National University of Loja
Loja, Ecuador
Time filter
Source Type

Ayala M.,University of Barcelona | Maldonado J.,National University of Loja | Paccha E.,University of Chile | Riba C.,University of Barcelona
Energy Procedia | Year: 2017

This paper describes a complex terrain wind farm case study in the Ecuadorian Andes. The Windfarm Villonaco is located in southern Ecuador, 640km of Quito, 2700 m a.s.l. with 16.5 MW power output. The objective is to compare actual power production from an existing wind farm with power production predicted by Meteodyn WT, which is a CFD tool based on a nonlinear flow model. The results of this work show that the calculation of the annual energy production of the Villonaco Wind Farm using Meteodyn WT is equal to 69.0 GWh / year, with a capacity factor of 53%. © 2017 The Authors.

Szekely D.,Technical University of Loja | Denoel M.,University of Liège | Szekely P.,Technical University of Loja | Cogalniceanu D.,National University of Loja
Journal of Zoology | Year: 2017

The hydroperiod of breeding habitats imposes a strong selection on amphibians and pond-breeding species usually exhibit a high degree of plasticity in the duration of larval period. However, the potential for phenotypic plasticity in fast developing species was investigated only in a small number of anurans, and the specific response to environmental cues such as low water versus decreasing water level, as well as the effects of such cues on particular developmental stages, are even less understood. In this context, we investigated the plastic response to pond desiccation in a neotropical species (Ceratophrys stolzmanni) by raising tadpoles in three water level treatments: constant high, constant low, and decreasing. The growth rates were the highest reported for amphibian tadpoles (up to 0.3 g day-1) and the time to metamorphosis was short in all treatments, with the fastest developing tadpole metamorphosing in only 16 days after egg deposition. Individuals from the constant high water level treatment had a higher growth rate than those in the other two treatments, whereas decreasing and constant low water levels had similar effects on development, speeding up metamorphosis. In turn, this involved a cost as these tadpoles had a lower body size and mass at metamorphosis than the ones raised in constant high water levels. The final stages of metamorphosis, when tadpoles are the most vulnerable, were shorter in tadpoles exposed to a decreasing water level, allowing them to leave water quickly. Our experiment demonstrates that phenotypic plasticity is maintained even in environments devoid of permanent aquatic habitats. Ceratophryd tadpoles are able to shorten their developmental time when they perceive a risk of desiccation and react similarly to cues coming from the two unfavorable water conditions showing their adaptation to ephemeral and unpredictable breeding habitats. © 2017 The Zoological Society of London.

Raes L.,Ghent University | Speelman S.,Ghent University | Aguirre N.,National University of Loja
Environmental Management | Year: 2017

This study investigates farmers’ preferences to participate in payment contracts to adopt silvopastoral systems in Ecuador. A choice experiment was used to elicit preferences between different contract attributes, including differing payment amounts and land management requirements. The research was carried out in the buffer zone of Podocarpus National Park in Southern Ecuador, an area where most land is dedicated to cattle husbandry. A choice experiment was conducted to measure farmers’ interest in different types of contracts. Based on existing incentive programs, contract choices varied with respect to the type of silvopastoral system, extra land-use requirements, payment levels and contract duration. In addition, contracts differed with regards to access by cattle to streams. Although the farmers did not show strong preferences for every contract attribute, the majority of farmers in the area showed interest in the proposed contracts. A latent class model identified three classes of respondents, based on their preferences for different contracts attributes or the “business as usual” option. The results suggest that farmland area, agricultural income, and landowners’ perceptions of environmental problems provide a partial explanation for the heterogeneity observed in the choices for specific contracts. Participation might increase if contracts were targeted at specific groups of farmers, such as those identified through our latent class model. Offering flexible contracts with varying additional requirements within the same scheme, involving farmers from the start in payments for environmental services design, and combining payments for environmental services with integrated conservation and development projects may be a better way to convince more farmers to adopt silvopastoral systems. © 2017 Springer Science+Business Media New York

Lattke J.E.,National University of Loja | Delsinne T.,Technical University of Loja
Myrmecological News | Year: 2016

Taxonomic clarifications and natural history data dealing with some species of the genus Gnamptogenys are offered: Gnamptogenys bufonis (MANN, 1926) is synonymized under G. simulans (EMERY, 1896); G. vriesi BRANDÃO & LATTKE, 1990 is redescribed and illustrated with SEM and montage images, the peculiar morphology of its compound eye is discussed. Also, an updated key for the G. minuta group species is presented and a nest of G. minuta (EMERY, 1896) is described. The species known up to now as G. costata (EMERY, 1889) is renamed G. coxalis (F. SMITH, 1857), and the species misidentified up to now as G. coxalis (ROGER, 1860) is renamed G. Sinhala LATTKE sp.n.

Larrea M.I.P.,Technical University of Loja | Daniela Calva Cabrera K.,National University of Loja
Iberian Conference on Information Systems and Technologies, CISTI | Year: 2016

The approval of the Communication law in Ecuador (LOC-2013), alerted to the journalists. In article number 42, related to the professionalization, is considered harmful to the right to the communication and will push the journalist, to return to the classrooms. This article analyzes the university offer related to the communication sciences, and the geographical coverage, showing the universities concentration in the province capitals of Ecuador, and this become in a difficult to be a professional in communication sciences. In Ecuador, the mass communication is deeply marked with the lack ot a professional title, strong critics to the mass media and negative reports about the freedom of speech, mostly in the last 5 years. What the universities have to offer, also have some deficiencies. © 2016 AISTI.

Rehmus A.,University of Bern | Bigalke M.,University of Bern | Valarezo C.,National University of Loja | Castillo J.M.,TU Munich | Wilcke W.,University of Bern
Plant and Soil | Year: 2014

Aims: In acid tropical forest soils (pH <5.5) increased mobility of aluminum might limit aboveground productivity. Therefore, we evaluated Al phytotoxicity of three native tree species of tropical montane forests in southern Ecuador. Methods: An hydroponic dose-response experiment was conducted. Seedlings of Cedrela odorata L., Heliocarpus americanus L., and Tabebuia chrysantha (Jacq.) G. Nicholson were treated with 0, 300, 600, 1200, and 2400 μ M Al and an organic layer leachate. Dose-response curves were generated for root and shoot morphologic properties to determine effective concentrations (EC). Results: Shoot biomass and healthy leaf area decreased by 44 % to 83 % at 2400 μ M Al, root biomass did not respond (C. odorata), declined by 51 % (H. americanus), or was stimulated at low Al concentrations of 300 μ M (T. chrysantha). EC10 (i.e. reduction by 10 %) values of Al for total biomass were 315 μ M (C. odorata), 219 μ M (H. americanus), and 368 μ M (T. chrysantha). Helicarpus americanus, a fast growing pioneer tree species, was most sensitive to Al toxicity. Negative effects were strongest if plants grew in organic layer leachate, indicating limitation of plant growth by nutrient scarcity rather than Al toxicity. Conclusions: Al toxicity occurred at Al concentrations far above those in native organic layer leachate. © 2014 Springer International Publishing Switzerland.

Wullaert H.,Johannes Gutenberg University Mainz | Homeier J.,University of Gottingen | Valarezo C.,National University of Loja | Wilcke W.,University of Bern
Forest Ecology and Management | Year: 2010

Atmospheric nitrogen (N) and phosphorus (P) depositions are expected to increase in the tropics as a consequence of increasing human activities in the next decades. In the literature, it is frequently assumed that tropical montane forests are N-limited, while tropical lowland forests are P-limited. In a low-level N and P addition experiment, we determined the short-term response of N and P cycles in a north Andean montane forest on Palaeozoic shists and metasandstones at an elevation of 2100m a.s.l. to increased N and P inputs. We evaluated experimental N, P and N+P additions (50kgha-1yr-1 of N, 10kgha-1yr-1 of P and 50kg+10kgha-1yr-1 of N and P, respectively) and an untreated control in a fourfold replicated randomized block design. We collected litter leachate, mineral soil solution (0.15 and 0.30m depths), throughfall and litterfall before the treatment began (August 2007) until 16 months after the first nutrient application (April 2009). Less than 10 and 1% of the applied N and P, respectively, leached below the organic layer which contained almost all roots and no significant leaching losses of N and P occurred to below 0.15m mineral soil depth. Deposited N and P from the atmosphere in dry and wet form were retained in the canopy of the control treatment using a canopy budget model. Nitrogen and P retention by the canopy were reduced and N and P fluxes in throughfall and litterfall increased in their respective treatments. The increase in N and P fluxes in throughfall after fertilization was equivalent to 2.5% of the applied N and 2% of the applied P. The fluxes of N and P in litterfall were up to 15% and 3%, respectively, higher in the N and N+P than in the control treatments. We conclude that the expected elevated N and P deposition in the tropics will be retained in the ecosystem, at least in the short term and hence, N and P concentrations in stream water will not increase. Our results suggest that in the studied tropical montane forest ecosystem on Palaeozoic bedrock, N and P are co-limiting the growth of organisms in the canopy and organic layer. © 2010 Elsevier B.V.

Mazon M.,University of Los Andes, Venezuela | Mazon M.,University of Alicante | Mazon M.,National University of Loja
Biodiversity and Conservation | Year: 2016

When trying to assess entomological diversity, identifying taxa at levels higher than species is much easier and may provide a wider vision of other ecological features. In this work, we used the data from several samplings made in across six cacao farms in Mérida state (Venezuela). Farms fell into two categories according to intensity of perturbation. In these samplings we identified all parasitoid Hymenoptera families. All individuals belonging to families Ichneumonidae, Braconidae and Chalcididae were sorted to subfamilies and then to morphospecies. The accuracy of subfamilies richness to predict the species richness and to detect differences in the conservation status of plantations was tested. The species aggregation according to the sampling size was also explored. The three families this study was focused on represented 23 % of the total sampling, comprising 40 subfamilies and 393 morphospecies. Results showed a significant high positive correlation between subfamilies and species richness, and species/subfamilies ratio was about 4.5:1, with logarithmic relationship with sampling size tending to stabilisation at sizes greater than 15 individuals per sampling day. Subfamily richness detected the nearly-significant differences in plantations with the same accuracy as species richness, and therefore surrogacy effectiveness of parasitoid Hymenoptera subfamilies richness may be accepted for cacao plantations. © 2015, Springer Science+Business Media Dordrecht.

Volland F.,Friedrich - Alexander - University, Erlangen - Nuremberg | Pucha D.,National University of Loja | Brauning A.,Friedrich - Alexander - University, Erlangen - Nuremberg
Erdkunde | Year: 2016

Variations of stable oxygen isotopes in tree-ring cellulose are a widely used proxy to reconstruct hydro-climate variability in tropical and subtropical regions. We present the first δ18O chronology from annual tree rings in tropical Cedrela montana trees growing in the mountain rain forest of the Podocarpus National Park (PNP) in southern Ecuador. The more than a century long data record (1885-2011) comes from up to 15 individual trees (1980-2005) and represents the best- replicated isotope tree-ring chronology from the tropics. In comparison with tree-ring width, stable isotope variations show considerably higher correlations between individuals and thus represent a more reliable climate proxy in this very humid environment. High teleconnections to other stable isotope chronologies from the Amazon lowland indicate a high degree of consistency of regional hydro-climate variations. The PNP δ18O record is correlated with seasonal precipitation (January to April, CRU TS 3.21), frequency of wet days, and cloud cover over the Andean Cordillera Real. Spatial correlations indicate that the El Niño-Southern Oscillation (ENSO) has strong impact on tree-ring δ18O variations. Sea Surface Temperatures (SSTs) of the Niño 3.4 region and Niño 4 region, and the Oceanic Niño Index (ONI) show strong positive correlations with Cedrela oxygen isotope ratios, whereas the ENSO precipitation index correlates negatively. The Niño 3.4 and 4 SST influence is stronger after 1960 than before, indicating a shift in the influence of the Pacific Ocean on moisture variations in the Ecuadorian Andes. In the same period, the positive correlation with oxygen isotope signals from Andean glacier ice cores (r=0.2; p<0.05, 1894-1993) increased strongly (r=0.51; p<0.01, 1960-1993). In conclusion, stable oxygen isotope series from tropical tree species can help reconstruct variations in the hydroclimate of the Andean mountains and their surrounding areas. © 2016, Erdkunde. All rights reserved.

Volland-Voigt F.,Friedrich - Alexander - University, Erlangen - Nuremberg | Brauning A.,Friedrich - Alexander - University, Erlangen - Nuremberg | Ganzhi O.,National University of Loja | Peters T.,Friedrich - Alexander - University, Erlangen - Nuremberg | Maza H.,National University of Loja
Trees - Structure and Function | Year: 2011

Stem diameter increments of the broadleaved deciduous tree species Tabebuia chrysantha were measured with high-resolution dendrometers in a tropical lower montane forest and in a dry forest in southern Ecuador, the latter showing a distinct dry season. Those analyses were complemented by wood anatomical studies on regularly collected microcores to determine the season of active cambial growth and the time of formation of annual growth boundaries. The length of the cambial active period varied between 3 and 7 months at the tropical lower montane forest and 2 and 4 months in the dry forest, respectively. During dry days, amplitudes of daily stem diameter variations correlated with vapour pressure deficit. During October and November, inter-annual climate variations may lead to dry and sunny conditions in the tropical lower montane forest, causing water deficit and stem diameter shrinkage in T. chrysantha. The results of the climate-growth analysis show a positive relationship between tree growth and rainfall as well as vapour pressure deficit in certain periods of the year, indicating that rainfall plays a major role for tree growth. © 2010 Springer-Verlag.

Loading National University of Loja collaborators
Loading National University of Loja collaborators