The Origin and Development of the Central European Man-made Landscape, Habitat and Species Diversity as Affected by Climate and its Changes – a Review

Climate optima, but also climate pessima, are shown to have strongly affected the origin of settlement in central Europe and the development of the man-made landscape and its habitat and species diversity. Driving forces for climate changes, until recently, were fluctuations of solar activity and radiation, but also comet impacts and volcano eruptions. It could be shown that climate optima increased landscape, habitat and species diversity as well as the expansion of open man-made habitats. Four climate optima were identified to have had a strong impact. In the Neolithic Age the climate optimum favoured the settlement of people which created the first man made habitats, arable fields, pastures and heathlands. High precipitations resulted in the expansion of wetlands and the origin of raised bogs. In a short climate optimum period in the Bronze Age Alp farming started creating new habitats through e.g. grazing practices. The climate optimum which started at the end of the Iron Age resulted in the first diversity revolution in the landscape during the following Roman Empire Period. Meadows, orchards and vineyards were established. Archaeobotanical remains have shown that during the Roman period most new species/100 years have established in arable fields and grasslands. The medieval climate optimum finally resulted in the largest expansion of open man-made habitats but also new habitats such as fish ponds. In contrast, during climate pessima abandonment of man-made habitats occurred. During the Migration Period and the Little Ice Age starting at the end of the Medieval Period forests increased. During the climate pessima in the Bronze Age we had the lowest number of new species/100 years. Actually, through recent laws concerning renewable resources as a reply to the recent climate warming, landscape is changing again. IANSA 2015 ● VI/2 ● 197–221 Peter Poschlod: The Origin and Development of the Central European Man-made Landscape, Habitat and Species Diversity as Affected by Climate and its Changes – a Review 198 (Weninger et al. 2006; Berger, Guilaine 2008; Clare et al. 2010). The movement started at many places at the same time (Ozdogan 2002; 2011). Ozdogan (2002) described this process as following: “Almost of a sudden we start seeing more habitation, (...) not only in Central Anatolia, but also in the Western Aegean regions, to be accompanied quickly by the Balkans. (...) the number of Pottery Neolithic sites increases dramatically, and almost all of a sudden. In the East, however, there is a decrease in the number of settlements, or the existing ones become smaller (...)... there must have been an endemic movement which started (...) towards the end of the Pre-Pottery Neolithic B. There must have been some kind of beginning stage of this westward movement. There is clearly a kind of a momentum to migrate in masses before the end of the thing. (...) All of a sudden you see that people are moving.” The flooding of the Black Sea through the Bosporus by the rising level of the Mediterranean Sea, often synonymous with Noah’s flood (Ryan, Pitman III 1998; Haarmann 2003; 2011; different dating of the start of flooding, earliest moment around 8500 BC, latest 5600 BC, see Poschlod 2015), might have caused another movement (Milisauskas 2011). However, the date, height and rate of the flooding are still under debate (Ryan et al. 1997; 2003; Bahr et al. 2006; Yanko-Hombach et al. 2007; Giosan et al. 2009; Lericolais et al. 2009; Thom 2010). Also, the origin of the man-made landscape in central Europe around 5500 BC started during a climate amelioration (Schonwiese 1995; Gronenborn, Sirocko 2010; see also Birks 2003 etc.) caused partially by an increased sun activity which started already in the Mesolithic Age (Steinhilber et al. 2009). The first farmers belonging to the LBK culture spread quite fast from the southeastern edge of central Europe and even Anatolia during this climate optimum which was shown through recent molecular studies of early LBK populations (Haak et al. 2010). Genetic discontinuity to the Mesolithic hunters supports the hypothesis that the first farmers were immigrants (Bramanti et al. 2009; Malmstrom et al. 2009). Since then the climate has changed in central Europe (see also Figure 1). Several climate optima and pessima have been described by several authors which, have had clear and distinct impacts on the history of mankind and its cultures (Lamb 1995; Le Roy Ladurie 2004; 2006; 2009a; 2009b; 2009c; Blumel 2006; Behringer 2007; Sirocko 2010). However, climate also affected land use and land use intensity (Bork et al. 1998; Bork 2006) and therefore the man-made landscape, the origin and development of habitats as well as their species diversity (Poschlod 2015). The latter were only reviewed on a local or regional level for certain periods (e.g. Zolitschka et al. 2003) but not for the whole time span since settlement started. This is therefore the aim of this review. Furthermore, the most recent knowledge on the causes of each particular climate change was included. 2. Climate and the origin of sedentism in central Europe The first climate optimum after the last ice age started around 6000 BC and lasted until 3250 BC (Figure 1; Table 1). Causes were an increased solar activity at the beginning and an increased solar radiation during this period (Steinhilber et al. 2009; Nussbaumer et al. 2011). Warmer temperatures permitted a much higher treeline than today. In the central Austrian Alps the treeline laid at Figure 1. Global average annual mean temperature trend during the Holocene after Schonwiese (1995) and Eitel (2007). Dotted line: Trend reversal in the temperature pattern during the Atlantic Period. PA – Palaeolithic, RE – Roman Empire period, MP – Migration period, MA – Modern Age, LG – Last glacial, PB – Preboreal. IANSA 2015 ● VI/2 ● 197–221 Peter Poschlod: The Origin and Development of the Central European Man-made Landscape, Habitat and Species Diversity as Affected by Climate and its Changes – a Review 199 Table 1. Characterization of the climate and its chronological classification into zones and respective archaeological and historical epochs. Historical and climate data after Poschlod (2015), mainly according to Schonwiese (1995) and Nelle (2002); biostratigraphical zones after Mangerud et al. (1974)1 and Walker et al. (2012)2. Biostratigraph. zone1 Biostratigraph. zone2 Archaeological/historical epochs Year BC/ AD Characterisation of the climate