An enhanced Machado Index of naturalness

Abstract

The landscape naturalness may be defined and analysed by various concepts and methods attempting to encapsulate as much as possible the degree of natural conditions over a given territory. The Machado Index (MI) was developed by the Spanish biologist Antonio Machado and uses a qualitative approach to naturalness, being characterized by its versatile application throughout different environments. The outcome of the expert-based evaluation is a score that corresponds to various degrees of naturalness. This research aims to turn the MI into a semi-objective tool, introducing land cover and the ‘neighbouring to natural’ criteria as quantitative components. The MI was applied for assessing the landscape naturalness over Romania, as a case-study, and the Expert Opinion Classification (EOC) method was performed in order to identify the primary benefits and limitations of the MI. Further, the study uses the Principle of Naturalness Spatial Gradient (PNSG) as the basis for conceiving a new approach, named the Edge Contrast method (ECON). The assessment of naturalness consists in the usefulness of a previous Landscape Ecology metric, the Edge Contrast Index (ECI). We finally propose a third method, encompassing the advantages of the prior two, named the Enhanced Machado Index (EMI). The main result of this study is an enhanced method which can be used for assessing the degree of naturalness in a semi-objective manner. A set of three examples taken from different areas of Romania are assessed in a comparative analysis in order to highlight the differences between the EOC, ECON and EMI methods. The EMI results are validated by comparison with different databases.