)</th><th>Lake depth at coring location (m)</th></tr></thead><tbody><tr><td>Itinera</td><td>547 000</td><td>1 559 000</td><td>45</td><td>18</td><td>ITI2018P2</td><td>110</td><td>18</td></tr><tr><td>Pingu</td><td>443 000</td><td>7 199 000</td><td>50</td><td>23</td><td>PINGU18P2</td><td>100</td><td>23</td></tr></tbody></table>

<table><caption>**Table 2**
Dates and calibration ages from Lake Pingu and Itinera in Kapisillit. The calibrated median ages expressed in years BP were used to establish the age-depth relationship.</caption><thead><tr><th>Sample name</th><th>Core</th><th>Mean depth (cm)</th><th>C14-dated element/<sup>210</sup>Pb, <sup>137</sup>Cs values</th><th>Dates (2σ BP)</th><th>Dates (BCE/CE)</th></tr></thead><tbody><tr><td>ITI-2</td><td>ITI2018P1</td><td>0,5</td><td>1999,45097</td><td></td><td>1999 ± 0,7 CE</td></tr><tr><td>ITI-3</td><td>ITI2018P1</td><td>1</td><td>1972,237836</td><td></td><td>1972 ± 3 CE</td></tr><tr><td>ITI-4</td><td>ITI2018P1</td><td>1,5</td><td>1947,344517</td><td></td><td>1947 ± 7 CE</td></tr><tr><td>ITI-5</td><td>ITI2018P1</td><td>2</td><td>1913,840509</td><td></td><td>1913 ± 17 CE</td></tr><tr><td>ITI-6</td><td>ITI2018P1</td><td>2,5</td><td>1896,512701</td><td></td><td>1896 ± 21 CE</td></tr><tr><td>ITI-7</td><td>ITI2018P1</td><td>3</td><td>1878,702934</td><td></td><td>1878 ± 22 CE</td></tr><tr><td>ITI-8</td><td>ITI2018P1</td><td>3,5</td><td>1878,702934</td><td></td><td>1871 ± 19 CE</td></tr><tr><td>ITI-6-7</td><td>ITI2018P1</td><td>6,5</td><td>Twig, wood</td><td>370 ± 30</td><td>1450–1528 cal. CE (52.4%)</td></tr><tr><td>ITI-9-11</td><td>ITI2018P1</td><td>10</td><td>Twigs, wood</td><td>1520 ± 30</td><td>530–608 cal CE (77,8 %)</td></tr><tr><td>ITI-19-20</td><td>ITI2018P1</td><td>19,5</td><td>Twig and leaf fragments</td><td>1640 ± 30</td><td>362–539 cal CE (94,9%)</td></tr><tr><td>ITI Poz-114344</td><td>ITI2018P1</td><td>39,5</td><td>Betula nana leaf's fragments</td><td>2920 ± 40</td><td>1231–1003 cal. BCE (94.9%)</td></tr><tr><td>ITI 65–66 Poz-114345</td><td>ITI2018P1</td><td>65,5 (65–66)</td><td>Charcoal, leaves, seed,</td><td>3600 ± 35</td><td>2039–1881 cal. BCE (93.6%)</td></tr><tr><td>PIN-1</td><td>PINGU18P2</td><td>0,5</td><td>1878,702934</td><td></td><td>2003 ± 2 CE</td></tr><tr><td>PIN-2</td><td>PINGU18P2</td><td>1</td><td>1984,923001</td><td></td><td>1984 ± 3 CE</td></tr><tr><td>PIN-3</td><td>PINGU18P2</td><td>1,5</td><td>1962,186936</td><td></td><td>1962 ± 7 CE</td></tr><tr><td>PIN-4</td><td>PINGU18P2</td><td>2</td><td>1942,314673</td><td></td><td>1942 ± 14 CE</td></tr><tr><td>PIN-5</td><td>PINGU18P2</td><td>2,5</td><td>1942,314673</td><td></td><td>1914 ± 25 CE</td></tr><tr><td>PIN-6</td><td>PINGU18P2</td><td>3</td><td>1879,769537</td><td></td><td>1879 ± 43 CE</td></tr><tr><td>PIN-7</td><td>PINGU18P2</td><td>3,5</td><td>1809,744845</td><td></td><td>1809 ± 96 CE</td></tr><tr><td>PIN 28-29</td><td>PINGU18P2</td><td>28,5</td><td>Leafs</td><td>1035 ± 30</td><td>952–1036 cal. CE (91.4%)</td></tr><tr><td>Poz-114346</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>PIN 57,5–58,5 Poz-114347</td><td>PINGU18P2</td><td>58</td><td>Leafs</td><td>2590 ± 35</td><td>827–750 cal. BCE (85.9%)</td></tr></tbody></table>

possible "reservoir effect" (Hajdas et al., 2021). Terrestrial macro-remains such as twigs, leaves, leaf fragments, and seeds were selected with care; however, charcoal were avoided due to the risk of reworking (Table 2). The selected macro-remains were weighed and washed before being sent to BETA Analysis and Poznan Laboratories in 2019. Six additional samples were collected in 2022, which were then freeze-dried to preserve and stabilize the macro-remains for dating. The freeze-drying process consists of three main stages: freezing, primary drying, and secondary drying. First, the water in the sediments is frozen at -80 °C, a crucial step that impacts the drying process (Cook, 2007).

The age-depth model was created using "ChronoModel" software (version 3.2.3), which employs Bayesian statistical methods to refine the chronology by incorporating stratigraphic relationships. This model was developed using various chronological data points from <sup>210</sup>Pb, <sup>137</sup>Cs, and <sup>14</sup>C, constrained by a smooth model with uncertainty sources for events (HPD). We employed three chains from Monte Carlo Markov Chains (MCMC) for over 10 000 iterations. All radiocarbon dates were calibrated using IntCal20 (Reimer et al., 2020) and rounded to the nearest decade. The data are expressed consistently in calibrated CE/BCE years (Before Common Era/Common Era), with intervals at a 95% confidence level and a posteriori distribution (Dye and Buck, 2015; Lanos and Dufresne, 2019). If available, stable carbon isotope (δ<sup>13</sup>C) values were included to confirm the terrestrial origin of the plant remains, thereby ensuring the accuracy of the radiocarbon dates.

## 2.3. Palynology and non-pollen palynomorphs (NPP) analysis

A high-resolution study of pollen grains, non-pollen palynomorphs (NPPs), and microscopic charcoal was conducted and compared with sedimentological results to detect human activities and vegetation changes. Cores were sampled every centimeter, with samples taken every 0.5 cm in the uppermost 4 cm of the core. Samples were prepared for pollen analysis using standard NaOH, sieving, acetolysis, and flotation procedures (Moore et al., 1991; Nakagawa, 1998). Lycopodium tablets (Stockmarr, 1971) were added to calculate concentration and

influx data. Pollen grains were observed and quantified using a ZEISS light microscope (×40 magnification) and counted with Polycounter 3.1.4 software (Nakagawa et al., 2012). At least 300 pollen grains of terrestrial vascular plants were counted for each sample (pollen sum). Taxa were identified using palynological references (Reille, 1999; Beug, 2004) and Greenland flora references (Fredskild, 1973; Feilberg et al., 1984; Rune, 2011). Influxes and percentages for pollen and NPP taxa were calculated using TILIA (Grimm, 1991). The total sum of squares (TSS) was used for the CONISS cluster method, calculating distances through vegetation changes to create Local Pollen Zones (LPZ) based on terrestrial pollen taxa (Grimm, 1987). Exotic taxa, primarily coniferous pollen grains (Abies, Pinus, Picea), likely originated from the Canadian coast and were transported to Greenland (Rousseau et al., 2006).

Among the herbaceous taxa, we identified hygrophilous taxa, including Cyperaceae and *Equisetum*, though it is important to note that many sedge species in this environment are components of drier vegetation units. While Cyperaceae is often a dominant pollen type in Greenlandic fossil assemblages, excluding it from the pollen sum could potentially lead to an overestimation of other vegetation units, such as scrub and heathland. However, the percentages for Cyperaceae in both pollen diagrams appear to be relatively low, so this may not be a critical concern in this study. *Myriophyllum*, *Hippuris*, and *Menyanthes trifoliata* were classified as aquatic taxa. *Rumex acetosa*-type according to Beug (2004) is a type including three taxa, *Rumex acetosella*, *Rumex acetosa* and *Oxyria digyna*. However, in this part of Greenland, only *Rumex acetosella* has been identified (Rune, 2011; Schofield et al., 2019) they are both included in the *Rumex acetosella*-type. Since most plant taxa other than herbs rarely grow taller than 1 m at these latitudes, distinguishing between trees and shrubs can be challenging; therefore, they are all classified as shrubs (Böcher et al., 1968; Rune, 2011). The identification of *Betula nana* is based on several earlier works (Birks, 1968; Karlsson et al., 2008) and the current vegetation in the Kapisillit area (Rune, 2011). However, since *Betula glandulosa* also often occurs in the area, albeit in smaller quantities and can be transported over long distances, we have retained the name *Betula spp.* in our study (Clegg et al.,
2005).

Non-Pollen Palynomorphs (NPPs) were determined according to Van Geel (2001), Van Geel and Aptroot (2006), Gauthier et al. (2010), Gauthier and Jouffroy-Bapicot (2021), and the NPP Image Database (Shumilovskikh et al., 2021). NPPs include spores of fungi, algae, di-noflagellates, cyanobacteria, flatworm cocoons, or invertebrate remains (Van Geel, 2001; et al., 2003; Van Geel and Aptroot, 2006). Spores of coprophilous fungi, such as Sporormiella (HdV-113), are often associated with animal dung in the pollen rain deposition site (van Geel et al., 2003; Davis and Shafer, 2006; Davies et al., 2019; Gauthier and Jouffroy-Bapicot, 2021). It is worth noting that fungal spores generally do not travel far from their source and thus serve as good indicators of the local presence of animals. However, in lake sites, the fungal spore signature, which largely results from spores being washed into the lake, can become diluted as you move toward the center of the basin (Raper and Bush, 2009). This consideration is relevant since these sediment cores were taken from the deepest part of the lake, as indicated in Table 1.

Percentages of pollen taxa and NPPs were calculated relative to the pollen sum of terrestrial plants, excluding Cyperaceae and aquatic taxa. Additionally, NPP and terrestrial pollen taxa influxes were calculated to better understand NPP variations, particularly for obligate coprophilous and saprophilous (non-obligate coprophilous: Coniochaetaceae, Ther-momycetes, Cercophora, etc.), such as *Gelasinospora* (HdV-1), or *Con-iochaetaceae* (HdV-172), and finally fungal spores such as *Meliolia-elisii* (HdV-14), or *Geoglossum* (HdV-77) (Gauthier and Jouffroy-Bapicot, 2021). The specific NPPs identified in each group should be clarified in the dataset, as this separation is not immediately apparent in the pollen diagrams.

To explore the variation in pollen data and spores, Principal Component Analysis (PCA) was applied using XLSTAT (Lumivero, 2023). Axes were compared based on chronology and components such as the percentage of plant taxa to determine whether taxa clusters in a particular environment are connected. The datasets were standardized according to Legendre and Legendre (2012) and Greenacre and Pri-micerio (2014). Only terrestrial plants are represented in the PCA biplot analysis. Rare pollen types occurring in fewer than five samples were excluded from each dataset. The threshold of five samples was chosen based on recommendations from the literature, such as Bennett (1996), which suggests using a certain percentage within at least one sample as a criterion for pollen zone determination.

## 2.4. Sedimentology

Magnetic susceptibility (MS) and spectrometry analyses were performed using a Geotek Multi-Sensor Core Logger at the Chrono-environnement Laboratory, University of Franche-Comté. Spectrometry measurements were taken at 0.5 cm intervals using a Konica Minolta color spectrophotometer, covering the wavelength range of 400-700 nm with a 10 nm step size at each 0.5 cm interval. For carbon-to-nitrogen ratio (C/N) analysis, samples were first dried, then ground, and weighed (100-150 mg) before being treated and analyzed in a CNS elemental analyzer. The samples were treated with carbon dioxide and nitrogen gas to determine the carbon and nitrogen content. Finally, X-ray fluorescence (XRF) analysis of elemental composition was conducted using an Avaatech XRF core scanner at the Edytem Laboratory, University of Savoie-Mont-Blanc in Chambéry. The XRF measurements were also performed at 0.5 cm intervals.

## 2.5. Micro-charcoals analysis

Sampled with the same methods as for pollen, microcharcoal samples were chemically treated prior to sieving (150 µm) following established protocols (Rhodes, 1998; Clark, 1988; Ohlson and Tryterud, 2000; Carcaillet et al., 2001). The charcoal fragments were then observed using a dissecting microscope (× 50 magnification),

quantified, and their area measured for plotting in influx diagrams.

Arctic and boreal regions, particularly in Greenland, are highly sensitive to fires (Brugger et al., 2019; Stivrins et al., 2019; Gosden et al., 2022). As such, microcharcoal analysis is a valuable tool for understanding paleofire dynamics and their implications for climatic changes (Rubino et al., 2016). Microcharcoal derived from wood and leaves has been identified in the sediments of the Eastern Settlement, likely associated with Norse clearing practices during the landnám period (Ledger et al., 2017). However, caution is advised when interpreting these findings, as few sites display visible charcoal layers specifically at the time of settlement. Microscopic charcoal values in peat and lake cores, while elevated during the settlement period, often vary over time and may peak after the initial landnám.

At Sandnes, analyses by Fredskild and Humle (1991) revealed the impact of local fires on vegetation, which they attributed to human activity. According to their research, the Norse settlers initiated colonization, or landnám, by burning vegetation in certain areas (Fredskild and Humle, 1991). For example, Iversen (1934) identified a continuous charcoal layer beneath the Norse church at Ujarassuit (V7), located approximately 60 km north of Sandnes. This charcoal layer was also found beneath a mossy heath at the Umiviarssuk farm (V52), 3 km southeast of Sandnes (Iversen, 1934; Fredskild, 1972, 1973). These findings suggest that fire was used as a tool for land management during the early phases of Norse settlement in Greenland.

Finally, it is essential to consider the possibility of long-distance transport of microscopic charcoal over hundreds of kilometers from the Canadian boreal forests. This potential was explored in studies such as Adolf et al. (2018) and Brugger et al. (2023), which directly observed microcharcoal in central Greenland, distant from local fire sources. Such long-distance transport could potentially influence the charcoal records in Greenland, complicating the interpretation of local fire events.

## 2.6. Macro-remains analysis for Pingu

In the Pingu core, a layer containing organic material was identified. To assess whether these remains had been subjected to burning, a macro-remains analysis was conducted on samples taken from a depth of 24-31 cm. The volume of each sample (3 mL) was measured, and the samples were processed using a water sieve with a 200 µm mesh after being weighed in their wet state. Organic fragments were manually extracted under a stereomicroscope, and classified into categories such as fruits, leaves, moss stems, twig fragments, and charcoal. The charcoal fragments were allowed to air dry, while the smaller organic components were preserved by mixing them with alcohol and water at 6 °C. These were then further treated with 50% ethanol and 50% glycerol to ensure their stability. The residues were identified and classified using established reference studies (e.g., Rune, 2011; Lauber et al., 2012).

# 3. Results

## 3.1. Itinera

### 3.1.1. Age-depth modeling

The Itinera age-depth model spans from the present (2018, the time of sampling) to approximately 2100 ± 95 cal. BCE (Fig. 2). Since the deepest date samples were taken from 90 cm depth and our study focuses on the first 24 cm depth, the age-depth model was extrapolated to cover the entire chronological range. Most dates are established after 400 CE (at 30 cm depth). Lead and cesium values are concentrated at the top of the sequence (from 2018 to 1905 cal. CE) and probably reflect the evolving sources of lead pollution that began in North America around 1850 CE, linked to the onset of industrialization and the subsequent increase in lead deposition (Massa et al., 2015). Consequently, within the first 5 cm of the core, lead and cesium values date back from the present to around 1890 CE. From today to 1950 CE, chronological uncertainties are small (mean of 3.9 years), but they increase to
<figure><img src="image_5.png" /><figcaption>**Fig. 2.** Itinera age-depth model for the full core (70 cm depth) from the present to 2100 BCE. A: focus on the last 600 years. Number of reference points: 13. Grey-brown shaded area represents the 95.4% probability range, while the colored bars show the probability ranges of calibrated ages for individual samples a posteriori. Chrono-Model software 3.2.3.</figcaption></figure>

approximately 20.8 years beyond this period. Radiocarbon dates are more stable, with uncertainties of about 30 years (95% confidence interval). The earliest radiocarbon date is approximately 1580 ± 30 CE, and the latest is 1650 ± 35 BCE. There are no significant outliers, and the sedimentation rate is gradual and stable, with a mean annual sedimentation accumulation rate of approximately 0.15 mm/year, decreasing slightly to 0.13 mm/year in the last 5 cm at the top.

exhibiting a brown to dark brown color. Three distinct phases were identified (Fig. 3):

**Phase I-1 (111–48 cm; 3440 ± 342 cal BCE to 1393 ± 85 cal BCE):**

This phase is characterized by stable values for titanium (Ti), iron (Fe), magnetic susceptibility (–4× 10⁻⁵ SI), total carbon (TC 14–16%), and C/N ratio (10.5).

**Phase I-2 (48–3.5 cm).**

### 3.1.2. Sedimentology and lithostratigraphy

The core consists predominantly of silty clay with organic inclusions,

<figure><img src="image_6.png" /><figcaption>**Fig. 3.** Diagram of Itinera sedimentation phases by sedimentology and geochemistry: magnetic susceptibility (SIx10⁻⁵), carbon/nitrogen ratio, total carbon (TC in %), and identified elements (lead, titanium, iron), XRF. The High definition (HD) pictures of the core at the left. The orange part represents the Norse period. Based on Picard (2019).</figcaption></figure>
* **I-2.1 (48–39 cm; up to 1075 ± 109 cal BCE):** Ti and Fe levels double rapidly, accompanied by an increase in C/N to 12.5, while CT decreases by 8%.

* **I-2.2 (39–22 cm; ends at 341 ± 58 cal CE):** The sediment lightens in color. Ti stabilizes, Fe triples then drops abruptly at 33 cm (576 ± 89 cal BCE), while organic matter (CT) rises to 13%, reducing the C/N value to 10.

* **I-2.3 (22–3.5 cm; until 1881 ± 20 cal CE):** A gradual stabilization occurs, with Ti increasing by 1.5x and C/N remaining between 12 and 13.5.

**Phase I-3 (3.5–0 cm; last 150 years):** C/N decreases by 3 as organic matter increases to 10.5%. Ti is reduced by half, while magnetic susceptibility increases sharply to $17 \times 10^{-5}$ SI, accompanied by a peak in manganese (Mn) (Picard, 2019).

### 3.1.3. Palynology and micro-charcoals at Itinera

The pollen analysis of the ITI2018P2 core from Itinera Lake identifies three key zones, each reflecting distinct environmental changes over time (Fig. 4).

**Zone ITI-I (23–12 cm, ca. 350–1050 cal. CE):** This zone, spanning 350–1050 cal. CE, is characterized by a dominance of shrub taxa, with *Betula* (~40%) and *Ericaceae* (including *Vaccinium*-type and *Empetrum nigrum*) (~25%) as the most prominent. Herbaceous plants, including Poaceae and Cyperaceae, are also well-represented. Early in this zone, the variety of herbaceous taxa increases, while coprophilous fungal spores such as *Sporormiella* peak around 500 CE. *Glomus*, indicative of soil disturbance, is notable early on but later disappears. Microcharcoal levels rise slightly around 300 CE, indicating regular fire activity. Around 900 CE, shrub taxa increase like *Betula*, while coprophilous fungal spores decline, and microcharcoal spikes around 1000 CE, while exogenous taxa appear.

**Zone ITI-II.A (12–8.5 cm, ca. 1050–1300 cal. CE):** From 1050 to 1300 cal. CE, there is a reduction in shrubs (*Salix*, *Alnus*), particularly around 1100 CE. Poaceae remains stable, while hygrophilous and aquatic taxa increase slightly. *Rumex acetosella*-type shows a modest rise between 1100 and 1250 CE, coinciding with peaks in *Oenotheraceae*.

Charcoal influxes also increase, particularly between 1000 and 1100 CE, suggesting continued fire activity. During this time, *Empetrum* becomes more dominant, while *Vaccinium*-type declines. Coprophilous fungal spores decrease or disappear.

Then, herbaceous diversity increases with the addition of *Campanulaceae*, *Caryophyllaceae*, and *Artemisia*. *Juniperus*, a pioneer taxa reappears after 1250 CE, while hygrophilous and aquatic taxa decrease towards the end of this zone. *Alnus* became as well very rare at this time. Charcoal levels rise around 1200 CE and stabilize until 1400 CE. Exotic taxa decline sharply around 1300 CE, with coprophilous taxa remaining stable at around 3%. Saprophilous fungal spores increase before 1300 CE and then decline.

**Zone ITI-II.B (8.5–4.5 cm, ca. 1300–1780 cal. CE):** This zone is marked by a dominance of shrub taxa, with *Betula* remaining the most represented (~55%). Aquatic taxa and Cyperaceae increase around 1700 CE. Fungal spores, particularly HdV-200, HdV-14, and HdV-44, become more abundant towards the end of this zone. Charcoal levels see a slight rise after 1400 CE, followed by a rapid decline after 1500 CE.

**Zone ITI-III (4.5–0.5 cm, ca. 1780–2018 cal. CE):** *Betula*, *Alnus*, and *Empetrum* dominate. After 1900 CE, *Alnus* and *Salix* increase slightly, while *Betula* gradually decreases to 30%. Poaceae becomes more abundant, but herbaceous diversity, as well as hygrophilous and aquatic taxa, declines. Coprophilous fungal spores increase significantly after 1950 CE, with peaks in *Sordariaceae* and *Delitschia*. Charcoal levels peak between 1700 and 1940 CE, then decline towards 2000 CE.

### 3.1.4. Numerical analysis

The Principal Component Analysis (PCA) reveals a clear separation of the data, with the first two axes accounting for 31.37% and 15.77% of the variance, respectively (Fig. 5). PCA 1 shows positive scores for shrub taxa such as *Betula* and *Vaccinium*-type, which are typical in the scrub and heathland vegetation of the Kapisillit region (Fredskild, 1983). In contrast, negative loadings on PCA 1 are observed for Poaceae, *Empetrum*, and saprophilous and coprophilous fungal spores, suggesting the presence of herbivores. *Rumex acetosella*-type and *Plantago maritima* also appear to respond similarly, indicating their association with environments influenced by animal activity.

<figure><img src="image_7.png" /><figcaption>**Fig. 4.** Diagram of pollen percentages (simplified by keeping the main taxa for this study) for Itinera and adding the charcoal influx (ch/cm²/yr). The values for tree and shrub taxa were stacked in the diagram. The exaggeration curve factor is x 6. Exotic taxa are excluded from the pollen sum, as are hygrophilous and aquatic taxa. The orange part corresponds to the chronology of the Norse period, which is based on several previous studies on Western Settlement (McGovern, 1981; Fredskild and Humle, 1991; Barlow et al., 1997; Dugmore et al., 2001; Arneborg et al., 2002; Schofield et al., 2019).</figcaption></figure>
<figure><img src="image_8.png" /><figcaption>Fig. 5. Biplots of the PCA analysis of the relative abundance of selected pollen, NPPs and charcoal influx (nb/cm²/yr) at Itinera.</figcaption></figure>

<figure><img src="image_9.png" /><figcaption>Fig. 6. Pingu age-depth model for the full core (100 cm depth) from nowadays to 1100 BCE. A: focus on the last 600 years. Number of ref points 10; Grey-brown shaded area represents 95.4% probability range, while the colored bars show the probability ranges of calibrated ages for individual samples a posteriori. Chrono-Model software 3.2.3.</figcaption></figure>
PCA 2, on the other hand, is characterized by positive scores for *Caryophyllaceae*, *Alnus*, and *Campanulaceae*. In contrast, negative loadings for charcoal, *Empetrum*, and saprophilous spores might reflect erosion processes in the watershed, possibly linked to fire events (Matthews, 1992; Van Geel, 2001). This connection to erosion underscores the importance of considering sedimentary and lithological information, which could further elucidate the intensity of these environmental changes.

## 3.2. Pingu

### 3.2.1. Age-depth modeling

Using the same dating methods as for the Itinera core, the Pingu age-depth model covers the last two millennia (from 1100 BCE ± 35 years), though our study focuses on the upper 40 cm of the core (Fig. 6). Chronological uncertainties are minimal at the top of the core (±0.8–10 years), but increase between 1800 and 1900 CE, ranging from ±25–96 years. The sedimentation rate appears to be consistent, although this may be influenced by the limited number of dated samples. The mean annual sediment accumulation rate is approximately 0.25 mm/yr, with a slight increase to 0.44 mm/yr between 1800 and 1850 CE. Below 30 cm depth (1200 cal. BCE), the accumulation rate averages around 0.28 mm/yr and remains stable at about 0.25 mm/yr.

A radiocarbon date from a dark layer, corresponding to 1035 ± 35 cal. CE, aligns with the very beginning of the Norse period in the region. To ensure comparability with the chronology established for the Itinera sequence, the analysis of the Pingu core was similarly extrapolated for consistency.

### 3.2.2. Sedimentology and lithostratigraphy

The Pingu core is predominantly clayey with light beige layers, and three distinct phases were previously identified (Fig. 7):

**Phase P1 (99–59.5 cm; 3220 ± 124 cal BCE to 947 ± 50 cal BCE):** Titanium (Ti) shows minor fluctuations, while iron (Fe) slightly decreases (by a factor of 1.2). The total carbon (TC) ratio increases by 1%–2.5%, along with a rise in the C/N ratio to 15.

**Phase P2 (61–3.5 cm):** XRF analysis indicates variations in Ti, with

decreasing magnetic susceptibility at 37 cm (488 ± 64 cal CE) and 23 cm (1182 ± 67 cal CE). Ti drops sharply after 45 cm (10 ± 47 cal CE), reducing by a factor of 15. A notable layer of macroplant residue appears at 28 cm (P'2: 32–3.5 cm) (1014 ± 88 cal CE). After this layer, Ti increases by 1.2x before stabilizing, while TC remains relatively stable (–0.5%), and the C/N ratio increases significantly from 19 to 11 cm, stabilizing after 17 cm (1384 ± 53 cal CE).

**Phase P3 (3.5–0 cm; 1838 ± 90 cal CE to 2018 CE):** The sediment becomes darker, with a drastic decline in Ti and a decrease in the C/N ratio from 15 to 11, while TC values increase by 6% (Picard, 2019).

### 3.2.3. Palynology and micro-charcoals

Three distinct pollen zones were identified in the PINGU18P core from Lake Pingu (Fig. 8).

**P-I.A (45–38 cm; ca. 200–450 cal. CE):** First, *Betula* gradually increases to 45% around 200 CE, while *Salix* declines to 5%. Herb diversity is low, dominated by Poaceae, Cyperaceae (10%), and *Artemisia*. Aquatic taxa are prevalent before 300 CE but decline along with *Alnus* and *Salix*. Fungal spores like *Meliolia* and *Sordaria* increase slightly (2%). Charcoal influx rises to 0.6 particles/cm²/yr, stabilizing by 450 CE.

**P-I.B (38–33 cm; ca. 450–900 cal. CE):** Shrubs increase (+10%), while herbs decline (–15%). *Empetrum* decreases initially (–10%), with *Betula* varying, peaking at 60% by 550 CE. *Juniperus* becomes less common (–5%). Poaceae gives way to Cyperaceae (15%), indicating potential climatic improvement. *Sporormiella* (HdV-113) increases slightly (+2%) before declining by 650 CE. Charcoal peaks at 0.81 particles/cm²/yr, then decreases to 0.23 particles/cm²/yr by 650 CE.

**P-I.C (33–28 cm; ca. 900–1050 cal. CE):** Shrubs increase slightly around 900 CE, with *Betula* and *Alnus* stabilizing. *Empetrum* peaks at 30%, coinciding with a charcoal influx peak of 0.23 particles/cm²/yr, suggesting a local fire event. *Juniperus* declines, while *Vaccinium*, Cyperaceae, and Poaceae increase toward the end of this period. Charcoal influx gradually decreases to 0.1 particles/cm²/yr, and increases in *Glomus*, indicating soil erosion.

**P-II.A (28–22 cm; ca. 1050–1250 cal. CE):** This zone is marked by a significant increase in shrub cover, reaching 95%, which suggests a stable, dense shrubland environment, dominated by *Betula*, *Alnus*, *Salix*,

<figure><img src="image_10.png" /><figcaption>**Fig. 7.** Diagram of Pingu's sedimentation phases by sedimentology and geochemistry: magnetic susceptibility (SIx10-5), carbon/nitrogen ratio, total carbon (TC in %), and identified elements (lead, titanium, iron), XRF. The High definition (HD) pictures of the core at the left. The orange part represents the Norse period. Based on Picard (2019).</figcaption></figure>
<figure><img src="image_11.png" /><figcaption>**Fig. 8.** Pollen percentages diagram (simplified by keeping the main taxon for this study) for Pingu, and adding charcoal influx (ch/cm²/yr). Tree and shrub taxa values were merged together in the diagram. Exaggeration curve factor 6. Exotic taxa are excluded for the pollen sum, as well as hygrophilous, and aquatic taxa. The orange part correspond to the chronology of the Norse period, based on several previous studies on the Western Settlement.</figcaption></figure>

and *Juniperus*. This period also sees a reduction in the diversity of herbaceous plants followed by *Vaccinium*. Charcoal influx peaks around 1085 CE (0.5 particles/cm²/yr), likely linked to local fire events, which may have impacted the herbaceous vegetation. This is further supported by a notable decline in coprophilous fungal spores, between 1100 and 1200 CE, suggesting a decrease in herbivore activity in the area. Additionally, the appearance of taxa like *Cichorioideae* and *Plantago* around 1100 CE, followed by their rapid disappearance, could reflect short-term environmental changes. The decline of *Rumex*, *Plantago*, and Poaceae after 1100 CE coincides with peaks in *Oenotheraceae* and *Gelasinospora* (HdV-1), indicating possible fire-related disturbances. Toward the end of this zone, around 1200 CE, the reappearance of erosion-related taxa like *Glomus* (HdV-207) and *Meliolia-elisii* (HdV-14), followed by *Kretzschmaria-deusta* (HdV-44), suggests increased soil erosion in the watershed, potentially linked to reduced vegetation cover. The disappearance of *Juniperus* and the decline of *Empetrum* (2%) during this interval further reflect significant ecological shifts, with a slight recovery of Poaceae (+5%) and *Vaccinium* (15%) by 1250 CE, accompanied by more stable hygrophilous and aquatic taxa.

**P-II.B (22–16 cm; ca. 1250–1350 cal. CE):** Coprophilous spores return after 1300 CE (+10%) while *Betula* peaks at 45%, with *Glomus* and *Meliolia-elisii* (5%) increasing. *Alnus* and *Salix* are less present (10%). A drop in Cyperaceae (10%) and aquatic taxa indicate a drier heathland environment, coinciding with Poaceae and *Empetrum* (10%) becoming abundant by 1250 CE. Charcoal influx peaks at 0.75 particles/cm²/yr around 1380 CE before declining.

**P-II.C (16–8 cm; ca. 1450–1700 cal. CE):** *Alnus* increases to 20%, while *Juniperus* decreases. *Vaccinium* is replaced by *Empetrum*, while *Rumex acetosa*-type and *Artemisia* together with coprophilous fungal spores reach a small peak around 1600 CE. Charcoal remains stable until 1630 CE, peaking slightly before declining, as does *Gelasinospora* (HdV-1), which follows the charcoal influxes around 1450 CE.

**P-III.A (8–4 cm; ca. 1700–1850 cal. CE):** *Alnus* increases (20%), while *Ericaceae* and *Juniperus* decline. Herbaceous taxa remain stable, with Cyperaceae dominating. Charcoal influx decreases to 0.3 particles/cm²/yr, as well as coprophilous (2%).

**P-III.B (4–0 cm; ca. 1850–2018 cal. CE):** *Betula* decreases slightly, while *Alnus*, *Salix*, and Poaceae remain stable. *Empetrum* and *Juniperus* initially decline but recover after 1900 CE, with *Vaccinium* following. Minor peaks in *Rumex acetosa*-type and *Plantago maritima* occur, but coprophilous spores are less abundant. Charcoal influx shows minor

peaks between 1960 and 1980 CE.

### 3.2.4. Numerical analysis

PCA (Fig. 9) shows a clear separation of data, with the first two axes accounting for 25.44% and 13% of the variance, respectively. PCA 1 is characterized by positive responses from non-obligate and obligate coprophilous fungal spores, hygrophilous taxa, and *Salix*, suggesting a strong influence of herbivore presence in moist environments. PCA 2 shows negative responses from *Betula*, representing dwarf-shrub heath, and positive responses from *Juniperus* and Poaceae, likely growing on Mount Pingu's dry rock ledges.

### 3.2.5. Macro-remains

The analysis of the macro-remains from the Pingu sediment core revealed distinct patterns in the composition of mineral and organic materials. In the more mineral-rich layers (24–26 cm, 29–31 cm), the remains primarily consisted of insect fragments and eggs, along with traces of *Bosmina* sp. (Adamczuk, 2016, Fig. 14 appendix). As depth increased to around 27 cm, there was a noticeable rise in the presence of bryophytes and other organic remains, including leaves and wood fragments, while *Bosmina* remains disappeared (Table 3). The organic remains also included *Betula nana* fruits, buds, and stems of Poaceae or Cyperaceae, as well as bryophytes, gemmules, and some unidentifiable charcoal fragments. Some leaves might belong to *Ericaceae* and *Salix*, though further identification was hindered by the lack of modern comparative material. Notably, around 27 cm, the abundance of macro-plant remains increased, correlating with the decline of *Bosmina* remains, similar to observations at the beginning of the analysis (Fig. 10).

## 4. Discussion

### 4.1. Environmental conditions before the norse settlement

Our high-resolution sampling, particularly from the Pingu sequence, provides more detailed insights into the environmental conditions preceding the Norse settlement compared to previous studies (Fredskild, 1973). The Pingu sequence, with its greater number of analyzed samples, provides a more comprehensive understanding than the Itinera sequence.

During the millennium before the Norse arrival, the lake's sequences
<figure><img src="image_12.png" /><figcaption>Fig. 9. Biplots of the PCA analysis of the relative abundance of selected pollen, NPPs charcoal influx (nb/cm²/yr).</figcaption></figure>

<figure><img src="image_13.png" /><figcaption>Fig. 10. Pictures of macro-remains from Pingu. 1: Bosmina capsule head; 2: Betula nana fruit; 3: Indeterminate leave (Salix spp., or Ericaceae). © Geset (2022).</figcaption></figure>

indicate an environment dominated by dwarf shrub tundra, with *Betula*, *Salix*, *Alnus*, and *Ericaceae*. *Betula* is the dominant taxon at both sites, while *Alnus* and *Juniperus* are more prevalent near Pingu. This vegetation pattern is consistent with earlier descriptions by Fredskild (1973, 1983) and Schofield et al. (2019), which suggest that the inner fjords were sufficiently sheltered for *Alnus* to thrive, while the outer coastal regions tended to be more dominated by *Betula* and *Empetrum nigrum*. *Juniperus communis*, a xeric taxon well-adapted to Arctic conditions, likely flourished on the slopes of Mount Pingu.

The denser shrub cover in Kapisillit contrasts with the vegetation in

the Sandnes area, where *Betula* rarely exceeds 20%, and *Alnus* is less common (Schofield et al., 2019). In the Itinera sequence, an increase in Poaceae and coprophilous fungal spores suggests rising grazing pressure between 300 and 1000 CE, which probably influenced *Betula* and *Vaccinium*-type cover, as indicated by pollen results and numerical analysis (Fig. 11). In Pingu, the consistent presence of coprophilous fungal spores points to a regular herbivore presence, corroborated by Meldgaard's (1986) observations of caribou (*Rangifer tarandus*) in the Nuuk fjord region, which remain common today (Dzik, 2016).

Fire activity was regularly recorded at both Pingu and Itinera, with a higher charcoal influx observed at Pingu (Fig. 12). These charcoal records likely reflect a series of fires rather than a single event, that impacted vegetation by promoting herbaceous plant growth and contributing to local soil erosion (Van Geel, 2001; Gauthier et al., 2010; Van Geel et al., 2013). An erosive phase in Pingu's sedimentology, particularly during the macro-remains-rich layer (P-A: 44-26 cm), suggests that numerous variations in the C/N ratio may be due to successful runoff from the catchment. A significant fire event is evident between 850 and 1050 CE, with a notable increase in micro-charcoal around 820-890 CE at both sites. These charcoal influxes may be linked to the onset of the Medieval Warm Period (MWP), a well-documented climatic phase in Greenland (Hughes and Diaz, 1994; Easterbrook, 2016), that may have promoted both regional and local fires.

## 4.2. The landnám and norse farming activities

The arrival of the Norse around 1000 CE is reflected differently in the Itinera and Pingu sequences. At Itinera, due to the poor resolution, minimal vegetation changes are observed, with slight declines in *Salix* and *Alnus*, accompanied by a decrease in coprophilous fungal spores. Notably, typical farming indicators like *Rumex acetosa*-type and *Plantago maritima* are absent, which is consistent with Pingu results, where *Rumex*
<figure><img src="image_14.png" /><figcaption>**Fig. 11.** Summary figure for the multi-proxy analysis in Itinera. The High definition (HD) images of the core at the left. Pollen, NPPs, and charcoal data in percent and influxes; coprophilous and saprophilous influxes are shown in shades of grey to compare with terrestrial plant and charcoal influxes; PCA1 axis and sedimentology description. Based on McGovern (1981); Hughes and Diaz (1994); Lamoureux and Gilbert (2004); Mann et al. (2008), Cronin et al.(2010); D'Andrea et al. (2011); Grove, 2009.</figcaption></figure>

<figure><img src="image_15.png" /><figcaption>**Fig. 12.** Charcoal influx (ch/cm²/yr) comparison between Itinera (black line) and Pingu (blue line) based on the chronology (BCE/CE). Norse period in the Western settlement is in purple. Climatic period cited in this paper with overlap chronology according to McGovern (1981); Hughes and Diaz (1994); Lamoureux and Gilbert (2004); Mann et al. (2008), Cronin et al.(2010); D'Andrea et al. (2011); Grove, 2009.</figcaption></figure>

*acetosella*-type was also scarce and later disappeared. The presence of *Rumex acetosella*-type before the Norse period is consistent with earlier studies suggesting that *Rumex acetosella*, introduced to the Eastern Settlement by the Norse, had been naturally present in the Western Settlement since the mid-Holocene (Schofield et al., 2013).

The pollen data from Pingu show no significant signs of human impact around 1000 CE. However, fire activity increased, especially at ca.1050 and 1250 CE which is related to an increase in *Empetrum*-type, a taxon often linked to fires in North American boreal forests (Bell and Tallis, 1973; Buizer et al., 2012). A thick macro-remains layer around 1041–1087 CE, is associated with peaks in charcoal and fire indicators such as *Gelasinospora* (HdV-1) and *Oenotheraceae*, suggesting a localized

fire event (Fig. 13). These events may have been anthropogenic, as suggested by elevated charcoal levels throughout the Norse period, possibly associated with human activities similar to those documented at Sandnes (Fredskild and Humle, 1991; Evangelou et al., 2019).

Interestingly, Fredskild (1983) identified a similar accumulation of micro-charcoals in Lake Iversen, attributed to the landnám, despite minimal vegetation change. This pattern suggests that human-induced fires could have occurred in the area, particularly around Mount Pingu, where *Juniperus communis*, a xeric taxon, may also have been used by the Norse as fuel, potentially explaining its decline (Lehejček et al., 2017; Guðmundsdóttir, 2024).

Coprophilous fungal spores decline in Itinera and remain present in
<figure><img src="image_16.png" /><figcaption>**Fig. 13.** Summary figure for the multi-proxy analysis at Pingu. The High definition pictures of the core on the left. Macro-remains analysis in blue, highlighting the organic layer on the HD image of the Pingu core. Pollen, NPPs and charcoal data in percentages and influxes; coprophilous and saprophilous fungal spores influxes are shown in shades of grey to compare with terrestrial plant and charcoal influxes, PCA 1 and sedimentation.</figcaption></figure>

<figure><img src="image_17.png" /><figcaption>**Fig. 14.** Appendix: Macro-remains identified at Pingu. a: thorax of an adult midge; b: indeteminate egg (crustacean ?); c: chironomid capsule head; d: Betula nana bract; e: carbonised twig; f: bryophyte; g: Indeterminate leave: Betula ? Salix ? Ericaceae ?; h: Saxifragaceae leave; i: Betula nana fruit. © Gesset (2022).</figcaption></figure>

Pingu. As it is impossible to distinguish wild from domestic herbivores on this basis, we can't assume that their presence is only due to farming activities. In Itinera, the hypothesis of a possible decline of wild herbivores such as caribou during the Norse period could suggest increased hunting activities (Grønnow, 1986; Meldgaard, 1986).

Finally, the low density of Norse farmsteads in Kapisillit, coupled with human impact on vegetation observed in pollen diagrams, suggests limited grazing pressure and farming activities. However, important fires have been identified before and during the Norse period. Of course, the size of the lakes and the more regional inputs of pollen rain may account for the poor perception of human activity in the area. The

presence of fire, which can be more easily perceived in a large lake, raises the question of its human or climatic origin. This makes it difficult to determine the exact timing of Kapisillit abandonment, suggesting a general regional abandonment rather than a local migration.

While these results highlight the complexity of Norse interactions with their environment, they also underscore the resilience of Norse settlers in adapting to climatic challenges, such as the Little Ice Age (Dugmore et al., 2001; Golding et al., 2011; Arneborg et al., 2012). Despite the lack of clear human impacts, the mixed economy of the Western Settlement, involving hunting, fishing, and limited agriculture, reflects a nuanced adaptation strategy to the region's harsh
environmental conditions.

## 4.3. The Little Ice Age and modern period

The Little Ice Age (LIA) began early in Greenland, around 1250 CE (Grove, 2009; Kuijpers et al., 2014), with no clear evidence of human impact in Kapisillit, though this does not necessarily imply that the Norse had left the area. The post-Norse period at Itinera showed minimal environmental changes. In contrast, Pingu exhibited high pollen and charcoal influxes, with frequent fires likely contributing to local erosion, suggesting a drier climate during the LIA until 1840–1900 CE (Hughes and Diaz, 1994; Fischer et al., 1998; Easterbrook, 2016). As demonstrated by the large fires recorded in 2017 and 2019 on the west coast of Greenland (Gosden et al., 2022), the Greenlandic vegetation may burn. In Kangerlussuaq, pollen and charcoal analyses have revealed a very cold and dry period between 1100 and 1600 CE, with wildfire events (Strunk et al., 2024). In Kapissilit, it is difficult to differentiate the climatic signal from an eventual anthropogenic fires signal in our records, especially in the geographical area where weak precipitation (less than an average of 874 mm/yrs) can favor the start of fires (Asiaq, 2021; Lennert, 2012, 2017; Schofield et al., 2019). The size of the charcoal particles suggests that some values may represent a regional background noise (Clark, 1988). However, the area around Pingu might have been drier and rockier, allowing for local fires which could explain the weaker charcoal influxes at Itinera, likely reflecting a more regional signal.

Numerical analysis suggests that herbivory was a primary driver of vegetation changes at both sites. At Itinera, low herbivore presence favored dwarf birch and Vaccinium-type vegetation, while at Pingu, the regular presence of herbivores and fires led to an increase in fire-related taxa such as Empetrum-type (Matthews, 1992; Villeneuve-Simard and Boudreau, 2016). The higher grazing intensity around Pingu compared to Itinera is puzzling but may be related to specific caribou grazing patterns, as noted by Fredskild and Holt (1993) in the Kangerlussuaq area. These findings are consistent with a recent study in the same region, where a dry LIA favored fires in shrubs and grasslands, while herbivores were absent (Strunk et al., 2024).

Both sequences document regional global warming, showing increased plant diversity in a shrub-dominated environment with some willows, alders, and herbs. Recent climate changes are not accompanied by significant signs of human activity, despite European settlements for hunting and fur trade being established less than 10 km from the lakes (Asiaq, 2021). Erosion decreased from 1750 to 1880 CE, as indicated by XRF and Ti concentrations, with a more pronounced decline at Itinera after 1930 CE, coupled with an increase in organic matter, suggesting improved climate conditions fostering vegetation growth in the catchment (Lamoureux and Gilbert, 2004; Massa, 2012). The increase in charcoal influxes and coprophilous fungal spores in the last Itinera sample may be related to a caribou domestication experiment in the 1950s, though the resolution limits further interpretation. At Pingu, the decline in coprophilous fungal spores in the late 18th century suggests reduced herbivore presence, possibly linked to increased hunting activities, highlighting the ongoing importance of wild herbivores for the Norse and later Inuit populations in the area (Seersholm et al., 2022a,b; Strunk et al., 2024).

## 5. Conclusions

The sediment sequences from Lakes Pingu and Itinera reveal a vegetation history shaped by herbivore grazing, fire events, and local environmental conditions. However, the micro-charcoal records show distinct differences: Itinera's charcoal likely reflects regional fire

activity, particularly during the Medieval Warm Period and recent global warming, while Pingu exhibits more frequent, localized fires during the Norse period, the Little Ice Age, and after 1950 CE. The organic layer around 1050 CE at Pingu, possibly linked to a similar layer at Johannes Iversen Sø, suggests a significant fire event (Fredskild, 1983), but the data does not definitively confirm its anthropogenic origin given the medieval warming context. The chronology of Kapisillit's abandonment remains unclear, with the Little Ice Age bearing a similar environmental signature to the Norse period, promoting erosion and some fires.

Norse activities did not leave a clear or significant impact on vegetation, with grazing pressure being the primary driver of changes before and after the medieval period. In Pingu, the effects of domesticated herbivores are indistinguishable from those of wild herbivores, however the regular presence of coprophilous fungal spores from the basis of the sequence suggest caribou seasonal grazing rather than intensive farming. While this study cannot conclusively confirm or deny farming activities in the Western Settlement, it highlights the existence of natural fires throughout the last two millennia studied and suggests that hunting resources, particularly caribou, may have been a key factor in the medieval settlement of the region.

Future research should focus on increasing sediment sampling resolution and improving chronological accuracy to better distinguish between human activities and natural events during the Norse period. Incorporating multiproxy approaches, such as sedimentary DNA (sedDNA) or biomarkers, could provide a more detailed view of both plant and animal presence and help differentiate between wild and domesticated herbivores. Further analysis of charcoal morphologies and isotopic signatures may also clarify whether fires during the Norse period were human-induced. Collaboration between archaeologists, paleoecologists, and climate scientists will be essential to developing a more comprehensive understanding of Norse interactions with their environment.

## Data availability

Data will be made available on request.

## Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

## Acknowledgments

We thank all the people who have participated in this project. Julien Didier for the Sedilog and the PEA2T technical equipment (Chrono-environment laboratory), which enabled us to carry out the fieldwork and laboratory analyses; Fanny Canone for the technical pollen and charcoal preparations; We also thank the coring team from 2018 mission: Damien Rius, Laurent Millet, Natasha Roy, Simon Belle; Laurent Millet for the methodology and reviewing; Isabelle Jouffroy-Bapicot for their help in the determination of non-pollen palynomorphs; Ludovic Gesset and Caroline Schaal for the macro-remains analysis; Charly Massa for the lyophilization methodology; and Thomas Girault for the editing. Many thanks to Dominique Marguerie for the great supervision, and to all the Chrono-environment laboratory. Coring campaign, palynological and sedimentological investigations, and internships were funded by the ANR InterArctic Project (Coord. Em. Gauthier) and the Belmont-forum NICH-ACRTIC project (PI A. De Vernal).
# Appendix

<table><caption>**Table 3**
Macro-remains table from Pingu (2022).</caption><thead><tr><th>Depths (cm)</th><th></th><th>24</th><th>25</th><th>26</th><th>27</th><th>28</th><th>29</th><th>30</th><th>31</th></tr></thead><tbody><tr><td rowspan="5">Macro-remains</td><td>Betula nana fruit</td><td>1</td><td>0</td><td>0</td><td>0</td><td>1</td><td>2</td><td>0</td><td>0</td></tr><tr><td>Leaves</td><td>1</td><td>1</td><td>2</td><td>16</td><td>19</td><td>6</td><td>1</td><td>0</td></tr><tr><td>Buds</td><td>0</td><td>0</td><td>3</td><td>8</td><td>23</td><td>4</td><td>0</td><td>0</td></tr><tr><td>Poaceae/Cyperaceae fragment</td><td>0</td><td>0</td><td>0</td><td>7</td><td>0</td><td>0</td><td>0</td><td>0</td></tr><tr><td>Indeterminate roots fragments</td><td>0</td><td>0</td><td>0</td><td>4</td><td>0</td><td>0</td><td>0</td><td>0</td></tr><tr><td rowspan="2">Bryophytes remains</td><td>Bryophyte leaves</td><td>19</td><td>8</td><td>9</td><td>339</td><td>40</td><td>6</td><td></td><td></td></tr><tr><td>Bryophyte steam</td><td>1</td><td></td><td>2</td><td>59</td><td>28</td><td>1</td><td></td><td></td></tr><tr><td rowspan="2">Charcoals</td><td>Macro-charcoals</td><td>1</td><td>14</td><td>12</td><td>17</td><td>21</td><td>11</td><td>33</td><td>11</td></tr><tr><td>Wood fragments</td><td>1</td><td></td><td></td><td>26</td><td>16</td><td>3</td><td></td><td></td></tr><tr><td rowspan="2">Invertebrates remains</td><td>Bosmina sp. (Antenules pairs)</td><td>6</td><td>107</td><td>91</td><td>13</td><td>97</td><td>82</td><td>111</td><td>72</td></tr><tr><td>Insects and crustacean indet.</td><td>20</td><td>27</td><td>19</td><td>8</td><td>16</td><td>16</td><td>7</td><td>10</td></tr><tr><td rowspan="3">Indeterminates</td><td>Indeterminates sum</td><td>47</td><td>44</td><td>8</td><td>35</td><td>66</td><td>36</td><td>26</td><td>11</td></tr><tr><td>Macro-remains total sum</td><td>97</td><td>201</td><td>149</td><td>533</td><td>328</td><td>165</td><td>178</td><td>104</td></tr><tr><td>Macro-remains/mL</td><td>32</td><td>67</td><td>75</td><td>178</td><td>109</td><td>55</td><td>89</td><td>52</td></tr></tbody></table>

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