CHAPTER 1 INTRODUCTION
1.2 The study areas
1.2.2 Land use history
Archaeological records confirm the presence of human settlements and agricultural practices as early as 7000 years before present in the two study regions (Beier & Einicke, 1994; Jantz, 2008).
The Neolithic people already cultivated emmer and einkorn wheat (Triticum dicoccon and T.
monococcum respectively), pea (Pisum sativum), lentil (Lens culinaris) and less commonly opium poppy (Papaver somniferum) and barley (Hordeum vulgare) (Behre, 2008).
These crops were cultivated on cleared forests plots. When the soil was depleted, the cultivation shifted to another site and the field was left fallow to regenerate for several years and/or used for grazing purposes (Willerding, 1986). This kind of management, also called ‘Feldgraswirtschaft’ (i.e.
the mixture of cropland and grassland periods), was practiced widely until the medieval ages throughout Central Europe (Pott, 1992). It led to the development of weed assemblages which rather resembled today’s grassland plant communities due to the high prevalence of perennial species (Pott, 1992; Hofmeister & Garve, 2006). Typical cropland species such as Bromus secalinus, Lapsana communis or Fallopia convolvulus have nevertheless been detected regularly in Neolithic fossil records (Hilbig et al., 2013). Lists of arable plant species found in Neolithic fossil records from Central Europe have been published by Willerding (1986) and Jacomet et al. (1991).
An important change in field management occurred during the early to high medieval when the more efficient three-field rotation system (‘Dreifelderwirtschaft’) replaced the ‘Feldgraswirtschaft’ in
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Fig. 1.9 Geology of the study regions (a) the Lower Saxon hills and (b) the Thuringian Basin. Map (a) is based on the geological map for Lower Saxony (GÜK500, 1:500,000; LBEG, 2014) and (b) is based on the soil geological map of Thuringia (1:100,000; Rau et al., 2000). Both maps are presented in Universal Transverse Mercator (UTM) projection; zone 32 N (WGS 1984).
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Central Europe (Pott, 1992; Karg, 1995). The crop rotation in the three-field system consisted of winter sown cereals, summer-sown crops (mostly cereals or legumes) and a fallow year during which fields were used as pastures (Pott, 1992). These three types of land use rotated across the holding. Due to the shortening of the fallow period, perennial species became less important in the arable plant assemblages and the proportion of annual species increased (Willerding, 1986; Pott, 1992; Karg, 1995). Historical sources confirm that the three-field system was the prevalent form of field management in the Thuringian Basin and in the Lower Saxon hills since medieval times and was practiced until the middle of the 19th century in many parts of the study areas (Scheidemann, 1959;
Rockstuhl, 2012; VG Schlotheim, n.d.). With the course of time, improvements of the three-field system such as land ameliorations, the introduction of new crops (i.e. potatoes and other root crops), improved breeds, and the introduction of mineral fertilisers in the 19th century led to changes in habitat conditions for the arable plant assemblages (Hofmeister & Garve, 2006). As fallow periods became less common and were largely replaced by root crop cultivation annual disturbance was prevalent on many fields. The importance of perennials declined further and species rich plant communities dominated by annual plant species developed (Pott, 1992). These species rich arable plant assemblages were widespread until the middle of the 20th century.
A major transition in agricultural practices in the study areas occurred after the Second World War.
With the wider introduction of synthetic herbicides, the increased availability of mineral fertilisers, improvements in seed cleaning techniques and technical advances of the field machinery the diversity of the arable plant assemblages started to impoverish rapidly (Hofmeister & Garve, 2006). With the new machinery, land amelioration progressed, leading to increased field sizes and the loss of landscape structural elements such as field margins, wetlands, hedges and copses (Pott, 1992).
This process of intensification differed between the study regions, due to differences in agricultural policies on both sides of the inner German border after 1949. As part of the agrarian reform in the German Democratic Republic many land owners in the Thuringian Basin were expropriated. The land was collectivised and farmed by agricultural production cooperatives (in German: Landwirtschaftliche Produktionsgenossenschaft or LPG). Small fields were joined and landscape features such as hedges, copses, rocks and ponds were removed to allow for more efficient agricultural production with larger machinery (Humm, 1999). A highly productive agricultural landscape with very large fields and few structural landscape elements developed. After the German reunification, the state-owned agricultural land was returned into private hands or reallocated to the regional administrative bodies (federal states or municipalities) to whom it formerly belonged (Dells, 2008). Many federal states, municipalities and private land owners subsequently rented their land to large, privately owned, agricultural cooperatives which are today responsible for farming the land. Consequently, the re-privatization of land did not result in overall decreases in field size. The average size of an administrative field unit is today 18.8 ha in the Thuringian Basin and fields of 20–100 ha dominate the landscape.
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In the Lower Saxon hills no such collectivization took place and the average field size is therefore smaller until today (6.6 ha). Only very few fields exceed 20 ha. Landscape features such as hedges and tree lines are nevertheless not very common, particularly in the areas with fertile loess soils. As a large number of family farm businesses were and are still economically directly dependent on the agricultural production in Western Germany, land use intensity is high and fertile land is only rarely spared from production. Due to these developments, many characteristic and formerly common plant species of arable habitats, such as the common corncockle (Agrostemma githago, Fig. 1.2) or the summer pheasant’s eye (Adonis aestivalis), suffered strong declines in Central Germany (Meyer et al., 2013) and are nowadays threatened in many regions of Central Europe.