Abstract

The groundwater extraction in the Pampa del Tamarugal, Atacama Desert, has put at risk the survival of Prosopis tamarugo, a strict phreatophyte endemic to the region. In this context, this thesis aims to determine the hydraulic strategy with which P. tamarugo faces water stress and survival. The hypothesis considers that P. tamarugo deploys an acclimatization strategy based on hydraulic security and plasticity of its hydraulic architecture under water stress due to phreatic level decrease. The results obtained in field studies with native trees in the Llamara Salt Flats, and semi-controlled conditions indicate that in the short-term, P. tamarugo deploys an anisohydric strategy (water stress tolerant) based on a low stomatal regulation on tissue embolism as water stress intensifies; and in the long-term, it modifies its hydraulic architecture at the tree, canopy (leaf shedding and foliar tolerance to stress) and branch vascular tissue level. Hydraulic architecture adjustments did not always occur in the continuous efficiency-safety, contributing in net terms to maintaining functional homeostasis of its water status and gas exchange. Based on the results obtained, the trees subjected to a decrease in phreatic level are in a deteriorated state that, to be prolonged or intensified, would result in death due to hydraulic failure, being this their probable death physiological mechanism. This is how conservation initiatives conducive to ensuring the source of water for the species are necessary.