Natural and Human-Transformed Vegetation and Landscape Reflected by Modern Pollen Data in the Boreonemoral Zone of Northeastern Europe
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Article Natural and Human-Transformed Vegetation and Landscape Reflected by Modern Pollen Data in the Boreonemoral Zone of Northeastern Europe Normunds Stivrins 1,2,3,* , Agrita Briede 1, Dace Steinberga 4, Nauris Jasiunas 1, Jurijs Jeskins 4, Laimdota Kalnina 1,3, Alekss Maksims 4, Zigmars Rendenieks 1 and Liva Trasune 1,5 1 Department of Geography, University of Latvia, Jelgavas iela 1, LV-1004 Riga, Latvia; [email protected] (A.B.); [email protected] (N.J.); [email protected] (L.K.); [email protected] (Z.R.); [email protected] (L.T.) 2 Department of Geology, Tallinn University of Technology, Ehitajate tee 5, EE-19086 Tallinn, Estonia 3 Lake and Peatland Research Centre, LV-4063 Aloja, Latvia 4 Department of Geology, University of Latvia, Jelgavas iela 1, LV-1004 Riga, Latvia; [email protected] (D.S.); [email protected] (J.J.); [email protected] (A.M.) 5 Department of Geosciences and Geography, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland * Correspondence: [email protected] Abstract: Modern pollen composition obtained from waterbody surface sediment represents sur- rounding vegetation and landscape features. A lack of detailed information on modern pollen from Latvia potentially limits the strength of various pollen-based reconstructions (vegetation composition, climate, landscape, human impact) for this territory. The aim of this study is to compare how modern pollen from natural and human-made waterbodies reflects the actual vegetation composition and landscape characteristics. Modern pollen analyses from surface sediment samples of 36 waterbodies Citation: Stivrins, N.; Briede, A.; from Latvia alongside oceanic-continental, lowland-upland, urban-rural and forested-agricultural Steinberga, D.; Jasiunas, N.; Jeskins, J.; Kalnina, L.; Maksims, A.; Rendenieks, gradients have been studied. In addition, we considered the dominant Quaternary sediment, soil Z.; Trasune, L. Natural and type and land use around the studied waterbodies in buffer zones with widths of one and four km. Human-Transformed Vegetation and The information on climate for the last 30 years from the closest meteorological station for each Landscape Reflected by Modern study site was obtained. Data were analyzed using Pearson correlation and principal component Pollen Data in the Boreonemoral analysis. Results show that relative pollen values from surface sediment of waterbodies reflect Zone of Northeastern Europe. Forests dominant vegetation type and land use. Modern forest biomass had a positive correlation with pollen 2021, 12, 1166. https://doi.org/ accumulation rate, indicating the potential use of pollen-based forest biomass reconstructions for the 10.3390/f12091166 boreonemoral zone after additional research and calibration. Received: 20 July 2021 Keywords: forest; agriculture; natural; urban; lake; pond; Latvia; CORINE Accepted: 25 August 2021 Published: 28 August 2021 Publisher’s Note: MDPI stays neutral 1. Introduction with regard to jurisdictional claims in published maps and institutional affil- Pollen is one of the most abundant microfossils (sub-fossils) preserved in sediment iations. archives, whose sedimentary assemblages are related to regional and local vegetation [1,2]. Whilst fossil pollen can be found in lake sediments extending back for thousands of years, modern pollen surface samples are a component of that fossil record found in the last decades. Modern pollen samples from lake surface sediment reflect differences in vegetation in a similar way to moss pollsters, pollen traps, and might be combined for Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. vegetation or climate calibration purposes [3]. This article is an open access article In a time when the modeling approach is significantly expanding, the production distributed under the terms and of raw data is less attractive to new and established researchers because it is time- and conditions of the Creative Commons labor-consuming. Nevertheless, modeling of climate, environmental change, forest biomass Attribution (CC BY) license (https:// reconstructions or distribution of biota, vegetation functionality and phylogenetic diversity creativecommons.org/licenses/by/ require input data and validation [4–9]. Although limited in spatial coverage and affected 4.0/). by uncertainties [10], proxy records are used in model-data comparisons and quantitative Forests 2021, 12, 1166. https://doi.org/10.3390/f12091166 https://www.mdpi.com/journal/forests Forests 2021, 12, x FOR PEER REVIEW 2 of 15 Forests 2021, 12, 1166 2 of 15 require input data and validation [4–9]. Although limited in spatial coverage and affected by uncertainties [10], proxy records are used in model-data comparisons and quantitative synthesessyntheses [ 11[11,12].,12]. ForFor example,example, climateclimate modelsmodels areare commonly commonly validatedvalidated againstagainst proxy-proxy- basedbased (e.g., (e.g., pollen) pollen) reconstructions. reconstructions. These These models models should should be ablebe able to reproduce to reproduce past climatepast cli- andmate vegetation and vegetation change change to be useful to be inuseful future in projectionsfuture projections (e.g., [13 (e.g.,]). To [13]). improve To improve our ability our toability reconstruct to reconstruct environments environments and climate, and modernclimate, proxymodern calibration proxy calibration studies along studies climatic along andclimatic ecological and ecological gradients gradients are needed. are Modernneeded. pollenModern surface pollen samplessurface samples currently currently have a lowhave spatial a low resolutionspatial resolution in Latvia, in i.e.,Latvia, 10 samplesi.e., 10 samples [14], therefore [14], therefore lacking lacking the full the potential full po- estimatedtential estimated current, current, past and past possible and possible future natural future andnatural anthropogenic and anthropogenic processes. processes. TheThe aim aim of of this this study study is is to to compare compare how how modern modern pollen pollen from from natural natural and and human- human- mademade waterbodies waterbodies in in Latvia, Latvia, northeastern northeastern Europe Europe reflect reflect actual actual vegetation vegetation composition composition andand landscape landscape characteristics. characteristics. ForFor thethe firstfirst timetime inin Latvia, Latvia, modern modern pollenpollen fromfrom 36 36 water- water- bodybody sediment sediment surfaces surfaces were were analyzed analyzed and and compared compared with with local local vegetation vegetation composition, composition, biomass,biomass, dominant dominant Quaternary Quaternary sediment sediment type type and and climate. climate. 2.2. Materials Materials and and Methods Methods 2.1.2.1. Study Study Sites Sites ◦ ◦ TheThe study study sites sites are are situated situated 55–58 55–58°N N and and 20–28 20–28°E E in in Latvia, Latvia, northeastern northeastern Europe Europe (Figure(Figure1 ;1; Table Table2) in1) in the the hemiboreal hemiboreal forest forest zone, zone, which which is characterizedis characterized by by a mixturea mixture of of coniferousconiferous and and deciduous deciduous tree tree species, species, such such as as the the Norway Norway spruce spruce ( Picea(Picea abies abies),), Scots Scots pine pine (Pinus(Pinus sylvestris sylvestris),), birch birch (Betula (Betulaspp.), spp.), alder alder ( Alnus(Alnus glutinosa glutinosa, Alnus, Alnus incana incana),), wych wych elm elm ( Ulmus(Ulmus glabraglabra),), European European ash ash ( Fraxinus(Fraxinus excelsior excelsior),), small-lived small-lived lime lime ( Tilia(Tilia cordata cordata)) and and pedunculate pedunculate oakoak ( Quercus(Quercus robur robur).). FigureFigure 1. 1.Study Study area area in in Europe Europe ( A(A)) and and the the location location of of waterbodies waterbodies in in Latvia Latvia used used in in current current article article (B): 1—Lake Liepājas, 2—Lake Durbes, 3—Dam Alsungas, 4—Lake Ķikuru, 5—Lake Pinku, 6— (B): 1—Lake Liepajas,¯ 2—Lake Durbes, 3—Dam Alsungas, 4—Lake K, ikuru, 5—Lake Pinku, 6— Pond Cūku, 7—Lake Usmas, 8—Lake Sūnezers, 9—Lake Lielais Pēterezers, 10—Lake Rūmiķis, 11— Pond Cuku,¯ 7—Lake Usmas, 8—Lake Sunezers,¯ 9—Lake Lielais Peterezers,¯ 10—Lake Rumi¯ k, is, Lake Vēžezers, 12—Lake Saldus, 13—Dam Vaides, 14—Lake Talsu, 15—Lake Sasmakas, 16—Lake 11—Lake Vežezers,¯ 12—Lake Saldus, 13—Dam Vaides, 14—Lake Talsu, 15—Lake Sasmakas, 16— Sesavas, 17—Lake Lielais Vipēdes, 18—Lake Vaskaris, 19—Lake Velnezers, 20—Lake Sekšu, 21— Lake Sesavas, 17—Lake Lielais Vipedes,¯ 18—Lake Vaskaris, 19—Lake Velnezers, 20—Lake Sekšu, Lake Mazais Baltezers, 22—Lake Lilastes, 23—Lake Āraišu, 24—Lake Trikātas, 25—Lake Bricu, 26— ¯ 21—LakePond Esplan Mazaisādes, Baltezers, 27—Lake 22—Lake Gubiščes, Lilastes, 28—Lake 23—Lake MazaisAraišu, Stropu, 24—Lake 29—Lake Trik Lielaisatas,¯ Stropu, 25—Lake 30—Lake Bricu, 26—PondGluhoje, 31—Lake Esplanades,¯ Lielais 27—Lake Svētiņ Gubišˇces,28—Lakeu, 32—Lake Čertoks, Mazais 33—Lake Stropu, Puderova 29—Lakes, 34—Lake Lielais Stropu,Zosnas, 30— 35— ˇ LakeLake Gluhoje, Dagdas, 31—Lake36—Pond Lielais Dagdas. Sv etiRoman¯ n, u, 32—Lake numbersCertoks, indicate 33—Lakecontinentality Puderovas, index zones: 34—Lake I—weak, Zosnas, II— 35—Lakemoderate, Dagdas, III—average, 36—Pond IV—strong. Dagdas. Roman numbers indicate continentality index zones: I—weak, II—moderate, III—average, IV—strong. Forests 2021, 12, 1166 3 of 15 Table 1. Study sites and related information. Coordinates,