Mediterranean Region Of Central Chile Research Articles

Preliminary records of abundance and morphometry of the tiger crab, Aegla concepcionensis (Schmitt, 1942) (Anomura, Aeglidae) in a lake of southern Chile

Abstract The tiger crab, Aegla concepcionensis, is a threatened endemic freshwater decapod of Chile, distributed throughout small areas of the Mediterranean region of Central Chile (37°30′-38°00′S). Its habitat includes streams and lakes with riparian areas dominated by native plants, with little or null human intervention. To our knowledge, the tiger crab’s distribution is limited and human stressors (e.g., water withdrawal, exotic tree plantations and climate change) have led to degradation of its habitat. Based on the presence of these stressors and the virtual lack of knowledge of its ecology, the tiger crab has been categorized as Endangered (EN). This study presents a preliminary description of the species’ ecology based on its abundance and its morphometrics, as well as on its feeding habits in Caburgua lake, South Central Chile. We established 16 sampling points, half of which in the shallow bathymetric stratum (0-10 m depth) of the lake itself, and half in the Lumaco stream, one of the lake’s tributaries. We used baited traps to capture specimens. A. concepcionensis appeared to be found in the lake’s shallow bathymetric stratum, but not in the stream. Individuals showed negative allometric growth, males were larger than females, and they showed scavenger feeding behaviour. Our findings provide useful information to help with tiger crab conservation, although more extensive surveys will be required to collect sufficient data for establishing a robust conservation program for the species in the study area.

The Atacama toad (Rhinella atacamensis) exhibits an unusual clinal pattern of decreasing body size towards more arid environments

BackgroundThe causes of geographic variation of body size in ectotherms have generally been attributed to environmental variables. Research in amphibians has favored mechanisms that involve water availability as an explanation for the geographic variation of body size. However, there are few studies at intraspecific level on amphibians that inhabit desert or semi-desert environments, where hydric restrictions are stronger. Here, we describe and inquire as to the causes of the geographic variation of body size in the semi-desert toad Rhinella atacamensis, a terrestrial anuran that is distributed over 750 km along a latitudinal aridity gradient from the southern extreme of the Atacama Desert to the Mediterranean region of central Chile. We measured the snout-vent length of 315 adults from 11 representative localities of the entire distribution of the species. Then, using an information-theoretic approach, we evaluate whether the data support eight ecogeographic hypotheses proposed in literature.ResultsRhinella atacamensis exhibits a gradual pattern of decrease in adult body size towards the north of its distribution, where the climate is more arid, which conforms to a Bergmann’s cline. The best model showed that the data support the mean annual precipitation as predictor of body size, favoring the converse water availability hypothesis.ConclusionsMost studies in amphibians show that adult size increases in arid environments, but we found a converse pattern to expected according to the hydric constraints imposed by this type of environment. The evidence in R. atacamensis favors the converse water availability hypothesis, whose mechanism proposes that the foraging activity determined by the precipitation gradient has produced the clinal pattern of body size variation. The variation of this trait could also be affected by the decreasing productivity that exists towards the north of the species distribution. In addition, we found evidence that both pattern and mechanism are independent of sex. Lastly, we suggest that behavioral traits, such as nocturnal habits, might also play an important role determining this differential response to aridity. Therefore, the support for the converse water availability hypothesis found in this study shows that amphibians can respond in different ways to water restrictions imposed by arid environments.

Genome-Wide Association of Stem Carbohydrate Accumulation and Remobilization during Grain Growth in Bread Wheat (Triticum aestivum L.) in Mediterranean Environments.

Water deficit represents an important challenge for wheat production in many regions of the world. Accumulation and remobilization of water-soluble carbohydrates (WSCs) in stems are part of the physiological responses regulated by plants to cope with water stress and, in turn, determine grain yield (GY). The genetic mechanisms underlying the variation in WSC are only partially understood. In this study, we aimed to identify Single Nucleotide Polymorphism (SNP) markers that account for variation in a suite of WSC and GY, evaluated in 225 cultivars and advanced lines of spring wheat. These genotypes were established in two sites in the Mediterranean region of Central Chile, under water-limited and full irrigation conditions, and assessed in two growing seasons, namely anthesis and maturity growth periods. A genome-wide association study (GWAS) was performed by using 3243 SNP markers. Genetic variance accounted for 5 to 52% of phenotypic variation of the assessed traits. A rapid linkage disequilibrium decay was observed across chromosomes (r2 ≤ 0.2 at 2.52 kbp). Marker-trait association tests identified 96 SNPs related to stem weight (SW), WSCs, and GY, among other traits, at the different sites, growing seasons, and growth periods. The percentage of SNPs that were part of the gene-coding regions was 34%. Most of these genes are involved in the defensive response to drought and biotic stress. A complimentary analysis detected significant effects of different haplotypes on WSC and SW, in anthesis and maturity. Our results evidence both genetic and environmental influence on WSC dynamics in spring wheat. At the same time, they provide a series of markers suitable for supporting assisted selection approaches and functional characterization of genes.

Landscape context but not management strategies affects the diversity of native and exotic semi-natural vegetation in Mediterranean agroecosystems of Central Chile

Current knowledge on the effects of farming type and landscape heterogeneity on plant diversity is biased towards temperate ecosystems in Europe and North America, while there is a paucity of information for the Mediterranean agroecosystems. In particular, the Mediterranean region of Central Chile concentrates most of the country's population and have experienced the greatest agricultural changes leading to the replacement of native vegetation remnants by monocultures and livestock ranching. This study aims to analyse the effects of farming type (organic versus conventional) and landscape heterogeneity (composition and configuration), in addition with local habitat type, on semi-natural vegetation. We addressed these effects considering both native and exotic herbs at 14 fruit farms and landscape metrics at three spatial scales (0.5, 1 and 2 km). In total, we recorded 32 native and 103 exotic plant taxa. Farming type and local habitat type did not influence the diversity of native and exotic herbs. We showed that increasing landscape compositional heterogeneity (i.e. percentage of grasslands, of woody elements) increased alpha and beta diversity of native herbs at the scale of 0.5 km and 2 km. Gamma diversity of native plants responded negatively to decreasing landscape configurational heterogeneity (i.e. largest patch index) at the scale of 0.5 km. Exotic specis did not respond to landscape context. Our findings suggest that semi-natural elements in the surrounding landscape of fruit farms particularly benefited native plant species. Therefore, agri-environment schemes designed to preserve native biodiversity in Mediterranean agroecosystems must promote landscape heterogeneity through the conservation of semi-natural elements at multiple spatial scales.

The Development of a Model for Recommending the Application of Zinc Fertilizer in the Mediterranean Region of Central Chile

The main aim of this study is to develop a mechanistic model of fertilization for recommending the application of zinc (Zn) fertiliser for maize based on the mass balance of Zn. The model would consider the critical Zn level for maize (ZnCL), Zn availability in the soil (ZnA) and Zn buffering capacity (Znb). Soil samples were collected from 78 maize fields for chemical and physical characterization including measuring ZnA and Znb. Additionally, a crop management survey was carried out in each field. The classification and regression trees method (CART) was used and relationships between Znb and some soil properties were established, clay content being the most relevant to the model, besides soil reaction (pH) and silt content. The application of Zn fertilizer can be adequately calculated by a mechanistic model that considers ZnA, Znb and ZnCL above that which maize crop yields do not increase. This work highlights the importance of Znb evaluation by the incubation procedure and the extraction of available Zn by DTPA solution. As hypothesised and then demonstrated in this work, Znb is closely related to soil pH and texture (clay and silt). Our results suggest that, in between 51 and 97% of fields examined, it would be necessary to apply Zn fertilisers to produce the maximum maize yield.

Remnants of native forests support carnivore diversity in the vineyard landscapes of central Chile

AbstractCarnivores play an important role in ecosystem functioning as apex predators. However, most carnivore species are threatened or have been extirpated in human-dominated landscapes. The Mediterranean region of central Chile is a biodiversity hotspot, but expansion of agricultural areas such as vineyards is degrading wildlife habitat. We estimated the species richness and composition of carnivore communities in remnant fragments of sclerophyllous forest-shrubland in the vineyard landscapes of central Chile to evaluate the effects of human disturbance at different spatial scales. We tested two hypotheses: (1) vineyard landscapes with higher levels of human disturbance support a lower diversity of native carnivores in fragments of remnant native vegetation compared to landscapes with larger areas of natural habitat, and (2) habitat specialists and generalists respond differentially to human influence at the habitat vs landscape spatial scale. We used camera traps at 12 sites across the study area and evaluated the impact of human disturbance indicators on the richness and detection frequency of carnivore species. We found that human population density negatively affected carnivore richness and was associated with a lower detection frequency of the Vulnerable guiñaLeopardus guigna. The presence of domestic dogs also had a negative effect on the detection frequency of the guiña and the two native species of foxes, the culpeoLycalopex culpaeusand South American grey foxLycalopex griseus. We conclude that protecting remnants of native forest in vineyard landscapes is crucial for carnivore conservation in central Chile.

Recent wildfires in Central Chile: Detecting links between burned areas and population exposure in the wildland urban interface

Wildfires are gaining importance in the Mediterranean regions owing to climate change and landscape changes due to the increasing closeness between urban areas and forests prone to wildfires. We analysed the dry season wildfire occurrences in the Mediterranean region of Central Chile (32°S–39°30′ S) between 2000 and 2017, using satellite images to detect burned areas, their landscape metrics and the land use and covers (vegetal) pre-wildfire, in order to determine the population living in areas that may be affected by wildfires. The existing regulations in western Mediterranean countries (Portugal, Spain, France, and Italy) were used to identify and define the wildland-urban interface (WUI) areas, quantifying the people inhabiting them and estimating the population affected by burned areas from 2001 to 2017. We used the Google Earth Engine to process MODIS products and extract both burned areas and land covers. We detected that 25% of the urban population inhabits WUI areas (i.e. Biobío, Araucanía and Valparaíso regions) where the urban population exposed to burned areas exceeds 40%. Most of the land use and land covers affected by wildfires are anthropogenic land covers, classified as savannas, croplands, evergreen broadleaf forests and woody savannas, representing >70% of the burned areas. Urban areas show only 0.6% of the burned surface from 2001 to 2017. We estimate that 55,680 people are potentially affected by wildfires, and 50% of them are in just one administrative region. These results show the imperative need for public policies as a regulating force for establishing WUI areas with the purpose of identifying wildfire risk in urban areas, such as establishing prevention methods as firewalls and prescribed fires.

Coupling of microbial nitrogen transformations and climate in sclerophyll forest soils from the Mediterranean Region of central Chile

The Mediterranean region of central Chile is experiencing extensive “mega-droughts” with detrimental effects for the environment and economy of the region. In the northern hemisphere, nitrogen (N) limitation of Mediterranean ecosystems has been explained by the decoupling between N inputs and plant uptake during the dormant season. In central Chile, soils have often been considered N-rich in comparison to other Mediterranean ecosystems of the world, yet the impacts of expected intensification of seasonal drought remain unknown. In this work, we seek to disentangle patterns of microbial N transformations and their seasonal coupling with climate in the Chilean sclerophyll forest-type. We aim to assess how water limitation affects microbial N transformations, thus addressing the impact of ongoing regional climate trends on soil N status. We studied four stands of the sclerophyll forest-type in Chile. Field measurements in surface soils showed a 67% decline of free-living diazotrophic activity (DA) and 59% decrease of net N mineralization rates during the summer rainless and dormant season, accompanied by a stimulation of in-situ denitrification rates to values 70% higher than in wetter winter. Higher rates of both free-living DA and net N mineralization found during spring, provided evidence for strong coupling of these two processes during the growing season. Overall, the experimental addition of water in the field to litter samples almost doubled DA but had no effect on denitrification rates. We conclude that coupling of microbial mediated soil N transformations during the wetter growing season explains the N enrichment of sclerophyll forest soils. Expected increases in the length and intensity of the dry period, according to climate change models, reflected in the current mega-droughts may drastically reduce biological N fixation and net N mineralization, increasing at the same time denitrification rates, thereby potentially reducing long-term soil N capital.

The role of social capital and labour exchange in the soils of Mediterranean Chile

The unirrigated Mediterranean region of Central Chile is characterised by high levels of soil degradation and rural poverty. One of the main institutional approaches to these issues have mainly focused on promoting the forest industry’s entrance along with the introduction of agricultural machinery and more efficient agricultural methods. These have been sponsored as an answer for the needed development, which, in most cases, is far from being suited to the ecological and cultural contexts. This article analyses the main historical and sociocultural factors behind this socio-environmental issue, emphasizing how qualitative factors related to the loss of social capital and the disintegration of communities have had fundamental implications for the environmental problem of soil degradation. Finally, it examines regional social dynamics and traditional agricultural activities that propose social cohesion and territorial empowerment as the bases for sustainable agriculture in environmentally vulnerable regions.

Understanding the effect of three decades of land use change on soil quality and biomass productivity in a Mediterranean landscape in Chile

Land-use and land-cover change (LUCC) can deeply alter soil quality (SQ), affecting important productivity functions like vegetation biomass. A further understanding of the history of LUCC is essential to explain natural or anthropic landscape cover. The Mediterranean region of central Chile has historically been affected by LUCC impacts on the vegetation gradient of the landscape, which ranges from natural cover to anthropic cover like grazing pastures and crop lands. The main objective of this study is to define the historical impact of LUCC on SQ in a Mediterranean landscape in central Chile. To conduct the study, historical LUCC trends between 1975 and 2011 were analyzed. A Soil Quality Index (SQI) was developed to comparatively assess six types of land use (Annual Crops, Perennial Crops, Grazing, Espinal, Dense Espinal and Native Forest); and finally, SQI was interpolated at landscape scale using the soil-adjusted vegetation index (SAVI) as an auxiliary variable. SAVI was selected to represent indirect information on vegetation biomass productivity. The results indicate that most LUCC dynamics were observed in the Espinal woodland, where agriculture and grazing activities have been developed historically. The SQI showed significant SQ deterioration when Native Forests (SQI=0.82) degrade and are transformed by anthropic interventions like Annual Crops (SQI=0.27), Perennial Crops (SQI=0.34) or Grassland (SQI=0.36). However, a slight improvement in SQ compared to the other land uses was identified in the Dense Espinal (SQI=0.46). Finally, the quality model at landscape scale showed clear differences in SQI values for all landscape covers.

The avifauna of Bosque Fray Jorge National Park and Chile's Norte Chico

The avifauna of Chile is relatively depauperate, comprising 469 extant species, of which 213 are terrestrial. However, the Coquimbo Region presents a broad ecological transition from the hyperarid Atacama Desert to the north, and the more mesic Chilean Mediterranean region of central Chile, resulting in relatively high species diversity. Approximately 130 species are found here, 8 of which are endemic to Chile although not to this region. Bosque Fray Jorge National Park is a 9959 ha Biosphere Reserve dominated by matorral habitat and hosting up to 123 bird species. Through avian surveys and banding over nearly a decade we have documented 63 terrestrial species and discerned predictable seasonal and interannual structure to avian assemblages, at least through an extended dry period. Recent studies in the matorral habitats of the park indicate seasonal patterns that fall into 4 patterns: year-round residents, winter visitors, summer breeders, and transients. Short-term banding studies demonstrate co-occurring wintering and breeding cohorts among species of Sierra-finches (Phrygilus) in the park; such assemblages and dynamics are reminiscent of North American Mediterranean avian assemblages and pose interesting ecological comparisons. In this period of surveys there appears to have been a gradual transition of the avifauna that may be a response to anthropogenic influence and/or climate change. Research on the foraging behavior of 2 insectivorous species indicate that one of these is convergent on better-known North American taxa while the other clearly is not; these efforts suggest useful avenues for further comparative research. A remarkable coevolutionary association between the Chilean Mockingbird (Mimus thenca) and endoparasitic mistletoes (Tristerix) provides insight into potential convergent ecologies in desert regions with different evolutionary histories.Less than 1% of the park comprises temperate forest remnants that subsist due to extensive water input from fog. Research in these remnants has emphasized the role of habitat fragmentation on avian assemblage composition and on reproductive ecology by forest-dependent species. The avifauna here comprises a subset of that found in intact Valdivian rainforest to the south, and forest remnant size alone explains over 90% of the variation in species numbers. One species has been particularly well studied; the Thorn-tailed Rayadito (Aphrastura spinicauda) is more abundant and has higher nestling survival in larger fragments. We summarize other work on stress responses and variation in song structure in this species. Finally, the role of birds in tree recruitment here has important implications in the face of a recent history of reduction in sizes of forest remnants; numerous birds consume the fruit of the dominant tree, olivillo (Aextoxicon punctatum), but they fail to promote successful recruitment because they defecate viable seeds in locations that provide poor survival of seedlings.Ornithological research in Chile is undergoing a modest renaissance, and while dryland avifaunas are characterized more by what is not known and has yet to be studied than by actual ecological understanding, they provide a baseline for many exciting studies ranging from natural history to the role of migration to comparative dynamics of independent lineages in North and South America.

Introduced European rabbit as main prey of the native carnivore culpeo fox (Lycalopex culpaeus) in disturbed ecosystems of central Chile

This study describes food habits of the culpeo fox (Lycalopex culpaeus) by scat analysis in two hills considered Priority Conservation Sites of the Mediterranean Region of central Chile, one of the most disturbed and modified ecosystems in the country. The results showed that foxes from both sites consume the introduced European rabbit (Oryctolagus cuniculus) as primary prey and native small mammals as secondary prey. This is the first record of feeding habits of the culpeo fox in central Chile that reports a higher consumption of European rabbit over pooled native small mammals. The reason for this result, as well as the higher trophic niche breadth and trophic niche diversity found in culpeo fox populations from the less disturbed hill, might be due to anthropogenic impacts on the study sites. However, to validate this claim, further studies on prey availability and human impact are required. The culpeo fox can have an important role in controlling pests such as the European rabbit; therefore, a more extensive study of this issue can bring important information for the conservation and management of natural areas of central Chile that show high human impact.Este estudio describe los hábitos alimentarios del zorro culpeo (Lycalopex culpaeus) en dos cerros considerados “Sitios Prioritarios de Conservación” de la eco-región mediterránea de Chile central, el cual es una de las zonas más intervenidas y modificadas del país. Los resultados encontrados muestran que los zorros de ambos cerros consumen como presa primaria al conejo europeo (Oryctolagus cuniculus) y a los pequeños mamíferos nativos como presa secundaria. Este es el primer registro de la dieta del zorro culpeo en Chile central que reporta un mayor consumo de conejo europeo por sobre el consumo de pequeños mamíferos nativos en su conjunto. La razón de este resultado, además de la mayor amplitud y diversidad de nicho trófico encontrado en la población de zorro culpeo en el cerro menos intervenido, podría deberse al impacto antropogénico en los sitios de estudios. Sin embargo, para validar esta afirmación se necesitan estudios sobre disponibilidad de presas e impacto humano. El zorro culpeo puede tener un papel importante en el control de plagas como el conejo europeo, por lo cual se requiere un estudio más acabado de esta temática, lo cual puede brindar información importante para la conservación y manejo de áreas naturales de Chile central que presenten un alto impacto antropogénico.

Persistent Acacia savannas replace Mediterranean sclerophyllous forests in South America

Mediterranean ecosystems are global hotspots of biodiversity threaten by human disturbances. Growing evidence indicates that regeneration of Mediterranean forests can be halted under certain circumstances and that successional stages can become notoriously persistent. The Mediterranean sclerophyllous forest in central Chile is been largely transformed into savannas dominated by the invasive legume tree Acacia caven as result of interacting management and ecological factors. We used multi-temporal satellite imagery to study the transition dynamics of these major vegetation types over the last four decades (1975–2008). Vegetation changes were related to indicators of resource availability (topography, water availability, solar radiance), potential propagule availability (distance to forest remnant patches) and disturbance regimes (grazing, fire occurrence and distance to roads and cities). During this study period, forests were mostly converted into Acacia savannas (46.1%). Acacia savanna was the most persistent natural vegetation type. The probability of sclerophyllous forest degradation into Acacia savanna increased on drier northern-exposed slopes, close to roads and further away from forest remnants. In contrast, forest regeneration from Acacia savanna was higher on moister southern-exposed slopes and closer to forest remnants. Acacia savannas are increasingly being converted into cultivated land on the moister locations or switching into a bare soil state in locations close to cities and further away from forest remnants. These results highlight the vulnerability of diverse sclerophyllous forests and its increasing conversion into persistent Acacia savannas in the Mediterranean region of central Chile and identify the ecological conditions for successful conservation and restoration of the native sclerophyllous forest vegetation that can be used for sensible land use planning.

Diversity patterns and composition of native and exotic floras in central Chile

Floristic changes in the Mediterranean region of central Chile brought about by human impact appear to be shared with other climatic regions, although there is a notable absence of empirical studies and available quantitative evidence for the central Chile region. This study examines the cover, richness and composition of native and exotic plant species in a representative area of central Chile. Through floristic characterization of 33 sites sampled using 40 × 40 m plots distributed along transect on which the two farthest sites were separated by 50 km, the floristic richness and cover patterns, as well as the general land use characteristics were evaluated (native matorral, espinal, abandoned farming field, forest plantations, periurban sites, road sites, river bank, and burnt site). We recorded 327 species of plants; 213 species were native and 114 were exotic. The average number of species was heterogeneous in all sites, showing a greater relative native frequency in those sites with a lower level of anthropic intervention. Except for the matorral, the cover of exotic species was greater than that of native species. No relation was found between richness and cover in relation to the different types of land use. The relationship between cover of native and exotic was negative, although for richness did not show relationship. Results show that the exotic species are limited by resources, although they have not completely displaced the native species. The native and exotic floras respond to different spatial distribution patterns, so their presence makes it possible to establish two facts rarely quantified in central Chile: first, that the exotic flora replaces (but does not necessarily displace) the native flora, and second, that at the same time, because of its greater geographic ubiquity and the abundance levels that it achieves, it contributes to the taxonomic and physiognomic homogenization of central Chile.

Restoration and Rehabilitation of Degraded Ecosystems in Arid and Semi‐Arid Lands. II. Case Studies in Southern Tunisia, Central Chile and Northern Cameroon

AbstractA model of ecosystem degradation and three possible responses to it—restoration, rehabilitation, and real‐location—is applied to ongoing projects in the arid mediterranean region of southern Tunisia, the subhumid mediterranean region of central Chile, and the semiarid tropical savannas of northern Cameroon. We compare both nonhuman and human determinants of ecosystem degradation processes in these contrasted regions, as well as interventions being tested in each. A number of quantifiable “vital ecosystem attributes” are used to evaluate the effects of ecosystem degradation and the experimental responses of rehabilitation on vegetation, soils and plant‐soil‐water relations. We argue that attempts to rehabilitate former ecosystem structure and functioning, both above‐ and below ground, are the best way to conserve biodiversity and insure sustainable long‐term productivity in ecosystems subjected to continuous use by people in arid and semi‐arid lands of “the South.” The success of such efforts, however, depends not only on elucidating the predisturbance (or slightly disturbed) structure and function of the consciously selected “ecosystem of reference,” but also on understanding and working with the socioeconomic, technical, cultural, and historical factors that caused the degradation in the first place.

EL GENERO NOTHOFAGUS Y SU IMPORTANCIA EN CHILE

The idea that the Nothofagus genus formed part of the Chilean southern-temperate floristic elements which originated in the southern end of the Gondwana continent about 45 million years ago is discussed. Both the present and the past distribution of the genus in South America and Australasia are given; the latter is not in agreement with the small dispersive capacity of the genus. Therefore, Nothofagus' possible origin is discussed. The chilean taxa are named, discribing the reproductive and vegetative morphology. On the basis of this information, three ecological groups are presented: decidous species of large leaves typical of the mediterranean region of Central Chile, decidous species of small leaves from the subantarctic region and perennials of small leaves that live in the Valdivian region. The names of the participans in the Biology of the Nothofagus Genus symposium are listed. The Symposium was held during the IV National Congress of Botany in Valdivia (Chile) in September 1986.

Seasonal Water Stress in Some Chilean Matorral Shrubs

Environmental and plant characteristics relating to plant water stress were measured in seven shrub species, Satureja gilliesii, Cryptocarya alba, Quillaja saponaria, Lithraea caustica, Colliguaya odorifera, Retanilla ephedra, and Proustia cinerea, growing on equator- (EFS) and pole-facing (PFS) slopes in the mediterranean region of central Chile. Midday air temperatures and vapor pressure deficits were greater on the EFS than on the PFS. Soil moisture was greater during the winter but less during the summer on the EFS. Midday xylem potentials in all species decreased during the summer, increased after the first rain, and were lower on the EFS. Mean leaf size was smaller on the EFS. Stomatal frequency differed only for Q. saponaria and C. odorifera. Species with shallow root systems had lower xylem potentials.