Publikationen
Es wurden 16 Publikationen gefunden
Landshuter, N.; Mölg, T.; Grießinger, J.; Bräuning, A.; Peters, T. & Institute of Geography, F.E.E.G. (2020): Characteristics of moisture source regions and their potential effect on seasonal isotopic signatures of d18O in tropical trees of southern Ecuador. Frontiers in Earth Science 8(604804), 1-22.
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DOI: 10.3389/feart.2020.604804
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Abstract:
Abstract:
Ratios of stable oxygen isotopes in tree rings (δ18O) are a valuable proxy for reconstructing past climates. Such reconstructions allow us to gain better knowledge of climate dynamics under different (eg warmer) environmental conditions, which also forms the basis for effective risk management. The latter aspect is particularly relevant for our study site on the
western flanks of the Andes in Southern Ecuador, since the region is frequently affected by droughts and heavy precipitation events during the rainy season (January to April), leading to enormous social and economic losses. In particular, we focus on precipitation amounts and moisture source regions as they are known to influence the δ18O signature of tree rings. Moisture source regions are based on 240 h backward trajectories that were
calculated with the trajectory model LAGRANTO for the rainy seasons 2008 to 2017. A moisture source diagnostic was applied to the air parcel pathways. The resulting moisture source regions were analyzed by calculating composites based on precipitation amounts, season, and calendar year. The precipitation amounts were derived from data of a local Automatic Weather Station (AWS). The analysis confirms that our study site receives its moisture both, from the Atlantic and the Pacific Oceans.
Heavy precipitation events are linked to higher moisture contributions from the Pacific, and local SST anomalies along the coast of Ecuador are of higher importance than those off the coast toward the central Pacific. Moreover, we identified increasing moisture contributions from the Pacific over the course of the rainy season. This change and also rain amount
effects are detectable in preliminary data of δ18O variations in tree rings of Bursera graveolens. These signatures can be a starting point for investigating atmospheric and hydroclimatic processes, which trigger δ18O variations in tree rings, more extensively in future studies.
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Keywords: |
precipitation |
South Ecuador |
South America |
tropical trees |
Tree Rings |
modelling |
stable isotopes |
Seidel, J.; Trachte, K.; Orellana-Alvear, J.; Figueroa, R.; Celleri, R.; Bendix, J.; Fernandez, C. & Huggel, C. (2019): Precipitation Characteristics at Two Locations in the Tropical Andes by Means of Vertically Pointing Micro-Rain Radar Observations. Remote Sensing 11(24), 2985.
Orellana-Alvear, J.; Celleri, R.; Rollenbeck, R. & Bendix, J. (2019): Optimization of X-Band Radar Rainfall Retrieval in the Southern Andes of Ecuador Using a Random Forest Model. Remote Sensing 11(14), 1632.
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DOI: 10.3390/rs11141632
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Abstract:
Abstract:
Despite many eorts of the radar community, quantitative precipitation estimation (QPE)
from weather radar data remains a challenging topic. The high resolution of X-band radar imagery
in space and time comes with an intricate correction process of reflectivity. The steep and high
mountain topography of the Andes enhances its complexity. This study aims to optimize the rainfall
derivation of the highest X-band radar in the world (4450 m a.s.l.) by using a random forest (RF)
model and single Plan Position Indicator (PPI) scans. The performance of the RFmodel was evaluated
in comparison with the traditional step-wise approach by using both, the Marshall-Palmer and a
site-specific Z–R relationship. Since rain gauge networks are frequently unevenly distributed and
hardly available at real time in mountain regions, bias adjustment was neglected. Results showed an
improvement in the step-wise approach by using the site-specific (instead of the Marshall-Palmer)
Z–R relationship. However, both models highly underestimate the rainfall rate (correlation coecient
< 0.69; slope up to 12). Contrary, the RF model greatly outperformed the step-wise approach in
all testing locations and on dierent rainfall events (correlation coecient up to 0.83; slope = 1.04).
The results are promising and unveil a dierent approach to overcome the high attenuation issues
inherent to X-band radars.
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Keywords: |
South Ecuador |
random forest |
radar |
calibration |
Cajas National Park |
Knüsting, J.; Brinkmann, M.C.; Silva, B.; Schorsch, M.; Bendix, J.; Beck, E. & Scheibe, R. (2018): Who will win where and why? An ecophysiological dissection of the competition between a tropical pasture grass and the invasive weed Bracken over an elevation range of 1000m in the tropical Andes. PlosOne 13, 1-24.
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DOI: 10.1371/journal.pone.0202255
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Abstract:
Abstract:
In tropical agriculture, the vigorously growing Bracken fern causes severe problems by
invading pastures and out-competing the common pasture grasses. Due to infestation by
that weed, pastures are abandoned after a few years, and as a fatal consequence, the biodi-
versity-rich tropical forest is progressively cleared for new grazing areas. Here we present a
broad physiological comparison of the two plant species that are the main competitors on
the pastures in the tropical Ecuadorian Andes, the planted forage grass Setaria sphacelata
and the weed Bracken (Pteridium arachnoideum).With increasing elevation, the competitive
power of Bracken increases as shown by satellite data of the study region. Using data
obtained from field measurements, the annual biomass production of both plant species, as
a measure of their competitive strength, was modeled over an elevational gradient from
1800 to 2800 m. The model shows that with increasing elevation, biomass production of the
two species shifts in favor of Bracken which, above 1800 m, is capable of outgrowing the
grass. In greenhouse experiments, the effects on plant growth of the presumed key vari-
ables of the elevational gradient, temperature and UV radiation, were separately analyzed.
Low temperature, as well as UV irradiation, inhibited carbon uptake of the C4-grass more
than that of the C3-plant Bracken. The less temperature-sensitive photosynthesis of
Bracken and its effective protection from UV radiation contribute to the success of the weed
on the highland pastures. In field samples of Bracken but not of Setaria, the content of flavo-
noids as UV-scavengers increased with the elevation. Combining modeling with measure-
ments in greenhouse and field allowed to explain the invasive growth of a common weed in
upland pastures. The performance of Setaria decreases with elevation due to suboptimal
photosynthesis at lower temperatures and the inability to adapt its cellular UV screen.
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Keywords: |
South Ecuador |
Bracken fern |
competition |
Bendix, J. & Beck, E. (2016): Environmental Change And Its Impacts In A Biodiversity Hotspot Of The South Ecuadorian Andes–Monitoring And Mitigation Strategies. Erdkunde 70(1), 1-4.
Knoke, T.; Paul, C.; Hildebrandt, P.; Calvas, B.; Castro, L.M.; Härtl, F.; Döllerer, M.; Hamer, U.; Windhorst, D.; Wiersma, Y.; Curatola Fernández, G.F.; Obermeier, W.A.; Adams, J.; Breuer, L.; Mosandl, R.; Beck, E.; Weber, M.; Stimm, B.; Haber, W.; Fürst, C. & Bendix, J. (2016): Compositional diversity of rehabilitated tropical lands supports multiple ecosystem services and buffers uncertainties. Nature Communications 7, Article number:11877.
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DOI: 10.1038/ncomms11877
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Abstract:
Abstract:
High landscape diversity is assumed to increase the number and level of ecosystem services. However, the interactions between ecosystem service provision, disturbance and landscape composition are poorly understood. Here we present a novel approach to include uncertainty in the optimization of land allocation for improving the provision of multiple ecosystem services. We refer to the rehabilitation of abandoned agricultural lands in Ecuador including two types of both afforestation and pasture rehabilitation, together with a succession option. Our results show that high compositional landscape diversity supports multiple ecosystem services (multifunction effect). This implicitly provides a buffer against uncertainty. Our work shows that active integration of uncertainty is only important when optimizing single or highly correlated ecosystem services and that the multifunction effect on landscape diversity is stronger than the uncertainty effect. This is an important insight to support a land-use planning based on ecosystem services.
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Keywords: |
ecosystem services |
South Ecuador |
sustainable land use |
land use modeling |
restoration |
Tapia Armijos, M.F.; Homeier, J.; Espinosa, C.; Leuschner, C. & de la Cruz, M. (2015): Deforestation and Forest Fragmentation in South Ecuador since the 1970s – Losing a Hotspot of Biodiversity. PLos ONE 10(9), e0133701.
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DOI: 10.1371/journal.pone.0133701
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Abstract:
Abstract:
Deforestation and fragmentation are major components of global change; both are contributing to the rapid loss of tropical forest area with important implications for ecosystem functioning and biodiversity conservation. The forests of South Ecuador are a biological 'hotspot' due to their high diversity and endemism levels. We examined the deforestation and fragmentation patterns in this area of high conservation value using aerial photographs and Aster satellite scenes. The registered annual deforestation rates of 0.75% (1976–1989) and 2.86% (1989–2008) for two consecutive survey periods, the decreasing mean patch size and the increasing isolation of the forest fragments show that the area is under severe threat. Approximately 46% of South Ecuador's original forest cover had been converted by 2008 into pastures and other anthropogenic land cover types. We found that deforestation is more intense at lower elevations (premontane evergreen forest and shrubland) and that the deforestation front currently moves in upslope direction. Improved awareness of the spatial extent, dynamics and patterns of deforestation and forest fragmentation is urgently needed in biologically diverse areas like South Ecuador.
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Keywords: |
South Ecuador |
deforestation |
fragmentation |
Bendix, J.; Beck, E.; Bräuning, A.; Makeschin, F.; Mosandl, R.; Scheu, S. & Wilcke, W. 2013: Ecosystem Services, Biodiversity and Environmental Change in a Tropical Mountain Ecosystem of South Ecuador.: Ecological Studies 221 (Springer-Verlag, Berlin Heidelberg).
Villota, A.; León Yánez, S. & Behling, H. (2012): Vegetation and environmental dynamics in the Páramo of Jimbura region in the southeastern Ecuadorian Andes during the late Quaternary. Journal of South American Earth Sciences 40, 85-93.
Fries, A. (2012): Implementation of new methods for the regionalization of climate data Uni Marburg, phd thesis
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Abstract:
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The thermal structure of a megadiverse mountain ecosystem in southern Ecuador is examined on the basis of temperature measurements inside the natural mountain forest and at open sites along an altitudinal gradient from 1700m to 3200m. The data is used to calculated maps of monthly average minimum, mean and maximum 2m air temperature for the period 1999-2007, needed by ecological projects. The maps are generated by combining the straightforward detrending technique by using a Digital Elevation Model and satellite-based land cover classification. The results reveal a clear thermal differentiation over the year, partly triggered by the change of synoptic weather situation but also by land cover effects. Thermal amplitudes are particularly low during the main rainy season when cloudiness and air humidity are high but markedly pronounced in the relative dry season when daily irradiance and outgoing nocturnal radiation causes distinct differences between the land cover units. Particularly the lower pasture areas gained by slash and burn of the natural forest exhibit the most extreme thermal conditions while the atmosphere inside the mountain forest is slightly cooler due to the regulating effects of the dense vegetation. Thus, clearing the forest clearly reduces the thermal regulation function (regulating ecosystem services) of the ecosystem which might become problematic under future global warming.
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Keywords: |
air temperature |
South Ecuador |
thermal structure |
regionalization |
forest and open land |
Fries, A.; Rollenbeck, R.; Nauss, T.; Peters, T. & Bendix, J. (2012): Near surface air humidity in a megadiverse Andean mountain ecosystem of southern Ecuador and its regionalization.. Agricultural and Forest Meteorology 152, 17-30.
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DOI: 10.1016/j.agrformet.2011.08.004
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Abstract:
Abstract:
The near surface humidity in a megadiverse mountain ecosystem in southern Ecuador is examined on the basis of Relative Humidity (RH) measurements inside the natural mountain forest and at open sites along an altitudinal gradient from 1700 to 3200 m. The main methodological aim of the current study is to generate a humidity regionalization tool to provide spatial datasets on average monthly mean, minimum and maximum RH, Specific Humidity (q) and Specific Saturation Deficit (DS) by using observation data of RH. The maps based on data of the period 1999–2009 are needed by ecological projects working on various plots where no climate station data are available. The humidity maps are generated by combining a straightforward detrending technique with a Digital Elevation Model and a satellite-based land cover classification which also provides the relative forest cover per pixel. The topical aim of the study is to investigate the humidity distribution and structure of both manifestations of our ecosystem (pastures and natural vegetation) with special considerations to the ecosystem regulation service by converting natural forest into pasture. The results reveal a clear differentiation over the year, partly triggered by the change of synoptic weather situation but also by land cover effects. Humidity amplitudes are particularly low during the main rainy season when cloudiness and rainfall are high, but markedly pronounced in the relative dry season when daily irradiance and outgoing nocturnal radiation causes distinct differences between the land cover units. Particularly the upper pasture areas gained by slash and burn of the natural forest exhibit the lowest humidity values while the humidity inside the mountain forest is significantly higher due to the regulating effects of the dense vegetation. Thus, clearing the forest clearly reduces the regulation function (regulating ecosystem services) of the ecosystem which might become problematic for reforestation under future global warming.
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Keywords: |
South Ecuador |
regionalization |
forest and open land |
distribution |
structure |
near surface humidity |
Bendix, J.; Trachte, K.; Palacios, E.W.; Rollenbeck, R.; Göttlicher, D.; Nauss, T. & Bendix, A. (2011): El Niño meets La Niña - anomalous rainfall patterns in the "traditional" El Niño region of southern Ecuador . Erdkunde 65, 151-167.
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DOI: 10.3112/erdkunde.2011.02.04
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Abstract:
Abstract:
In this paper, the central Pacific cold event of 2008 and its exceptionally warm conditions in the eastern tropical
Pacific are analyzed by using rainfall data of south Ecuadorian meteorological stations, sea surface temperatures in the El
Niño3 and 1+2 regions, and simulations with the Weather Research and Forecasting (WRF) model. It can be shown that El
Niño-like rainfall conditions with severe inundations occur particularly in the coastal plains of southern Ecuador while a
central Pacific cold event prevails. In contrary to previous situations, positive rainfall anomalies as a result of El Niño-like
conditions in the El Niño1+2 region during the 2008 La Niña event occurred in both regions, the coastal plains and the
highlands, for the first time. A detailed analysis of the ocean-atmosphere system during episodes of heavy rainfall reveals
typical El Niño circulation and rainfall patterns as observed during previous El Niño events for the coastal area and La
Niña-like conditions for the highlands. The spreading of Pacific instability in the Niño1+2 region to the eastern escarpment
of the Andes could be the result of a temporary eastward shift of the Walker circulation. The unusual combination of El
Niño-like conditions in the eastern tropical Pacific during a La Niña state in the central Pacific is the newest indicator for
an impact mode shift regarding severe rainfall anomalies during El Niño/La Niña events in the traditional El Niño area
of southern Ecuador since the end of the last century. Since 2000, El Niño events unexpectedly provide below average
rainfall while central Pacific La Niña conditions generate exceptional severe flooding in the normally drier coastal plains.
The novel sea surface temperature (SST) anomaly dipole structure between the eastern and central/western tropical Pacific
and the weakening of El Niño events since 2000 could be due to natural decadal oscillations in the El Niño background
state, the Pacific Decadal Oscillation (PDO). However, the observed atmospheric patterns and the recent increase of the
SST anomaly difference between the central and the eastern tropical Pacific resemble structures that also result from climate
change simulations.
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Keywords: |
South Ecuador |
el nino |
la nina |
ENSO |
rainfall anomalies |
sea surface temperature anomalies |
Deubler, C. (2010): Schwebstoffmessungen im Einzugsgebiet des Rio San Francisco, Süd-Ecuador Institute of Resources Management, University of Giessen, master thesis
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Abstract:
From July to October 2009 different methods for the measurement of suspended sediment yield and related particulate carbon (C) and nitrogen (N) loss were investigated in a mountainous cloud forest catchment in South-Ecuador. Humid mountainous regions in the tropics are often characterized by highly variable discharge, high rainfall erosivity and geomorphic instability which result in a greatly increased erosion risk. Additionally this danger is enhanced in the studied catchment by the conversion of cloud forests to pasture and crop land as well as landslides caused by road construction. To be able to quantify suspended sediment yield and the associated particulate organic carbon (POC) and nitrogen (NOC) export, a direct approach of suspended sediment sampling, gravimetric ascertainment of the quantity and C and N analysis was combined with the application of two different turbidity sensors. The first one, a ViSolid sensor (WTW, Weilheim, Germany), was set up at the catchment outlet. The second one, a TSS Portable sensor (Hach Lange, Düsseldorf, Germany), was used as a mobile hand held unit. Relations from correlation and regression analysis between suspended sediment concentration and discharge and turbidity respectively made it possible to calculate first extrapolations of yearly suspended sediment yield between 26,5 t ha-1 and 46,3 t ha-1. These numbers are clearly below the global average of 200 t suspended sediment ha-1 a-1. For POC export, the results were between 272,8 kg ha-1 a-1 and 446,9 kg ha-1 a-1 and for NOC export between 21,2 kg ha-1 a-1 and 34,7 kg ha-1 a-1. The PON value fits to literature data whereas POC value is above literature data. The differing results and the unexpected low suspended sediment yield can be explained by the fact that more data integrating the temporal variation of suspended sediment discharge during the year are needed for an adequate calculation. Furthermore emphasis to a greater extent should be placed on the improvement of the data calibration for the ViSolid sensor.
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Keywords: |
South Ecuador |
quantification of suspended sediment |
turbidity measurement |
mountainous cloud forest |
Fries, A.; Rollenbeck, R.; Göttlicher, D.; Nauss, T.; Homeier, J.; Peters, T. & Bendix, J. (2009): Thermal structure of a megadiverse Andean mountain ecosystem in southern Ecuador and its regionalization. Erdkunde 63, 321-335.
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DOI: 10.3112/erdkunde.2009.04.03
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Abstract:
Abstract:
The thermal structure of a megadiverse mountain ecosystem in southern Ecuador is examined on the basis of temperature measurements inside the natural mountain forest and at open-sites along an altitudinal gradient from 1600 to 3200 m. The main methodological aim of the current study is to develop an air temperature regionalization tool to provide spatial datasets on average monthly mean, minimum and maximum temperature by using observation data. The maps, based on data of the period 1999?2007, are needed by ecological projects working on various plots where no climate station data are available. The temperature maps are generated by combining a straightforward detrending technique with a Digital Elevation Model and a satellite-based land cover classification which also provides the relative forest cover per pixel. The topical aim of the study is to investigate the thermal structure of both manifestations of our ecosystem (pastures and natural vegetation) with special considerations to the ecosystem temperature regulation service by converting natural forest into pasture. The results reveal a clear thermal differentiation over the year, partly triggered by the change of synoptic weather situation but also by land cover effects. Thermal amplitudes are particularly low during the main rainy season when cloudiness and air humidity are high, but markedly pronounced in the relative dry season when daily irradiance and outgoing nocturnal radiation cause distinct differences between the land cover units. Particularly the lower pasture areas gained by slash and burn of the natural forest exhibit the most extreme thermal conditions while the atmosphere inside the mountain forest is slightly cooler due to the regulating effects of the dense vegetation. Thus, clearing the forest clearly reduces the thermal regulation function (regulating ecosystem services) of the ecosystem which might become problematic under future global warming.
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Keywords: |
air temperature |
South Ecuador |
thermal structure |
regionalization |
forest and open land |
Kuptz, D.; Grams, T. & Günter, S. (2010): Light acclimation of four native tree species in felling gaps within a tropical mountain rain forest. Trees - Structure and Function 24(1), 117-127.
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DOI: 10.1007/s00468-009-0385-1
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Abstract:
Abstract:
Ecuadorian mountain rainforests are declining dramatically due to deforestation. Exploitation of remaining forests has led to low abundances of native, valuable timber species. Enrichment planting of selected native tree species into forest gaps is a strategy that may increase their abundance and maintain biodiversity. However, the development of successful planting strategies requires knowledge of environmental demands on, and ecological requirements of, native species during their establishment. This knowledge is currently lacking for midand latesuccessional species in Central American forests. Two deciduous, mid-successional (Cedrela montana, Tabebuia chrysantha) and two evergreen, late-successional native tree species (Nectandra membranacea, Podocarpus sprucei) were planted into felling gaps. Photosynthetic performance and growth in height of these species were assessed along light gradients during seedling establishment to test whether species-specific light responses were related to plant successional traits. Both mid-successional species benefited from higher light levels in gaps up to 30% canopy openness60. In larger gaps, C. montana exhibited a significant decline in growth. As expected, growth of the latesuccessional species was only marginally increased at higher light levels. Nevertheless, the photosynthetic apparatus of N. membranacea displayed rapid acclimation to higher light conditions in gaps. Plant response to felling gaps may not always be predicted based on successional status. Our results suggest that the four investigated species may coexist in the same gap by occupying different niches along light gradients. This arrangement may offer an ecological basis to increase the abundance of valuable timber species through enrichment planting in Ecuador mountain rainforests.
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Keywords: |
South Ecuador |
photosynthesis |
light assessment |
height growth |
natural forest management |
successional plant traits |
Preussig, M.; Nebel, M.; Oberwinkler, F. & Weiß, M. (2009): Diverging diversity patterns in the Tulasnella (Basidiomycota, Tulasnellales) mycobionts of Aneura pinguis (Marchantiophyta, Metzgeriales) from Europe and Ecuador. Mycorrhiza -, xx-xx.
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DOI: 10.1007/s00572-009-0275-9
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Abstract:
Abstract:
Aneura pinguis (Aneuraceae) is a cosmopolitan
thalloid liverwort that shows a specific mycorrhiza-like
interaction with basidiomycetes. To date, tropical specimens
have not been studied in great depth. Samples of A.
pinguis were collected from 48 individuals in one plot in
South Ecuador and 54 individuals in five European
countries. Light and transmission electron microscopy and
molecular analyses based on nuclear rDNA coding for the
ribosomal large subunit (nucLSU) and from the 5.8s-ITS2
regions were carried out to identify the associated mycobionts
and to study their phylogenetic relationships. Microscopic
and ultrastructural investigations of the fungal colonisation
showed a high congruence between the European and the
Ecuadorian sites and confirmed previous results. Tulasnellales
are the only mycobionts that could be detected from
ultrastructural characters with certainty. Molecular phylogenetic
analysis indicated the presence of tulasnelloid fungi
from at least 13 distinct clades. The composition of the
communities of tulasnelloid fungi in A. pinguis differs
between Ecuador and Europe. The diversity of tulasnelloid
fungal partners was much higher at the Ecuadorian site.
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Keywords: |
South Ecuador |
Tulasnellales |
diversity |
aneura pinguis |
aneuraceae |
mycobiont |
europe |
neotropical mountain rain forest |