Chilean Coastal Desert Research Articles

Remote sensing based mapping of Tillandsia fields - A semi-automatic detection approach in the hyperarid coastal Atacama Desert, northern Chile

Unique fog ecosystems that occur inland along the Chilean coastal desert are dominated by Tillandsia landbeckii. The average annual precipitation in this hyperarid area lies below 1 mm per year. Tillandsia are specialized in the foliar uptake of fog as a main source of water. The detailed mapping of the distribution of Tillandsia is lacking, making it difficult to understand their geo-ecological niche and to determine the impacts that climate change may have on this species. The objective of this study is to create a detailed spatial distribution of Tillandsia in the Atacama Desert in northern Chile based on remote sensing semi-automatic detection process. For this purpose, high-resolution WorldView-3 optical satellite data has been acquired. The extraction of Tillandsia was done with ENVI Deep Learning tools. As a result, a map of Tillandsia has been created. Several fields were found between Cerro Huantajaya in the north and Cerro Soronal in the south in the study area between 800 and 1300 m a.s.l. For validation purposes ground truth data has been used. The overall accuracy of this classification is 92.02%. The results can be used as a basis for geo-ecological niche modeling, further monitoring and for the development of conservation strategies.

Mistletoe infection changes arthropod community on its cactus host through indirect effects

Abstract Parasitic plants and herbivores show similarities in their interactions with host plants. Herbivore‐induced resistance/susceptibility in plants can scale up to the arthropod community. Similar evidence regarding parasitic plants is scarce. We evaluated the indirect effects initiated by the mistletoe Tristerix aphyllus on the arthropod community of the cactus Echinopsis chiloensis in the Chilean coastal desert. Field observations suggested that a stem‐borer beetle bores more brood chambers in mistletoe‐parasitised cacti than in non‐parasitised cacti, and that arthropods colonise these chambers. We compared tissue toughness, chamber density and morphology in mistletoe‐parasitised and non‐parasitised cacti. We also compared richness, total abundance, abundance per taxa, diversity and composition of the colonising arthropod community. Parasitised cacti showed a 14% reduction in tissue toughness. Chamber density in parasitised cacti was four times greater and chambers were larger: 35% more volume, an entrance‐opening area 30% greater, and twice the area of the maximum‐width section. Arthropod species richness and diversity were higher in chambers of parasitised cacti. Arthropod community composition was different in chambers of parasitised and non‐parasitised cacti. Thus, spiders and moths were more abundant in parasitised cacti, and pseudoscorpions, scolopendras, ants and flies were exclusively present there, while non‐parasitised cacti had no exclusive taxa. Mistletoe infection results in a richer, more diverse and distinct arthropod community on its cactus host, which occurs through induced susceptibility to stem‐borers whose brood chambers are colonised by arthropods. Tristerix aphyllus could be a key‐stone species in these arid ecosystems, where arthropod diversity is relatively low.

Bioprospecting of cyanobacterium in Chilean coastal desert, Geitlerinema sp. molecular identification and pressurized liquid extraction of bioactive compounds

This study presents a new cyanobacterium of the genus Geitlerinema sp. isolated from the Chilean coastal desert as a rich source of bioactive compounds. Phylogenetic tree is shown along with a broad biochemical characterization using conventional and pressurized liquid extraction. Variables as extraction yield, phycobiliproteins, lipids and methyl palmitate (C16:0) were studied by means of two experimental designs based on a response surface methodology (RSM) employing two factorial design 32. Factors as temperature (20–200 °C) and percentage of solvents were selected resulting in Factorial Design A with 0–100% (v/v) of ethanol–water and Factorial Design B with 0–100 (v/v) of ethanol–limonene solvents. The main bioactive compounds were total proteins (∼52% wt), phycobiliproteins (especially C-phycocyanin) and methyl palmitate (C16:0). Data obtained showed that water and ethanol:water (1:1, v/v) improved the extraction yield and phycobiliproteins recovery. As for ethanol:limonene extracts, they were better for lipids and methyl palmitate extractions. In general, high temperatures only improved the extraction yield whereas low temperatures favor the extraction of phycobiliproteins. Therefore, results indicated that Geitlerinema sp. could be one of the several cyanobacteria genera that display functional properties for nutritional, pharmaceutical or industrial use as sustainable and cost-effective bioactive compounds in algal biorefinery model.

Brachistosternus cepedai (Scorpiones: Bothriuridae), primer escorpión clasificado en peligro de extinción para el Desierto de Atacama: Fundamentos y consecuencias

We analyze the reasons for considering Brachistosternus cepedai (Scorpiones: Bothriuridae), the first scorpion to be included in a conservation category in the Atacama Desert. We also discuss the systematic position and restricted distribution of B. cepedai, as well as potential threats and conservation measures for this species, which is endemic to a reduced area of the Chilean coastal desert.

Phylogeography and population structure of twoBrachistosternusspecies (Scorpiones: Bothriuridae) from the Chilean coastal desert - the perils of coastal living

Coastal deserts are geologically dynamic areas of the Earth, affected by historical changes in sea levels and in some cases also by fault-line tectonic activity. An example of such a dynamic area is the Chilean coastal desert of the Antofagasta and Atacama regions, which harbours many endemic species, such as the bothriurid scorpion species Brachistosternus paposo and Brachistosternus roigalsinai. In this work, we carry out phylogeographic and population genetic analyses on these scorpions, using two mitochondrial (COI and cyt b) and two nuclear (Actin 5C and wingless) markers to identify species and population structuring, and link these findings to the geological history of the area. The geographical feature separating the two species is identified as the Huasco River, and distinguishing morphological features for these scorpions are presented. Population genetic and phylogeographic outcomes reflect an unstable history across this region for B. paposo and B. roigalsinai, related to sea-level changes affecting coastal habitats, including nearby islands.

Resource economics and coordination among above- and below-ground functional traits of three dominant shrubs from the Chilean coastal desert

Aims Plant functional traits determine how plants respond to environmental factors and influence ecosystem processes. Among them, root traits and analyses of relations between above and below-ground traits in natural communities are scarce. We characterized a set of above- and below-ground traits of three dominant shrub species in a semiarid shrub-steppe that had contrasting leaf phenological habits (deciduous, semideciduous and evergreen). We analysed if there was coordination among above- and below-ground resource economics patterns: i.e. patterns of biomass allocation, construction costs and lifespan. Important Findings Above- and below-ground traits and their resource economics relations pointed to species-specific functional strategies to cope with drought and poor soils and to a species ranking of fast to slow whole-plant strategies in terms of resource uptake, biomass construction costs and turnover. The deciduous shrub, Proustia cuneifolia, had relatively deep and even distribution of roots, and high proportion of short-lived tissues of low C construction costs: it had high fine to coarse root and high leaf-to-stem biomass ratios, high specific leaf area (SLA), and stems of low wood density. This strategy allows Proustia to maximize and coordinate above- and belowground resources uptake as long as the most limiting factor (water) is available, but at the cost of having relative high plant biomass turnover. The evergreen Porlieria chilensis, instead, displayed a more conservative and slow strategy in terms of resource economics. It had ~80% of the roots in the 40 cm topsoil profile, low proportion of fine compared with coarse roots and low leaf-to-stem ratios, low SLA and stems of high wood density, i.e. it invested in C costly tissues that, overall, persist longer but probably at the cost of having lower plant resource uptake rates. Traits in the semideciduous Adesmia bedwellii were in between these two functional extremes. Our results revealed high functional diversity and aboveand below-ground complementarity in resource economics among these three codominant species in the Chilean coastal desert.

First Record of Acrocercops serrigera serrigera Meyrick (Lepidoptera: Gracillariidae) from Chile

Acrocercops Wallengren (Gracillariidae) is recorded for the first time from Chile. The little known Acrocercops serrigera serrigera Meyrick is reported from the Azapa Valley, Arica Province, northern Chilean coastal desert. Specimens were reared from Malva nicaeensis and Waltheria ovata (both Malvaceae). Specimen identification is based on comparisons of the male genitalia with that of the lectotype of the species originated from Peru. Sequences of a fragment of the mitochondrial gene cytochrome oxidase subunit I of specimens reared on both plants indicate that there is only one Acrocercops species involved as only one substitution site was found over the 524-bp sequenced.

The ecology, distribution and conservation status of Myrcianthes coquimbensis: a globally endangered endemic shrub of the Chilean Coastal Desert

Background: Myrcianthes coquimbensis is an endangered shrub endemic to Chile. No published account is known about its biology, ecology or threats to its continued existence. Aims: To document the current state of knowledge of M. coquimbensis regarding its geographic distribution, and population and reproductive parameters, and to evaluate threats in its distribution range. Methods: Historical records and recent survey data of 110 localities were used to characterise its known distribution. Plots were established in seven localities to determine the proportion of flowering individuals, recruitment and estimate population size and structure. Finally, levels of post-dispersal seed predation were determined in one locality. Results: The current distribution of M. coquimbensis extends along 82.8 km of the Chilean coast, where the species is mainly threatened by habitat loss. Only 13% of the individuals flowered during 2010, and 66% of these plants lost their entire flower crop due to desiccation. Few seeds (7.5%) were lost to post-dispersal seed predation. The populations are composed mainly of adult plants (70% of the individuals), and little to no recruitment was observed. Conclusions: M. coquimbensis populations are threatened by habitat loss and are not naturally recruiting through sexual reproduction. This exemplifies a case where studies on the ecology of a species are urgently needed to be able to design effective conservation and management plans.

Phytogeographic divisions, climate change and plant dieback along the coastal desert of northern Chile

Along the hyper-arid Chilean coastal desert between 30°S and 18°S the Loma vegetation undergoes a gradual transition from open shrubland to small isolated areas of a scarce plant cover. Floristic and physiognomic features allow a differentiation of five Loma formations, each of them characterized by a distinctive spectrum of plant communities. However, particularly in the northern section of the investigation area, numerous indications point to a strong vegetation decline including a deterioration of plant cover, reduction of the vitality of various taxa, probably also a local loss of some perennial species, and even a dieback of specific populations. These signs of a retrogression, which coincide with a regional disappearance of Guanaco herds in the coastal area between 20°S and 23°30’S, became apparent in the second half of the past century and were most likely provoked by recent climate change in the arid coastal region. Especially the decrease of rainfall frequency might have negative implications for the regeneration and preservation of plants. In addition, a strong reduction of cloudiness in the northernmost section affects plant growth due to further limitations in the water disposability. A projected sustained decline of rainfall is expected to continue endangering the surprisingly high floristic diversity of the sensitive ecosystem complexes in the coastal desert.

Hydraulic lift in three shrub species from the Chilean coastal desert

Hydraulic lift is defined as the passive movement of water through roots from wetter, deeper soil layers into drier shallower layers along a gradient in soil water potential. This process is generally found in plant species with dimorphic root systems, which use water from both shallow and deep layers. We assessed the ability of three shrub species of the Chilean coastal desert, Porlieria chilensis, Adesmia bedwellii and Proustia cuneifolia, to act as hydraulic lifters. Our results showed evidences that the three species are hydraulic lifters with larger fluctuations of soil water potentials in summer 2004 and smaller fluctuations in winter 2004 and summer 2005. The soil water potential was higher beneath P. chilensis than beneath P. cuneifolia and A. bedwellii. Soils were significantly wetter at 60 cm than at 30 cm depth. The movement of water from wetter and deeper soil layers to drier and shallower soil layers through hydraulic lift may allow these shrubs to extend their metabolic activity into the lengthy drought period that characterizes the Chilean desert ecosystems.

TWO NEW SPECIES OF GYRIOSOMUS GUÉRIN-MÉNEVILLE FROM THE CHILEAN COASTAL DESERT (COLEOPTERA: TENEBRIONIDAE: NYCTELIINI)

Abstract Two new species from the Chilean coastal desert, Gyriosomus granulipennis and Gyriosomus multigranulosus (Pimeliinae: Nycteliini), are described and included in the most recent key for the genus. Distributional and habitat records, habitus photographs, and illustrations of the pronotum and prosternum for these two new species are included.

Variation in soil micro-organisms and nutrients underneath and outside the canopy of Adesmia bedwellii (Papilionaceae) shrubs in arid coastal Chile following drought and above average rainfall

Micro-organisms and nutrients were determined in soil samples (top 20 cm) collected underneath and outside the canopy of Adesmia bedwellii in mid fall (April 1997), after 8 months of drought, and in mid spring (October 1997) after heavy winter rains associated with the 1997-ENSO in a Chilean coastal desert site. Bacteria and fungi were two orders of magnitude higher in mid spring, but no seasonal effects were detected for chemical parameters. Micro-organisms, organic matter and nitrogen content were significantly higher underneath shrub canopies, especially in mid fall. Micro-organism abundances were positively correlated with nitrogen levels and soil moisture.

Diet selection in captivity by a generalist herbivorous rodent (Octodon degus) from the Chilean coastal desert

Five captive adult female degus (Octodon degus) were offered leaves and twigs to eat from three woody (Adesmia bedwellii,Porlieria chilensisandProustia pungens) and two suffruticose (Baccharis paniculataandChenopodium petiolase) shrubs that provide cover in their natural habitat. The degus discriminated among the plant species, consuming lower amounts ofP. chilensis. Daily body mass losses of degus were significantly higher when they were fed uponP. pungensandP. chilensis. The nutritional value of plants, concomitant with degu nutritional requirements, may explain changes in shrub cover previously found to follow removal of degus from experimental plots.

Phenology of the edaphic microarthropods in a Chilean coastal desert site and their response to water and nutrient amendments to the soil

Phenology of the edaphic microarthropods in a Chilean coastal desert site and their response to water and nutrient amendments to the soil

Effects of low water supplementation and nutrient addition on the aboveground biomass production of annual plants in a Chilean coastal desert site.

The effects of low water supplementation and nutrients on the aboveground biomass production of annual plants was tested in the field by mimicking small rainfall events of 5mm per month and by adding fertilizers to experimental quadrats. Field measurements were made during an extremely dry year, so the potential additional effects of rainfall probably had no important effect on plant responses. Biomass of non-native species was higher in irrigated than in non-irrigated quadrats. No significant responses to irrigation treatments were detected in native species. This lack of response may be due to higher thresholds of watering being required for either germination and/or growth. Because of the low water inputs, fertilizer additions did not promote any biomass response in either native or non-native species. Responses of non-native species to low and frequent pulses of water, which is characteristic of this arid system, may be important for the persistence of these species in this environment.

An alternative water supply for chilean coastal desert villages

The measured domestic water consumption rates in two fishing villages on the arid north coast of Chile were 14.2 and 19.7 l/pers/day. The villagers pay 10% of their family income for water in Chungungo and 6% in Los Hornos. The true subsidized cost of the water would represent 39% and 26% respectively of average family income. These high water costs led to the establishment of a project to determine if fog water collection could provide a lower cost water supply. The site, on the ridge above the village of Chungungo, has produced 7200 l/day, an average of 22 I/day for each of the 330 people in the village, during its first 32 months of operation, at a cost estimated to be one‐quarter of that of the current water supply. In addition, the fog water supply should be more reliable and of equal or better quality.