85 
21 
running as a strip from northwest to southeast, is obvious. 
How city planners could make best use of the proposed indices, 
cannot be discussed here in detail. Obviously for downtown areas dif 
ferent demands for green supply should be defined than for modern com 
mercial business areas and for residential districts. Moreover, the 
local situation of green supply is not even defined comprehensively by 
only two indices; this could be done, however, using another two indices, 
which can be obtained very easily both from aerial photographs of any 
kind or from maps : the distance of the investigated units to the next 
public park of at least 1 hectare size, and the nearest distance to a 
forest or to a recreation area. 
By all means, the indices which can be worked out easily for any 
planning unit and which can be checked by anybody, because the basic 
documents (aerial photography and statistical data) are always avail 
able, can serve as objectified criteria, whenever construction inten 
tions have to be discussed and to be controlled in order to regard the 
public interests; if necessary, they are good enough to serve as a con 
crete evidence, if conditions and restrictions, expressed by municipal 
authorities with regard to the constitutional ’'social obligation of 
private property” have to be pulled through against excessive private 
interests. 
The development of urban green supply can be shown both in general 
and in detail, if CIR-aerial photography is available at the beginning 
and at the end of a period of some years. The value of this material 
as a document has to be considered as very high. 
REFERENCES 
Fabricius, H. 
1973: Ergebnisse der Volks- und Arbeitsstättenzählung nach Stadtbezirken, 
Statistischen Bezirken und Blocks 1970; Beiträge zur Statistik der 
Stadt Freiburg im Breisgau. 
Kadro, A. and Kenneweg, H. 
1973: "Das Baumsterben" auf dem Farb-Infrarotluftbild. Das Gartenamt, 
H. 3, S. 149-157. 
Kenneweg, H. 
1974: Interpretation von Luftaufnahmen für die Erforschung und Gestaltung 
von Vegetationsbeständen in westdeutschen Ballungsräumen. 
Proceedings Symposium IUFRO S 605 Freiburg 1973, S. 87-116. 
2) 
For an area of very similar shape and position, microclimatic investiga 
tions in Freiburg (incidently?) reveal the lowest amounts of air quality.