The South Harz and Kyffhäuser Gypsum Karst – A Unique Landscape

by Friedhart Knolle and Stephan Kempe

Abstract

The South Harz gypsum karst area in the German states Lower Saxony, Thuringia and Saxony-Anhalt, its karst phenomena, biotopes and landscapes, international importance and threats for this unique area caused by gypsum quarrying are described. There are alternatives for the gypsum market in the form of FGD gypsum.

Where?

The landscape of the South Harz is dominated by gypsum karst forming one of the largest continuous gypsum karst areas in Europe (Kempe 1996). It occupies a narrow belt extending through the States of Lower Saxony, Thuringia and Saxony-Anhalt (Federal Republic of Germany) from Osterode am Harz in the West to Sangerhausen in the East (Fig. 1). This gypsum belt has developed a remarkable density of a large variety of karst phenomena throughout the Pleistocene and Holocene. Karstification occurs mostly in the gypsified anhydrite layers of the Upper Permian, i.e. the anhydrite members A1, A2, A3 of the Werra, Staßfurt and Leine Zechstein salinar series, respectively. This outstanding area is worth of preservation, and several parts are protected, however, its importance is not well known internationally.


Fig. 1. Overview of the South Harz Gypsum Karst area. Drawing by F. Knolle & R. Nielbock.

What?

The most pronounced features of the South Harz landscape are more than 20,000 sinkholes in addition to countless uvalas, ponors and karstic springs (e.g. Kempe et al. 1975), periodic lakes (Fig. 2, 3), more than fifty larger caves (Kempe 1972, 1978, 1980) and other karst phenomena (Kempe & Emeis 1981) plus many archeological sites, all confined in the small spaces of the individual gypsum outcrops. The product of these natural conditions combined with the mostly extensive management is a vast mosaic of closely interconnected but diverse habitats, including dry meadows, limebeech forests, gypsum escarpments (Fig. 4), stony terrain, spring bogs, and water-filled fens. The South Harz gypsum karst area is also an important habitat for many bat species and the European Wildcat (Felis syvlestris).


Fig. 2. Bauerngraben, an episodic sinkhole pond near Roßla, Saxony-Anhalt. Foto by S. Wielert.


Fig. 3. Geological situation of the Zechstein karst of the Bauerngraben area near Roßla, Saxony-Anhalt. Drawing by R. Völker.


Fig. 4. Gypsum cave Heimkehle near Uftrungen, partly in Saxony-Anhalt and in Thuringia.
Foto by E. Schuhose.
 
Landscape history

The fens in the South Harz gypsum karst sinkholes are excellent archives for the reconstruction of vegetation, land use and emission rates over millennia. The reason is the usually very good preservation of pollen, the high portion of low density organic material with very low background concentrations of heavy metals, and the near-neutral pH-values in most of these mires preventing migration of heavy metals. Immissions of dust and harmful elements can easily be correlated with changes in vegetation. Karst sinkhole fens of the South Harz gypsum karst were investigated by geochemistry, via pollen analysis and dated by 14C and palynology by Hettwer et al. (2002).

Studies of the Lake Jues sinkhole in Herzberg (Fig. 5) provided a well-dated, continuous and highly sensitive environmental and climatic reconstruction of the Holocene for the mid-latitudes in Central Europe and can serve as an important link between the better investigated neighbouring regions. Climate shifts, mainly in phase with those recorded from other European regions, are inferred from changing limnological conditions and terrestrial vegetation. Significant changes occurred at 11,600 a BP (Preboreal warming), between 10,600 and 10,100 a BP (Boreal cooling), and between 8,400 and 4,550 a BP (warm and dry interval of the Atlantic). Since 4,550 a BP the climate became gradually cooler, wetter and more oceanic. This trend was interrupted by warmer and dryer phases between 3,440 and 2,850 a BP and, likely, between 2,500 and 2,250 a BP (after Voigt et al. 2008).


Fig. 5. Lake Jues sinkhole in Herzberg, Lower Saxony. Foto by D. Tront.

Threats and chances

Unfortunately, parts of this landscape have already been destroyed: In many places gypsum is quarried predominantly by globally operating business groups. Every year, millions of tons are processed for construction materials such as gypsum wallboards, plaster, etc., and karst phenomena are irrevocably lost together with their characteristic flora and fauna. Valuable natural heritage and long-term development prospects for the region are sacrificed for short-term jobs and profits. But this must not happen any more, since natural gypsum can be substituted by synthetic (especially REA gypsum from flue gas desulphurisation FGD) in all fields of application (Öko-Institut 1997).

FGD gypsum is a waste product of smoke desulfurization. Only a very small percentage is used for the building industry, as they use mostly mined natural gypsum up to now. Meanwhile gypsum of smoke desulfurization is stored. Gypsum karst areas, which are now unnecessarily destroyed, developed over hundred thousands of years and represent geosites and biotopes with a significant ecological importance for biodiversity, groundwater systems and the defining landscape elements in Europe. Compensatory measures such as restoration can never substitute primary ecotopes that evolved in geological and not in biological ages. An enfolding restoration would take centuries and the geomorphological structure of this unique habitat is irrecoverably lost. Because of the current - due to the climate change aggravated - tempo of species extinction, ecological niches like the gypsum karst became indispensable. For this reason sustainable production in the case of utilisation of FGD gypsum instead of natural gypsum is an economical advantage, resource efficiently and above all a guarantee for the protection of biodiversity and landscape ecology in Europe (Röhl 2003, Vogel & Grebe 2008).


Fig. 6. Gypsum quarry near Osterode am Harz, Lower Saxony. Foto by M. Henning-Hahn.

Since 2002, the South Harz gypsum karst is part of the National Geopark Harz . Braunschweiger Land . Ostfalen (www.geopark-harz.de) and was declared a German National Geosite in 2006 (www.geoakademie.de).

So far, Saxony-Anhalt has been the only German state consistently protecting its share of the gypsum karst belt as a Biosphere Reserve (www.bioreskarstsuedharz.de). There is no other Biosphere Reserve in a gypsum karst area world-wide.
 



Fig. 7. Signet of the Biosphere Reserve “Karstlandschaft Südharz” in Saxony-Anhalt.
From www.bioreskarstsuedharz.de.

Fig. 8. Area covered by the Biosphere Reserve “Karstlandschaft Südharz” in Saxony-Anhalt – the only Biosphere Reserve in a gypsum karst area world-wide.
From www.bioreskarstsuedharz.de.

The environmental NGOs in Lower Saxony and Thuringia vigorously object to the issuing of new extraction permits. In order to ensure the long-term protection of the gypsum karst landscape they demand the establishment of a cross-boundary UNESCO Biosphere Reserve, designated "Karstlandschaft Südharz", and the nomination of more gypsum karst areas as Natura 2000 sites also in Lower Saxony and Thuringia. The environmental NGOs have lodged a complaint with the EU, because important gypsum areas comprising habitat types and species worth of protection have not been nominated for protection in the interest of the continued gypsum mining.
 

Literature and Links

Hettwer, K., Deicke, M. & Ruppert, H. (2002): Fens in Karst Sinkholes – Archives for Longlasting „Immission“ Chronologies.- Water, Air, and Soil Pollution 149:363-384

Kempe, S. (1972): Cave genesis in gypsum with particular reference to underwater conditions. – Cave Sci., J. Brit. Spel. Ass. 49: 1-6

Kempe, S. (1978): Gypsum caves of the world. – Nat. Spel. Soc. News 1978/11: 159-161

Kempe, S. (1980): Les plus grandes cavités du gypse. – In "Les grandes cavités en roches pseudokarstiques ou non-karstiques" (ed. C. Chabert), Spelunca 1980/3: 109-115

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Kempe, S. & Emeis, K. (1981): Carbonaceous sediments in a gypsum karst (Hainholz/South Harz, Fed. Rep. of Germany). – Proc. 8th Intern. Spel. Congr. Bowling Green, Kentucky: 568-570

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Knolle, F. & Vladi, F. (1999): Von den Hainholz-Prozessen bis zur Planung des Biosphärenreservats „Südharz" (Niedersachsen, Sachsen-Anhalt und Thüringen) - knapp 40 Jahre Naturschutz für die Südharzer Gipskarstlandschaft. – Gött. Naturkdl. Schr. 5:151–167 [slightly modified in www.karstwanderweg.de]

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Röhl, S. (2003): The example of the Südharz gypsum karst landscape: striving to preserve a
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