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Woodland managers in northern Chile require efficient means of estimating fruit production to improve their ability to sustainably manage mesquite tree ecosystem. We assessed the accuracy of the indirect visual count (VC) method for quantifying fruit production of two endangered mesquite trees, tamarugo (Prosopis tamarugo) and algarrobo (Prosopis alba), by comparing it with the fruit trap (FT) method, during three fruit dissemination periods. We studied two natural populations of trees of P. tamarugo and P. alba in the Pampa del Tamarugal ecosystem, Atacama Desert, northern Chile. We placed FTs beneath the crowns of the trees to measure the fruit crop during the mast dissemination period. The VC method was performed at the same trees used for FT. We used linear regressions and coefficient of variation to assess the relationship between the two methods. There was a positive correlation between both methodologies in all three periods for P. alba, but the relationship for P. tamarugo was not statistically significant. Analysis of the variability in fruit production estimates using the FT method showed significant interannual differences for P. tamarugo and significant differences among individuals for both species. The VC method had better results for fruit production in P. alba, whereas the use of the FT method is more suitable for P. tamarugo.

The species Helicoperva titicacae is reported for the first time in Chile outside it’s of natural distributional range in Peru. During 2011-2013 adults of this moth were collected in forests of tamarugo (Prosopis tamarugo F. Philippi), located in the Pampa del Tamarugal National Reserve, Tarapacá Region, Chile (20°24´S - 69°44’W). There is no evidence of when this species could have expanded his range of distribution from southeast Peru to the Atacama Desert in Northern Chile. Helicoperva is a particularly invasive pest and his presence in the country could represents a potential threat to several crops and native forests.

Morphology and DNA barcode sequences were used to assess the taxonomic status of a micro-moth of the genus Ithome Chambers, 1875 (Lepidoptera, Cosmopterigidae, Chrysopeleiinae), whose larvae feed on inflorescences of Prosopis tamarugo Phil. (Fabaceae), a tree native to the Pampa del Tamarugal, Atacama Desert, northern Chile. As a result, Ithome tamarugensis Vargas, sp. nov. is described and illustrated. Its genitalia are remarkably similar to those of Ithome tiaynai Vargas, 2004 from coastal valleys of the Atacama Desert. However, the two species can be recognized by the shape of the phallus in males and the shape of the antrum and ductus bursae in females. The genetic distance between DNA barcodes of I. tamarugensis and I. tiaynai was 3.0–3.3% (K2P), and a maximum likelihood analysis indicated that they are in reciprocally monophyletic clusters, providing additional support for the heterospecific status suggested by morphology.

Prosopis tamarugo undergoes several modifications of its hydraulic architecture, which has a homeostatic effect on its performance under descent of phreatic level. Groundwater extraction for mining has generated a large area of descent of phreatic level in the Llamara Salt Flat, Atacama Desert, where Prosopis tamarugo lives as a strict phreatophyte. We study different hydraulic architecture traits of P. tamarugo after 12 years of exposure to a descent of phreatic level of ~ 11 m to assess its acclimation capacity. Under this condition, tree size was reduced making the structure of trees shrubbier. At branch level, leaf shedding increased Huber Value and theoretical leaf-specific hydraulic conductivity. At vascular tissue level, vessel composition decreased significantly due to an increase in vessel density and a slight decrease in mean vessel area. This meant that there were no differences of theoretical sapwood-specific hydraulic conductivity and wood density between conditions of descent of phreatic level. Although the theoretical hydraulic efficiency is high under descent of phreatic level, a lower midday water potential indicates other possible factors that may affect its performance (e.g., microclimate, daily loss of conductivity and a high root resistances). The above is consistent with a higher leaf mass per area of the remaining leaves, but no differences were observed in stomatal conductance, leaf 13C isotopic composition and predawn water potential between descent condition. While the adjustment of hydraulic architecture traits has a homeostatic effect on P. tamarugo performance, it is necessary to evaluate the limits of its resistance to contribute to its conservation in a context of intervention of its habit, mainly due to demographic growth and non-metallic mining.

The first hostplant record on Prosopis tamarugo (Fabaceae) is given for the Chilean green stink bug Chinavia chilensis . Observations were made in San Pedro de Atacama, Antofagasta Region, Chile. It was recorded that the females oviposite on the three. Later, nymphs develop on the fruits. The significance of this finding is discussed and it is concluded that C. chilensis may be highly specialized to feed on this vegetal species.

This study investigated the influence of treated greywater on growth and protein content of multipurpose (forage and ornamental) transplants, Prosopis juliflora L., Prosopis tamarugo L., and Albizia lebbeck L. Transplants of tested species were irrigated with treated greywater, diluted greywater (grey + distilled water, 1:1/by volume), and distilled water (control) for seven months. Water quality analysis showed that the concentrations of nutrients and heavy metals found in the greywater were within the acceptable range compared with Jordan Institution for Standard and Metrology (JISM) and the World Health Organization (WHO) thresholds for safe use of greywater. Escherichia coli found in the greywater were lower compared to JISM and WHO guidelines for the safe use of greywater. Irrigation with treated greywater increased shoot fresh weight by 24–39% and dry weight by 34–40% compared to diluted greywater and control. No significant difference in crude protein was noticed between water treatments. Prosopis species (P. juliflora Albizia lebbeck L. and P. tamarugo Albizia lebbeck L.) had higher shoot fresh (35%) and dry weight the same species had lower crude protein (44%) when compared to Albizia lebbeck Albizia lebbeck L. The reuse of treated greywater for landscaping or forage production alleviates the demand for water resources and reduces the pressure on wastewater treatment plants. However, considering the controversial findings of previous studies on greywater quality (especially, long-term reuse), the reuse of treated greywater needs to be considered with caution and periodic quality analyses and economic assessments are required.

Chile is one of the major copper producers in the world, which entails a high economic benefit for the country. However, it has generated environmental impacts of several kinds, wherein the largest ones correspond to mine tailings. Mine tailings occupying large areas of soil and cause severe environmental impacts, either because of its toxicity and concentration or due to its interaction with environmental factors such as oxygen and water. Environmental problems associated with tailings disposal depends, among other factors, on the local climate. In the case, arid or semiarid climates, tailings are distributed to the environment through wind dispersion and erosion processes caused by water. In arid and semiarid regions, the establishment of the plant is restricted by several physicochemical factors that include extreme temperatures and high-speed winds. Phytoremediation, a low-cost in-situ technology, has emerged as the most promising remediation method for mine tailings with multielement contamination through the introduction of tolerant plants. These set of technologies using plants to clean contaminated sites, has a minimal negative impact on the environment when treating mine tailings, reducing the dispersion and bioavailability of metals, and returning the substrate to an acceptable ecological condition. The objective of this chapter is to offer the reader the results obtained by the team working with native or endemic plant species on mine tailings located in the Antofagasta region. The species under study were Adesmia atacamensis, Atriplex nummularia, Prosopis tamarugo, Schinus molle, Gazania rigens, and Pelargonium hortorum.

The effect of water deficit on growth, water status and stomatal functioning of Prosopis tamarugo was investigated under controlled water conditions. The study was done at the Antumapu Experiment Station of the University of Chile. Three levels of water stress were tested: (i) well-watered (WW), (ii) medium stress intensity (low-watered (LW)) and (iii) intense stress (non-watered (NW)), with 10 replicates each level. All growth parameters evaluated, such as twig growth, specific leaf area and apical dominance index, were significantly decreased under water deficit. Tamarugo twig growth decreased along with twig water potential. The stomatal conductance and CO2 assimilation decreased significantly under the water deficit condition. Tamarugo maintained a high stomatal conductance at low leaf water potential. In addition, tamarugo reduced its leaf area as a strategy to diminish the water demand. These results suggest that, despite a significant decrease in water status, tamarugo can maintain its growth at low leaf water potential and can tolerate intense water deficit due to a partial stomatal closing strategy that allows the sustaining of CO2 assimilation in the condition of reduced water availability.

The Propopis tamarugo Phil, also known as Tamarugo, is an endemic and protected tree that survives in the Atacama Desert&mdash, 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&ndash, 1.5 m), soil moisture can drastically decrease (0.25&ndash, 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&rsquo, s health state.

Arbuscular mycorrhizal (AM) fungi affect ecosystem processes improving plant tolerance in (hyper)arid/saline environments. However, there are no previous studies on the presence of AM fungi in the Atacama Desert (Northern Chile), the driest desert in the world. Here, we studied the root and rhizosphere in 111 samples of representative plants from three elevation gradients: (i) hyperarid desert (700–2000 m a.s.l.), (ii) pre-Puna (2000–3100 m a.s.l.) and (iii) Puna (3100–4500 m a.s.l.) elevation belts. Soil pH, electrical conductivity (EC), organic matter, cations and the AM colonization and fungal structures were determined. All plants showed colonization and fungal structures. Root colonization ranged from 3.5 to 87%, hyphae showed densities from 0.13 to 204 m g−1, and spore densities between 20 and 45,500 per 100 g of soil. The highest fungal structure abundances were found in Prosopis tamarugo, Baccharis scandens, Werneria pinnatifida, Deyeuxia curvula and Festuca deserticola rhizospheres. In general, EC and cations showed strong relationship with fungal structure abundance. Here, we reported for the first time the widespread presence of AM symbiosis in all the elevation belts of the Atacama Desert, constituting a first step to understand the ecological role that AM fungi play under extreme aridity and salinity conditions.

A national‐scale study of outcrossing potential within Chilean vascular flora was conducted using an upgraded algorithm, which adds parameters such as pollinator agents, climate, and geographic conditions. Datasets were organized and linked in a Web platform (www.flujogenico.cl), in which the development of a total outcrossing potential (TOP) predictor was formulated. The TOP predictor is the engine in the Web platform, which models the effect of a type of agricultural practice on others (coexistence calculation mode) and on the environment (biodiversity calculation mode). The scale for TOP results uses quintiles in order to define outcrossing potential between species as “very low,” “low,” “medium,” “high,” or “very high.” In a coexistence analysis considering 256 species (207 genera), the 10 highest TOP values were for genera Citrus, Prunus, Trifolium, Brassica, Allium, Eucalyptus, Cucurbita, Solanum, Lollium, and Lotus. The highest TOP for species in this analysis fell at “high” potential, 4.9% of the determined values. In biodiversity mode, seven out of 256 cultivated species (2.7%) were native, and 249 (97.3%) corresponded to introduced species. The highest TOP was obtained in the genera Senecio, Calceolaria, Viola, Solanum, Poa, Alstroemeria, Valeriana, Vicia, Atriplex, and Campanula, showing “high” potential in 4.9% of the values. On the other hand, 137 genetically modified species, including the commercial and pre‐commercial developments, were included and represented 100 genera. Among these, 22 genera had relatives (i.e., members of the same genus) in the native/introduced group. The genera with the highest number of native/introduced relatives ranged from one (Ipomea, Limonium, Carica, Potentilla, Lotus, Castanea, and Daucus) to 66 species (Solanum). The highest TOP was obtained when the same species were coincident in both groups, such as for Carica chilensis, Prosopis tamarugo, and Solanum tuberosum. Results are discussed from the perspective of assessing the possible impact of cultivated species on Chilean flora biodiversity. The TOP predictor (http://epc.agroinformatica.cl/) is useful in the context of environmental risk assessment.

Groundwater-dependent ecosystems occur in arid and semi-arid areas worldwide and are sensitive to changes in groundwater availability. Prosopis tamarugo Phil, endemic to the Atacama Desert, is threatened by groundwater overexploitation due to mining and urban consumption. The effect of groundwater depletion on two representative sites (low -and high-depletion) was studied using a multi-scale approach, combining remote sensing based estimations of canopy growth and water condition, and tree-ring based analysis of stem growth. On the stand level two NDVI (Normalized Difference Vegetation Index) -derived parameters: NDVI in winter and the difference between NDVI in summer and winter showed significant negative trends in the high-depletion site, indicating drought stress. Radial stem growth of viable P. tamarugo trees was 48% lower in the high-depletion site. At the tree level, the Green Canopy Fraction (GCF) also indicated drought stress since a larger percentage of trees fell within lower GCF classes. Groundwater depletion of 3 m, reaching a groundwater depth of >10 m, increased drought stress, and led to reduced growth in viable trees. Viable trees may be able to adapt to the drop in groundwater levels by increasing root growth, whereas for non-viable trees, the effects might be detrimental. © 2016 Elsevier Ltd. All rights reserved.

Groundwater-dependent ecosystems are threatened worldwide by unsustainable groundwater (GW) extraction. This is the case of the Prosopis tamarugo Phil forest in the hyper-arid Atacama Desert (Northern Chile), one of the most extreme ecosystems on Earth. Despite concerns about the conservation of this ecosystem, little research has been done to quantify the effects of the increasing GW depth (GWD) on the Tamarugo population. Here we provide a spatio-temporal assessment of the water condition of Tamarugo trees and propose GWD thresholds for their conservation. We studied spatio-temporal changes of GWD and the water status of the forest using Landsat images and hydrogeological records (1988–2013). This was complemented with a digital inventory and estimation of the green canopy fraction (GCF) of all trees using fine resolution satellite images. Since Tamarugos are solar trackers, their canopy spectral reflectance changes on a diurnal and seasonal basis. Thus, novel remote sensing drought stress indicators were defined: the mean NDVI in winter (NDVIW) accounting for foliage loss and the NDVI difference between mean winter and summer (¿NDVIW-S) accounting for canopy water loss. NDVIW and ¿NDVIW-S of the Tamarugo forest declined on average 19% and 51%, respectively, while GW depleted on average 3 m over the period 1988–2013. About 730,000 trees were identified in the study area, from which 5.2% showed a GCF 12 m increasingly limited the paraheliotropic leaf movement, leading to dehydration and foliage loss. Tamarugos at 12–16 m GWD suffered moderate drought stress while GWD of 16–20 m implied severe drought stress. We suggest 20 m GWD as a critical threshold for the survival of Tamarugo trees.

Aims of the study: Phreatophyte species of the Prosopis genus are very important to natural ecosystems in Africa, South America and Asia due to their uses as food and seed sources and in agroforestry. In this research, through next-generation sequencing, we sought to search for and develop SSR markers in Prosopis tamarugo, in addition to assessing their transferability to other species in the Strombocarpa section.Area of study: The study was carried out in species of the Strombocarpa section collected in the “Pampa del Tamarugal”, located in the Atacama Desert (Chile); which is considered the driest and oldest desert on Earth.Materials and methods: The next-generation sequencing for the development of simple sequence repeat (SSR) or microsatellite loci for genetic research in P. tamarugo and their transferability in Prosopis burkartii and Prosopis strombulifera was used.Main results: A total of ~90.000 microsatellite loci in P. tamarugo were found, and a set of 43 primer pairs was used for validating SSR locus amplification. We found a large difference in the percentage of amplified SSR markers between species of the Strombocarpa and Algarobia sections.Research highlights: The present study provides for the first time 24 polymorphic SSR markers for species in the Strombocarpa section, which could be a useful tool for estimating genetic structure, developing breeding programs, quantifying genetic diversity and performing population studies.Keywords: Strombocarpa section; Prosopis tamarugo; Atacama Desert; microsatellites; NGS.

Water extraction from the underground aquifers of the Pampa del Tamarugal (Atacama Desert, Chile) reduced the growing area of Prosopis tamarugo, 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 P. tamarugo subjected to three groundwater depletion intervals (GWDr)

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.

Actions aimed at reforesting arid areas around the world are increasingly complex. In our study, we evaluated the physiological resistance of Prosopis (mesquite) seedlings from different collection sites in the Atacama Desert, northern Chile. Our results show that seedlings of the most hyperarid habitats had the highest tolerance to water stress, as compared to seed collected from less arid sites. These findings are useful for increasing knowledge of the endogenous ecophysiological behaviour of Prosopis spp., which will be instrumental to elaborate upon well-planned forestation plans directed at regenerating and preserving these endangered woodlands., Initiatives to restore natural ecosystems have had little success in arid and hyperarid ecosystems. In this context, the natural seedling establishment is particularly affected by drought patterns and climatic variability. Likewise, the effect of plant provenance on forest restoration success remains unclear, although previous studies have concluded that some seed locations might be better able to tolerate water stress. In this study, we examined the physiological mechanisms involved in the drought stress resistance of Prosopis tamarugo and Prosopis alba seedlings from different arid and hyperarid locations of the Atacama Desert in northern Chile. We measured the xylem water potential (Ψ), cuticular transpiration (Ec), specific leaf area (SLA) and pressure–volume curves at the intrapopulation and interpopulation levels of seedlings of both species subjected to three drought-induced treatments. In addition, plant characteristics such as seedling height (Sh), stem diameter (Sd), leaf biomass (Lb), root biomass (Rb) and seedling survival (Ss) were measured during the treatments. Seedlings of most hyperarid habitats had the highest values of Ψ and water content relative to the turgor loss point, as well as decreased SLA, especially during the strongest drought treatment. Ψ was strongly correlated with Sh in both species, and soil humidity was correlated with Sd. This study highlights the high variability of physiological responses to water stress in both species at the interpopulation and intrapopulation levels, which provides us with a powerful seed selection tool for future reforestation programmes aimed at the early selection and genetic improvement of species of the Prosopis genus.

The hyper-arid Atacama Desert is one of the most extreme environments for life and only few species have evolved to survive its aridness. One such species is the tree Prosopis tamarugo Phil. Because Tamarugo completely depends on groundwater, it is being threatened by the high water demand from the Chilean mining industry and the human consumption. In this paper, we identified the most important biophysical variables to assess the water status of Tamarugo trees and tested the potential of WorldView2 satellite images to retrieve these variables. We propose green canopy fraction (GCF) and green drip line leaf area index (DLLAIgreen) as best variables and a value of 0.25 GCF as a critical threshold for Tamarugo survival. Using the WorldView2 spectral bands and an object-based image analysis, we showed that the NDVI and the Red-edge Chlorophyll Index (CIRed-edge) have good potential to retrieve GCF and DLLAIgreen. The NDVI performed best for DLLAIgreen (RMSE = 0.4) while the CIRed-edge was best for GCF (RMSE = 0.1). However, both indices were affected by Tamarugo leaf movements (leaves avoid facing direct solar radiation at the hottest time of the day). Thus, monitoring systems based on these indices should consider the time of the day and the season of the year at which the satellite images are acquired.

Located in the Atacama desert of northern Chile, Pampa del Tamarugal is a hyperarid ecosystem characterized by extreme arid conditions ( Prosopis tamarugo . These unfavorable environmental conditions can affect the quantity and diversity of prey available for carnivores, making Pampa del Tamarugal an interesting environmental scenario for the study of the trophic ecology of raptors. Our analyses of the seasonal diet of the burrowing owl Athene cunicularia (Molina, 1782) indicate that insects and scorpions were the most common prey (58.3% and 27.5%, respectively). However, the rodent Phyllotis darwini was the most important prey in biomass (49.5%). Significant differences were observed in diverse trophic statisticians between summer and winter seasons. Unlike similar studies carried out in arid areas of South America and North America, we observe that the diet of the burrowing owl in Pampa del Tamarugal shows a higher trophic niche breadth and trophic diversity, but a lower species-prey richness.

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 δ(13)C and δ(18)O 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.

Prosopis tamarugo Phil. is a legume tree native to the Atacama Desert, Chile. Tamarugo has physiological characteristics that are highly adapted to extreme life conditions in the Pampa del Tamarugal. Null precipitation makes tamarugo completely dependent on groundwater, developing in areas where the groundwater depth is closest to the surface. Groundwater extraction for domestic consumption, mining, and agriculture affects the desert ecosystem by lowering the water table. Measuring and describing the impacts on vegetation through the monitoring of physiological variables along with groundwater depletion in salt flats where extraction wells are located has contributed to a better understanding of tamarugo response to this stress factor. Integrated variables such as green canopy fraction, normalized difference vegetation index (NDVI), 18O isotope enrichment in foliar tissue, and twig growth proved to be far more reactive toward groundwater depth increase and presented lower error values. These variables respond to mechanisms that tamarugo has to maintain a stable water condition when water offer (water table depth (WTD)) decreases regarding water demand (transpiration). Defoliation along with twig growth diminishment would combine toward a canopy reduction strategy in order to reduce water demand. Green biomass loss, beyond a certain WTD, would lead to complete drying of the tamarugo. Up to 10 m of groundwater table depth, Tamarugo grows, has photosynthetic activity, and has the ability to perform pulvinary movements. Beyond 20 m of water table depth, tamarugo survival is compromised and hydraulic failure is inferred to occur. The current scenario is of groundwater over-exploitation; if economic efforts will be made to conserve and/or restore tamarugo, habitat groundwater extraction is a key element in effective management. Reaching of the thresholds depends on the adequate authority management of groundwater. The objectives of this review are (a) to review information collected from scientific studies regarding tamarugo condition and its response, over time, to WTD increase, (b) to identify WTD thresholds that affect tamarugo’s functioning, and (c) to propose a sequence of physiological events triggered by groundwater (GW) depletion.

In the present study the diet of the barn owl Tyto alba was analysed in the ecosystem of Pampa del Tamarugal, in the Atacama Desert, northern Chile. The area is characterised by extremely dry conditions, and relatively homogeneous and poor vegetation, dominated mainly by tamarugo forests (Prosopis tamarugo). The results indicated that small mammals were the greatest proportion (76.2%) in the diet of the barn owl, which predated only four species, of which the rodent Phyllotis darwini (approximately 62%) represented the major proportion. Nevertheless, reptiles and arthropods were also relevant prey for the barn owl, with a proportion of 5% and 15.1%, respectively. The general dietary composition of the tamarugos barn owl showed a wide-ranging diet pattern, characterised mainly by a poor diversity of small mammals and a significant consumption of reptiles and arthropods, in contrast to the sites in the central region and south Chile, where the diet included a greater diversity of small mammals, especially rodents. This pattern might reflect the conditions of extreme aridity, and low primary productivity in the ecosystem of Pampa del Tamarugal, restricting the abundance and diversity of the preferential prey (e.g. rodents). Hence, T. alba tends to increase its trophic diversity, adding other kinds of alternative prey to compensate for the low proportion of preferential prey available in the field.

A new ennomine species (Geometridae: Ennominae: Macariini) is described from northern Chile: Macaria mirthae sp. nov. Morphology of male and female genitalia of M. mirthae indicates close relationship to Macaria abydata Guenee, 1858. The latter species is widely distributed in the Neotropical and Indo-Pacific regions. Both species can be easily distinguished on the basis of habitus features and male and female genitalia. Larval stages of the new species M. mirthae are associated with Acacia macracantha Humb et Bonpl ex Willd., Prosopis tamarugo Phil. and Geoffroea decorticans (Gill ex Hook et Arn.) Burkart (Fabaceae) in the north of Chile.

Heliotropic leaf movement or leaf 'solar tracking' occurs for a wide variety of plants, including many desert species and some crops. This has an important effect on the canopy spectral reflectance as measured from satellites. For this reason, monitoring systems based on spectral vegetation indices, such as the normalized difference vegetation index (NDVI), should account for heliotropic movements when evaluating the health condition of such species. In the hyper-arid Atacama Desert, Northern Chile, we studied seasonal and diurnal variations of MODIS and Landsat NDVI time series of plantation stands of the endemic species Prosopis tamarugo Phil., subject to different levels of groundwater depletion. As solar irradiation increased during the day and also during the summer, the paraheliotropic leaves of Tamarugo moved to an erectophile position (parallel to the sun rays) making the NDVI signal to drop. This way, Tamarugo stands with no water stress showed a positive NDVI difference between morning and midday (ΔNDVI mo-mi) and between winter and summer (ΔNDVI W-S). In this paper, we showed that the ΔNDVI mo-mi of Tamarugo stands can be detected using MODIS Terra and Aqua images, and the ΔNDVI W-S using Landsat or MODIS Terra images. Because pulvinar movement is triggered by changes in cell turgor, the effects of water stress caused by groundwater depletion can be assessed and monitored using ΔNDVI mo-mi and ΔNDVI W-S. For an 11-year time series without rainfall events, Landsat ΔNDVI W-S of Tamarugo stands showed a positive linear relationship with cumulative groundwater depletion. We conclude that both ΔNDVI mo-mi and ΔNDVI W-S have potential to detect early water stress of paraheliotropic vegetation.

Photosynthetic parameters were investigated in relation to light intensity (PAR and UV-B) in two Chilean Prosopis sp., Prosopis chilensis and Prosopis tamarugo in their natural habitats. The objective of this work was to compare the photosynthetic responses and to determine the degree of adaptation of both species to visible- and UV-radiation stress. One of the study sites was Refresco in the Atacama Desert, where P. tamarugo is an endemic plant and P. chilensis was introduced, and the other was Peldehue in the valley of Central Chile where only P. chilensis is present. Due to latitude, light intensity (UV-B and PAR) is higher in Refresco than in Peldehue. The parameters investigated in both species were photosystem II fluorescence, CO 2 assimilation, stomatal conductance, photosynthetic pigment composition, flavonoid absorption patterns and composition of chlorophyll–protein complexes. Fluorescence studies, CO 2 assimilation and stomatal conductance studies demonstrated that photosynthetic activity is more efficient and stable throughout the day in P. tamarugo than in P. chilensis in Refresco. Chlorophyll–protein complexes also seemed to be more stable in P. tamarugo than in P. chilensis . Photosynthetic pigment analyses indicated possible photodamage in P. chilensis trees in Refresco, but not in Peldehue. Such photodamage was absent in P. tamarugo . There was a considerable change in the flavonoid pattern between noon and afternoon hours in both species at both study sites. The physiological implications of these changes indicate that P. tamarugo is more adapted to high solar radiation than P. chilensis.

The proximate and amino acid compositions of the leaves and pods of Prosopis chilensis and P tamarugo and the leaves of P alba have been assessed. The biological activity of the leaves and pods of the first two species as well as the leaves and exudate of P alba has been determined for free radical scavenging activity, xanthine oxidase inhibition and DNA binding. The best protein source among the forage trees was the leaves of P chilensis; P alba and P tamarugo leaves showed higher crude protein, fat and nitrogen-free extract values than reported in previous studies. According to their amino acid profiles, all species surveyed are deficient in essential amino acids. The alkaloids β-phenethylamine and tryptamine were isolated from P chilensis, and phenethylamine was detected in P tamarugo. At 0.50 mg ml−1, both compounds showed DNA binding activity, with values of 18.5 and 11% respectively. The exudate of P alba showed a strong free radical scavenging effect. The activity was related with the total phenolics content, consisting mainly of catechin. © 2000 Society of Chemical Industry

In this paper, we carried out a laboratory experiment to study changes in canopy reflectance of Tamarugo plants under controlled water stress. Tamarugo (Prosopis tamarugo Phil.) is an endemic and endangered tree species adapted to the hyper-arid conditions of the Atacama Desert, Northern Chile. Observed variation in reflectance during the day (due to leaf movements) as well as changes over the experimental period (due to water stress) were successfully modelled by using the Soil-Leaf-Canopy (SLC) radiative transfer model. Empirical canopy reflectance changes were mostly explained by the parameters leaf area index (LAI), leaf inclination distribution function (LIDF) and equivalent water thickness (EWT) as shown by the SLC simulations. Diurnal leaf movements observed in Tamarugo plants (as adaptation to decrease direct solar irradiation at the hottest time of the day) had an important effect on canopy reflectance and were explained by the LIDF parameter. The results suggest that remote sensing based assessment of this desert tree should consider LAI and canopy water content (CWC) as water stress indicators. Consequently, we tested fifteen different vegetation indices and spectral absorption features proposed in literature for detecting changes of LAI and CWC, considering the effect of LIDF variations. A sensitivity analysis was carried out using SLC simulations with a broad range of LAI, LIDF and EWT values. The Water Index was the most sensitive remote sensing feature for estimating CWC for values less than 0.036 g/cm2, while the area under the curve for the spectral range 910–1070 nm was most sensitive for values higher than 0.036 g/cm2. The red-edge chlorophyll index (CIred-edge) performed the best for estimating LAI. Diurnal leaf movements had an effect on all remote sensing features tested, particularly on those for detecting changes in CWC.

Tree species in the genus Prosopis have been recognized as valuable for reforestation in the world's semi-arid regions. Self-incompatibility and the mandatory outcrossing of Prosopis species results in a high degree of genetic variability, resulting in a need for asexual propagation of trees with desirable characteristics. Five species from Prosopis section Algarobia (Prosopis articulata, Prosopis chilensis, Prosopis juliflora, Prosopis glandulosa var. torreyana and Prosopis alba) and one species from the section Strombocarpa (Prosopis tamarugo) were reciprocally grafted to each other to determine their graft compatibility. All species from Prosopis section Algarobia were graft compatible with each other. Graft compatibility barriers apparently exist between P. tamarugo from the section Strombocarpa and the species from section Algarobia. A simple and effective method for grafting Prosopis has been identified.

Seedlings of Prosopis tamarugo were grown in artificial substrates with additions, of 200, 400 and 600 mm NaCl. and without salt treatment. Salinity induced anatomical changes in the roots, stems and leaflets. The diameters of the roots of seedlings grown in the increasing salt concentrations (up to 400 mm) were progressively smaller and differentiation of the stelar tissues was delayed. At an NaCl concentration of 600 mm, the root structure was strongly altered. On the contrary, stem diameter increased as salinity rose. In the stems of seedlings grown in a concentration of 200 mm NaCl, secondary xylem differentiation appeared earlier than in the controls. At a concentration of 400 mm NaCl, disorganization of the vascular cylinder of the stem was evident. Leaflets of seedlings grown in 200 mm NaCl showed a delay in structural differentiation: no water-storage cells or 'special cells' could be seen. The leaflets from plants grown in 400 mm NaCl, had larger numbers of intercellular air spaces; probably an indication of the beginning of tissue disorganization. A progressive decrease in cell size of leaflets as salinity rose was also demonstrated.

The paper describes past experience and the present state of reforestation in the arid and semi-arid zones of Chile. Some edaphoclimatic reference information is given for the areas. A summary is given of species introduction trials carried out to date with their initial results and indications of the experimental designs employed. Information is included concerning silvicultural experience with Atriplex nummularia Lindl. in the areas where it is extensively planted. Some important results obtained with the species Simmondsia chinensis (Link.) Schneider are presented. This species is currently being planted on a commercial scale in Chile. Information is also included on experience with Prosopis tamarugo Phil, a species growing in the Pampa del Tamarugal, one of the most inhospitable deserts in the world. Information is presented on nursery techniques and planting of this species, with results on yield and technical coefficients used. Finally, a summary is given of the policy that Chile is applying in the development of land in the arid and semi-arid zones.

The main aim of this research was to compare the photosynthetic responses of two species of Prosopis, Prosopis chilensis (algarrobo) and Prosopis tamarugo (tamarugo) subjected to heat and water stress, to determine how heat shock or water deficit, either individually or combined, affect the photosynthesis of these two species. The photosynthetic rates expressed as a function of photon flow density (PFD) were determined by the O(2) liberated, in seedlings of tamarugo and algarrobo subjected to two water potentials: -0.3 MPa and -2.5 MPa and to three temperatures: 25 degrees C, 35 degrees C and 40 degrees C. Light response curves were constructed to obtain light compensation and light saturation points, maximum photosynthetic rates, quantum yields and dark respiration rates. The photochemical efficiency as the F(v)/F(m) ratio and the amount of RUBISCO were also determined under heat shock, water deficit, and under the combined action of both stress. Photosynthetic rates at a light intensity higher than 500 micromole photons m(-2)s(-1) were not significantly different (P>0.05) between species when measured at 25 degrees C under the same water potential. The maximum photosynthetic rates decreased with temperature in both species and with water deficit in algarrobo. At 40 degrees C and -2.5 MPa, the photosynthetic rate of algarrobo fell to 72% of that of tamarugo. The quantum yield decreased in algarrobo with temperature and water deficit and it was reduced by 50% when the conditions were 40 degrees C and -2.5 MPa. Dark respiration increased by 62% respect to the control at 40 degrees C in tamarugo while remained unchanged in algarrobo. The photochemical efficiency decreased with both, high temperature and water deficit, without differences between species. RUBISCO content increased in algarrobo 35 degrees C. Water deficit reduced the amount of RUBISCO in both species. The results of this work support the conclusion that in both Prosopis species, the interaction between high temperature and water deficit affects photosynthesis responses greater than each individual stress, and that the interactive effect is more pronounce in algarrobo than in tamarugo.

Se presenta una descripción del adulto de Macaria mirthae sp. nov. (Geometridae: Ennominae: Macariini) sobre la base de ejemplares colectados en el norte de Chile. La morfología genital del macho y de la hembra de M. mirthae es muy similar a la de Macaria abydata Guenée, 1858, especie ampliamente distribuida en el Neotrópico y en la región Indo-Pacífica. Sin embargo, ambas pueden ser fácilmente separadas. Los estados inmaduros de M. mirthae están asociados a Acacia macracantha Humb et Bonpl ex Willd., Prosopis tamarugo Phil. y Geoffroea decorticans (Gill ex Hook et Arn.) Burkart (Fabaceae) en el norte de Chile A new ennomine species (Geometridae: Ennominae: Macariini) is described from northern Chile: Macaria mirthae sp. nov. Morphology of male and female genitalia of M. mirthae indicates close relationship to Macaria abydata Guenée, 1858. The latter species is widely distributed in the Neotropical and Indo-Pacific regions. Both species can be easily distinguished on the basis of habitus features and male and female genitalia. Larval stages of the new species M. mirthae are associated with Acacia macracantha Humb et Bonpl ex Willd., Prosopis tamarugo Phil. and Geoffroea decorticans (Gill ex Hook et Arn.) Burkart (Fabaceae) in the north of Chile.

Se describe el adulto de una nueva especie de Eupithecia Curtis, aparentemente endémica de la Pampa del Tamarugal, Chile. Sus larvas son antófagas sobre Prosopis tamarugo Phil. (Fabaceae). Se ilustra el adulto, VIII segmento abdominal del macho y la gentalia del macho y de la hembra. A description of the adult of a new species of Eupithecia Curtis, apparently endemic to the Pampa del Tamarugal, Chile, is presented. Its larvae are anthophagous on Prosopis tamarugo Phil. (Fabaceae). Adult, male abdominal segment VIII and male and female genitalia are illustrated.

Se describe el adulto de una nueva especie de Eupithecia Curtis, aparentemente endémica de la Pampa del Tamarugal, Chile. Sus larvas son antófagas sobre Prosopis tamarugo Phil. (Fabaceae). Se ilustra el adulto, VIII segmento abdominal del macho y la gentalia del macho y de la hembra.

The tricyclic compound maltoxazine was isolated as the DNA binding compound occurring in the basic extract of Prosopis tamarugo pods. The structure was elucidated by spectroscopic methods. El compuesto tricíclico maltoxazina se identificó como el producto bioactivo con capacidad de unión al ADN presente en el extracto básico de frutos de Prosopis tamarugo. La estructura se determinó por métodos espectroscópicos

Studies of Prosopis tamarugo Phil. leaflet surfaces by scanning and transmission electron microscopy disclosed an aggregate coating of basic wax structures of various shapes along with large semi-vertical plates. The basic structures, with some degree of variation, were also present on P. velutina Woot. and on several other Prosopis species which had been previously investigated. However, the plates, about 3 ,um in size, were observed only on P. tamarugo. The basic wax structures were first observed on very young leaflets, about 6 h after emergence from the apical bud. The plates appeared after 24 to 72 h. Both plates and basic structures were larger on seedlings grown in a low (20-25%) relative humidity as compared to high (70%) humidity. When grown side-by-side in the greenhouse, leaflets of P. tamarugo seedlings were more isolateral in structure than those of P. velutina, suggesting a greater xeromorphic adaptation. The unusual epicuticular configuration described could be a mechanism that enhances the foliar absorption of atmospheric moisture, or at least minimizes cuticular transpiration, thereby aiding survival of this unique tree in its native habitat of northern Chile.

SUMMARY The structural and histochemical characteristics of the Prosopis tamarugo Phil. seed-coat have been investigated by bright-field, fluorescence and scanning electron microscopy. P. tamarugo seed dormancy is exclusively due to the hardness of the seed-coat. The water barrier is thought to be located in the superficial portion of the palisade cells named “cylindrical part”, sited directly under the cone-like endings of the palisade cells themselves. The periclinal disposition of the “cylindrical parts” originates a line particularly evidenced by histochemical procedures of fluorescence that indicate their lipidic nature. It is believed that under natural environmental conditions a process of cracking deeper than this level permits water entry.

Prosopis tamarugo, a tree native to the Atacama desert of Chile apparently has unique water relations. It is proposed that in its native habitat, where there is essentially no precipitation, establishment occurs during the rare flooding periods, with water coming as runoff from the Andes. These plants subsequently exist as phreatophytes tapping the relatively shallow ground water. Although phreatophytic, the plants appears to come under increasing drought stress as the growing season progresses. Because of the very low water potentials of the salty surface soils, water evidently moves from the plant into the soil under certain conditions. This water may be reabsorbed subsequently and used by the plant as the water table capillary fringe is depleted toward the end of the leafy period.

This paper reviews the uses of the nitrogen-fixing trees Prosopis tamarugo (tamarugo) and P. chilensis (algarrobo) in the deserts of northern Chile where the rainfall is less than 1 mm yr−1. These forests consist of 3200 ha of natural stands and 22,980 ha of plantations. The primary use of these trees has been to support goat and sheep production through grazing of the leaves and pods. The water for these trees comes from an underground water table whose level does not fall and that appears to be fed from an aquifer whose origin must be of higher elevation in the Andes. The water table generally ranges from 3 to 10 m in depth and the underground salinity is about 1500 mg 1−1 of total dissolved solids. The height growth of the trees is significantly greater where the water table is less than 4 m below the surface. The fruit and foliage of small, medium, and large tamarugo trees and medium and large algarrobo trees were collected to determine forage yield per tree and to develop regression equations relating total pod production per tree and forage collections from smaller litter collection boxes. The mean algarrobo production (largest trees) was 31 kg per tree in 1981 and 117 kg per tree in 1982. The mean tamarugo forage production was 87 kg per tree in 1981 and 104 kg per tree in 1982. Great variation in production per tree and production between years was observed and this greatly complicates management of the trees for forage production. The digestible protein of the leaves and fruits of both species was too low to support growth and reproduction of the animals without supplementation. Management of 5000 sheep of the breeds Precoz Merino, Australian Merino, and Karakul showed that Karakul sheep were best adapted to these desert conditions. Hereford, Galloway, and Santa Gertrudis cattle were also examined. Angora goats were examined for use in the Pampa for mohair production but their long hair became a problem with the thorny trees and this breed was eliminated in favor of the meat breeds Criollo and Pampinos. A supplement feed consisting of 25% alfalfa hay, 45% wheat bran, and 30% sheep feces was used for cattle. Feces were not used in the supplement for sheep and goats. An excellent reproduction rate was obtained (90% of the cattle, sheep and goats produced an average of 1 offspring per animal bred) when a management system was used that included vitamin A,D, and E supplementation, pregnancy determination, and supplemental feed for pregnant animals.

Tamarugo is a very interesting tree growing in desert and semidesert areas in the north of Chile. The mature fruit and dry leaves of tamarugo fall over the soil forming a thick layer which can be used all year round as the sole feedstuff for sheep and cows. The existence of tamarugo therefore suggests the possibility of keeping breeding ruminants in a desert area. Consequently a chemical and toxicological investigation has been carried out. Results for chemical composition, caloric content, mineral composition (Ca, P, Fe, Na, K, Cu, Zn, Co, Mg and Mn) in mature and green fruits, dry and green leaves and mature seeds, are presented and discussed in comparison with other feedstuffs and with nutritional requirements of sheep. Protein quality studies on the seed were carried out in rats. Attention was given to the presence of possible toxic components: cyanogenetic glucosides, haemagglutinins, saponines and antitryptic factor(s).

The salt tolerance of Prosopis from highly saline environments of West Africa, Chile, Argentina, and the United States was compared to high-biomass-producing Prosopis identified in earlier field trials and to a Leucaena leucocephala cultivar. One hundred seedlings of each of ten accessions were grown in a hydroponic sand-culture system in the greenhouse in which the NaCl concentration of the nutrient solution was increased from 0.0%, 1.2%, 1.8%, 2.4%, 3.0%, to 3.3% (seawater). Prosopis tamarugo died early in the experiment due to fungal diseases. Leucaena leucocephala K67 and P. pubescens died at the 1.2% NaCl concentration. A Prosopis glandulosa var. glandulosa 1115 accession from Texas grew in the 1.2% NaCl but died in 3.0% NaCl. Prosopis alba 0166, P. alba/nigra 1117, P. articulata 0016, P. chilensis 0009, and P. juliflora 0044 all had seedlings which grew in the 3.3% NaCl treatment. Eighty of the seedlings which grew in the 3.3% NaCl have been repotted and propagated by rooting of cuttings. Each of the species which grew in 3.3% NaCl have been previously shown to fix nitrogen so these clones have potential for use as N-fixing halophytes. No other legume genus has been demonstrated to have such high salt tolerance, and Casuarina is the only other terrestrial N-fixing genus with equivalent salt tolerance.