RWE Power AG processes 100 million tonnes of brown coal in the Rhineland annually, of which 85% are turned into electricity. This supplies 15% of Germany’s and 53% of North- Rhine Westphalia’s electricity. The tertiary brown coal layers are covered by layers of quaternary shingle, sand and clay and can only be extracted by open cast mining. The rehabilitation and the reclamation of the open cast mines aims to produce a highly sustainable and productive ecosystem – for man and animal. All the processes necessary to develop this new landscape are described as land reclamation and rehabilitation: design, selection of suitable soil substrate, agricultural management, re-forestation, natural and other developments. Since the beginning of the 20th century, over 8,000 ha have been restored to woodland areas and 10,000 ha have been reclaimed for agricultural cultivation. Coal mining affects two landscape features dramatically: the relief and the soil. These features determine, together with the local climate, the potential of the site. The relief is partly affected by the mining procedures and the storage facilities, however, it is mostly determined by targeted strategies and design. One aim is to optimise the recovered agricultural area in this fertile landscape as farming has played an important part in this man-made environment. Furthermore, other areas are designed to increase the proportion of restored woodland: hedgerows, groves, wide trenches, embankments and other green corridors are embedded into agricultural land.
Loess is used as a soil substrate for agricultural land reclamation; the soil for woodland restoration, on the other hand, consists of a mixture of loess, shingle and sand (Ger.: Forstkies). Other types of soil are used in small areas to increase the diversity of the site. The protection of the soil from soil compaction has highest priority during the application of the soil substrate and subsequently, the cultivation of the land. The agricultural areas are temporarily cultivated during a seven-year period to prepare them for their return to the farmers. Initially, alfalfa is cultivated for three years on these areas, after this, winter grain is predominantly grown. During this time blemishes can be recognised and fixed with the use of air surveillance. After returning the land to the farmers, the fields are cultivated with the crop rotation method typical for this area: one third sugar beet and two thirds grain – potatoes and other vegetables are sometimes grown as well. The returns of this land are comparable to the yields of natural grown loess sites and the bay of Cologne (Ger.: Kölner Bucht): in this respect farming on reclaimed land could be described as highly profitable. To achieve this success, the protection of the soil during the temporary cultivation is ensured by using wide-base tyres, cautious ploughing methods and no-till farming.
The re-forestation is carried out using native broad-leaved trees (European beech, Common oak) and mixed woodland species to 80%; non-native species such as Douglas fir, Scots pine, larch and red oak take up 15% and the remaining areas are covered by grassland or left to natural succession. The trees are planted manually applying 4,500 mixed trees per hectare. Alfalfa is used as a catch crop to enrich the soil. Black poplar and red alder are planted as umbrella tree species. All tree species show high growth rates particularly on loose loess- enriched substrate (Ger.: Forstkies).
The research station “Forschungsstelle Rekultivierung” in Hackhausen near Jüchen has been founded to bring together the diverse and interdisciplinary research areas of land reclamation. Till August 2012 it is in forum: terra nova [2.322 KB]
To ensure the success of land reclamation it was and is always important to constantly monitor the ecological effects of different approaches through scientific studies. This collaboration of practice and theory has a long tradition in the domain of land reclamation. Since Heuson – one of the pioneers of re-forestation of open cast mines – published his long- time experiences in his book “Die Kultivierung roher Mineralböden” in 1947, endless studies have been issued concerning particular problems of open cast mine reclamation. At the beginning of the 1960s the studies of Wittich and Heide laid the foundation for the modern use of “Forstkies”. Since then, many aspects of soil science, silviculture and agricultural land use as well as the natural succession of re-forested and open areas have been investigated. Thus, through a constant learning curve it was possible to continuously improve the methods of land reclamation.
The Kölner Büro für Faunistik is an independent ecological consultancy firm which is responsible for the supervision of the research station and at the same time conducts continuous research on the reclaimed land. The “Forschungsstelle Rekultivierung” is a co-operation of RWE Power AG and the Kölner Büro für Faunistik.
The “Forschungsstelle Rekultivierung” accommodates a library which comprises many dissertations, theses and research reports that date back to the research of the last years and decades. This allows continuing researchers to use this usually not available grey literature for further work. The samples collected can be analysed in the workspace available and subsequently the data is stored in the general database. Thus, the data is available to everyone who works here. The results are presented to experts and the public during seminars.
The primary functions of the research station are:
– documentation: standardised data collection – primarily for long-term research which has to be repeated in long time intervals
– exchange of information: study groups are provided with provisional results; regular progress meetings
– provision of basic data: the distribution of soil substrate and the age of the sites; maps; climate data; existing research; continuous literature search
– communication: regular talks with the public