Fruit-tree expansion on hillsides of the Mallarauco Valley

Abstract

This work examined the recent expansion of citrus and Avocado fruit-trees on hillside terrains aforetime occupied by native vegetation (schlerophyll forest/shrubs) on the Mallarauco Valley, Central Chile. To do this, the crops of interest placed on hillside terrains of the study area were mapped on satellite images acquired on 2006 and 2017, and an error matrix enabled to know their temporal changes. Additionally, the NDVI (normalized difference vegetation index), calculated and classified in three ranges for the hillside terrains by a Landsat satellite image acquired before the period of interest (2003), was used as proxy of the native biomass preexisting the aforementioned crops. The results show that for the period of interest the citrus increased their cultivated surface by 31%, while the Avocados decreased it by 24%. In both years, the crops were distributed on a similar way across the native vegetal biomass classes derived from the NDVI, regardless of the hillside. A 41.48% of the Avocados’ surface mapped on 2006 was not observed on 2017, mainly because their conversion into citrus, characterized by a higher tolerance to frost. A similar methodology could be replicated in other areas of the country exhibiting similar territorial conflicts between occupation and vocation.