Studia Quaternaria, vol. 31, no. 1 (2014): 51–60. DOI: 10.2478/squa-2014-0005 LATE HOLO CENE CHANGES IN VEGE TA TION OF THE MR¥GOWO LAKELAND (NE POLAND) AS REGIS TERED IN THE POLLEN RECORD FROM LAKE SALÊT Marta Szal1, Mi ros³awa Ku pry janowicz1, Mariusz Wyczó³kowski2 1 Insti tute of Biol ogy, Uni ver sity of Bia³ystok, Œwierkowa 20b, 15-950 Bia³ystok, Poland; e-mail: [email protected], [email protected] 2 Wojciech Kêtrzyñski Museum, Plac Zamkowy 1, 11-400 Kêtrzyn, Poland; e-mail: [email protected] Ab stract Pol len anal y sis of sedi ments from the upper part of bot tom de posits from Lake Salêt al lowed re con struc tion of main stages of the Late Ho lo cene veg e ta tion trans for mation in the Mr¹gowo Lake Dis trict (from ca. 3600 cal. years BC) and to cor re late some of these changes with im migra tion and eco nomic ac tiv ity of lo cal hu man groups. Signif i cant spread - ing of sec ond ary semi-nat u ral birch for est, de vel op ment of horn beam for est and in creas ing im por tance of anthro- pogenic open com mu ni ties were the most char ac ter is tic fea tures of veg e ta tion evo lu tion. A def i nite break down of elm took place be tween 2900 and 2500 cal. years BC, slightly af ter in creased con tri bu tion of birch in woodlands. Dis ap - pear ance of ha zel around 1200 cal. years BC, ac compa nied by ex pan sion of horn beam has been ob served and should be linked with ac tiv ity of the Z¹bie-Szestno type cul ture and the Lusatian cul ture tribes during the Bronze Age, but not with a cli mate change. Con sid er able in ten si fi ca tion of set tle ment pro cesses re corded in the youn ger part of the Subat- lantic chronozone was one of the im por tant rea sons that were re sponsi ble for quick changes in for est struc ture. Strong and con tin ued de for es ta tion started as early as the end of the 10th cen tury AD and was substan tially inten si fied in the first half of the 13th century. Key words: veg e ta tion trans for ma tions, Late Ho lo cene, pol len anal y sis, Mr¹gowo Lake Dis trict, Masuria, NE Po land. Manuscript re ceived 28 October 2013, accepted 14 May 2014 IN TRO DUC TION From a paleoecological per spec tive north east ern Poland Pollen analy sis is one of the most widely used re search is an inter esting re gion, because it is under influ ence of a tools in paleoecology that helps in detect ing re sponses of nat- tran sitional cli mate (e.g. Woœ 1999). Oc currences of differ - u ral vege ta tion to human im pacts through history, as well as ent air masses have wide range of in fluence upon natu ral dis- to climate and envi ron men tal change on a vari ety of tem po ral tri bu tions of plants typ i cal for both the mar i time (e.g. Cla- and spa tial scales (e.g. Prentice, 1988; Hunt ley, 1990). Pol- dium mariscus and Juncus subnodulosus) and the boreal cli- len records have been used to study biostratigraphy, veg eta - mate (among others: Polemonium caeruleum, Nymphaea tion patterns and agrarian history of the Masurian Lakeland candida and Nuphar pumila; Ga³ka et al., 2014). Such spe- for many years. Among the sites that have been paly no logi- cific char ac ter of this part of Po land is re flected also in geo- cal ly exam ined within mod ern standards, only a few in - bo tani cal divi sion of the country, in which it was in cluded in cluded pollen sequences cover ing the Subatlantic chrono- the Masuria-Belarus North Divide (Matuszkiewicz 2008). zone. These were pol len se quences from: Lake Miko³ajskie Palaeo eco logi cal re search in this area is a key to un der stand - (Ralska-Jasiewiczowa, 1966), Lakes Kruklin, Mamry and ing of mecha nisms and reasons for plant migra tion (Kupryja- Ta³ty (Stasiak, 1967, 1971), Lake Dga³ Wielki (Filbrandt- nowicz 2008; Lamentowicz et al., 2008). To assess, to what Czaja, 2000), Lakes Mi³kowskie, Wojnowo and £azduny, extent the records from mari time and more conti nental re- for mer Lake Staœwiñskie and the Szczepanki site (Wacnik, gions are dif ferent from one another, more research and espe - 2009a, b; Wacnik et al., 2012a), Wielkie B³oto mire (Kar- cially multi-proxy in ves ti ga tion is needed. piñska-Ko³aczek et al., 2013) and Skaliski Forest (Ko³aczek Ar chae ol o gists have al ready dem on strated a spe cific and et al., 2013). However, beyond the profiles described by unique char ac ter of eco nomic ac tiv ity in north east ern Po land Wacnik (2009a, b; Wacnik et al., 2012a) most studied se- in re lation to central Europe (e.g. Okulicz 1973; Karczewski quences were poorly supported by ra diocar bon dating, or the 2011). A partic u lar feature of this area was a prolonged ex is- ages were miss ing. This fact re stricted pos si ble re con struc - tence of for ag ing and a very late ac cep tance of farming as the tion of rate of envi ron men tal changes and their corre la tion basis for food procure ment, in contrary to the rest of Poland with ar chae o log i cal, his tor i cal and cli ma tic data. (Wacnik et al., 2012a). 52 M. SZAL et al. The lake is of glacial ori gin and is located in a depres sion surrounded by morainic hills. Steep escarp ments, over 10 m high, slope down to the water surface on both eastern and west ern lakesides; whereas northern and southern slopes are more gentle. The lake is divided into two parts – the smaller, northern part is named Lake Salêt Ma³y and the larger south- ern part is Lake Salêt Wielki (Fig. 1). Max i mum wa ter depth is 17.2 m and mean depth is 4.9 m (Jañczak, 1999). The lake is fed by a single stream and in ad dition to surface runoff, an inflow of shallow under ground water from the sur round ing mo raine up land is prob a bly also pos si ble. The veg eta tion around Lake Salêt is almost de void of forest and indi cates substan tial anthropogenic changes. The forest occurs in 10% of the area only whereas most is occu - pied by grass lands: meadows and pastures 30%, ar able land of 60%. A land strip of 500 m around the lake is overgrown by her ba ceous veg e ta tion, with scat tered trees oc cur ring near build ings, along roads and streams and at the lakeshore only. Coring and dat ing In winter 2010 a core of sedi ments was taken from the Fig. 1. Lo ca tion of Lake Salêt and cor ing site. frozen sur face of Lake Salêt with the use of the Wiêc- kowski’s piston corer and the Kajak gravity corer. Cor ing was per formed close to the deep est part of the lake (wa ter This study is focused on recon struc tion of the Late Holo - depth 15 m), with bottom depos its 15.70 m thick (Fig. 1). The cene vege ta tion changes in the Mr¹gowo Lake District, present pa per deals with a top part of the log only (depth to based on pollen analy sis and supported by AMS radio car bon 10.80 m). This part of the core is com posed of calcar e ous dating. The pri mary aim was to present veg eta tion devel op - gyttja, rich in organic matter and rela tively poor in sand, clay ment in the surround ings of Lake Salêt from ca. 3600 cal. and silt. years BC and to pro vide data for eval u ation of woodland AMS ra dio car bon dat ing of seven pol len con cen trate trans for ma tion by a man. samples was per formed in the Gliwice Ab so lute Dat ing Meth ods Centre (Table 1). The isola tion of pollen con cen- MA TE RIAL AND METH ODS trates from the sed iment was per formed by re moval of cal - cium carbon ate using 38% HCl and humic acids, us ing 10% Descrip tion of the study site KOH and 2–4 cm2 of sedi ment was used for this purpose. Lake Salêt (53°56'22.09"N, 21°19'20.19"E) is a eutro- Short-lived radionuclides 210Pb were measured in the up- phic water body with area of 327.7 hect ares (Jañczak, 1999). per most layer, 30 cm thick. The anal ysis was car ried out in It is lo cated be tween the villages Szestno, Ruska Wieœ, the In stitute of Geolog i cal Sciences of the Polish Academy of Brodzikowo and Wyszembork in the centre of the Mr¹gowo Sci ences in War saw.