The Use of Plant Macrofossils for Paleoenvironmental Reconstructions in Southern European Peatlands

quaternary Review The Use of Plant Macrofossils for Paleoenvironmental Reconstructions in Southern European Peatlands Martin Souto 1,*, Daniel Castro 1, Eduardo García-Rodeja 2and Xabier Pontevedra-Pombal 2 1 Department Bot á nica, Fac. Biolox í a, Universidade de Santiago de Compostela, Campus Vida, 15782 Galicia, Spain; [email protected] 2Department Edafoloxía e Quimica Agrícola, Fac. Bioloxía, Universidade de Santiago de Compostela, Campus Vida, 15782 Galicia, Spain; eduardo.garcia-r[email protected] (E.G.-R.); xabier[email protected] (X.P.-P.) *Correspondence: [email protected] Received: 2 July 2019; Accepted: 29 September 2019; Published: 1 October 2019   Abstract: The analysis of plant macrofossils in peatland ecosystems has been widely used for the climatic and ecological reconstruction of the Holocene in the high latitudes of the northern hemisphere. By contrast, perhaps associated with rarity of these ecosystems, this proxy has barely been explored for southern Europe. In this work, a compilation and review of existing knowledge on the study of plant macrofossils of peatlands in southern Europe has been carried out, both from a paleoenvironmental perspective and in terms of biodiversity dynamics. Although small in surface area, the peatlands of southern Europe stand out for their diversity (botanical, edaphogenic, morphological, etc.), which has allowed the recovery of a large number of macrofossils from both vascular plants and bryophytes. The southern zone of Europe contains refuge zones with a high plant diversity that have not suffered the intense glaciation of the northern zones, this allows a continuous record since the beginning of the Holocene and the detection of climatic events in lower latitudes, where the ice recession was earlier. Keywords: paleobotany; paleoclimatic reconstructions; plant remains; mires; bogs 1. Introduction Peatland ecosystems occupy 3% of the Earth’s surface, around 420 million ha. mostly in the boreal zone of the northern hemisphere [ 1 ]. The distribution of these habitats has been reduced especially in southern Europe; c. 60% of European peatlands have been destroyed due to human activities [ 2 , 3 ]. The Habitats Directive 92/43/EEC of the European Union [ 4 ], considers peatlands as ecosystems of priority community interest, for which it is necessary to designate areas for their conservation. Peatlands provide a detailed record of the climatic and ecological changes that occurred during the Holocene, because they preserve a continuous record of fossil remains in very good state of conservation [ 5 , 6 ]. There is a rich history of paleobotanical research in Europe focused on plant macrofossils, however, most of these studies consider fossils that are older than Holocene. The analysis of plant macrofossils has been commonly used in oceanic regions of Europe, mainly in Great Britain; however, despite the potential wealth of information there are few studies in peatlands of southern Europe. This region has a variety of peatlands, which provide habitats for numerous relict, disjunct and endemic species, and communities. Holocene plant macrofossils in southern Europe are generally related to archaeological studies on the beginnings of agriculture, the expansion of different cereals, the diversity of food of different cultures, etc. In recent decades the interest in paleoenvironmental studies and the recognition of the value of information on flora and vegetation of past times, has led to increased studies on plant macrofossils, within the time frame of the Holocene. Quaternary 2019,2, 34; doi:10.3390/quat2040034 www.mdpi.com/journal/quaternary Quaternary 2019,2, 34 2 of 16 Plant macrofossil records are spatially much more precise than the pollen data. They present great taxonomic resolution, if the samples are well preserved, they can be identified at species level such as Carex or Potamogeton [ 7 , 8 ]. They are a valuable tool for obtaining good radiocarbon dating [ 9 , 10 ] and are very helpful in the reconstruction of the forest development, tree and, timber line shifts in the mountain ecosystems [ 11 ] or to reconstruct trails of plants spreading and migration. Another use of these macrofossils is to deliver reference conditions during reconstruction of the vegetation population, that is necessary for restoration process [ 12 , 13 ]. Southern Europe is heavily populated and in recent decades many of these ecosystems have been exposed to human land use change (peat bedding, grazing, fuel, acidifying, etc.), which has affected species composition. Analyses of plant macrofossils from peat cores provides a high-resolution record of vegetation change through time. The study of peat slices 1 or 2 cm thin, allows to obtain data for very small time escals. This is especially valuable to reconstruct local plant development. Peat accumulation is primarily the result of the slow decay rate of the species in the plant communities under certain climate and anoxic conditions [ 14 , 15 ]. The more decomposition, the less identifiable macrofossils remain in the peat, however a biochemical footprint remains, and in recent decades numerous works have focused on identifying some of the major changes in vegetation by analyzing these biomarkers by pirolisis-GC/MS [16–21]. In this paper, we will focus on plant macrofossils data. The existence of common or biogeographically conditioned patterns and the relevance of the data from the botanical and paleoenvironmental standpoint will be explored. 2. Material and Methods Peatlands are widelydistributed across northernEurope, however inthesouthern partits extension is much smaller, occupying mainly mountainous areas. We review the various types of peatland and lake systems along the continuum of terrestrialization. Occasionally some peaty paleo-deposit has been included, due to the paleoenvironmental interest of the identified macrofossils. Figure 1shows the distribution of peatlands in Europe according to Moen et al. [ 22 ] the numbers refer to Table 1. All localities below 50 ◦ N parallel have been considered and a summary of basic core data grouped by zone is given in Table 1. Only those studies that have explicitly processed and identified plant macrofossils have been included, excluding data provided by coals, oospores of Characeae, and invertebrate remains. The summary Tables 2–4group the macrofossil taxa identified in each work and include the type of remains found through a series of abbreviations for vascular plants: Leaf (LF), stomata (ST), epidermis (E), needles (NE); rhizome (R), wood (W), cones (C), bud scales (BS), bark (BK), roots (R), seeds (S), fruit (F), these last two concepts appear often confused in the different identifications, are considered fruits, achenes, or nuts (nutles) of all Cyperaceae and many Rosaceae, as well as the cariopsis of Poaceae. In the case of Bryophyta, the filidia are more abundant in the remains and only in very well conserved peat do filidia, caulidia, or large fragments of moss appear and very rarely capsules and the term vegetative part (VP) has been chosen. Data referring to sclerotia (SCL) of fungi have been included, as they are large and common in numerous papers. Quaternary 2019,2, 34 3 of 16 Quaternary 2019, 2, x FOR PEER REVIEW 3 of 18 Figure 1. Distribution of peatlands in Europe and the location of sites mentioned in the text. The references correspond to the numbering in the bibliography (modified from Moen et al. 2017). Table 1. Description of sites mentioned in the text. Ref: The references correspond to the numbering in the bibliography. SITE LOCATION DEPTH (cm) Yrs. Cal. BP MATERIAL ALT (m a.s.l.) REF AUTOR WEST ZONE Zalama, De Ordunte Mts. (ES) 226 8000 Peat 1330 38 Souto, 2018 Borralleiras, Cabaleiros Mts. (ES) 230 5500 Peat 600 38 Souto, 2018 Pena da Cadela, Serra do Xistral (ES) 183 5500 Peat 970 51 Castro et al., 2015 Chan de Veiga Mol,Serra do Xistral (ES) 845 8000 Peat 695 52 Castro, 2017 Pedrido, Serra do Xistral (ES) 250 4750 Peat 770 53 Stefanini et al., 2018 Noja, Cantabric Coast (ES) 100 3200–4600 Coast peat deposit 50 49 García et al., 2008 Merón, Cantabric Coast (ES) 20 6000–7000 Coast peat deposit 50 49 García et al., 2008 Baldaio, Cantabric Coast (ES) 30 870 Coast peat deposit 25 49 García et al., 2008 Le Moura, Cantabric Coast (FR) 600 10000 Peat 50 Oldfield, 1964 Figure 1. Distribution of peatlands in Europe and the location of sites mentioned in the text. The references correspond to the numbering in the bibliography (modified from Moen et al. 2017). Table 1. Description of sites mentioned in the text. Ref: The references correspond to the numbering in the bibliography. SITE LOCATION DEPTH (cm) Yrs. Cal. BP MATERIAL ALT (m a.s.l.) REF AUTOR WEST ZONE Zalama, De Ordunte Mts. (ES) 226 8000 Peat 1330 38 Souto, 2018 Borralleiras, Cabaleiros Mts. (ES) 230 5500 Peat 600 38 Souto, 2018 Pena da Cadela, Serra do Xistral (ES) 183 5500 Peat 970 51 Castro et al., 2015 Chan de Veiga Mol, Serra do Xistral (ES) 845 8000 Peat 695 52 Castro, 2017 Pedrido, Serra do Xistral (ES) 250 4750 Peat 770 53 Stefanini et al., 2018 Noja, Cantabric Coast (ES) 100 3200–4600 Coast peat deposit 50 49 García et al., 2008 Merón, Cantabric Coast (ES) 20 6000–7000 Coast peat deposit 50 49 García et al., 2008 Baldaio, Cantabric Coast (ES) 30 870 Coast peat deposit 25 49 García et al., 2008 Le Moura, Cantabric Coast (FR) 600 10,000 Peat 50 Oldfield, 1964 Quaternary 2019,2, 34 4 of 16 Table 1. Cont. SITE LOCATION DEPTH (cm) Yrs. Cal. BP MATERIAL ALT (m a.s.l.) REF AUTOR CENTRAL ZONE Grande Basse, Vosges Mts. (FR) 200 3000 Peat 945 64 Kalis et al., 2006 Canard Ib, Taillefer Massif (FR) 125 10,000 Peat 2200 58 Ponel et al., 1992 Lac Lauzons, Hautes-Alpes (FR) 170 10,000 Peat 2180 59 Ponel et al., 2011 Egelsee-Moor Mire, Salzburg (AT) 600 10,000 Peat 700 69 Krisai et al., 2016 Fuorn Mire, Fuorn Valley (CH) 255 8500 Peat-Gyttja 1805 63 Stahii et al., 2006 Lac de Fully, Rhône Valley (CH) 270 11,000 Gyttja 2135 62 Finsinger and Tinner, 2007 Gerzensee (CH) 190–200 11,500 Gyttja 630 61 Tobolski and Ammann, 2000 Leysin (CH) 320–350 10,850–12,050 Gyttja 1230 61 Tobolski and Ammann, 2000 Northern Black Forest (GR) 80 2000 Peat 430 72 Hölzer and Hólzer, 2000 Palughetto, Lapisina Valley (IT) 50 12,200 Paleo peat 1040 67 Avigliano et al., 2000 Totenmoos, South Tyrol (IT) 800 15,000 Peat 1718 68 Heiss et al., 2005 Paludetto S2, Venetian plain (IT) 500–1050 8700 Peat 50 75 Miola et al., 2010 Fiorentina, Venetian plain (IT) 1100–1800 3000–17,000 Peat-clay-silt 50 74 Miola et al., 2006 La Rota, Posta Fibreno (IT) 400 600 Peat 76 Zaccone et al., 2017 EAST ZONE Begbunar, Osogovo Mts (BG) 105 5000 Peat 1800 95 Lazarova et al., 2015 Lake Ostrezko, Rila Mts (BG) 200 6000 Peat 2340 92 Tonkov and Marinova, 2005 Lake Besbog, Pirin Mts (BG) 380 15,000 Peat-Gyttja 2200 94 Stefanova et al., 2006 Vodniza, Rila Mts (BG) 500 9500 Peat-Gyttja 2113 91 Tonkov et al., 2018 Tara, Mts. (RS) 270 9000 Peat 1600 97 Fisinger et al., 2017 Nagymohos (HU) 140–280 4000–7500 Peat 300 85 Magyari et al., 2001 Báb-tava, Bereg Plain, (HU) 142–176 1000–2300 Peat 100 86 Magyari et al., 2008 Sirok Nyírjes-to, Mátra Mts, (HU) 400 9000 Peat 250 m 42 Jakab & Sümegi, 2010 Gärgäläu fen, Rodna Mts. (RO) 150 9500 Peat 1810 11 Feurdean et al., 2016 Valea Morii, North western (RO) 100 1100 Peat 640 88 Galka et al., 2018 Tăul Muced, Rodna Mts. (RO) 500 9000 Peat 1360 84 Galka et al., 2016 BelanskéLúky, Tatra Mts. (SK) 230 10,000 Peat 700 79 Hájkováet al., 2012 Nádas Lake, Cserhát Mts. (HU) 340 8000 Peat-Clay 360 87 Sümegi et al., 2009 Starunia, Carpathos (UA) 300–500 12,000 Peat-Clay 400 83 Stachowicz-Rybka et al., 2009 Quaternary 2019,2, 34 5 of 16 3. Results and Discussion Southern Europe contains numerous refugia with a high plant diversity that did not suffer the intense glaciation of the northern areas. The long persistence of peat “islands” has allowed the development of endemic plants and communities. The age of many of these peatlands, with records beginning before the Holocene (Table 1), allows a continuous recording and detection of climatic events in lower latitudes, where the ice recession was earlier. We can define three basic areas of study: A western area where most peatland habitats are mainly on the Iberian Peninsula; a central area in the Alps; and an eastern area that encompasses the Carpathians and Balkans. 3.1. Problems in the Identification of Plant Macrofossils The analysis of macrofossils is not a technique with a complicated methodology, nor does it require great investment, or equipment, but it does require expert knowledge in botany (taxonomy), plant histology (morphology), and plant ecology. The identification of plant macrofossils is based on comparisons with published descriptions and illustrations and the use of reference material. Few publications cover the range of plant material found in peatlands and in many cases corresponds to works from Russia [ 23 – 26 ] or northern Europe [ 27 – 31 ]. An importantcomponent ofthe remains preserved inpeat are seedsand fruits, whose identification is easy from monographs of each botanical group; some families or typical genus of peatlands have been studied from this point of view, as for example Cyperaceae [ 32 ]; Juncus [ 33 ]; Vaccinium [ 34 ]; Menyanthes [35]; or Betula [36]. Some species are only represented by fruits and seeds (e.g., Drosera). These are often herbaceous species with small or delicate vegetative tissues (Figure 2). Other species, such as Eriophorum have resistant and perennial organs; the macrofossils found in the fossil record correspond mainly to remains of subterranean organs, roots, rhizomes, or basal areas of aerial parts and occasionally fruits (Figure 2), its identification depends on the epidermal cell pattern, stomas, hairs, or foliar margin and when not enough diagnostic characters of the species are preserved its identification results more difficult. For plant macrofossils found in ombrophic peatlands, descriptive and illustrated work by Souto et al. [ 37 ] can be consulted. Quaternary 2019, 2, x FOR PEER REVIEW 6 of 18 Figure 2. Fresh plants and corresponding macrofossils: Drosera rotundifolia (a) habit, (b) seeds; Drosera intermedia (c) habit, (d) seeds; Eriophorum sp (e) habit, (f) achenes, (g) remains of stems, (h) remains of rhizomes (Souto, 2018) [38]. The bryophytes are relatively easy to identify, since the determination of material in vivo is based mainly on the anatomy of the leaves and on their small size and it is common that they are well conserved in the peat. Sometimes they are altered by decay, keeping only certain parts, such as the zones of insertion of filidia or only the caulidia (Figure 3). They are important components of peatland flora, so their identification in macrofossil studies is vital to the interpretation of these habitats [39– 42]. A detailed description of fossil bryophytes for ombrotrophic peatlands of the Cantabrian coast can be found in Souto et al. [43]. Figure 2. Fresh plants and corresponding macrofossils: Drosera rotundifolia ( a ) habit, ( b ) seeds; Drosera intermedia ( c ) habit, ( d ) seeds; Eriophorum sp ( e ) habit, ( f ) achenes, ( g ) remains of stems, ( h ) remains of rhizomes (Souto, 2018) [38]. Quaternary 2019,2, 34 6 of 16 The bryophytes are relatively easy to identify, since the determination of material in vivo is based mainly on the anatomy of the leaves and on their small size and it is common that they are well conserved in the peat. Sometimes they are altered by decay, keeping only certain parts, such as the zones of insertion of filidia or only the caulidia (Figure 3). They are important components of peatland flora, so their identification in macrofossil studies is vital to the interpretation of these habitats [ 39 – 42 ]. A detailed description of fossil bryophytes for ombrotrophic peatlands of the Cantabrian coast can be found in Souto et al. [43]. Quaternary 2019, 2, x FOR PEER REVIEW 6 of 18 Figure 2. Fresh plants and corresponding macrofossils: Drosera rotundifolia (a) habit, (b) seeds; Drosera intermedia (c) habit, (d) seeds; Eriophorum sp (e) habit, (f) achenes, (g) remains of stems, (h) remains of rhizomes (Souto, 2018) [38]. The bryophytes are relatively easy to identify, since the determination of material in vivo is based mainly on the anatomy of the leaves and on their small size and it is common that they are well conserved in the peat. Sometimes they are altered by decay, keeping only certain parts, such as the zones of insertion of filidia or only the caulidia (Figure 3). They are important components of peatland flora, so their identification in macrofossil studies is vital to the interpretation of these habitats [39– 42]. A detailed description of fossil bryophytes for ombrotrophic peatlands of the Cantabrian coast can be found in Souto et al. [43]. Figure 3. Example of differential degradation in Racomitrium. lanuginosum: ( a,b ) central parts of fossil leaves, ( c ) mid-leaf cells (fossils), ( d,e,f ) current leaves, hyaline apex and papillary rim (Souto, 2018) [ 38 ]. 3.2. Macrofossils: West Zone (Iberian Peninsula) In the Iberian Peninsula, the first studies of macrofossils in peatlands consisted of specific identifications, the works of Maldonado et al. [ 44 ] in Sierra de Gredos stand out. They prospected a wide area of peatlands and small lakes, located between 1100 and 1840 m a.s.l., collecting a great quantity of samples, among which stand out stumps in position of life, trunks of up to 5 m of length and 40 cm of diameter and numerous strobilus, dated between 850 and 5500 years cal BP. Other sampling areas include a synthesis on macrofossils collected in coastal areas, from the Cantabrian region to southern Portugal [ 45 – 48 ], the quaternary sediments that preserve peat bog deposits found in Noja, Oyambre-Mer ó n, and Baldaio [ 49 ] stand out for their diversity in species. Although these works improve knowledge in the Iberian Peninsula mainly of forest species, they are not paleoenvironmental reconstructions of the same ecosystem over time. The work in the peatland of Le Moura [ 50 ] (Biarritz, south-west France), is the first that conserves a continuous sample of the flora since 10,000 years cal BP. In the last decade, more precise paleobotanical investigations have been carried out, based on the analysis of plant macrofossils extracted from peat samples from different ombrotrophic peatlands in the north of the Peninsula [ 37 , 38 , 43 , 51 – 53 ]. These works provide a precise vision of the vegetation in each peatland, and the similarities between different proxy can offer more solid data for this region. In the Iberian Peninsula, the different types of peatlands of the Atlantic region and some types of the Mediterranean and alpine region are present [ 54 – 57 ]. In the northwest of the Iberian Peninsula, Quaternary 2019,2, 34 7 of 16 the largest area is located, forming a complex system (macrotope) (Serras Septentrionais of Galicia, about 10,000 hectares). In this area, blanket bogs find their most southwestern distribution limit in Europe, they are currently restricted to mountain oceanic sectors, under an Atlantic hyperhumic climate very similar to that of northwestern Europe. Due to their ombrotrophic these peatlands are excellent paleoenvironmental archives and have been the subject of numerous studies from a multiproxy approach [37,38,43,51–53]. The high resolution at which these analyses have been carried out (peat samples were studied every 1 cm deep), has made it possible to study the transition of the different plant communities over time, whether or not they represent autogenic successions. The different macrofossils found in these bogs (Table 2) allowed us to reconstruct with great accuracy the plant communities that developed in the peat bog over time. Highlighting that there are no remains of vegetation that may have reached the bog by transport from other places, such as pollen. All the taxa found correspond to species that are currently present in these peatlands. In these ombrotrophic peatlands, plant macrofossils show a great diversity of bryophytes, an herbaceous stratum dominated by Cyperaceae and Poaceae that accompanies different species of Ericaceae shrubs (Table 2). The quotation from Andromeda polifolia L. [ 53 ], a species not present in the peninsula, stands out, so this quotation is of doubtful interpretation. Many of these peatlands have a strong component of Poaceae and Cyperaceae. Their greatest contribution to the fossil record is in the form of remains of rhizomes, however these are difficult to identify at the species level. Future studies should focus on these structures due to the importance of this group of plants. Table 2. Macrofossil taxa for ombrotrofic mires in North of Spain. Abbreviations: S—seeds, SCL—sclerotia, LF—leaf, F—fruit, R—Rhizome, W—wood, VP—vegetative part. Ref.: The references correspond to the numbering in the bibliography. REF. BIBLIOGRAPHY [53] [52] [38] [51] [38] MACROFOSSIL TAXA Betula pubescens S Ericaceae LF, F, W LF, F, W Erica tetralix LF LF, S Erica mackaiana LF, S LF, S LF, S LF, S Calluna vulgaris S LF, S LF, S LF, S LF, S Andromeda polifolia LF, S Daboecia cantabrica S S Vaccinium myrtillus LF LF, W Poaceae LF Agrostis curtisii LF,R LF,R Molinia caerulea LF,R,F LF,R,F LF,R,F LF,R,F Potentilla erecta LF, F F LF, F Drosera intermedia S Drosera rotundifolia S S S S Narthecium ossifragum S S S Caltha palustris S S Cyperaceae LF LF, R LF, R LF, R Eriophorum sp. S, LF LF, R, S LF, R, S LF, R, S S, LF, R Carex echinata F Carex demissa F Carex binervis F Carex durieui F F Rhynchospora alba F Trichophorum sp LF Quaternary 2019,2, 34 8 of 16 Table 2. Cont. REF. BIBLIOGRAPHY [53] [52] [38] [51] [38] Luzula multiflora S Juncus bulbosus S S S Juncus squarrosus S S S BRYOPHYTA Aulacomnium palustre VP VP Calliergonella cuspidata VP Campylopus sp VP VP Dicranum scoparium VP Hypnum cupressiforme VP VP VP VP VP Leucobryum juniperoideum VP VP VP Polytrichum sp. VP Racomitrium lanuginosum VP VP VP Spagnum capillifolium VP Spagnum tenellum VP VP VP Sphagnum acutifolia VP Sphagnum compactum VP VP Sphagnum cuspidatum VP Sphagnum molle VP Sphagnum papillosum VP VP Sphagnum sec. acutifolia VP VP VP VP Sphagnum sec. cuspidata VP VP Thuidium tamariscinum VP Calypogeia sphagnicola VP Odontochisma sphagni VP FUNGI Cenoccocum geophilum SCL SCL SCL 3.3. Macrofossils: Central Zone (Alps) In France there are few works based on plant macrofossils. In most of the cases they have not been carried out in peatlands, among them, it can be highlighted from the work of Ponel et al. [ 58 , 59 ] in the French Alps above 2000 m a.s.l. It is based on multiproxy analysis that combined palynology with identification of plant macrofossils and insects remains (mainly Coleoptera) this significantly improved the interpretations based on pollen analysis. The Val-de-Lans basin (western French Alps) provides a rare opportunity to study Middle Pleistocene interglacial sediments, in this lacustrine interglacial deposit a rich flora of wetlands has been sampled [ 60 ]. Moreover, lacustrine deposits in Switzerland have recovered an important representation of the flora between the Younger Dryas and the Preboreal [ 61 – 63 ]. In the Vosges an interesting work [ 64 ] reconstructs fossil phytosociological communities, comparing groups of plant macrofossils to current communities. In this central zone, many of the macrofossils are the remains of trees (Table 3) and in many of the peat cores one of the most studied groups is that of the Pinaceae [ 65 , 66 ]. The remains of conifers found in the excavation of a paleo-peatland near Venice [ 67 ] and in South Tyrol [ 68 ] with dates around the Younger Dryas stand out for their good conservation and abundance. Quaternary 2019,2, 34 9 of 16 Table 3. Macrofossil arboreal taxa for central zone. Abbreviations: S—seeds, F—fruit, W—wood, BS—bud scales; NE—needles; BK—bark; ST—stomata. Ref.: The references correspond to the numbering in the bibliography. REF. BIBLIOGRAPHY [50] [64] [58] [69] [63] [62] [61] [61] MACROFOSSIL TAXA Pinus sp. ST S Pinus cembra BS, NE NE NE, S, W Pinus mugo W, NE Pinus uncinata NE, S Pinus sylvestris NE, BS,S NE,BS,S Picea abies NE, S NE, W, S NE, ST S Abies alba NE NE Juniperus sp. W NE Juniperus communis NE, S NE, W Larix sp. Ne BS,BK Larix decidua NE, ST NE, S, W Salix sp. BS BS Populus tremula BS,F BS,F Alnus glutinosa S, BS S, W Betula sp. F, W BS S, W Betula alba F F, BS F, BS F Betula carpatica F Betula pendula S, BS F Betula pubescens F, BS F Betula nana F Sambucus racemosa S Fagus sylvatica BS, W, F On the other hand, it is remarkable the absence of identified remains of bryophytes, of all the works studied in the area of the alps, only four [ 69 – 72 ] offer data of mosses. For the reconstructions based on the ecological needs of moss communities, Mitchell et al. [ 73 ] used bryophyte presence/absence data from sub-alpine peatlands in the SE Swiss Alps, and bootstrapping cross-validation showing that the best performing single-proxy transfer functions for both DWT (deep water table) and pH were those based on mosses. In Italy marine transgression has been studied during the last 8000 BP and as an effect on the development of marsh plant communities, in samples of more than 10 m the layers of peat were much rich in plant remains (Cyperaceae and Poaceae) [ 74 , 75 ]. "La Rota" a free-floating mire in lake of Posta Fibreno is an exceptional case of relic mire in central Italy, the top 220–230 cm of this free-floating mire consists almost exclusively of Sphagnum palustre [76]. 3.4. Macrofossils East Zone The numerous peatlands studied in the Carpathian area have provided a large amount of bryophyte data, both from the genus Sphagnum and Amblystegiaceae (Table 4.) Recent advances in biogeography include the application of macrofossil analysis to study the past distribution of many species and determine if a current species is relict. These models have made it possible to compare current distributions with past distributions, for example, relict bryophytes in the Czech Republic and Slovakia [ 77 – 79 ] and know the degree of regression that some taxa shows today [ 79 ]; in some cases it has been demonstrated the existence of an entire community that at present no longer exists as the case of Stygio-Caricion limosae alliance [80]. 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