The Kaiserwald is a forest area in the Austrian province of Styria, a few kilometers south-southwest of the provincial capital of Graz. Its geological location, the Kaiserwald Terrace, is a clay-covered glacial gravel plateau above the Grazer field. The clay cap, which in the past enabled a local brick industry, provides a characteristic groundwater hydrology. Botanically, it is a mixed forest with pines and oaks as the dominant trees, providing a habitat for a wide variety of animal species and serving as a princely forest for centuries. The area is also significant for its numerous Roman burial mounds.
During the Second World War, the Kaiserwald was the site of armament activities of the German Armed Forces. Today, large parts of the 30-square-kilometer forest serve as recreational areas and commercial forests. Parts of the forest have been designated as protected areas. Due to its ecological and climatic relevance, the forest is anchored as a green zone in the local development concepts of the surrounding communities. With the Graz-Köflach railway (GKB) and the A2 South motorway, two important traffic routes cross the Kaiserwald.
Geography
Location and surroundings
The Kaiserwald is located in the region of Western Styria. In the south, it borders on the foothills of the Plabutsch-Buchkogel mountain range and the Western Styria Hügelland, and in the east, it runs parallel to the Grazer Feld (Murtal). To the west and south, the Kaiserwald terrace is bordered by the lower Kainachtal. The geomorphologic boundary lies in the north at about above sea level, where the terrain is directly divided, and in the northwest in the Spatenhof area.Hans Peter Leditzky & Hans Zojer: Zur Hydrogeologie der Kaiserwaldterrasse. In: Mitteilungen der Abteilung für Geologie, Paläontologie und Bergbau am Landesmuseum Joanneum, Issue 39, Graz 1978, p. 85–97 (zobodat.at [PDF]).
It is difficult to draw a historically accurate boundary to the north and northwest. Until the forest was sold in the 19th
century, some of the land on the other side of Packer Street was also owned by the prince and was called Kaiserwald.Heinrich Purkarthofer: Kaiserwald, Gjaidhof zu Dobl und Tobelbad. Von Forst und Bauernwald, Forstamt und Bad. In: Zeitschrift des Historischen Vereines für Steiermark, Volume 78, Graz 1987, p. 87–119. The forest stretches about 13 kilometers in a northwest–southeast direction and is 1.5 to 2.5 kilometers wide. The total area is about 30 square kilometers, including the enclosed farmland.Measurement with Amap Fly 5.0/ÖK 1:50,000 (area status: 2010). Federal Office of Metrology and Surveying. The center of Graz is located about nine kilometers from the northeastern edge of the forest near Pirka.
The following municipalities (from north to south) are part of the Kaiserwald:
Seiersberg-Pirka Haselsdorf-Tobelbad Premstätten Lieboch Dobl-Zwaring Wundschuh Wildon
Geology
The Kaiserwald Terrace is a plateau dissected by gullies that is morphologically and geologically distinct from its surroundings. On average, the terrace rises 27 meters above the Grazer field and 35 meters above the Kainachtal valley. Numerous boreholes, wells, and slope fractures have revealed a gravel terrace covered by loam of varying thickness. Due to ongoing erosive processes, only about 55 percent of the Kaiserwald terrace has the character of a plateau, while the remainder has steeper slopes and therefore less sediment thickness.
Arthur Winkler-Hermaden dated the landform to the Gunz and Mindel glaciation periods of the Pleistocene and interpreted the clay cap as an interglacial loam formation. At the eastern edge of the Kaiserwald terrace are younger terrace remnants, e.g. between Windorf and Hautzendorf from the Riss glaciation, remnants of which can also be found in Graz-Wetzelsdorf.Helmut Flügel: Zur neogen-quartären Morphogenese und Verkarstung des Plabutschzuges westlich von Graz (Steiermark). In: Mitteilungen des Naturwissenschaftlichen Vereins für Steiermark, Volume 113, Graz 1983, p. 15–23 (zobodat.at [PDF]). The southeastern continuation of the Kaiserwald terrace between Steindorf, Ponigl, and Weitendorf is only ten meters above the level of the Würm main terrace (Grazer Field) and was assigned to the Helfbrunn level by Winkler-Hermaden.Hans Peter Leditzky: Die hydrogeologischen Verhältnisse im südlichen Grazer Feld und im unteren Kainachtal. Unpublished report, Graz 1975.Grundwasserkörper (GK) 100097 Grazer Feld. Hydrogeologische Charakterisierung. Federal Environment Agency. Document download While the Pleistocene origin of the gravel terrace is now considered certain,Digitaler Atlas der Steiermark: Geologie & Geotechnik. Styria, retrieved on November 19, 2017. Julius Fink invalidated the Aeolian clay theory. He interpreted the loams as multiphase aeolian drifts from the nearby gravel fields of the Mur.Julius Fink: Die Südostabdachung der Alpen. In: Mitteilungen der Österreichischen Bodenkundlichen Gesellschaft, Volume 6, Vienna 1961. Loess samples with different quartz and feldspar proportions also indicate this.Hans Kolmer: Über Lößsedimente des Murtales. In: Mitteilungen des Naturwissenschaftlichen Vereins für Steiermark, Volume 98, Graz 1968, p. 11–16 (zobodat.at [PDF]).
The gravel body with an average thickness of 13 meters and silty-sandy admixtures consist of gneiss, crystalline schist, pegmatite, amphibolite, and quartz. Carbonate rocks are absent from the partly strongly weathered gravel. X-ray diffraction studies also revealed kaolinite as a product of feldspar weathering. The clay cap, with varying proportions of clay, silt, and sand, has an average thickness of six meters, although this varies greatly, and is divided by fossil soil horizons. The boundary between the two layers is sometimes fluid.Helmut Flügel: Die Geologie des Grazer Berglandes. In: Mitteilungen der Abteilung für Geologie, Paläontologie und Bergbau am Landesmuseum Joanneum, Special issue 1, Graz 1975, p. 153 (zobodat.at [PDF; 37 MB]). As a result of relatively high rainfall, pseudogleyes have formed, which are unusable for agriculture.Herbert Paschinger: Steiermark: Steirisches Randgebirge, Grazer Bergland, Steirisches Riedelland. Borntraeger, Berlin 1974, , p. 142–149.
The brick industry used clay roof tiles for a long time. In 1869, on the initiative of Ferdinand Portugall, the first factory was built in Unterpremstätten, which developed into the First Premstätten Interlocking brick factory Anton Haas & Co. founded in 1893. At its peak, between 150 and 200 workers produced more than seven million roof tiles per year.Bernd Gassler: Die Geschichte Unterpremstättens 1848–1995. In: Walter Brunner (Ed.): Unterpremstätten im Wandel der Zeit, p. 566–652. In the early 1970s, the plant was still producing four million tiles a year. During construction work in Weitendorf, a more than 10,000-year-old molar of a woolly mammoth (Mammuthus primigenius) was found in the clay and gravel deposits.Schotterterrassen und Mammut: Zeugen der Eiszeit (Infotafel). (PDF) Cultural Park Hengist, retrieved on November 22, 2017.
At the southern end of the Kaiserwald is the Weitendorf basalt quarry, where a small part of an up to 40 meter thick basalt layer is exposed. It extends over an area of about ten square kilometers between Weitendorf and Wundschuh. The quarry is located in the area of Weitendorf on the one hand and in the area of Wundschuh on the other hand,Hartmut Hiden: Der Vulkan von Weitendorf. In: Association Kulturpark Hengist (ed.): Hengist Magazin. Issue 2, 2006, p. 4-9. where the volcanite was found in the 1950s and 1960s during drilling at a depth of 25 to 35 meters.Haymo Heritsch: Das vulkanische Gestein aus einer Bohrung bei Wundschuh, südlich von Graz. Ed.: Institute of Mineralogy and Petrography of the University of Graz. March 11, 1966, p. 59.
Hydrology and hydrogeology Due to the water-accumulating clay cap, runoff on the Kaiserwald terrace is largely above ground. The dominant watercourses, the Gepringbach and the Poniglbach, contribute to the strongly furrowed morphology of the plateau. While the Poniglbach erodes the gravel complex, the Gepringbach cuts deep into the bedrock. The gravel body, which has a low water flow due to its high clay content, rests on a base of young Tertiary fine sediments, the upper edge of which extends above the level of the Würm terraces surface. Numerous overflow springs were mapped at this boundary in the mid-1970s.
A total of 36 springs are distributed along the southern part of the terrace. While on the southwest side, the springs are continuously discharged at a height of seven to eight meters above the valley floor of the Kainach, in the east they only occur between Premstätten and Wundschuh, where the Wurm terrace directly adjoins the Kaiserwald terrace. The investigation of three selected springs revealed discharge rates of about 1.5 l/s. As the clay cap largely prevents leachate and good mixing in the aquifer, the low variation in discharge can be explained by the uniform inflow. After heavy rainfall, meteoric water often accumulates in ponds and lowlands in the Kaiserwald. Groundwater recharge occurs in the extreme north of the terrace by infiltration from the southern foothills of the Florianiberg, where the Kaiserwald terrace is in direct contact with the dolomitic--sandstone sequence and coarse clastic loose sediments of the Graz Highlands. In the south, the relatively high-temperature fluctuations of the springs mentioned above have led to infiltration through the surface channels, which break up sand and gravel in the course of their erosive activity. This connection is important in terms of water management since the perennial inflow ensures regular water extraction. In addition, the clay cover provides good protection against groundwater contamination, which is often characterized by high iron content and oxygen deficiency.Alexander Salamon (Red.): Wasserversorgungsplan Steiermark 2015. Styria – Department 14 - Water Management, Resources and Sustainability, Graz 2015, p. 31. wasserwirtschaft.steiermark.at (PDF; 9.1 MB) retrieved on January 16, 2018.
Climate The Kaiserwald is part of the climate region Grazer field with the lower Kainachtal, which is characterized by a continental climate with average annual temperatures of about 8.7 °C - the January average is -2.4 °C, the July average is 19.1 °C - and annual precipitation of about 833 mm at the ZAMG station Graz Airport. The growing season (average temperature ≥ 5 °C) lasts on average 230 days from the beginning of March to the beginning of November. The relative sunshine duration, which varies depending on the location, averages 42 percent throughout the year.Herwig Wakonigg: Klimaatlas Steiermark – Kapitel 4: Niederschlag. Central Institution for Meteorology and Geodynamics. umwelt.steiermark.at (PDF; 3,9 MB) retrieved on January 16, 2018Herwig Wakonigg: Klimaatlas Steiermark – Kapitel 2: Temperatur. Central Institution for Meteorology and Geodynamics. umwelt.steiermark.at (PDF; 4,5 MB) retrieved on January 16, 2018.Herwig Wakonigg: Klimaatlas Steiermark – Kapitel 1: Strahlung. Central Institution for Meteorology and Geodynamics. umwelt.steiermark.at (PDF; 3,1 MB) retrieved on January 16, 2018.