CEAZA
Response of photosynthesis and respiration to temperature under water deficit in two evergreen Nothofagus species.
Sanhueza, C., Bascunan-Godoy, L., Turnbull, M., & Corcuera, L.
Respiration and photosynthesis were studied in two Nothofagus species with different drought tolerance in order to evaluate the effect of water deficit on foliar carbon balance and the possible role of the alternative pathway on respiratory adjustment. We propose that under severe water deficit the more drought-tolerant species N. dombeyi is able to decrease its respiration more than the less drought-tolerant species N. nitida, thus carbon gain could be maintained when photosynthesis is suppressed by drought. Dark respiration (Rd) and carbon assimilation under saturating light (Asat) were evaluated under seasonal field conditions and during drying and re-watering cycles under glasshouse. In addition, respiratory pathway changes were evaluated by oxygen isotope fractionation. In the field, N. dombeyi displayed greater light-saturated photosynthetic capacity than N. nitida, but Rd did not differ between species during summer. In the glasshouse, N. dombeyi displayed an unchanged rate of Rd and increased carbon loss under severe water deficit. Nothofagus nitida displayed a more flexible respiratory response to water deficit, with a lower thermal sensitivity of respiration (decrease in Q10) and a decrease in Rd. This contributed to maintaining leaf carbon balance during the water deficit period. Respiratory electron flow was mainly via the cytochrome pathway for both species and under all treatments, indicating no strong participation of alternative respiration. Our results suggest that under severe water stress, N. dombeyi could be more injured than N. nitida and that the lack of control in the carbon loss under prolonged periods of drought could be limiting for its survival.
Año: 2015
Palabras claves: Alternative oxidase; carbon balance; drought tolerance; isotopic discrimination; temperate forest.
Referencia APA: Sanhueza, C., Bascunan-Godoy, L., Turnbull, M., & Corcuera, L. (2015). Response of photosynthesis and respiration to temperature under water deficit in two evergreen Nothofagus species. Plant Species Biology, 30(3), 163-175.
A hydrogeochemistry and isotopic approach for the assessment of surface water–groundwater dynamics in an arid basin: the Limarí watershed, North-Central Chile.
Oyarzún, R., Jofré, E., Morales, P., Maturana, H., Oyarzún, J., & Kretschmer, N. et al.
This paper describes the results of a hydrochemistry and isotopic study of surface water and groundwater dynamics at the Limarí River basin, arid North-Central Chile. The study involved two sampling campaigns, performed in April (Fall, at the end of the irrigation season) and December 2010 (late Spring, at the peak of the irrigation season). The main results show the effect of La Paloma and Hurtado dams on the chemical and isotopic compositions of the Grande and Hurtado rivers (main tributaries of the Limarí River), the influence of return flows to the Limarí River from surface water irrigation in agricultural areas, the local effects of metallurgical operations in the El Ingenio Creek, the effect of water–rock interaction processes, and the nearby coastal belt influence on the Punitaqui Creek area and the lower part of the Limarí River. In addition, this study shows an active interaction between surface water and shallow groundwater, and a minor importance of local precipitation events, on the hydrological behavior in the study area. An exception is the Rinconada de Punitaqui zone where the results are consistent with the origin of the water being associated with local precipitation. Also, sources of sulfate, which is present in high levels especially in surface waters, have been assessed. The results of this study, based on an integrated use of chemical and isotopic tracers, provide sound and useful information to establish the level of interaction between surface water and groundwater, allowing the development of a hydrological conceptual model for the area.
Año: 2015
Palabras claves: Environmental isotopes, River−aquifer interaction, Flow conceptual model.
Referencia APA: Jofré, E., Morales, P., Maturana, H., Oyarzún, J., & Kretschmer, N. et al. (2015). A hydrogeochemistry and isotopic approach for the assessment of surface water–groundwater dynamics in an arid basin: the Limarí watershed, North-Central Chile. Environ Earth Sci, 73(1), 39-55.
A holistic picture of Austronesian migrations revealed by phylogeography of Pacific paper mulberry.
Chang, C., Liu, H., Moncada, X., Seelenfreund, A., Seelenfreund, D., & Chung, K.
The peopling of Remote Oceanic islands by Austronesian speakers is a fascinating and yet contentious part of human prehistory. Linguistic, archaeological, and genetic studies have shown the complex nature of the process in which different components that helped to shape Lapita culture in Near Oceania each have their own unique history. Important evidence points to Taiwan as an Austronesian ancestral homeland with a more distant origin in South China, whereas alternative models favor South China to North Vietnam or a Southeast Asian origin. We test these propositions by studying phylogeography of paper mulberry, a common East Asian tree species introduced and clonally propagated since prehistoric times across the Pacific for making barkcloth, a practical and symbolic component of Austronesian cultures. Using the hypervariable chloroplast ndhF-rpl32 sequences of 604 samples collected from East Asia, Southeast Asia, and Oceanic islands (including 19 historical herbarium specimens from Near and Remote Oceania), 48 haplotypes are detected and haplotype cp-17 is predominant in both Near and Remote Oceania. Because cp-17 has an unambiguous Taiwanese origin and cp-17–carrying Oceanic paper mulberries are clonally propagated, our data concur with expectations of Taiwan as the Austronesian homeland, providing circumstantial support for the “out of Taiwan” hypothesis. Our data also provide insights into the dispersal of paper mulberry from South China “into North Taiwan,” the “out of South China–Indochina” expansion to New Guinea, and the geographic origins of post-European introductions of paper mulberry into Oceania.
Año: 2015
Palabras claves: Broussonetia papyrifera, commensal approach, DNA of herbarium specimens, out of Taiwan hypothesis, Voyaging Corridor Triple I .
Referencia APA: Chang, C., Liu, H., Moncada, X., Seelenfreund, A., Seelenfreund, D., & Chung, K. (2015). A holistic picture of Austronesian migrations revealed by phylogeography of Pacific paper mulberry. Proceedings Of The National Academy Of Sciences, 112(44), 13537-13542.
Fungal endophytes associated with roots of nurse cushion species have positive effects on native and invasive beneficiary plants in an alpine ecosystem.
Molina-Montenegro, M., Oses, R., Torres-Díaz, C., Atala, C., Núñez, M., & Armas, C.
Facilitation has been proposed to be a fundamental mechanism for plant coexistence, being particularly important in highly stressful environments such as alpine environments. In this type of environment, species called “cushion plants” can ameliorate the stressful conditions, acting as nurses for other plants. Of the several mechanisms proposed in the positive-interactions framework, plant–microorganism interaction may be one of the most common, but least documented. Here we show that the presence of endophytes isolated from the roots of cushion plants Laretia acaulis can play a fundamental role in the establishment, performance and survival of both native and exotic plant seedlings that are known to be facilitated by the cushion species.
To test this, we measured survival and growth of two native and one invasive species at 3200 m in the Andes of Central Chile. Plants were grown inside artificial cushions filled with native soil, with or without sterilization, and with or without fungal endophytic inoculation to evaluate the role of fungal endophytes on survival and growth. In addition, we conducted a second experiment in a greenhouse with the invasive species to evaluate the effect of fungal endophytic infection/association on plant ecophysiological performance, dry biomass and seed output.
Overall, our results showed a strong positive effect of fungal endophytes on the survival and growth of both native and invasive species. Moreover, maximum quantum efficiency (Fv/Fm), biomass accumulation and seed production were enhanced in the invasive species when soils were inoculated with endophytes. Thus, facilitation by root endophytic fungi on native and invasive alpine plants could determine survival and establishment in this harsh environment.
Several studies have shown that direct facilitation by cushion plants in alpine environments improves the performance and fitness of both native and exotic plants. Our results suggest that there are indirect effects, mediated by microorganism associations that may also help to explain the successful establishment of native and invasive species in these environments. If indirect plant–plant facilitation through root fungal endophytes proves to be a widespread phenomenon in alpine ecosystems, it could be a key component in the structuring of plant communities in those stressful environments.
Año: 2015
Palabras claves: Cushion plants; Endophytic fungi; Facilitation; Invasive species; Positive interactions; Taraxacum officinale.
Referencia APA: Molina-Montenegro, M., Oses, R., Torres-Díaz, C., Atala, C., Núñez, M., & Armas, C. (2015). Fungal endophytes associated with roots of nurse cushion species have positive effects on native and invasive beneficiary plants in an alpine ecosystem. Perspectives In Plant Ecology, Evolution And Systematics, 17(3), 218-226.
Ecophysiological responses to drought followed by re-watering of two native Chilean swamp forest plants: Myrceugenia exsucca (DC.) O. Berg and Luma chequen (Molina) A. Gray
Bascuñán-Godoy, L., Alcaíno, C., Carvajal, D., Sanhueza, C., Montecinos, S., & Maldonado, A.
Myrceugenia exsucca (DC.) O. Berg and Luma chequen (Molina) A. Gray are two predominant species of Myrtaceae from the swamp forest which are strongly threatened by destruction of their habitat. Conservation programs include the creation of new protected areas which often have different environmental conditions respect their natural habitat. The drought tolerance and the capability to restore their physiological performance after stress relief are characteristic of great importance for the successful conservation programs on these kinds of plants. Understanding how these plants respond to episodic drought and watering pulse was the principal aim of this work. In this sense, water relations, soluble sugars, pigments and photosystem II (PSII) performance were studied. In general the water relationships were less affected by drought in L. chequen than in M. exsucca which was consistent with a higher maintenance of photochemical quenching (qP) in the first one. In addition, L. chequen exhibited complete recovery of water potential and maximum PSII efficiency and increasing the proportion of photochemical processes and soluble sugars related with a higher photosynthetic recovery. Contrastingly, M. exsucca was unable to recover its water potential and the proportion of open reaction centers of PSII under re-watering indicating a lower capacity of recovery. These results shown different capabilities to cope and reestablish physiological performance after water scarcity episode between these two native chilean swamp forest plants. We hope that these results will be important for conservation and re-vegetation managements programs.
Año: 2015
Palabras claves: Myrtaceae, photosynthetic performance, water deficit, re-watering.
Referencia APA: Bascuñán-Godoy, L., Alcaíno, C., Carvajal, D., Sanhueza, C., Montecinos, S., & Maldonado, A. (2015). Ecophysiological responses to drought followed by re-watering of two native Chilean swamp forest plants: Myrceugenia exsucca (DC.) O. Berg and Luma chequen (Molina) A. Gray. Gayana Bot., 72(2), 203-212.
Castaways can’t be choosers — Homogenization of rafting assemblages on floating seaweeds.
Gutow, L., Beermann, J., Buschbaum, C., M. Rivadeneira, M., & Thiel, M.
After detachment from benthic habitats, the epibiont assemblages on floating seaweeds undergo substantial changes, but little is known regarding whether succession varies among different seaweed species. Given that floating algae may represent a limiting habitat in many regions, rafting organisms may be unselective and colonize any available seaweed patch at the sea surface. This process may homogenize rafting assemblages on different seaweed species, which our study examined by comparing the assemblages on benthic and floating individuals of the fucoid seaweeds Fucus vesiculosus and Sargassum muticum in the northern Wadden Sea (North Sea). Species richness was about twice as high on S. muticum as on F. vesiculosus, both on benthic and floating individuals. In both seaweed species benthic samples were more diverse than floating samples. However, the species composition differed significantly only between benthic thalli, but not between floating thalli of the two seaweed species. Separate analyses of sessile and mobile epibionts showed that the homogenization of rafting assemblages was mainly caused by mobile species. Among these, grazing isopods from the genus Idotea reached extraordinarily high densities on the floating samples from the northern Wadden Sea, suggesting that the availability of seaweed rafts was indeed limiting. Enhanced break-up of algal rafts associated with intense feeding by abundant herbivores might force rafters to recolonize benthic habitats. These colonization processes may enhance successful dispersal of rafting organisms and thereby contribute to population connectivity between sink populations in the Wadden Sea and source populations from up-current regions.
Año: 2015
Palabras claves: Epibiota; Wadden Sea; Population Connectivity; Habitat Destruction; Migration; Dispersal.
Referencia APA: Gutow, L., Beermann, J., Buschbaum, C., M. Rivadeneira, M., & Thiel, M. (2015). Castaways can't be choosers — Homogenization of rafting assemblages on floating seaweeds. Journal Of Sea Research, 95, 161-171.
Facilitative Effect of a Generalist Herbivore on the Recovery of a Perennial Alga: Consequences forPersistence at the Edge of Their Geographic Range.
Aguilera MA, Valdivia N, Broitman BR.
Understanding the impacts of consumers on the abundance, growth rate, recovery and persistence of their resources across their distributional range can shed light on the role of trophic interactions in determining species range shifts. Here, we examined if consumptive effects of the intertidal grazer Scurria viridula positively influences the abundance and recovery from disturbances of the alga Mazzaella laminarioides at the edge of its geographic distributions in northern-central Chilean rocky shores. Through field experiments conducted at a site in the region where M. laminarioides overlaps with the polar range edge of S. viridula, we estimated the effects of grazing on different life stages of M. laminarioides. We also used long-term abundance surveys conducted across ~700 km of the shore to evaluate co-occurrence patterns of the study species across their range overlap. We found that S. viridula had positive net effects on M. laminarioides by increasing its cover and re-growth from perennial basal crusts. Probability of occurrence of M. laminarioides increased significantly with increasing density of S. viridula across the range overlap. The negative effect of S. viridula on the percentage cover of opportunistic green algae—shown to compete for space with corticated algae—suggests that competitive release may be part of the mechanism driving the positive effect of the limpet on the abundance and recovery from disturbance of M. laminarioides. We suggest that grazer populations contribute to enhance the abundance of M. laminarioides, facilitating its recolonization and persistence at its distributional range edge. Our study highlights that indirect facilitation can determine the recovery and persistence of a resource at the limit of its distribution, and may well contribute to the ecological mechanisms governing species distributions and range shifts.
Año: 2015
Palabras claves: Algae, Fronds, Grazing, Herbivory, Plant-herbivore interactions, Species interactions, Geographic distribution,Trophic interactions.
Referencia APA: Valdivia N, Broitman BR. (2015). Facilitative Effect of a Generalist Herbivore on the Recovery of a Perennial Alga: Consequences for Persistence at the Edge of Their Geographic Range. PLoS ONE 10(12): e0146069.
A recolonization record of the invasive Poa annua in Paradise Bay, Antarctic Peninsula: modeling of the potential spreading risk.
Molina-Montenegro, M., Pertierra, L., Razeto-Barry, P., Díaz, J., Finot, V., & Torres-Díaz, C.
Antarctica is one of the most extreme environments for vascular plants occurrence worldwide, and only two native vascular plants have colonized this continent: Deschampsia antarctica and Colobanthus quitensis. Nevertheless, in recent years, several alien plant species has been found in Antarctica with negative effects on the native flora. In this study, we show a recolonization record of the most widespread plant invader in Antarctica (Poa annua) and the risk of a potential spreading in a highly visited site on the Antarctic Peninsula. Overall, two new P. annua individuals were recorded, where four specimens were previously reported and removed in 2010, suggesting that either a propagule load is continuous, or that a seed bank prevailed in the site. On the other hand, the spreading modeling suggests that the probability to colonize and spreading of P. annua increases notoriously with the possibility of dispersion of propagules, with consequent risk of displacement for the native flora. Biological invasions are a major threat to the integrity of native biodiversity in all biomes, and they have the potential to change irreversibly Antarctica’s fragile ecosystems.
Año: 2015
Palabras claves: Antarctica, Biodiversity, Invasions, Poa annua.
Referencia APA: Molina-Montenegro, M., Pertierra, L., Razeto-Barry, P., Díaz, J., Finot, V., & Torres-Díaz, C. (2015). A recolonization record of the invasive Poa annua in Paradise Bay, Antarctic Peninsula: modeling of the potential spreading risk. Polar Biol, 38(7), 1091-1096.
Geographical Variation of Shell Thickness in the Mussel Perumytilus purpuratus Along the Southeast Pacific Coast.
Briones, C., M.m., Rivadeneira, M., Fernández, R., Guiñez.
At broad geographical scales, the variation in bivalve shell thickness can be modulated by environmental factors that vary with latitude, such as sea surface temperature (SST), seawater pH, or calcium carbonate availability. Mussels usually form multilayered beds, and shell thickness is also expected to be affected by density and layering due to intraspecific competition. In this work, we explored the geographical variation of shell thickness in the intertidal mussel Perumytilus purpuratus between 18° and 42°S along the southeastern Pacific coast. We tested the hypothesis that there was a positive relationship between shell thickness and SST, and then we explored other variables that could have an effect on thickness, such as density, number of layers, and others environmental variables (pH and calcite concentration). The expected positive linear relationship between shell thickness and sea surface temperature was not found, but when the other population variables were included in the analysis, an unexpected inverse SST-thickness relationships appeared as significant, probably because this species could be adapted to colder and more acid seawater as are those of the tips of South America. Thickness was also negatively affected by density, which was expected for a gregarious species howing high intraspecific competition.Finally, our results highlight the importance of including density and crowding effects when macroscale patterns are explored, particularly in gregarious species, since these patterns could also be modulated by density-dependent processes, which might then override latitudinal trends of shell thickness when they are not included in the analyses.
Año: 2014
Palabras claves:
Referencia APA: Briones, C., M.m., Rivadeneira, M., Fernández, R., Guiñez. (2014). Geographical Variation of Shell Thickness in the Mussel Perumytilus purpuratus Along the Southeast Pacific Coast. Biol. Bull. 227: 221–231.
How does spatial variability of climate affect catchment streamflow predictions?.
Patil, S., Wigington, P., Leibowitz, S., Sproles, E., & Comeleo, R.
Spatial variability of climate can negatively affect catchment streamflow predictions if it is not explicitly accounted for in hydrologic models. In this paper, we examine the changes in streamflow predictability when a hydrologic model is run with spatially variable (distributed) meteorological inputs instead of spatially uniform (lumped) meteorological inputs. Both lumped and distributed versions of the EXP-HYDRO model are implemented at 41 meso-scale (500–5000 km2) catchments in the Pacific Northwest region of USA. We use two complementary metrics of long-term spatial climate variability, moisture homogeneity index (IM) and temperature variability index (ITV), to analyze the performance improvement with distributed model. Results show that the distributed model performs better than the lumped model in 38 out of 41 catchments, and noticeably better (>10% improvement) in 13 catchments. Furthermore, spatial variability of moisture distribution alone is insufficient to explain the observed patterns of model performance improvement. For catchments with low moisture homogeneity (IM < 80%), IM is a better predictor of model performance improvement than ITV; whereas for catchments with high moisture homogeneity (IM > 80%), ITV is a better predictor of performance improvement than IM. Based on the results, we conclude that: (1) catchments that have low homogeneity of moisture distribution are the obvious candidates for using spatially distributed meteorological inputs, and (2) catchments with a homogeneous moisture distribution benefit from spatially distributed meteorological inputs if they also have high spatial variability of precipitation phase (rain vs. snow).
Año: 2014
Palabras claves: Hydrologic model; Climate variability; Streamflow; Catchment.
Referencia APA: Patil, S., Wigington, P., Leibowitz, S., Sproles, E., & Comeleo, R. (2014). How does spatial variability of climate affect catchment streamflow predictions?. Journal Of Hydrology, 517, 135-145. http://dx.doi.org/10.1016/j.jhydrol.2014.05.017
Environmental and climatic changes in central Chilean Patagonia since the Late Glacial (Mallín El Embudo, 44° S).
de Porras, M., Maldonado, A., Quintana, F., Martel-Cea, A., Reyes, O., & Méndez, C.
Multi-millennial environmental and climatic changes in central Chilean Patagonia (44–49° S) during the Last Glacial–Interglacial cycle have been of particular interest as changes in the position and strength of the southern westerlies are the major forcing factor conditioning the environmental dynamics. Recent attempts to reconstruct regional environmental and climatic signals from central Chilean Patagonia reveal some discrepancies and unclear issues among the records. This paper presents the 13 ka pollen and charcoal records from Mallín El Embudo (44° 40' S, 71° 42' W) located in the deciduous Nothofagus forest in the middle Río Cisnes valley. The paper aims to (1) establish the timing and magnitude of local vegetation changes and fire activity since the Late Glacial and (2) integrate these results at the regional scale in order to discuss the discrepancies and depict the environmental and climatic dynamics in central Chilean Patagonia since the Late Glacial. Open landscapes dominated by grasses associated with scattered Nothofagus forest patches dominated the middle Río Cisnes valley between 13 and 11.2 ka suggesting low effective moisture but also indicating that landscape configuration after glacial retreat was still ongoing. At 11.2 ka, the sudden development of an open and quite dynamic Nothofagus forest probably associated with the synchronous high fire activity occurred, suggesting a rise in effective moisture associated with dry summers. Since 9.5 ka, the record reflects the presence of a closed Nothofagus forest related to higher effective moisture conditions than before combined with moderate dry summers that may have triggered a high frequency of low-magnitude crown fires that did not severely affect the forest. The forest experienced a slight canopy opening after 5.7 ka, probably due to slightly drier conditions than before followed by a sudden change to open forest conditions around 4.2 ka associated with fire and volcanic disturbances. Around 2 ka, the recovery of a closed Nothofagus forest related to slightly wetter conditions (similar to present) occurred and persisted under highly variable climatic conditions up to 0.1 ka when massive forest burning and logging due to European settlements occurred. Central Chilean Patagonian climatic and environmental changes at millennial–centennial timescales since the Late Glacial were driven by changes in the southern westerlies latitudinal position and/or intensity, but during the late Holocene fire, volcanism and humans arose as forces contributing to environmental dynamics.
Año: 2014
Palabras claves:
Referencia APA: de Porras, M., Maldonado, A., Quintana, F., Martel-Cea, A., Reyes, O., & Méndez, C. (2014). Environmental and climatic changes in central Chilean Patagonia since the Late Glacial (Mallín El Embudo, 44° S). Climate Of The Past, 10(3), 1063-1078.
Induced twining in Ipomoea purpurea (L.) Roth.: response threshold and induction by volatiles and snail damage.
Atala, C., Quilodrán, M., & Molina-montenegro, M.
Twining in some Convolvulaceae can be induced by leaf damage and jasmonic acid application. This induced response is believed to reduce the likelihood of future leaf damage and it is limited by drought. This response has been detected in the Convolvulaceae family using artificial damage. The mechanisms and ecological implications of this response are still unknown. In this study was tested if the induced twining requires a threshold level and if it is induced by volatiles and/or by snail damage. Three separated greenhouse experiments were conducted in order to test the induced twining in Ipomoea purpurea (Convolvulaceae) by applying different levels of artificial damage (0, 1, 5, 10 perforations to the leaves), volatiles (ground leaves) and natural damage by snails. Plants receiving the two higher damage levels twined faster than the individuals exposed to the two lower damage levels. Plants exposed to grounded leaves (volatiles) twined faster than control plants. Finally, twining was induced by snail damage more than in undamaged plants. Most growth traits did not change in any treatment. Twining in I. pupurea can be induced by artificial or natural damage, and also by volatiles emitted by damaged leaves of neighbor plants, making the induced twining an ecologically relevant response.
Año: 2014
Palabras claves: Induced twining, Ipomoea purpurea, Convolvulaceae, induced responses, herbivory.
Referencia APA: Atala, C., Quilodrán, M., & Molina-montenegro, M. (2014). Induced twining in Ipomoea purpurea (L.) Roth.: response threshold and induction by volatiles and snail damage. Gayana Bot., 71(2), 181-187.