Indicators and Indices

Evaluation of the Physiographic Units

The evaluation of the landscape physiographic units consists in the definition of the indexes of "Ecological value", "Ecological sensibility," "Human pressure" (calculated by using specific indicators for each unit) and of an overall index resulting from the combination of the first three indexes.
The indicators of value take into account essentially the composition of the unit, the indexes of sensibility its structure and those of pressure the anthropogenic agents operating inside the unit.
In brief, the evaluation procedure is divided into the following phases:

• implementation of the "Map of Ecological Systems", necessary to calculate various indicators, using the "Map of Habitat at the scale 1:50.000";
• normalization of values of each indicator, which allows to bring back the values on a continuous scale between 0 and 1, in order to compare values originally uneven;
• developmet of standardized indicators, calculating the value of three synthetic indexes ("Ecological value", "Ecological sensibility," "Human pressure") through the application of the TOPSIS statistical method (Hwang & Yoon 1981) for each unit;
• classification into five classes of values calculated for each index;
• definition of an overall index, called "Environmental Profile", which provides an approximate measure of the risk of environmental degradation for each landscape physiographic unit.

The fundamental principles, the indexes and the procedure followed by this evaluation methodology are similar to those defined for the 1:50,000 scale, but they are obviously calibrated for the scale 1:250,000. This choice allowed to maintain an overall consistency in the "Map of the Nature" project.