Biodiversity forms the foundation on which human societies are built. Naturally formed biocοenoses usually develop high biodiversity rates in comparison to those influenced by man. However, an astonishing number of flora and fauna species lives in urban areas. Nature conservation in the city requires special measures. As a first step biotopes must be preserved. As a second step communication between biotopes should be restored. Transfer of animals and plants ought to be as free of obstacles as possible. This is necessary for securing genetic material exchange among individuals of the same species. Thus, populations gain a greater variety of features, fulfilling an important condition for stability.
The open spaces’ fragmentation in cities hinders communication of flora and fauna. The creation of a green network could offer the solution. Some cities describe open spaces’ axes in order to connect green spaces with each other and with the countryside in the suburbs.
The city of Hamburg is a pioneer. Local authorities have created the Hamburg Green Network, a system of interconnected open spaces through broad belts of green (picture 8). The network consists of the οpen spaces’ axes and the green rings, which form an axe-to-axe-connection (picture 2). Open spaces' axes consist of interconnected open spaces, with or without green, which cross the city from the suburbs to the centre. Peripherally, the axes comprise extended forests, agricultural (pictures 6, 7) and protected areas (picture 10). Deeper inside the city green spaces obtain a more urban character and become parks (picture 3), gardens (picture 4), cemeteries (picture 5) and sports’ venues. Rivers, lakes (pictures 9, 11) and streets lined with trees complete the axes.
Two green rings connect the open spaces’ axes (picture 2). The 1st ring runs parallel to the city centre outline, in a spread of 1 km from Town Hall. The 2nd ring is bigger and follows the city border in an 8-10 km distance from Town Hall (picture 12). It incorporates large parks, lakes (picture 13) and wide belts of green (picture 14). Some additions are still needed in order to complete the connection of green areas to a continuous Green Ring.
The idea of a green network can be of interest for Greek local authorities. Even densely built Athens could start thinking of the connection of its green areas to a network in order to protect biodiversity and offer higher life standards to its residents (picture 16).
Βiocoenosis: a group of interacting organisms that live in a particular habitat and form a self-regulating ecological community