Constructed Images of Iguazú National Park (Argentina) Related to Visitors’ Origins

We analyzed the perceptions of tourists visiting the famous waterfalls in Iguazú National Park to define how they envisaged the park with their constructed images. Nine hundred and seventy six questionnaires were completed by personally interviewing visitors in February and April 2011. They were asked to describe the park by choosing between 17 fixed features (tranquility, grandiosity, water, harmony, beauty, horizon, sound of nature, colors, rainforest, extension, green, maintenance, animals, diversity, nature, peace and wilderness) and also an open option. The constructed images were classified in categories of Beauty, Sublime, Picturesque and Spiritual and explored with SPSS and multivariate analyses. Results showed that the appeal of the waterfalls is multidimensional, combining different elements of the Picturesque, Sublime, Beauty, and also Spiritual, categories in different proportions. We identified associations between visitors’ origins and the constructed images among groups of visitors from North America, Latin-America, Europe, Australia, South Africa and East Asia. We confirmed the widespread election of picturesque and sublime features as visions with which to describe the national park. Water, beauty and grandiosity were the main features mentioned. Peace, tranquility and horizon were found as possible explanations for the divergence in visions between the six groups studied, especially segregating East Asians and South Africans from the other groups. The observed similarities and differences in the constructed images of Iguazú National Park of visitors coming from different parts of the world could be explained by both evolutionary and cultural frameworks. Some recommendations for park management and city planning are given

Floristic Composition and Dynamics Analysis of Two Seasonal Communities of Weeds

Se analizó la dinámica y algunas características de las especies de dos comunidades estacionales de malezas, una correspondiente al ciclo de cultivos invernales y otra correspondiente a los estivales. A fin de determinar los cambios en la composición florística se realizaron muéstreos que incluyeron cinco parcelas de 1m2 elegidas al azar en seis momentos durante el desarrollo de cada comunidad Las especies fueron ordenadas por el momento de aparición, la persistencia y la frecuencia de ocurrencia, y caracterizadas por la familia botánica, la forma de vida y el período estacional de crecimientoLas familias más representadas en ambas comunidades fueron las Asteráceas y las Poáceas observándose, además, el predominio de la forma de vida terófita La composición florística inicial mostró una baja similitud entre ambas comunidades (ISMo=52%). Valores similares fueron obtenidos aun al comparar muéstreos realizados en fechas próximas dentro de una misma estación.Durante el desarrollo comunitario se observaron cambios progresivos en la composición florística. Si bien en la comunidad correspondiente al ciclo de cultivos estivales los cambios ocurrieron a un ritmo más intenso. Este hecho estuvo asociado a diferencias en el reemplazo de especies con diferente período estacional de crecimientoCommunity dinamics and characteristics of species of two seasonal communities of weeds, one corresponding to winter crop cycle and another to summer crop cycle, were analyzed. To determine floristic changes were taken samples at random from five 1m2 plots, six times during the development of both communities. The species of each community were arranged by emergence date, persistence and ocurrence frequency, and were characterized by botanic family, life form and seasonal growing period Both communities showed a dominance of Asteraceae and Poaceae and therophyte life form The starting floristic composition of both communities showed a low similarity (IS Hp=52%). Similar values were obtained even when comparing samplings carried out in dates near to each other within the same seasonDuring the community development gradual floristic changes took place. However, the changes ocurred more rapidly in the community corresponding to summer crop cycle. This last feature was related to differences in replacement of species with different seasonal growing periodsFacultad de Ciencias Agrarias y Forestale

Fire effects on a Spartina densiflora salt marsh in the floodplain of the Paraná River, Argentina

We studied the effects of fire on the structural attributes of a Spartina densiflora salt marsh. The study was carried out from November 1995, spring (N95S) to December 1996, late spring (D96LS). In November 1995, we installed 37 permanent plots. In January 1996, 32 of the plots were accidentally burned (B) and the remaining were not burned (NB). Vegetation on each plot was sampled seasonally, plant species were identified and cover-abundance was estimated. We analyzed and compared seasonal variations in plant species richness, diversity, composition and cover-abundance in burned and non-burned plots. In addition, we analyzed variations in biological types (forbs, graminoids) and types of life cycles (annuals, perennials) in B and NB plots before and after the fire .Principal Component Analysis (PC A) was performed on cover-abundance data for each treatment and sampling date. We included coded dummy variables for each date and treatment as supplementary variables. Results indicated that S. densiflora was the dominant species and Limonium brasiliensis and Dipsacum fullonum were the accompanying species for all treatments and sampling dates. Thirty out of 47 species were present before the fire (N95S). All species in NB plots were also recorded in B plots, and 15 species were exclusively found in B plots. The increases in species richness and diversity observed in B plots after the fire were higher than those in NB plots at the same sampling dates. When comparing the B plots before and after the fire, perennials decreased in cover-abundance and increased in richness, while both attributes increased for annuals; the same pattern was followed by forbs, and graminoids decreased in cover abundance and showed almost similar values of richness. PCA results showed that NB plots were subject to smooth temporal changes in composition and cover abundance, and that B plots underwent greater changes. In D96LS, B and NB plots exhibited a different spatial distribution, which in turn differed from that observed in pre-fire plots in N95S. © 2007 Sociedad de Biología de Chile.Fil:Madanes, N. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Fischer, S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Comparison between valuations of argentinean beaches according to the age of the user

En el presente trabajo analizamos y comparamos la valoración de playas arenosas bonaerenses y patagónicas desde un punto de vista objetivo y subjetivo. Para valorar el estado real de cada playa y su calidad como recurso recreativopaisajístico se consideraron en cuatro playas de Necochea y cinco de Pto. Madryn aspectos fisicos, biológicos ambientales y de infraestructura asignándole puntajes a distintas variables. La valoraciòn subjetiva de la playa,se basó en la opinión y actitud de los usuarios que las visitan, mediante encuestas para conocer qué percepción tenían de las condiciones biofísicas, sociales y de infraestructura de las playas. Los resultados indican una alta similitud entre valoraciones. Al comparar la valoración subjetiva con la objetiva según diferentes grupos etarios discriminados en jóvenes menores de 25 años, adultos de 25 a 49 años y adultos mayor de 49 años, sólo en 7 casos se encontraron diferencias significativas entre ambas valoraciones. Los usuarios de Quequén adjudican mayores valores que los observados por el técnico. Esto se repite para los dos grupos de adultos de Escollera, para los Adultos II de Mimosa y para los jóvenes en Rancho. Los resultados confirman la utilidad de ambas metodologías de valoración, las cuales podrían considerarse análogas, no registrándose grandes diferencias en la percepción según la edad en la mayoría de los casos. En las playas argentinas estudiadas encontramos público con distintas predilecciones para satisfacer sus necesidades de recreación. De acuerdo a nuestros resultados, para la optimizaciòn del recurso turístico, cada ciudad debería respetar la opinión de los usarios garantizando una oferta diversa de balnearios.This paper analyzes and compares the valuation of the sandy beaches in Buenos Aires and Patagonia from an objective and a subjective point of view. To value the real state of each beach and its quality as a recreation- landscape resource, the physical, biologic, ambient aspects and infrastructure have been considered in four beaches from Necochea and five from Pto. Madryn, to which different variables were scored. The subjective valuation of the beach was based in the opinion and attitude of the users that visit them, through polls to know what was their perception from the biophysic, social and infrastructural conditions of the beaches. The results show a high similarity between valuations. Only seven cases showed any significant differences between valuations when compared the subjective with the objective valuation in different age groups distinguished according to: young people under 25 years old, adults between 25 to 49, and adults over 49. The users of Quequén awarded higher values that observed by the technician. This is repeated for the two adults groups of Escollera, for the Adults II of Mimosa and for young people in Rancho. The results confirm the utility of both methodological valuations, which could be considered equal, not registering big differences in the perception according to the age in most of the cases. In the Argentinean beaches studied we found public with different predilections to satisfy their recreation needs. According to our results, to optimize the tourism resource, each city should respect the opinion of the users to guarantee a diverse beach offer.Fil: Madanes, N.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Faggi, Ana Maria. Universidad de Flores; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Espejel, I.. Universidad Autónoma de Baja California Sur; Méxic

Water Storage Discharge and Refilling in the Main Stems of Canopy Tree Species Investigated Using Frequency Domain Reflectometry and Point Electronic Dendrometers

Water storage in the trunks of large trees plays an important role in whole-plant water balance on both daily and seasonal bases. To investigate the dynamics of water storage and usage in tree trunks, diurnal changes in volumetric water content (VWC) of the sapwood and tree radius including the bark were monitored continuously using frequency domain moisture sensors and electronic point dendrometers in 10 canopy tree species of a subtropical seasonal forest in northern Argentina. In addition, species-specific water storage capacitance of the active xylem was assessed using pressure volume relationships determined with a psychometric method. In nearly all the species, trunk VWC and radius length decreased during the day when the air saturation deficit increased, suggesting that the trunk water storage was drawn by canopy transpiration, while the increase of VWC during the night suggests stem water storage recharge. Species with higher water storage capacitance exhibited lower wood density and higher average VWC, suggesting the influence of wood structural properties on its water storage function.Fil: Carrasco, L. O.. Consejo Nacional de Investigaciones Cienti­ficas y Tecnicas. Centro Cientifico Tecnologico Nordeste. Instituto de Biologia Subtropical. Instituto de Biologia Subtropical - Nodo Puerto Iguazu; ArgentinaFil: Bucci, Sandra Janet. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Scholz, Fabian Gustavo. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Campanello, Paula Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Instituto de Biologia Subtropical. Instituto de Biologia Subtropical - Nodo Puerto Iguazu; ArgentinaFil: Madanes, Nora. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución. Laboratorio de Ecología Funcional; ArgentinaFil: Cristiano, Piedad María. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución. Laboratorio de Ecología Funcional; ArgentinaFil: Hao, G. Y.. Harvard University; Estados UnidosFil: Wheeler, J. K... Harvard University; Estados UnidosFil: Holdbrook, N. M.. Harvard University; Estados UnidosFil: Goldstein, Guillermo Hernan. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución. Laboratorio de Ecología Funcional; Argentin

Water storage dynamics in the main stem of subtropical tree species differing in wood density, growth rate and life history traits

Wood biophysical properties and the dynamics of water storage discharge and refilling were studied in the trunk of canopy tree species with diverse life history and functional traits in subtropical forests of northeast Argentina. Multiple techniques assessing capacitance and storage capacity were used simultaneously to improve our understanding of the functional significance of internal water sources in trunks of large trees. Sapwood capacitances of 10 tree species were characterized using pressure?volume relationships of sapwood samples obtained from the trunk. Frequency domain reflectometry was used to continuously monitor the volumetric water content in the main stems. Simultaneous sap flow measurements on branches and at the base of the tree trunk, as well as diurnal variations in trunk contraction and expansion, were used as additional measures of stem water storage use and refilling dynamics. All evidence indicates that tree trunk internal water storage contributes from 6 to 28% of the daily water budget of large trees depending on the species. The contribution of stored water in stems of trees to total daily transpiration was greater for deciduous species, which exhibited higher capacitance and lower sapwood density. A linear relationship across species was observed between wood density and growth rates with the higher wood density species (mostly evergreen) associated with lower growth rates and the lower wood density species (mostly deciduous) associated with higher growth rates. The large sapwood capacitance in deciduous species may help to avoid catastrophic embolism in xylem conduits. This may be a low-cost adaptation to avoid water deficits during peak water use at midday and under temporary drought periods and will contribute to higher growth rates in deciduous tree species compared with evergreen ones. Large capacitance appears to have a central role in the rapid growth patterns of deciduous species facilitating rapid canopy access as these species are less shade tolerant than evergreen species.Fil: Oliva Carrasco, Laureano. Consejo Nacional de Investigaciones Cienti­ficas y Tecnicas. Centro Cientifico Tecnologico Nordeste. Instituto de Biologia Subtropical. Instituto de Biologia Subtropical - Nodo Puerto Iguazu; Argentina. Universidad Nacional de Misiones. Facultad de Ciencias Forestales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Bucci, Sandra Janet. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia "san Juan Bosco". Facultad de Cs.naturales - Sede Esquel. Laboratorio de Ecologia Acuatica; ArgentinaFil: Di Francescantonio, Débora. Consejo Nacional de Investigaciones Cienti­ficas y Tecnicas. Centro Cientifico Tecnologico Nordeste. Instituto de Biologia Subtropical. Instituto de Biologia Subtropical - Nodo Puerto Iguazu; ArgentinaFil: Lezcano, Oscar Antonio. Consejo Nacional de Investigaciones Cientiâ­ficas y Tecnicas. Centro Cientifico Tecnologico Nordeste. Instituto de Biologia Subtropical. Instituto de Biologia Subtropical - Nodo Puerto Iguazu; ArgentinaFil: Campanello, Paula Inés. Consejo Nacional de Investigaciones Cienti­ficas y Tecnicas. Centro Cientifico Tecnologico Nordeste. Instituto de Biologia Subtropical. Instituto de Biologia Subtropical - Nodo Puerto Iguazu; ArgentinaFil: Scholz, Fabian Gustavo. Universidad Nacional de la Patagonia "san Juan Bosco". Facultad de Ciencias Naturales - Sede Comodoro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rodríguez, Sabrina Andrea. Consejo Nacional de Investigaciones Cienti­ficas y Tecnicas. Centro Cientifico Tecnologico Nordeste. Instituto de Biologia Subtropical. Instituto de Biologia Subtropical - Nodo Puerto Iguazu; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Madanes, N.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución. Laboratorio de Ecología Funcional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Cristiano, Piedad María. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución. Laboratorio de Ecología Funcional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Hao, Guang You. Chinese Academy Of Sciences; República de China. Harvard University; Estados UnidosFil: Holbrook, N. Michele. Harvard University; Estados UnidosFil: Goldstein, Guillermo Hernan. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución. Laboratorio de Ecología Funcional; Argentina. University Of Miami; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentin