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Nutrient exchange in arbuscular mycorrhizal symbiosis from a thermodynamic point of view

Autores:

Dreyer, I., Spitz, O., Kanonenberg, K., Montag, K., Handrich, M., & Ahmad, S., Schott‐Verdugo, S., Navarro‐Retamal, C., Rubio‐Meléndez, M.E., Gomez‐Porras, J.L., Riedelsberger, J., Molina‐Montenegro, M.A., Succurro, A., Zuccaro, A., Gould, S.V., Bauer, P., Schmitt, L., Gohlke, H.

Resumen:

To obtain insights into the dynamics of nutrient exchange in arbuscular mycorrhizal (AM) symbiosis, we modelled mathematically the two‐membrane system at the plant–fungus interface and simulated its dynamics.

In computational cell biology experiments, the full range of nutrient transport pathways was tested for their ability to exchange phosphorus (P)/carbon (C)/nitrogen (N) sources.

As a result, we obtained a thermodynamically justified, independent and comprehensive model of the dynamics of the nutrient exchange at the plant–fungus contact zone. The predicted optimal transporter network coincides with the transporter set independently confirmed in wet‐laboratory experiments previously, indicating that all essential transporter types have been discovered.

The thermodynamic analyses suggest that phosphate is released from the fungus via proton‐coupled phosphate transporters rather than anion channels. Optimal transport pathways, such as cation channels or proton‐coupled symporters, shuttle nutrients together with a positive charge across the membranes. Only in exceptional cases does electroneutral transport via diffusion facilitators appear to be plausible. The thermodynamic models presented here can be generalized and adapted to other forms of mycorrhiza and open the door for future studies combining wet‐laboratory experiments with computational simulations to obtain a deeper understanding of the investigated phenomena.

Año: 2018

Palabras claves: computational cell biology, modelling, nutrient transport, plant biophysics, plant–fungus interaction

Referencia APA: Dreyer, I., Spitz, O., Kanonenberg, K., Montag, K., Handrich, M., & Ahmad, S., Schott‐Verdugo, S., Navarro‐Retamal, C., Rubio‐Meléndez, M.E., Gomez‐Porras, J.L., Riedelsberger, J., Molina‐Montenegro, M.A., Succurro, A., Zuccaro, A., Gould, S.V., Bauer, P., Schmitt, L., Gohlke, H. (2019). Nutrient exchange in arbuscular mycorrhizal symbiosis from a thermodynamic point of view. New Phytologist, 222(2), 1043-1053. doi: 10.1111/nph.15646

Coastal biophysical processes and the biogeography of rocky intertidal species along the south-eastern Pacific

Autores:

Lara, C., Saldías, G., Cazelles, B., Rivadeneira, M., Haye, P., & Broitman, B.

Resumen:

Aim
We assess the spatial distribution of a suite of coastal biophysical characteristics and how their variability is related to the distribution and geographic range of a diverse assemblage of coastal benthic species with different larval dispersal strategies.

Location
South‐eastern Pacific (SEP) coast between 18°20′S and 42°35′S.

Methods
Biophysical variability was assessed using chlorophyll‐a concentration, sea surface temperature and the signal of turbid river plumes derived from MODIS onboard the Aqua satellite. We established the dominant spatial components using wavelet and coherence analysis, and evaluated the biogeographic structure of 51 rocky intertidal species sampled over ~2,600 km along the SEP using multivariate classification and regression trees.

Results
Biogeographic breaks detected here were consistent with recent biogeographic classification schemes. Distribution breakpoints for species with lecithotrophic larvae clustered around 30°S. We observed a previously unreported break in the distribution of species with planktotrophic larval dispersal strategies around 35°S. These breaks are related to coherence in the spatial structure of sea surface temperature, chlorophyll‐a and river outflow over different temporal scales. Regions with similar biophysical characteristics, and the breaks the separate them, are in striking agreement with the biogeographic patterns revealed by the multivariate classification trees.

Main conclusions
Our results reconcile patterns of biogeographic structure reported for other groups of species along the SEP coast. We suggest that river outflow, a poorly studied coastal environmental forcing, may play an important role in determining the geographic distribution of rocky shore species, probably through its effects on larval dispersal patterns.

Año: 2018

Palabras claves: biogeographic provinces, larval dispersal, MODIS, multiscale coherence, river outflows, rocky shore invertebrates

Referencia APA: Lara, C., Saldías, G., Cazelles, B., Rivadeneira, M., Haye, P., & Broitman, B. (2019). Coastal biophysical processes and the biogeography of rocky intertidal species along the south-eastern Pacific. Journal Of Biogeography, 46(2), 420-431. doi: 10.1111/jbi.13492

Asymmetric competitive effects during species range expansion: An experimental assessment of interaction strength between “equivalent” grazer species in their range overlap

Autores:

Aguilera, M., Valdivia, N., Jenkins, S., Navarrete, S., & Broitman, B.

Resumen:

Biotic interactions are central to the development of theory and concepts in community ecology; experimental evidence has shown their strong effects on patterns of population and community organization and dynamics over local spatial scales. The role of competition in determining range limits and preventing invasions at biogeographic scales is more controversial, partly because of the complexity of processes involved in species colonization of novel habitats and the difficulties in performing appropriate manipulations and controls.

We examined experimentally whether competition is likely to affect poleward range expansion hindering or facilitating the establishment of the limpet Scurria viridula along the south‐eastern Pacific rocky shore (30°S, Chile) in the region occupied by the congeneric S. zebrina. We also assessed whether competition with the “invader” or range‐expanding species could reduce individual performance of the “native” S. zebrina and depress local populations.

Geographic field surveys were conducted to characterize the abundance and identity of limpets along the south‐eastern Pacific coast from 18°S to 41°S, and the micro‐scale (few cm) spatial distribution across the range overlap of the two species. Field‐based competition experiments were conducted at the southern leading edge of the range of S. viridula (33°S) and at the northern limit of S. zebrina (30°S).

Field surveys showed poleward range expansion of S. viridula of ca. 210 km since year 2000, with an expansion rate of 13.1 km/year. No range shift was detected for S. zebrina. The resident S. zebrina had significant negative effects on the growth rate of the invading juvenile S. viridula, while no effect of the latter was found on S. zebrina. Spatial segregation between species was found at the scale of cms.

Our results provide novel evidence of an asymmetric competitive effect of a resident species on an invader, which may hamper further range expansion. No negative effect of the invader on the resident species was detected. This study highlights the complexities of evaluating the role of species interactions in setting range limits of species, but showed how interspecific competition might slow the advance of an invader by reducing individual performance and overall population size at the advancing front.

Año: 2018

Palabras claves: field experiments, grazers, Pacific Ocean, range overlap, range shift, transitional zone

Referencia APA: Aguilera, M., Valdivia, N., Jenkins, S., Navarrete, S., & Broitman, B. (2018). Asymmetric competitive effects during species range expansion: An experimental assessment of interaction strength between “equivalent” grazer species in their range overlap. Journal Of Animal Ecology, 88(2), 277-289. doi: 10.1111/1365-2656.12917

Temperature and pCO2 jointly affect the emergence and survival of cercariae from a snail host: implications for future parasitic infections in the Humboldt Current system

Autores:

Leiva, N., Manríquez, P., Aguilera, V., & González, M.

Resumen:

Ocean warming and acidification are general consequences of rising atmospheric CO2 concentrations. In addition to future predictions, highly productive systems such as the Humboldt Current System are characterized by important variations in both temperature and pCO2 level, but how these physical–chemical ocean changes might influence the transmission and survival of parasites has not been assessed. This study experimentally evaluated the effects of temperature (14, 18 and 25 °C) and the combined effects of temperature (∼15 and 20 °C) and pCO2 level (∼500 and 1400 microatmospheres (µatm) on the emergence and survival of two species of marine trematodes—Echinostomatidae gen. sp. and Philophthalmidae gen. sp.—both of which infect the intertidal snail Echinolittorina peruviana. Snails were collected from intertidal rocky pools in a year-round upwelling area of the northern Humboldt Current System (23°S). Two experiments assessed parasite emergence and survival by simulating emersion-immersion tidal cycles. To assess parasite survival, 2 h old cercariae (on average) were taken from a pool of infected snails incubated at 20–25 °C, and their mortality was recorded every 6 h until all the cercariae were dead. For both species, a trade-off between high emergence and low survival of cercariae was observed in the high temperature treatment. Species-specific responses to the combination of temperature and pCO2 levels were also observed: the emergence of Echinostomatidae cercariae was highest at 20 °C regardless of the pCO2 levels. By contrast, the emergence of Philophthalmidae cercariae was highest at elevated pCO2 (15 and 20 °C), suggesting that CO2 may react synergistically with temperature, increasing transmission success of this parasite in coastal ecosystems of the Humboldt Current System where water temperature and pH are expected to decrease. In conclusion, our results suggest that integrating temperature-pCO2 interactions in parasite studies is essential for understanding the consequence of climate change in future marine ecosystem health.

Año: 2018

Palabras claves: Cercariae, Climate change, Gastropod, Intertidal ecosystems, pCO2, Transmission, Trematodes

Referencia APA: Leiva, N., Manríquez, P., Aguilera, V., & González, M. (2019). Temperature and pCO2 jointly affect the emergence and survival of cercariae from a snail host: implications for future parasitic infections in the Humboldt Current system. International Journal For Parasitology, 49(1), 49-61. doi: 10.1016/j.ijpara.2018.08.006

First insight into the heritable variation and potential response to selection of phototaxis and locomotion behavior associated to the light/dark stimuli in the abalone Haliotis discus hannai

Autores:

Defranchi, Y., Winkler, F., Farías, W., Herbinger, C., & Brokordt, K.

Resumen:

Abalones are especially susceptible to environmental lighting conditions. This factor greatly affects crucial biological process such as feeding rates, energy balance, physiological stress status, and consequently, growth and survival of farmed abalone. Most of these effects have been studied in the economically valuable abalone Haliotis discus hannai. The use of specific photoperiods, and/or light qualities and intensities, have been proposed as managing strategies to increase its production; however, for extensive off-shore or in intensive land-based farming systems, lighting conditions are not likely to be easily managed. Despite the great importance of the biological responses to the light/dark stimuli for abalone farming production, to the best of our knowledge the genetic control upon the variation associated behavioral traits have not been studied. Therefore, the aim of this study was to estimate the heritable variation and potential responses to selection for the phototaxis [i.e., displacement towards (positive) or against (negative) the light source] and locomotion behaviors associated to the intensity of the response (i.e., crawling speed and displacement distance) to the light/dark stimuli in juvenile H. discus hannai. Genetic and phenotypic correlations between these traits were also estimated. Results showed moderate but significant heritable variations for phototaxis (h2 = 0.15) and locomotion responses (h2 = 0.18–0.37); and significant positive genetic correlations among them. Expected gain responses to selection per generation (with a selection intensity of 2.06, i.e., selecting 5% of the individuals from a population) were moderate for phototaxis variation (16%) and high for locomotion responses variation (33–67 or 36–73%, depending on the model used for the estimations). As a consequence, the potential for reducing (or incrementing, depending on the breeding goal) the reactivity or the sensibility to the light stimulus by selective breeding is good, and can be an attractive way of indirectly improving growth, survival and general welfare of farmed H. discus hannai.

Año: 2018

Palabras claves: Abalone phototaxis, Locomotion to light/dark, Phototaxis heritability, Abalone farming, Selective breeding, Haliotis discus hannai

Referencia APA: Defranchi, Y., Winkler, F., Farías, W., Herbinger, C., & Brokordt, K. (2019). First insight into the heritable variation and potential response to selection of phototaxis and locomotion behavior associated to the light/dark stimuli in the abalone Haliotis discus hannai. Aquaculture, 500, 645-650. doi: 10.1016/j.aquaculture.2018.10.065

Asymmetric competitive effects during species range expansion: An experimental assessment of interaction strength between “equivalent” grazer species in their range overlap

Autores:

Aguilera, M., Valdivia, N., Jenkins, S., Navarrete, S., & Broitman, B.

Resumen:

Biotic interactions are central to the development of theory and concepts in community ecology; experimental evidence has shown their strong effects on patterns of population and community organization and dynamics over local spatial scales. The role of competition in determining range limits and preventing invasions at biogeographic scales is more controversial, partly because of the complexity of processes involved in species colonization of novel habitats and the difficulties in performing appropriate manipulations and controls.

We examined experimentally whether competition is likely to affect poleward range expansion hindering or facilitating the establishment of the limpet Scurria viridula along the south‐eastern Pacific rocky shore (30°S, Chile) in the region occupied by the congeneric S. zebrina. We also assessed whether competition with the “invader” or range‐expanding species could reduce individual performance of the “native” S. zebrina and depress local populations Geographic field surveys were conducted to characterize the abundance and identity of limpets along the south‐eastern Pacific coast from 18°S to 41°S, and the micro‐scale (few cm) spatial distribution across the range overlap of the two species. Field‐based competition experiments were conducted at the southern leading edge of the range of S. viridula (33°S) and at the northern limit of S. zebrina (30°S).

Field surveys showed poleward range expansion of S. viridula of ca. 210 km since year 2000, with an expansion rate of 13.1 km/year. No range shift was detected for S. zebrina. The resident S. zebrina had significant negative effects on the growth rate of the invading juvenile S. viridula, while no effect of the latter was found on S. zebrina. Spatial segregation between species was found at the scale of cms.
Our results provide novel evidence of an asymmetric competitive effect of a resident species on an invader, which may hamper further range expansion. No negative effect of the invader on the resident species was detected. This study highlights the complexities of evaluating the role of species interactions in setting range limits of species, but showed how interspecific competition might slow the advance of an invader by reducing individual performance and overall population size at the advancing front.

Año: 2018

Palabras claves: Field experiments, Grazers, Pacific Ocean, Range overlap, Range shift, Transitional zone

Referencia APA: Aguilera, M., Valdivia, N., Jenkins, S., Navarrete, S., & Broitman, B. (2018). Asymmetric competitive effects during species range expansion: An experimental assessment of interaction strength between “equivalent” grazer species in their range overlap. Journal Of Animal Ecology, 88(2), 277-289. doi: 10.1111/1365-2656.12917

The 2017 coastal El Niño

Autores:

Takahashi, K.; Aliaga-Nestares, V.; Avalos, G.; Bouchon, M.; Castro, A.; Cruzado, L.; Dewitte, B.; Gutiérrez, D.; Lavado-Casimiro, W.; Marengo, J.; Martínez, A. G.; Mosquera-Vásquez, K.; Quispe, N.

Resumen:

The original concept of El Niño consisted of anomalously high sea surface temperature and heavy rainfall along the arid northern coast of Peru (Carranza 1891; Carrillo 1893). The concept evolved into the El Niño–Southern Oscillation (ENSO; Bjerknes 1969), although the original El Niño and the Southern Oscillation do not necessarily have the same variability (Deser and Wallace 1987), and the strong El Niño episode in early 1925 coincided with cold-to-neutral ENSO conditions (Takahashi and Martínez 2017). To distinguish the near-coastal El Niño from the warm ENSO phase, Peru operationally defines the “coastal El Niño” based on the seasonal Niño 1+2 SST anomaly (ENFEN 2012; L’Heureux et al. 2017). While recent attention has been
brought to the concept of ENSO diversity (e.g., “central Pacific” vs “eastern Pacific” events; Capotondi et al. 2015), the coastal El Niño represents another facet of ENSO that requires further study in terms of its mechanisms and predictability.

Año: 2018

Palabras claves:

Referencia APA: Takahashi, K.; Aliaga-Nestares, V.; Avalos, G.; Bouchon, M.; Castro, A.; Cruzado, L.; Dewitte, B.; Gutiérrez, D.; Lavado-Casimiro, W.; Marengo, J.; Martínez, A. G.; Mosquera-Vásquez, K.; Quispe, N. (2018). The 2017 coastal El Niño. Bulletin of the American Meteorological Society. https://doi.org/10.1175/2018BAMSStateoftheClimate.1

Extreme El Niño Events

Autores:

Dewitte, B., & Takahashi, K.

Resumen:

Every few years the tropical Pacific warms abnormally in association with a relaxation of the trade winds, a phenomenon known as the El Niño–Southern Oscillation (ENSO) that represents the strongest fluctuation of the global climate system. Although the contemporary observational record indicates that all El Niño events are not alike, differing in amplitude, warming pattern, and teleconnection, there is a class of events that stands out in terms of the societal and economical impacts: the extreme El Niño events that have occurred every 15–20 years. In this chapter, we propose an overview of the state of knowledge and of some current lines of research dedicated to extreme El Niño events. Building on the recently proposed concept of ENSO diversity, we further synthesize our current understanding of the nonlinear dynamics of this class of events and their expected evolution in a warmer climate and highlight some challenges in ENSO research.

Año: 2018

Palabras claves: El Niño, ENSO diversity, External forcing, Global warming, Teleconnection.

Referencia APA: Dewitte, B., & Takahashi, K. (2019). Extreme El Niño Events. Tropical Extremes, 165-201. doi: 10.1016/b978-0-12-809248-4.00006-6

Is Precipitation a Good Metric for Model Performance?

Autores:

Tapiador, F., Roca, R., Del Genio, A., Dewitte, B., Petersen, W., & Zhang, F.

Resumen:

Precipitation has often been used to gauge the performances of numerical weather and climate models, sometimes together with other variables such as temperature, humidity, geopotential, and clouds. Precipitation, however, is singular in that it can present a high spatial variability and probably the sharpest gradients among all meteorological fields. Moreover, its quantitative measurement is plagued with difficulties, and there are even notable differences among different reference datasets. Several additional issues sometimes lead to questions about its usefulness in model validation. This essay discusses the use of precipitation for model verification and validation and the crucial role of highly precise and reliable satellite estimates, such as those from NASA’s Global Precipitation Mission Core Observatory.

Año: 2018

Palabras claves:

Referencia APA: Tapiador, F., Roca, R., Del Genio, A., Dewitte, B., Petersen, W., & Zhang, F. (2019). Is Precipitation a Good Metric for Model Performance?. Bulletin Of The American Meteorological Society, 100(2), 223-233. doi: 10.1175/bams-d-17-0218.1

Chapter 29 – Chile: Environmental Status and Future Perspectives

Autores:

Aguilera, M., Aburto, J., Bravo, L., Broitman, B., García, R., & Gaymer, C., Gelcich, S., López, B.A., Montecino, V., Pauchard, A., Ramos, M., Rutllant, J.A., Sáez, C.A., Valdivia, N., Thiel, M.

Resumen:

The coast of mainland Chile extends from 18°S to about 56°S, and is about 4200 km long. In the north, the coast is characterized by continuous, regular, and wave-exposed shores, while to south of 40°S it is highly fragmented, with extensive fjords and small archipelagos with many wave-protected zones. The Humboldt Current System (HCS) determines oceanographic and ecological processes in the northern part, with persistent upwelling fronts and episodic “El Niño” events. In the southern part the southward-flowing Magellan Current is important. Coastal upwelling along the HCS sustains a diverse pelagic and benthic food web structure. Rocky coastal habitats are dominated by large kelp forests and filter-feeding species like reef-forming mussels and tunicates.

The main coastal habitats along the coast of Chile are rocky shores, sandy beaches, coastal wetlands, and dunes. The main populated zones are concentrated between 33°S to 35°S in central Chile, with economically important trading ports. Sewage discharges from large cities have the potential to increase nutrients levels in nearshore habitats causing localized eutrophication. Mining activities in northern Chile contaminate coastal waters, while in the south intensive aquaculture affects the fjord ecosystem. Also, subsistence harvesting (of kelps, molluscs, fish) is dramatically reducing the abundance of top consumers or habitat-forming species.

The diverse and productive coastal marine ecosystems are used by different socioeconomic activities and exposed to interventions which are potentially harmful. Ecosystem services should be managed, and necessary interventions carefully planned. Achieving sustainable use of natural marine resources and coastal ecosystem integrity is challenging, and a basic understanding of ecosystem responses to direct human impacts and global climate change require better monitoring strategies. The establishment of a marine reserve “Humboldt Current System” would be a major step toward this goal.

Año: 2019

Palabras claves: Continental Chile, Climate, Coastal Ecology, Human interventions, Humboldt Current System, Oceanography, Southeastern Pacific.

Referencia APA: Aguilera, M., Aburto, J., Bravo, L., Broitman, B., García, R., & Gaymer, C., Gelcich, S., López, B.A., Montecino, V., Pauchard, A., Ramos, M., Rutllant, J.A., Sáez, C.A., Valdivia, N., Thiel, M. (2019). Chile: Environmental Status and Future Perspectives. World Seas: An Environmental Evaluation, 673-702. doi: 10.1016/b978-0-12-805068-2.00046-2

Cross-cultural invariances in the architecture of shame

Autores:

Sznycer, D., Xygalatas, D., Agey, E., Alami, S., An, X., & Ananyeva, K., Atkinson, Q.D., Broitman, B.R., Conte, T.J., Flores, C., Fukushima, S., Hitokoto, H., Kharitonov, A.N., Onyishi, C.N., Onyishi, I.E., Romero, P.P., Schrock, J.M., Snodgrass, J., Sugiyama, L.S., Takemura, K., Townsend, C., Zhuang, , J-Y., Athena Aktipis, C., Cronk, L., Cosmides, L., Tooby, J.

Resumen:

Human foragers are obligately group-living, and their high dependence on mutual aid is believed to have characterized our species’ social evolution. It was therefore a central adaptive problem for our ancestors to avoid damaging the willingness of other group members to render them assistance. Cognitively, this requires a predictive map of the degree to which others would devalue the individual based on each of various possible acts. With such a map, an individual can avoid socially costly behaviors by anticipating how much audience devaluation a potential action (e.g., stealing) would cause and weigh this against the action’s direct payoff (e.g., acquiring). The shame system manifests all of the functional properties required to solve this adaptive problem, with the aversive intensity of shame encoding the social cost. Previous data from three Western(ized) societies indicated that the shame evoked when the individual anticipates committing various acts closely tracks the magnitude of devaluation expressed by audiences in response to those acts. Here we report data supporting the broader claim that shame is a basic part of human biology. We conducted an experiment among 899 participants in 15 small-scale communities scattered around the world. Despite widely varying languages, cultures, and subsistence modes, shame in each community closely tracked the devaluation of local audiences (mean r = +0.84). The fact that the same pattern is encountered in such mutually remote communities suggests that shame’s match to audience devaluation is a design feature crafted by selection and not a product of cultural contact or convergent cultural evolution.

Año: 2018

Palabras claves: emotion, cognition, culture, cooperation, evolutionary psychology.

Referencia APA: Sznycer, D., Xygalatas, D., Agey, E., Alami, S., An, X., & Ananyeva, K., Atkinson, Q.D., Broitman, B.R., Conte, T.J., Flores, C., Fukushima, S., Hitokoto, H., Kharitonov, A.N., Onyishi, C.N., Onyishi, I.E., Romero, P.P., Schrock, J.M., Snodgrass, J., Sugiyama, L.S., Takemura, K., Townsend, C., Zhuang, , J-Y., Athena Aktipis, C., Cronk, L., Cosmides, L., Tooby, J. (2018). Cross-cultural invariances in the architecture of shame. Proceedings Of The National Academy Of Sciences, 115(39), 9702-9707. doi: 10.1073/pnas.1805016115

Pedogenic and microbial interrelations to regional climate and local topography: New insights from a climate gradient (arid to humid) along the Coastal Cordillera of Chile

Autores:

Bernhard, N., Moskwa, L., Schmidt, K., Oeser, R., Aburto, F., & Bader, M., Baumann, K., von Blanckenburg, F., Boy, J., van den Brink, L., Brucker, E., Büdel, B., Canessa, R., Dippold, M.A., Ehlers, T.A., Fuentes, J.P., Godoy, R., Jung, P., Karsten, U., Köster, M., Kuzyakov, Y., Leinweber, P., Neidhardt, H., Matus, F., Mueller, C.W., Oelmann, Y., Oses, R., Osses, P., Paulino, L., Samolov, E., Schaller, M., Schmid, M., Spielvogel, S., Spohn, M., Stock, S., Stroncik, N., Tielbörger, K., Übernickel, K., Scholten, T., Seguel, O., Wagner, D., Kühn, P.

Resumen:

The effects of climate and topography on soil physico-chemical and microbial parameters were studied along an extensive latitudinal climate gradient in the Coastal Cordillera of Chile (26°–38°S). The study sites encompass arid (Pan de Azúcar), semiarid (Santa Gracia), mediterranean (La Campana) and humid (Nahuelbuta) climates and vegetation, ranging from arid desert, dominated by biological soil crusts (biocrusts), semiarid shrubland and mediterranean sclerophyllous forest, where biocrusts are present but do have a seasonal pattern to temperate-mixed forest, where biocrusts only occur as an early pioneering development stage after disturbance. All soils originate from granitic parent materials and show very strong differences in pedogenesis intensity and soil depth.

Most of the investigated physical, chemical and microbiological soil properties showed distinct trends along the climate gradient. Further, abrupt changes between the arid northernmost study site and the other semi-arid to humid sites can be shown, which indicate non-linearity and thresholds along the climate gradient. Clay and total organic carbon contents (TOC) as well as Ah horizons and solum depths increased from arid to humid climates, whereas bulk density (BD), pH values and base saturation (BS) decreased. These properties demonstrate the accumulation of organic matter, clay formation and element leaching as key-pedogenic processes with increasing humidity. However, the soils in the northern arid climate do not follow this overall latitudinal trend, because texture and BD are largely controlled by aeolian input of dust and sea salts spray followed by the formation of secondary evaporate minerals. Total soil DNA concentrations and TOC increased from arid to humid sites, while areal coverage by biocrusts exhibited an opposite trend. Relative bacterial and archaeal abundances were lower in the arid site, but for the other sites the local variability exceeds the variability along the climate gradient. Differences in soil properties between topographic positions were most pronounced at the study sites with the mediterranean and humid climate, whereas microbial abundances were independent on topography across all study sites. In general, the regional climate is the strongest controlling factor for pedogenesis and microbial parameters in soils developed from the same parent material. Topographic position along individual slopes of limited length augmented this effect only under humid conditions, where water erosion likely relocated particles and elements downward. The change from alkaline to neutral soil pH between the arid and the semi-arid site coincided with qualitative differences in soil formation as well as microbial habitats. This also reflects non-linear relationships of pedogenic and microbial processes in soils depending on climate with a sharp threshold between arid and semi-arid conditions. Therefore, the soils on the transition between arid and semi-arid conditions are especially sensitive and may be well used as indicators of long and medium-term climate changes. Concluding, the unique latitudinal precipitation gradient in the Coastal Cordillera of Chile is predestined to investigate the effects of the main soil forming factor – climate – on pedogenic processes.

Año: 2018

Palabras claves: Climate, Topography, Soil texture, Total organic carbon, Carbon isotope ratio (δ13CTOC), Microbial abundance.

Referencia APA: Bernhard, N., Moskwa, L., Schmidt, K., Oeser, R., Aburto, F., & Bader, M., Baumann, K., von Blanckenburg, F., Boy, J., van den Brink, L., Brucker, E., Büdel, B., Canessa, R., Dippold, M.A., Ehlers, T.A., Fuentes, J.P., Godoy, R., Jung, P., Karsten, U., Köster, M., Kuzyakov, Y., Leinweber, P., Neidhardt, H., Matus, F., Mueller, C.W., Oelmann, Y., Oses, R., Osses, P., Paulino, L., Samolov, E., Schaller, M., Schmid, M., Spielvogel, S., Spohn, M., Stock, S., Stroncik, N., Tielbörger, K., Übernickel, K., Scholten, T., Seguel, O., Wagner, D., Kühn, P. (2018). Pedogenic and microbial interrelations to regional climate and local topography: New insights from a climate gradient (arid to humid) along the Coastal Cordillera of Chile. CATENA, 170, 335-355. doi: 10.1016/j.catena.2018.06.018