Acta Palaeobotanica 53(2): 235–261, 2013 DOI: 10.2478/acpa-2013-0012 Vegetation changes and human activity around Lake Łańskie (Olsztyn Lake District, NE Poland) from the mid Holocene, based on palynological study JACEK MADEJA Department of Palaeobotany and Palaeoherbarium, Institute of Botany, Jagiellonian University, Lubicz 46, 31-512 Kraków, Poland; e-mail: [email protected] Received 3 September 2013; accepted for publication 24 November 2013 ABSTRACT. Bottom sediments of Lake Łańskie in NE Poland (Olsztyn Lake District) were studied by pollen analysis, and vegetation changes from ca 4800 BC to modern times were reconstructed based on the results. Due to rapid sedimentation the changes in plant cover are recorded with high resolution. The variation of pollen spectra composition reflects changing shares of deciduous trees and the continuous dominance of pine forest. Nowadays the surroundings of Lake Łańskie are also heavily forested but as early as 1100 AD the deciduous trees began to be eliminated. On the basis of pollen data, five phases of increased human activity were distin- guished. Based on the available archaeological chronology of local settlements, the first stage is connected with para-Neolithic groups of Ząbie-Szestno type and the Lusatian culture. They are followed by the West Baltic Barrow culture, Wielbark culture and Early Medieval Prussian tribes. The pollen record shows low intensity of exploitation of the terrain around Lake Łańskie, probably attributable to the brevity of episodes of human occu- pation in the near vicinity of the lake. The last phase, covering part of the Middle Ages (since ca 1000 AD) and modern times, is reflected in the most distinct vegetation changes on the pollen diagram, caused by increased intensity of settlement. In spite of the distinct diminution of forest cover around the lake the scale of deforesta- tion was much lower than at other sites in NE Poland. The main aims of this paper were to describe the changes in the palaeoenvironment which took place around Lake Łańskie (Olsztyn Lake District) and to find those changes in the plant cover which were the effect of human activity, and to confirm whether the changes of palaeoenvironment around Lake Łańskie were noted at the same time in adjacent areas. KEYWORDS: palynology, human impact, vegetation history, settlement history, late Holocene, NE Poland INTRODUCTION The Mazurian Lake District, with its selected for study because it comes from a site specific natural environment, is also distin- of archaeological investigations on a former guished by the record of the particular pop- island of Lake Łańskie where remnants of ulation groups that lived there at the Neo- human groups connected with assemblages lithic/Bronze Age transition, described as of Ząbie-Szestno type were identified, as well forest zone or para-Neolithic societies (Mana- as traces of tribes representing younger cul- sterski 2009). To reconstruct the vegetation tures. This paper describes the phases of cover changes there, including those caused vegetation development in the surroundings by human activity, bottom sediments from of Lake Łańskie and assesses the extent of Lake Łańskie in NE Poland (Fig. 1) were human impacts on the natural environment studied by pollen analysis. This material was from the end of the Atlantic period. 236 Fig. 1. Map of Poland and location of Olsztyn Lake District If we include only the palynological sites PREVIOUS PALYNOLOGICAL STUDIES that have been studied following recently IN THE REGION adopted standards and which relate to postgla- cial plant cover changes, it is evident that the The history of palynological studies carried majority of pollen sites in the Dobrzyń-Olsztyn out in north-eastern Poland was reviewed by Lake District (region P-w) are located in its Kupryjanowicz (2008) and then Kołaczek et al. western part. However, only a few of them give (2013). It appears that palynological sites are information about regional vegetation changes not evenly distributed in the palaeogeographi- and can be used to draw isopollen maps for cal regions distinguished by Ralska-Jasiewi- Poland (Ralska-Jasiewiczowa et al. 2004). czowa (1989). Their density is greatest in the These are Lake Oleczno (Filbrandt-Czaja 1999), Great Mazurian Lake District (region P-x) and Lake Klasztorne (Noryśkiewicz 1997), Mielno Suwałki-Augustów Lake District (region P-y). (Kępczyński 1960), Steklin (Noryśkiewicz 1982, The number of sites is much lower in the much Noryśkiewicz & Ralska-Jasiewiczowa 1989), larger area of region P-w (Dobrzyń-Olsztyn Starżym (Noryśkiewicz 1987), Rudnickie Małe Lake District), which includes the Olsztyn peat-bog (Drozdowski 1974, Drozdowski & Ber- Lake District. The first palynological studies glund 1976), Napole, Czystochleb (Filbrandt- in north-eastern Poland were begun by Gross Czaja & Noryśkiewicz 2003, Filbrandt-Czaja (e.g. 1935, 1936) before World War II. Unfor- et al. 2003), and Czarne Błota (Niewiarowski tunately the lack of radiocarbon datings and & Noryśkiewicz 1983). The Woryty site, the ref- pollen counts, often limited to tree pollen, limit erence site for the Olsztyn Lake District, located their usefulness for palaeoecological inves- in the central part of region P-w (Dąbrowski tigations. That is why some regions are still 1981a, Pawlikowski et al. 1982, Noryśkiewicz poorly investigated in spite of the relatively & Ralska Jasiewiczowa 1989) is the site suit- large number of palynological sites (e.g. region able for palaeoecological comparisons nearest to P-y). the Lake Łańskie palynological site. 237 THE STUDY REGION soils, primarily peaty and gleyey soils, occur in depressions along rivers and around lakes. According to the physicogeographic divi- A special kind of intrazonal soil is gyttja soil sion of Poland (Kondracki 2002) the Olsztyn formed from lake sediments (Bednarek & Pru- Lake District (area 3820 km2) is situated at sinkiewicz 1999). the western border of the Mazurian Lake Dis- According to the geobotanical division of trict where it adjoins the Iława Lake District. Poland the Olsztyn Lake District belongs to To the east it borders the Mragowo Lake Dis- the Baltic Division, the Pomeranian Lake Dis- trict. The northern border is formed by the tricts Province and the Olsztyn Region (Szafer Old Prussian Lowland (Nizina Staropruska), & Zarzycki 1972). The diversified topography and the southern one by the Mazurian Plain and uneven distribution of lakes and rivers (Równina Mazurska) and Lubawa Hummock contribute to the formation of different habitat (Garb Lubawski). The Olsztyn Lake District types and their diversified locations. The most covers the range of the glacial Łyna lobe, significant associations among the forest com- which was separated during the last glaciation munities are Pino-Quercetum on slightly acidic (mainly the Poznań and Pomerania phases). sandy soils and Tilio-Carpinetum on fertile The traces of the glacier standstill are vis- soils. Melico-Fagetum and Luzulopilosae-Fage- ible in the form of 7 concentric curves of front tum are frequent associations, particularly in moraines running latitudinally. These hills, the western part of the region. reaching 300 m a.s.l., are intersected by rivers The potential natural vegetation of the flowing south-north, among which the Łyna Olsztyn Lake District would be formed mainly river is the largest in the region. Glacier activ- by the sub-Atlantic oak-hornbeam forest com- ity left lakes distributed mostly in the south- munity Stellario-Carpinetum in the northern ern part of the region. The biggest lakes in the and western parts, by the sub-continental Łyna river catchment are Lake Łańskie and, lime-oak-hornbeam forest Tilio-Carpinetum in a few kilometres away from it, Lake Pluszne the central and eastern parts, and by forest (surface area 9 km2, depth 52 m). The deep- communities representing the sub-continental est lake of the Mazurian Lake District, Lake oak-pine Querco-Pinetum and fresh pine Peu- Wuksniki (surface area 1.2 km2, depth 68 m), cedano-Pinetum forests in the southern sec- is in the catchment of the second-largest river, tion (Fig. 2). Locally, elm carr Fraxino-Alne- the Pasłęka, which drains the western part of tum would cover wet habitats along slowly the Olsztyn Lake District. flowing waters, and wet alder woods Carici In respect of climate the Olsztyn Lake Dis- elongatae-Alnetum may have grown in depres- trict belongs to the West Mazurian Region, sions around overgrown lakes and on peat-bog which includes the western part of the Mazu- margins (Matuszkiewicz 2008, Matuszkiewicz rian Lake District and is characterized as cold et al. 2012). The disparity between the poten- lowland climate (Woś 1999). Mean January tial and actual vegetation is due mainly to temperature varies from –2.4 to –4.0°C, mean the present dominance of pine and the sharp July temperature reaches 18.0°C, and mean reduction of forests with Quercus, Carpinus, annual temperature is 6.0–7.0°C. Winter lasts Tilia, and Alnus, caused by deforestation of ca 100 days, snow cover 70–80 days, and the their habitats for economic purposes. vegetation period 190–210 days. Mean annual precipitation is ca 600 mm, most of it falling in summer. South-west winds prevail (Woś 1999, CHRONOLOGY OF LOCAL Starkel 1999, Kożuchowski 2011). SETTLEMENT CHANGES The thickness of Quaternary sediments overlying the Cretaceous and Tertiary depos- The settlement history of the surroundings its varies between 60 and 200 m. Soil cover of of Lake Łańskie is known thanks to archaeo- the Olsztyn Lake District is formed by a com- logical work undertaken in the first half of the plex of zonal soils, mainly brown soils and 20th century. Surface surveys carried out on an podzols, which developed chiefly from fluvio- island in Lake Pluszne (site VII at Pluski) in glacial sands and boulder clays. Higher areas 1938 by L. Fromm and in 1989 by M. Hoff- often are covered by very poor rusty soils. man revealed numerous flint pieces with use- Intrazonal hydrogenic and semi-hydrogenic wear patterns and fragments of hand-made 238 Fig.