Description of space-time variability of the potential productivity of Acacia caven espinales based on MODIS images and the Enhanced Vegetation Index (EVI)

Abstract

Acacia caven espinales are important communities of sclerophyllus vegetation in central Chile. To increase its productivity, it is necessary to study the community's condition, their relationships with the surrounding environment and the interactions between them. The present study was carried out in a series of three years: 2004, 2005 and 2006. The 68 EVI images used represent the amount of radiation absorbed and emitted (from a Moderate Resolution Imaging Spectroradiometer) for the vegetation, which is related to the photosynthetic performance. The results show that during the summer and autumn seasons, there was more space homogeneity and less photosynthetic activity and potential productivity of the communities; in winter and spring, the period in which the grassland develops, there was more biological activity and potential productivity as well as an increase in the spatial heterogeneity. As for anisotropy, the communities were noticeably more homogeneous in the 150° north-northwest direction and more heterogeneous in the 60° east-northeast direction.