Evaluation of Morpho-Physiological Traits Adjustment of Prosopis tamarugo Under Long-Term Groundwater Depletion in the Hyper-Arid Atacama Desert

• Published in: Frontiers in plant science Vol. 9; p. 453
• Main Authors: Garrido, Marco, Silva, Herman, Franck, Nicolás, Arenas, Jorge, Acevedo, Edmundo
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 09.04.2018
• Subjects: hydraulic lift; leaf isotopic composition; phreatophyte; Plant Science; stomatal behavior; water table depth; stomatal behavior; hydraulic lift; water table depth; phreatophyte; leaf isotopic composition
• ISSN: 1664-462X; 1664-462X
• DOI: 10.3389/fpls.2018.00453

Water extraction from the underground aquifers of the Pampa del Tamarugal (Atacama Desert, Chile) reduced the growing area of , a strict phreatic species endemic to northern Chile. The objective of this work was to evaluate the effect of various architectural and morpho-physiological traits adjustment of subjected to three groundwater depletion intervals (GWDr): <1 m (control), 1-4 m and 6-9 m. The traits were evaluated at three levels, plant [height, trunk cross-section area, leaf fraction ( GCC), and crown size], organ [length of internodes, leaf mass per unit area (LMA), leaflet mass and area], and tissue level [wood density (WD), leaf C, O isotope composition (δ), and intrinsic water use efficiency (iWUE)]. In addition, soil water content (VWC) to 1.3 m soil depth, pre-dawn and midday water potential difference (ΔΨ), and stomatal conductance (g ) were evaluated. At the deeper GWDr, experienced significant growth restriction and reduced GCC, the remaining canopy had a significantly higher LMA associated with smaller leaflets. No differences in internode length and WD were observed. Values for δ C and δ O indicated that as GWDr increased, iWUE increased as a result of partial stomata closure with no significant effect on net assimilation over time. The morpho-physiological changes experienced by allowed it to acclimate and survive in a condition of groundwater depletion, keeping a functional but diminished canopy. These adjustments allowed maintenance of a relatively high g ; ΔΨ was not different among GWDrs despite smaller VWC at greater GWDr. Although current conservation initiatives of this species are promising, forest deterioration is expected continue as groundwater depth increases.