CEAZA
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.
Dust fluxes and iron fertilization in Holocene and Last Glacial Maximum climates.
Lambert, F., Tagliabue, A., Shaffer, G., Lamy, F., Winckler, G., & Farias, L. et al.
Mineral dust aerosols play a major role in present and past climates. To date, we rely on climate models for estimates of dust fluxes to calculate the impact of airborne micronutrients on biogeochemical cycles. Here we provide a new global dust flux data set for Holocene and Last Glacial Maximum (LGM) conditions based on observational data. A comparison with dust flux simulations highlights regional differences between observations and models. By forcing a biogeochemical model with our new data set and using this model's results to guide a millennial-scale Earth System Model simulation, we calculate the impact of enhanced glacial oceanic iron deposition on the LGM-Holocene carbon cycle. On centennial timescales, the higher LGM dust deposition results in a weak reduction of <10 ppm in atmospheric CO2 due to enhanced efficiency of the biological pump. This is followed by a further ~10 ppm reduction over millennial timescales due to greater carbon burial and carbonate compensation.
Año: 2015
Palabras claves: Paleoclimate; dust; iron fertilization; atmospheric CO2; carbon cycle; LGM.
Referencia APA: Lambert, F., Tagliabue, A., Shaffer, G., Lamy, F., Winckler, G., & Farias, L. et al. (2015). Dust fluxes and iron fertilization in Holocene and Last Glacial Maximum climates. Geophys. Res. Lett., 42(14), 6014-6023.
Biogeographic structure of the northeastern Pacific rocky intertidal: the role of upwelling and dispersal to drive patterns.
Fenberg, P., Menge, B., Raimondi, P., & Rivadeneira, M.
Identifying the environmental conditions that drive biogeographic structure remains a major challenge of biogeography, evolutionary ecology and increasingly, conservation biology. Here, we use multivariate classification trees to assess the biogeographic structure of northeast Pacific (∼ 26–58°N) rocky intertidal species (406 species of algae and invertebrates) from 102 field sites. Random forest analyses are used to assess the importance of 29 environmental variables, encompassing a broad range of potential drivers, to predict biogeographic structure. Analyses are repeated for species with different larval dispersal capabilities and by broad taxonomic categories (invertebrates and algae). Results show that overall biogeographic structure is in general agreement with classic classification schemes, but patterns are variable among species with different larval dispersal capabilities. Random forest models show a very high fit (pseudo r2 > 0.94) and indicate that biogeographic structure can be predicted by a relatively modest subset of variables. Upwelling related variables are the best overall predictors of biogeographic structure (nutrient concentrations, sea-surface temperature, upwelling/downwelling seasonal switch index), but the relative importance of predictors is geographically variable and top predictors are dependent on the type of larval dispersal. Upwelling related variables are more important to predict biogeographic structure for invertebrates with lower-medium dispersal capabilities and algae, whereas species with high larval dispersal (planktotrophic) are better predicted by a different subset of variables (i.e. salinity, precipitation seasonality). Our results lend support to the influence of coastal upwelling in structuring biogeographic patterns and highlight the potential for climate change-induced alterations of upwelling regimes to profoundly affect biodiversity at biogeographic scales.
Año: 2015
Palabras claves:
Referencia APA: Fenberg, P., Menge, B., Raimondi, P., & Rivadeneira, M. (2015). Biogeographic structure of the northeastern Pacific rocky intertidal: the role of upwelling and dispersal to drive patterns. Ecography, 38(1), 83-95.
Poa annua L. in the maritime Antarctic: an overview.
Chwedorzewska, K., Giełwanowska, I., Olech, M., Molina-Montenegro, M., Wódkiewicz, M., & Galera, H.
Poa annua is the only flowering plant species that has established a breeding population in the maritime Antarctic, through repeated anthropogenic introduction. The first appearance of this species in the Antarctic was observed in 1953. Annual bluegrass inhabits mainly anthropogenic sites, but recently has entered tundra communities. The functioning of P. annua in the Antarctic could not have been possible without adaptations that enable the plants to persist in the specific climatic conditions typical for this zone. Poa annua is highly adaptable to environmental stress and unstable habitats: huge phenotypic and genotypic variability, small size, plastic life cycle (life-history types ranging from annual to perennial forms). The spreading of P. annua in the Antarctic Peninsula region is a classic example of the expansion process following anthropogenic introduction of an invasive species, and illustrates the dangers to Antarctic terrestrial ecosystems that are associated with increasing human traffic.
Año: 2015
Palabras claves:
Referencia APA: Chwedorzewska, K., Giełwanowska, I., Olech, M., Molina-Montenegro, M., Wódkiewicz, M., & Galera, H. (2015). Poa annua L. in the maritime Antarctic: an overview. Polar Record, 51(06), 637-643.
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.
Hydrologic landscape classification assesses streamflow vulnerability to climate change in Oregon, USA.
Leibowitz, S., Comeleo, R., Wigington, P., Weaver, C., Morefield, P., Sproles, E., & Ebersole, J.
Classification can allow for evaluations of the hydrologic functions of landscapes and their responses to stressors. Here we demonstrate the use of a hydrologic landscape (HL) approach to evaluate vulnerability to potential future climate change at statewide and basin scales in the state of Oregon. The HL classification has five components: climate, seasonality, aquifer permeability, terrain, and soil permeability. We evaluate changes when the 1971–2000 HL climate indices are recalculated using 2041–2070 simulation results from the ECHAM (European Centre HAMburg) and PCM (Parallel Climate Model) climate models with the A2, A1b, and B1 emission scenarios. Changes in climate class were modest (4–18%) statewide. However, there were major changes in seasonality class for five of the six realizations (excluding PCM_B1): Oregon shifts from being 13% snow-dominated to 4–6% snow-dominated under these five realizations, representing a 56–68% reduction in snowmelt-dominated area. At the basin scale, simulated changes for the Siletz Basin, in Oregon's Coast Range, include a small switch from very wet to wet climate, with no change in seasonality. However, there is a modest increase in fall and winter water due to increased precipitation. For the Sandy Basin, on the western slope of the Cascades, HL climate class does not change, but there are major changes in seasonality, especially for areas with low aquifer permeability, which experiences a 100% loss of spring seasonality. This would reduce summer baseflow, but effects could potentially be mitigated by streamflow buffering effects provided by groundwater in the high aquifer permeability portions of the upper Sandy. The Middle Fork John Day Basin (MFJD), in northeastern Oregon, is snowmelt-dominated. The basin experiences a net loss of wet and moist climate area, along with an increase in dry climate area. The MFJD also experiences major shifts from spring to winter seasonality, representing a 20–60% reduction in snowmelt-dominated area. Altered seasonality and/or magnitude of seasonal streamflows could potentially affect survival, growth and reproduction of salmonids in these watersheds, with the greatest effects projected for the MFJD. A major strength of the HL approach is that results can be applied to similarly classified, ungaged basins. Information resulting from such evaluations can help inform management responses to climate change at regional and basin scales without requiring detailed modeling efforts.
Año: 2014
Palabras claves:
Referencia APA: Leibowitz, S., Comeleo, R., Wigington, P., Weaver, C., Morefield, P., Sproles, E., & Ebersole, J. (2014). Hydrologic landscape classification evaluates streamflow vulnerability to climate change in Oregon, USA. Hydrology and Earth System Sciences, 18(9), 3367-3392.
Assessing the importance of human activities for the establishment of the invasive Poa annua in Antarctica.
Molina-Montenegro, M., Carrasco-Urra, F., Acuña-Rodríguez, I., Oses, R., Torres-Díaz, C., & Chwedorzewska, K.
Because of its harsh environmental conditions and remoteness, Antarctica is often considered to be at low risk of plant invasion. However, an increasing number of reports have shown the presence and spread of non-native plants in Antarctica; it is therefore important to study which factors control the invasion process in this ecosystem. Here, we assessed the role of different human activities on the presence and abundance of the invasive Poa annua. In addition, we performed a reciprocal transplant experiment in the field, and a manipulative experiment of germination with P. annua and the natives Colobanthus quitensis and Deschampsia antarctica, in order to unravel the effects of physical soil disturbance on the establishment and survival of P. annua. We found a positive correlation between abundance of P. annua and level of soil disturbance, and that survival of P. annua was 33% higher in sites with disturbed soil than non-disturbed. Finally, we found that disturbance conditions increased germination for P. annua, whereas for native species germination in experimentally disturbed soil was either unchanged or reduced compared to undisturbed soil. Our results indicate that human activities that modify abiotic soil characteristics could play an important role in the abundance of this invasive species. If the current patterns of human activities are maintained in Antarctica, the establishment success and spread of P. annua could increase, negatively affecting native flora.
Año: 2014
Palabras claves: Alien species; Colobanthus quitensis; Deschampsia antarctica; human disturbance; Poa annua; tourists.
Referencia APA: Molina-Montenegro, M., Carrasco-Urra, F., Acuña-Rodríguez, I., Oses, R., Torres-Díaz, C., & Chwedorzewska, K. (2014). Assessing the importance of human activities for the establishment of the invasive Poa annua in Antarctica. Polar Research, 33(0).