Semi-arid Region Of Chile Research Articles

The burrowing crayfish Parastacus pugnax (Decapoda: Parastacidae) in the Semiarid Region of Chile: findings of a naturalized or threatened population?

ABSTRACT Parastacus pugnax is an endemic burrowing crayfish from the basins of the Mediterranean and Temperate Wet regions of Chile. For the first time, specimens were found incidentally in the Semiarid Region of Chile (Choapa River Basin). In these regions, hydrological changes derived from global warming and the intensive use of water for irrigation have resulted in highly fragmented habitats, where the effects of the dry season are exacerbated by periods of permanent drought. Unfortunately, in the Semiarid Region there are not regulatory measures for the conservation of the native biota. The aims of this study were to determine the spatial distribution patterns of P. pugnax in the Choapa River Basin (⁓31°S) to expand and contribute with updated knowledge about the distribution and natural history of this species highlighting local environmental management issues. Seasonal occurrence surveys were carried out at eight sites stratified by elevation in the lower, middle, and upper zones of this basin. This was complemented by semi-structured interviews within local prawn´s fisher. Parastacus pugnax was distributed across ⁓25 km in the lower and middle zone of the basin, and it is present in lentic and lotic environments. The occurrence of this excavator species in lotic environments is somehow unusual according to its ecology, which suggests that it is a primary facultative excavator, so a re-evaluation of its current ecological category (category 1; primary excavator) is necessary. According to the interviewees, P. pugnax corresponds to a naturalized species introduced by humans ⁓25–30 years ago for artisanal aquaculture in ponds. The wide altitudinal distribution of P. pugnax in the Choapa River Basin indicates the need to re-evaluate its distribution limits, which traditionally placed the Parastacidae family to the south of Aconcagua River Basin (⁓33°S). To understand the origin of the species in the Choapa River Basin, is clue to specify the phylogenetic structure and determinate whether the presence in the Semiarid Region is constrained to the Choapa River Basin or extends to other basins within this region.

Water Crisis in Petorca Basin, Chile: The Combined Effects of a Mega-Drought and Water Management

Since 2010, Chile has experienced one of the most severe droughts over the last century, the so-called mega-drought (MD). The MD conditions, combined with intensive agricultural activities and the current water management system, have led to water scarcity problems in Mediterranean and Semi-arid regions of Chile. An emblematic case is the Petorca basin, where a water crisis is undergone. To characterize this crisis, we analyzed water provision by using tree-ring records, remote sensing, instrumental data, and allocated water rights within the basin. Results indicate that the MD is the most severe dry period over the last 700-years of streamflow reconstruction. During the MD, streamflow and water bodies of the upper parts of the basin have been less affected than mid and low areas of this valley, where consumptive withdrawals reach up to 18% of the mean annual precipitation. This extracted volume is similar to the MD mean annual precipitation deficits. The impacts of the current drought, along with the drier climate projections for Central Chile, emphasize the urgency for faster policy changes related to water provision. Climate change adaptation plans and policies should enhance the current monitoring network and the public control of water use to secure the water access for inhabitants and productive activities.

Perspectives of abandonment/continuity of typological groups of sheep farms in the semi-arid region of Central Chile

<p>An exploratory study was conducted to analyze combinations of variables that define typological groups that condition the abandonment/continuity of sheep farming in the semi-arid region of Chile. Three typological groups were identified. Group I is made up of middle-aged farmers with the largest flocks. Group II has typical farms from an arid zone, own by elderly male farmers. Group III is located in areas near urban centers and has a greater presence of women farmers. The study allowed to identify the variables that influence the continuity of sheep farmers and to determine strategies that avoid/delay the abandonment of the activity.</p>

Population Differentiation in the Body Architecture of Creole Goats in the Semi Arid Region of Chile

Population Differentiation in the Body Architecture of Creole Goats in the Semi Arid Region of Chile

Response of xerophytic plants to glacial cycles in southern South America.

Quaternary glaciations strongly affected the distribution of species from arid and semi-arid environments, as temperature drops were accompanied by strong fluctuations in rainfall. In this study, we examined the response of xerophytic species to glacial cycles, determining the genetic patterns and climatic niche of Echinopsis chiloensis var. chiloensis, an endemic columnar cactus of arid and semi-arid regions of Chile. We analysed 11 polymorphic microsatellites for 130 individuals from 13 populations distributed across the entire distribution of the species. We examined genetic diversity and structure, identified possible patterns of isolation by distance (IBD) and tested two competing population history scenarios using Approximate Bayesian Computation. The first scenario assumes a constant population size while the second includes a bottleneck in the southern population. The latter scenario assumed that the southernmost populations experienced a strong contraction during glaciation, followed by a postglacial expansion; by contrast, the area of the northernmost populations remained as a stable refugium. We also used ecological niche modelling (ENM) to evaluate the location and extension of suitable areas during the Last Glacial Maximum (LGM) and the mid-Holocene. We found a decline in genetic diversity towards high latitudes and a significant IBD pattern that together with ENM predictions suggest that E. chiloensis var. chiloensis experienced range contraction northwards during wet-cold conditions of the LGM, followed by expansion during aridification of the mid-Holocene. In addition to IBD, we detected the presence of a strong barrier to gene flow at 32°30'S, which according to coalescence analysis occurred 44 kyr BP. The resulting genetic clusters differed in realized climatic niche, particularly in the variables related to precipitation. Our results suggest that the cactus E. chiloensis var. chiloensis experienced range contraction and fragmentation during the wet-cold conditions of the LGM, which may have facilitated ecological differentiation between northern and southern populations, promoting incipient speciation.

The effect of water status on productive and flowering variables in young ‘Arbequina’ olive trees under limited irrigation water availability in a semiarid region of Chile

The intense drought affecting olive production in Northern Chile underscores the need to research non-traditional irrigation strategies to obtain the best crop performance. Accordingly, this study aimed to obtain preliminary data to guide future research on this topic. Different water replenishment levels on crop evapotranspiration (ETc; 13.5, 27.0, 40.5, and 54%) were established in a young orchard, cv. Arbequina, from the end of fruit drop (EFD) to full bloom in the next season. We evaluated the influence of plant water status (Ψstem) and crop load, considered as function of fruit number divided by trunk cross-sectional area, on reproductive and productive variables using multiple linear regressions. Our results show that crop load and Ψstem measured from EFD to harvest affected yield components. Nevertheless, Ψstem had the strongest influence on fruit size, pulp development, oil accumulation, and yield. Oil content and yield were reduced by 54% and 50% for each MPa, respectively, from Ψstem EFD-H − 1.8 MPa, an effect that intensified as crop load increased. During the period of flower development (September–November), the number of flowers per inflorescence and percentage of perfect flowers were reduced when Ψstem was less than − 2.0 MPa. These preliminary results showed that bud differentiation, inflorescence and flower formation are highly sensitive to water deficit.

The Accretional Beach Ridge System of Tongoy Bay: An Example of a Regressive Barrier Developed in the Semiarid Region of Chile

The Accretional Beach Ridge System of Tongoy Bay: An Example of a Regressive Barrier Developed in the Semiarid Region of Chile

Commoditization of Rural Lands in the Semi-Arid Region of Chile—The Case of the Huentelauquén Agricultural Community

The agri-pastoralist communities of the semi-arid region of Chile, with their unusual common land ownership, have not escaped economic neo-liberalism. The general pattern of insatiable demand of land for agricultural production, mining, energy generation and real-estate development has become a challenge for these communities. How are these processes affecting the traditional practices of these localized agri-food systems, based on rain-fed-agriculture, pastoralism and the fading practice of transhumance? In this article, we look at how the Huentelauquén Agricultural Community in the Canela Commune has dealt with, reacted to, and been affected by regional economic shifts geared towards market liberalization. In particular, we analyze the structural changes in the community in regard to alienation of the commons and changes in land tenure. Qualitative interviews were conducted with key informants in this setting. To provide a richer contextual setting, this article draws on several other empirically-based works on the commons’ emergence and evolution, land commoditization and local struggles for livelihoods. Our study shows that a community can adopt different strategies when dealing with powerful sectoral development that can involve resistance as well as positioning that seeks to find favorable terms of engagement. Our findings highlight that processes affecting the traditional commons are resulting in the re-appropriation and re-occupation of the land. This is resulting in social differentiation, weakening of the community’s social bonds, depeasantization and further degradation of an already vulnerable ecosystem. In sum, these shifts are posing an existential threat to this form of traditional agri-pastoralism.

Productivity and phenological responses of natural vegetation to present and future inter-annual climate variability across semi-arid river basins in Chile.

Time series of vegetation indices and remotely sensed phenological data offer insights about the patterns in vegetation dynamics. Both are useful sources of information for analyzing and monitoring ecosystem responses to environmental variations caused by natural and anthropogenic drivers. In the semi-arid region of Chile, climate variability and recent severe droughts in addition to land-use changes pose threats to the stability of local ecosystems. Normalized difference vegetation index time series (2000-2013) data from the moderate resolution imaging spectroradiometer (MODIS) was processed to monitor the trends and patterns of vegetation productivity and phenology observed over the last decade. An analysis of the relationship between (i) vegetation productivity and (ii) precipitation and temperature data for representative natural land-use cover classes was made. Using these data and ground measurements, productivity estimates were projected for two climate change scenarios (RCP2.6 and RCP8.5) at two altitudinal levels. Results showed negative trends of vegetation productivity below 2000ma.s.l. and positive trends for higher elevations. Phenology analysis suggested that mountainous ecosystems were starting their growing period earlier in the season, coinciding with a decreased productivity peak during the growing season. The coastal shrubland/grassland land cover class had a significant positive relation with rainfall and a significant negative relation with temperature, suggesting that these ecosystems are vulnerable to climate change. Future productivity projections indicate that under an RCP8.5 climate change scenario, productivity could decline by 12% in the period of 2060-2100, leading to a severe vegetation degradation at lower altitudes and in drier areas.

Heritability of stem straightness and genetic correlations in Eucalyptus cladocalyx in the semi-arid region of Chile

The aim of this study was to determine genetic parameters for straightness of the trunk of Eucalyptus cladocalyx, with a view to the selection of straight trees, while keeping the impact on growth minimal. The tests were conducted at two locations in the semi-arid region of Chile, using a randomized block design, with 30 replications and 49 half-sib families. The parameters were estimated by a bi-character model of individual trees, using Bayesian inference by Gibbs algorithm. The heritability for stem straightness was shown to be moderate, with h2=0.40 [0.29-0.57]. Heritabilities for diameter and height were moderate: 0.30 [0.24-0.38] and 0.30 [0.22-0.44]. Genetic correlations between straightness and growth were statistically not different from zero. The genotype-environment interaction was not significant (p>0.05) for the traits. The moderate degree of genetic control allows significant genetic gains in environments under water stress.

Winter Arctic Oscillation signal in a European tree-ring δ18O network

In South America, the arid and semiarid subtropical regions through the Atacama Desert and north-central Chile between 19° and 32°S are currently a gap in the tree-ring chronology network. Only a short tree-ring chronology has been published for this vast region and little is known about the suitability of many woody species for tree-ring analysis and dendroclimatology. In this paper we present the first detailed analysis of the climate responses and influences of the El Niño-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) on the tree-rings of three species new to dendrochronology and that typically occur at high elevations in the Andes of central and north-central Chile. Three well-replicated tree-ring chronologies of Kageneckia angustifolia, Proustia cuneifolia and Fabiana imbricata are compared with century-long regional records of precipitation and temperature, and with the N3.4 SST and PDO indices in both time and frequency-domains using correlation and wavelet analysis. The radial growth of these species is controlled by winter precipitation and is also positively correlated with temperature during most of the rainy season from April to September (autumn–spring). The regional climate as well as tree growth is strongly modulated by ENSO and ENSO-like conditions in the equatorial Pacific at both interannual and interdecadal timescales. The decadal and interdecadal variability is not correlated with PDO and appears to be related to the Interdecadal Pacific Oscillation (IPO), a Pacific-wide ENSO-like mode of climate variability. Despite their relatively short lifespans, these three new species have a high potential for dendrochronological and dendroclimatic studies in the semiarid region of Chile over the last two centuries.

Superoxide dismutase is a critical enzyme to alleviate oxidative stress in Aloe vera (L.) Burm. plants subjected to water deficit

Background: Aloe vera, a plant with crassulacean acid metabolism naturally adapted to water deficit, was introduced in the semi-arid regions of Chile in 1999. Aims: Our objective was to evaluate how A. vera scavenged the superoxide ion (O2 •‐), formed during oxidative stress, induced by water deficit. Methods : Total and specific activity, enzyme accumulation and expression of genes encoding superoxide dismutase (SOD) were determined in leaf tips and leaf bases collected from plants subjected to different levels of water deficit. Results: Two isoenzymes, Mn-SOD and Cu/Zn-SOD, accumulated significantly under water deficit, with a higher accumulation of Mn-SOD in the leaf bases, and of Cu/Zn-SOD in the leaf tips of plants under different degrees of water deficit (soil water availability ranged from 100% to 25% of field capacity; FC). The expression of sod genes increased only in gradually stressed individuals, where plants were pre-treated at 75% FC or 50% FC prior to being subjected to a severe water deficit of 25% FC. The superoxide ion levels increased more in the tips than in the leaf bases when plants were grown at 50% and 25% FC. Under gradually increasing water stress conditions, the accumulation of superoxide ions decreased to 50% of that of the control plants, associated with an increment in Cu/Zn-SOD accumulation and a higher expression of the mn-sod and cu/zn-sod genes. Conclusions: These results indicate that A. vera plants are stressed under severe water deficit and suggest that SOD is a key enzyme to decrease the reactive oxygen species levels induced by water deficit.

Regional frequency analysis for mapping drought events in north-central Chile

Summary Droughts are among the most important natural disasters, particularly in the arid and semiarid regions of the world. Proper management of droughts requires knowledge of the expected frequency of specific low magnitude precipitation totals for a variety of durations. Probabilistic approaches have often been used to estimate the average recurrence period of a given drought event. However, probabilistic model fitting by conventional methods, such as product moment or maximum likelihood in areas with low availability of long records often produces highly unreliable estimates. Recognizing the need for adequate estimates of return periods of severe droughts in the arid and semiarid region of Chile, a regional frequency analysis method based on L-moments (RFA-LM) was used for estimating and mapping drought frequency. Some adaptations to the existing procedures for forming homogeneous regions were found necessary. In addition, a new 3-parameter distribution, the Gaucho, which is a special case of the 4-parameter Kappa distribution, was introduced, and the analysis procedure was improved by the developments of two new software tools named L-RAP, to perform the RFA-LM analysis, and L-MAP, to map the resulting drought maps. Eight homogeneous sub-regions were delineated using the Gaucho distribution and used to construct return period maps for drought events with 80% and 40% precipitation of the normal. The study confirms the importance of a sub-regional homogeneity test, and the usefulness of the Gaucho distribution. The RFA-LM showed that droughts with a 40% precipitation of the normal have return periods that range from 4 years at the northern arid boundary of the study area to 22 years at the southern sub-humid boundary. The results demonstrate the need for different thresholds for declaring a drought than those currently in use for drought characterization in north-central Chile.

Climate signals in high elevation tree-rings from the semiarid Andes of north-central Chile: Responses to regional and large-scale variability

In South America, the arid and semiarid subtropical regions through the Atacama Desert and north-central Chile between 19° and 32°S are currently a gap in the tree-ring chronology network. Only a short tree-ring chronology has been published for this vast region and little is known about the suitability of many woody species for tree-ring analysis and dendroclimatology. In this paper we present the first detailed analysis of the climate responses and influences of the El Niño-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) on the tree-rings of three species new to dendrochronology and that typically occur at high elevations in the Andes of central and north-central Chile. Three well-replicated tree-ring chronologies of Kageneckia angustifolia, Proustia cuneifolia and Fabiana imbricata are compared with century-long regional records of precipitation and temperature, and with the N3.4 SST and PDO indices in both time and frequency-domains using correlation and wavelet analysis. The radial growth of these species is controlled by winter precipitation and is also positively correlated with temperature during most of the rainy season from April to September (autumn–spring). The regional climate as well as tree growth is strongly modulated by ENSO and ENSO-like conditions in the equatorial Pacific at both interannual and interdecadal timescales. The decadal and interdecadal variability is not correlated with PDO and appears to be related to the Interdecadal Pacific Oscillation (IPO), a Pacific-wide ENSO-like mode of climate variability. Despite their relatively short lifespans, these three new species have a high potential for dendrochronological and dendroclimatic studies in the semiarid region of Chile over the last two centuries.

Drought Frequency and its Social Impacts in the Semi-Arid Region of Chile

Drought Frequency and its Social Impacts in the Semi-Arid Region of Chile

Evaluation of jojoba clones grown under water and salinity stresses in Chile

Jojoba ( Simmondsia chinensis (Link) Schneider) could be a potentially profitable crop for arid and semi-arid regions of Chile. Thus, several selected jojoba clones were established at representative saline (Quebrada de Camarones: EC 38 dS m −1 in soil and 7.32 dS m −1 in water) and non-saline (Las Cardas: EC 1.5 dS m −1 in soil and 1.0 dS m −1 in water) sites in Chile to evaluate productivity potential. At the Las Cardas field trial, under severe water stress, seed yields for 17 clones ranged from 81 to 1131 g/plant in the fourth year of growth. Even with the very low application of water used at this site (6 l/plant/week=approximately 20 mm per year), the average seed yield in the fourth year of the five highest producing clones was 466 g/plant. At Q. de Camarones, under extreme salinity seed yields for seven clones ranged from 202 to 1070 g/plant. At this location, the three highest yielding clones averaged 815 g/plant. Results suggest that these clones are suitable for commercial production in a saline condition similar to that of Q. de Camarones. Seed oil concentration of the clones was highest at Q. de Camarones. Economic analysis indicated that commercial plantations using the best clones could be a profitable alternative for the arid and semi-arid regions of Chile.

Body mass dynamics and growth patterns of leaf-eared mice Phyllotis darwini in a semi-arid region of the Neotropics

Authors report on body mass dynamics, field growth rates and age-specific growth curves for the leaf-eared mouse Phyllotis darwini (Waterhouse, 1837). Mark-recapture methods provided data for a population of P. darwini in a semi-arid region of Chile from 1987 to 1996. There were significant effects of sex, season, and slope exposure on body mass. In addition, authors found significant effects of sex, mass class, and season on field growth rates.

Biomass equations for quillay ( Quillaja saponaria mol) in the semiarid region of Central Chile

Quillaja is one of the most important species growing in the semiarid region of Chile because of the high content of saponin in its bark. The wood is normally used as charcoal. Biomass equations to estimate the weight of total stem bark, commercial bark, stem wood, branches and total tree were developed. Data were obtained in three areas located in the north, centre and south of the Chilean semiarid region. Thirty trees were completely weighed. Individual tree components and total tree weights were regressed against DBH, basal diameter, total height and number of main branches, and a combination of them, using the allometric equation of the form Y = a X b and a multiple linear model, both weighted and unweighted. The best results were obtained with the second kind of model, giving better estimates for total tree and stem bark weights. The poorest estimates were obtained for commercial bark.

Pest outbreaks and rainfall in the semi-arid region of Chile

The paper has two main objectives: (i) to document rodent and insect outbreaks in the three main agricultural valleys of the semi-arid region of central Chile (30–32°S) and (ii) to attempt to relate these outbreaks to rainfall in these same areas. Rodent and insect outbreaks are documented on the basis of qualitative complaint records by subsistence farmers of the area. Contingency table analysis of standard rainfall data and complaint records show a statistically significant relationship between these variables, for both types of pests. The relation between outbreaks of these wild species in agricultural valleys, primary productivity on the between-valley areas and presumptive movements of those species are discussed, particularly in relation to eventual pest management strategies.

Biological and environmental aspects of a mouse outbreak in the semi-arid region of Chile

Biological and environmental aspects of a mouse outbreak in the semi-arid region of Chile