2. The Upper Danube Valley
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:
-
Marked hiking trails
3500 km
-
Marked cross-country ski runs
340 km
-
Parking areas with hiking information
130
-
Other parking areas
102
-
Keep-fit trails with facilities for sportsmen
8
-
Information trails about forestry, geology and archeology
19
-
Campgrounds
14
-
Cabins and huts
60
-
Playgrounds
33
-
Lookout towers
4
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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