Ecological hiking trail – Stop 11:
|Stand in awe of the tree. It is a unique wonder and it was sacred to your ancestors. (Alexander von Humboldt)
Alexander von Humboldt
The jubilee oak at the memorial and the peace oak (donated by Josef Fiedler from Almesbach in 1871) in the place’s center are English oaks. The Quercus robur is a deciduous tree that can reach up to 50 m in height. When the tree stands in an open place, the tree’s top is very wide and may seem uneven. Since time immorial, the tree has been cultivated from the point of view of forestry and as a streetside tree. The fruits of the oak (acorns), which ripen in September or October, have long stalks 2 – 10cm in length. This is where these oaks have their name from (the German name for the English oak is stalk oak, ed.). The fruits of the related grape oak (Quercus petraea) do not have stalks.
The oak as a city tree
Both trees at Schlörplatz are prime examples of the harmonious interaction between town and nature. Moreover, each tree represents a biotope per se – microorganisms and fungi live in a symbiotic relationship with the oaks’ roots; creepers, moss, and lichens grow on the bark. Research proved that the native oak trees are home to up to 423 species of insect and 28 species of bird. (Cf. Klausnitzer, B. 1993.“Fauna.” In H. Sukopp, R. Wittig (Ed.), Stadtökologie. Stuttgart. 239-270)Furthermore, the oaks’ enormous production of biomass is able to convert tons of carbon dioxide and oxygen every year, considerably improving the climate of a town. For example, on sunny summer day, during which the rate of photosynthesis is very high, a 100 year old oak is capable of removing 9,400 liters of carbon dioxide from the air. This carbon dioxide enters the leaf through stomata (=small openings). Consequently, the leaf releases 9,400 liters of oxygen into the air, thus covering the daily oxygen supply of 25 people. The shadow of a tree both increases humidity and decreases the temperature by evaporation. Hence, the tree’s shadow has the immediate effect of cooling streets and buildings and decreasing the temperature of the shadow’s surrounding area to up to 6°C. Nonetheless, trees not only bring about a more agreeable and tolerable climate in the summer but also healthier: trees can act as a filter which can remove 80 % of dust and a large part of noxious substances from the air. Layers of raised dust cover the leaves and are washed off with the rain. In this way, a tree can filter 1 ton of dust from the air a year.
Rain water seeping into the (not sealed off) soil is stored in the roots of trees. Many people are often unaware of the large size of the roots and thus tend to underrate the water-storing capacity of trees: if you lined up the large and small roots of a tree, you would create a line of several 100 km in length. The bulk of the stored water is drawn up the tree by root pressure and capillary action. It then evaporates (or transpires) through the tree’s foliage, resulting in an increase of humidity and in a continuous transpiration stream. Due to the growing soil sealing and the installation of new sewers, the normal water storage process gradually decreases: the fast draining of water leads both to an even faster rise of high water and to a shortage of moisture for the transpiration stream.
About 90 % of Weiden’s population feels disturbed by the noisy traffic. Industrial plants and loud neighbors add to this nuisance. Trees are capable of muffing noise, especially in between narrow streets where sounds are reflected off the walls of buildings. The foliage changes high frequency into the less disturbing low frequency.
Trees have always had an effect on humans. They have been playing an important role in religious and cultural life where they are often depicted as symbols of life and fertility. In our region, a tree was considered to be the seat of an oracle where court was held and meetings took place.
Even today, trees give off an aura of mystical attraction. Humans see them as peaceful and invigorating sites which mark popular meeting places in the town. Trees can designate inner city spaces or invite to rest, communicate, or play. They can also be used as landmarks of a person’s ‘mental map’ of a town.Extensive greenery contributes to the health of a town’s inhabitants and to a positive assessment of one’s living space. In addition, plants in or near a house or apartment are of a particular importance in regard to the socialization of children. Children can experience the change of seasons and learn to familiarize themselves with open and closed spaces.
Augustinus Gymnasium Weiden:
Heike Büchl, Thomas Hüttinger, Siegfried Klarner