Assessing Water Stress of Desert Tamarugo Trees Using in situ Data and Very High Spatial Resolution Remote Sensing

Chávez, Roberto O.; Clevers, J.G.P.W.; Herold, Martin; Acevedo, Edmundo; Ortiz, Mauricio

doi:10.3390/rs5105064

Cited by 24 publications

(38 citation statements)

References 37 publications

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“…Water stress strongly increases the rate of defoliation of P. tamarugo under controlled conditions, decreases its paraheliotropic capacity (Chávez et al, 2013a ), and its photosynthetic rate (Delatorre et al, 2008 ). Field studies in mature trees have shown that the effect of lowering the water table, increases the variability among individual trees of P. tamarugo (Altamirano, 1994 ), decreases its water potential, and causes loss of foliage (Chávez et al, 2013b ), decreases NDVI (Normalized Difference Vegetation Index) as canopy activity indicator (Ortiz et al, 2012 ; Chávez et al, 2014 ) and eventually there is loss of paraheliotropic ability (Chávez et al, 2014 ).…”

Section: Introductionmentioning

confidence: 99%

Water Relations and Foliar Isotopic Composition of Prosopis tamarugo Phil., an Endemic Tree of the Atacama Desert Growing at Three Levels of Water Table Depth

2016

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Prosopis tamarugo Phil. is a strict phreatophyte tree species endemic to the “Pampa del Tamarugal”, Atacama Desert. The extraction of water for various uses has increased the depth of the water table in the Pampa aquifers threatening its conservation. This study aimed to determine the effect of the groundwater table depth on the water relations of P. tamarugo and to present thresholds of groundwater depth (GWD) that can be used in the groundwater management of the P. tamarugo ecosystem. Three levels of GWD, 11.2 ± 0.3 m, 10.3 ± 0.3 m, and 7.1 ± 0.1 m, (the last GWD being our reference) were selected and groups of four individuals per GWD were studied in the months of January and July of the years 2011 through 2014. When the water table depth exceeded 10 m, P. tamarugo had lower pre-dawn and mid-day water potential but no differences were observed in minimum leaf stomatal resistance when compared to the condition of 7.1 m GWD; the leaf tissue increased its δ13C and δ18O composition. Furthermore, a smaller green canopy fraction of the trees and increased foliage loss in winter with increasing water table depth was observed. The differences observed in the physiological behavior of P. tamarugo trees, attributable to the ground water depth; show that increasing the depth of the water table from 7 to 11 m significantly affects the water status of P. tamarugo. The results indicate that P. tamarugo has an anisohydric stomatal behavior and that given a reduction in water supply it regulates the water demand via foliage loss. The growth and leaf physiological activities are highly sensitive to GWD. The foliage loss appears to prevent the trees from reaching water potentials leading to complete loss of hydraulic functionality by cavitation. The balance achieved between water supply and demand was reflected in the low variation of the water potential and of the variables related to gas exchange over time for a given GWD. This acclimation capacity of P. tamarugo after experiencing increases in GWD has great value for the implementation of conservation strategies. The thresholds presented in this paper should prove useful for conservation purposes of this unique species.

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Section: Introductionmentioning

confidence: 99%

Water Relations and Foliar Isotopic Composition of Prosopis tamarugo Phil., an Endemic Tree of the Atacama Desert Growing at Three Levels of Water Table Depth

2016

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“…Chávez et al (2013a) indicated that tamarugo is a plant capable of changing the angle of its leaflets in order to avoid high levels of radiation in the afternoon. This ability would be associated with the level of turgor in pulvinar structures in the leaf, and the authors note that individuals undergoing certain threshold of drought stress would be less capable of carrying out this process, therefore being more susceptible to damage by photoinhibition (Chávez et al, 2013b andChávez et al, 2016).…”

Section: Situation Of P Tamarugo In Thementioning

confidence: 99%

Water relations and growth response to drought stress of Prosopis tamarugo Phil. A review

Time

Garrido

Acevedo

2018

J. Soil Sci. Plant Nutr.

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Understanding the physiological mechanisms of response that allow plants to survive under suboptimal conditions such as drought stress is of particular interest, because of global climate change that threat the suitability of most terrestrial habitats for plant growth, as well as habitat disturbance of desert plants due to water extraction for human supply. Prosopis tamarugo Phil. of the Pampa del Tamarugal is frequently subjected to drought stress due to groundwater extraction for urban areas, mining industry and agriculture supply. The aim of this review is to analyze information concerning the plant growth response to drought stress and specifically P. tamarugo water relations and growth response to drought stress. P. tamarugo, being a desert plant, has physiological mechanisms that permit its adaptation to extreme environmental conditions like the Pampa del Tamarugal. It has mechanisms as osmotic adjustment, that allow some growth through osmoregulation; changes the angle of its leaflets to avoid high levels of radiation in the afternoon; partially closes its stomata to decrease water loss; maintains high stomata conductance to deal with increasing temperature and atmospheric demand.

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“…Based on a statistical analysis, it has been determined that water table depths of more than 13.3 m increase the probability of finding an ill-conditioned Tamarugo tree [15]. Satellite indices, such as the green canopy fraction (GCF) [16] and the normalized difference vegetation index (NDVI) [17], have been used for analyzing the health of the Tamarugo trees. The GCF is the ratio between the volumes of green canopy and total canopy and corresponds to an indirect measurement of the photosynthetic activity of the trees [16], whereas the NDVI represents the fraction of photosynthetically active radiation absorbed by the vegetation [17].…”

Section: Introductionmentioning

confidence: 99%

“…Satellite indices, such as the green canopy fraction (GCF) [16] and the normalized difference vegetation index (NDVI) [17], have been used for analyzing the health of the Tamarugo trees. The GCF is the ratio between the volumes of green canopy and total canopy and corresponds to an indirect measurement of the photosynthetic activity of the trees [16], whereas the NDVI represents the fraction of photosynthetically active radiation absorbed by the vegetation [17]. Chávez et al [18] proposed a relationship between water table depth and the vital state of the Tamarugo tree in which the GCF is integrated along with the NDVI, the 18 O isotope enrichment in foliar tissue and the twig growth to determine a range of tree damage as a function of water table depth.…”

Section: Introductionmentioning

confidence: 99%

An Unsaturated/Saturated Coupled Hydrogeological Model for the Llamara Salt Flat, Chile, to Investigate Prosopis tamarugo Survival

et al. 2019

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The Propopis tamarugo Phil, also known as Tamarugo, is an endemic and protected tree that survives in the Atacama Desert—a hyper arid and highly saline environment. The Tamarugo is threatened because of groundwater overexploitation, and its preservation depends on the soil moisture in the vadose zone, as many of the tree roots do not reach the current water table levels. To improve the estimation of soil moisture available for the Tamarugo trees, we applied a hydrogeological model that couples the unsaturated and saturated zones. The model was used to represent different groundwater exploitation and recharge scenarios between February 2006 and September 2030 to predict simultaneously groundwater levels and soil moisture. The model results show that even at locations where water table depletion is relatively small (~1–1.5 m), soil moisture can drastically decrease (0.25–0.30 m3/m3). Therefore, Tamarugo survival can be better addressed, as the applied model provides a management tool to estimate response of Tamarugo trees to changing soil moisture. To further improve the model and its use to assess Tamarugo survival, more field data, such as soil hydrodynamic properties and soil moisture, should be collected. Additionally, relationships between the state of the Tamarugo trees and soil moisture should be further constructed. In this way, the developed model will be able to predict future conditions associated to the Tamarugo’s health state.

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Assessing Water Stress of Desert Tamarugo Trees Using in situ Data and Very High Spatial Resolution Remote Sensing

Cited by 24 publications

References 37 publications

Water Relations and Foliar Isotopic Composition of Prosopis tamarugo Phil., an Endemic Tree of the Atacama Desert Growing at Three Levels of Water Table Depth

Water Relations and Foliar Isotopic Composition of Prosopis tamarugo Phil., an Endemic Tree of the Atacama Desert Growing at Three Levels of Water Table Depth

Water relations and growth response to drought stress of Prosopis tamarugo Phil. A review

An Unsaturated/Saturated Coupled Hydrogeological Model for the Llamara Salt Flat, Chile, to Investigate Prosopis tamarugo Survival

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