2. The Upper Danube Valley

2.1 Morphology and Location

The Upper Danube Valley ("Oberes Donautal") stands for the landscape unit along the rise of the Danube through the low mountain range of the "Schwaebische Alb". This diverse, scenic landscape is legally designated as a so called "Naturpark", a rural area which is to be protected and developped under recreational and ecological aspects. The "Naturpark Obere Donau" corresponds to our study area.
The low mountain range of the "Schwaebische Alb" reaches about 200 km from southwest to
northeast, from the city of Schaffhausen on the river Rhine at the Swiss border to the "Noerdlinger Ries", an ancient meteorite crater. The entire low mountain range is not wider than 50 km.
The "Naturpark Obere Donau" (Upper Danube Valley) is located in the very southwest of the
"Schwaebische Alb".The Naturpark itself reaches along the Danube from west to east, from the city of Tuttlingen to the city of Sigmaringen. Its total area is about 85.000 ha and includes 46 towns and villages.
The scenic attraction of the Naturpark are the steep jurassic rocks of the unique valley and the Danube with the famous monastery "Beuron" on its side.
Off the Danube Valley the Naturpark area includes plain fields and forests, the locally famous juniper pastures and a few other tributary rivers.
The altitude above sea-level reaches from 536 metres on the Danube to 1015 meters on the peak of the Lemberg mountain, the highest point of the "Schwaebische Alb".
 

2.2 Climate

The climate in the study area corresponds to the temperate, humid and relatively cool climate of Central Europe with continental accent. The mean annual temperature is ca. 6,5 degrees Celsius; it­s slightly increasing towards the south and the east. Located on the leeward side of the Black Forest, the highest amount of precipitation is 900 mm - 1000 mm on top of the steep western slope of the "Schwaebische Alb". Towards the east rainfall decreases to 800 mm.
 

2.3 Geology

The low mountain range of the "Schwaebische Alb" was created by marine deposits 150 -180 million years ago. More than 3/4 of the study area is dominated by the hard limestones of the White Jurassic (Malm). In the west you can find the Brown Jurassic layers (Dogger). This jurassic underground was the basis for the development of chalky soils. In the southeast quarternary gravels and moraines of the Riss Ice Epoch are dominant.
The penetration of the Danube water into the ground which is developped to karst is a geological phenomena of international significance. Nearby Immendingen and Fridingen the river dries up during 200 days a year. The infiltratet water reappears 12 km further south at the Achquelle, a well from where the water flows to the river Rhine.
 

2.4 Landuse and Forests

Almost half of the study area is forested, which is an important criteria for the high recreational value of the Naturpark Obere Donau. The chosen area has a high diversity in the range of marginal rocky sites with extremely thin soil layers to very rich and deep soils. Primarily the steep slopes of the Danube Valley and its tributary river valleys as well as the wet moraine sites in the east are covered with forests of all age classes. Unfortunately the scenery has been spoiled during the past years by huge spruce afforestations on marginal agricultural sites on the higher located plains of the Naturpark area.
The native forest vegetation are continental, submontaneous or montaneous beech forests. The composition of native forests varies with the exposition of a site: there is a dryer variation on steep slopes of the Danube Valley and a ravine variation in narrow tributary river valleys.
Since the end of the sheep pasture management 100 years ago, the percentage of spruce has been increased. Nowadays 57% of the tree species are spruces; beeches, once the predominant species, have a percentage of about 30%. Nevertheless beech remains as the dominant tree species on the scenic steep slope of the Danube Valley. On hilltops pine stands are common.
 

Percentage of tree species in the study area (estimated):

Spruce                    57%
Other conifers           8%
Beech                    30%
Oak                         2%
Other broadleaves    3%

Forest Ownership:

Corporate Forests                 60%
Private Forests > 200 ha        20%
Private Forests < 200 ha        15%
State Forests                            5%

About 3/4 of the forests are mapped as designated sites with protection function: Primarily these forests protect from soil erosion and debris on steep slopes; secondarily they protect watersheds of wells on the karsted high located plains of the study area, and finally 10% of the forests are designated as recreation forests, mainly around the Danube rise and the western edge of the "Schwaebische Alb".

About 37% of the Study area is agricultural land; 6% are shrubland, hedges, wet sites,rivers and lakes.
The study area is traditionally used for hiking and other outdoor activities. Most of the visitors stay for a weekend or a day. People who spend their holidays in the area are less frequent. The infrastructure for recreation is well developped as the following numbers may introduce:
  

etc.
Conflicts between the increasing number of cyclists, free-climbers, hikers and people practising other outdoor activities and the interests of nature conservation and forestry are the main issues of the Naturpark management.
 

2.5 Test Sites

We are going to select 3 test sites with different ecological, economical and scenic aspects in the Naturpark Obere Donau.
One test site will be the center of recreation and one of the main attraction of the Upper Danube Valley, the area around the monastery of Beuron. This site includes the pittoresque jurassic rocks above the meandering Danube and the bottom of the valley where most of the outdoor activities take part.
The second site will be on the higher plains a few kilometres off the Danube Valley. The main issues in this area are conflicts between nature conservation (aesthetically and ecologically) and the local forest management with regard to recent spruce afforestations.
The third site is located on a valley of a tributary river, the Bera Tal. The changes of the landscape due to afforestations in the scenic valley are the main issues.
 

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