The human impact on the environment is of growing preoccupation to be able to understand the formation of the contemporary landscapes and to be able to analyse the various phases of the development of a particular cultural landscape. The impressive mountain landscapes in the Andean region in South America we observe today are not as pristine and untouched, as one could be tempted to believe but it is only recently being recognized as such. The arrival the Spaniards in the 16^th century changed the landscape with the introduction of new crops, animals and technology. But the Pre-Hispanic cultures had long before altered the landscape. Changes in subsistence strategies, demography, or perception illustrate complex causes that provide important insights into different utilization systems. Examples are taken from the author's fieldwork in the Andes and in the Ceja de Montaña.