Trade-offs Between Water Transport Capacity and Drought Resistance in Neotropical Canopy Liana and Tree Species

In tropical forest canopies, it is critical for upper shoots to efficiently provide water to leaves for physiological function while safely preventing loss of hydraulic conductivity due to cavitation during periods of soil water deficit or high evaporative demand. We compared hydraulic physiology of upper canopy trees and lianas in a seasonally dry tropical forest to test whether trade-offs between safety and efficiency of water transport shape differences in hydraulic function between these two major tropical woody growth forms. We found that lianas showed greater maximum stem-specific hydraulic conductivity than trees, but lost hydraulic conductivity at less negative water potentials than trees, resulting in a negative correlation and trade-off between safety and efficiency of water transport. Lianas also exhibited greater diurnal changes in leaf water potential than trees. The magnitude of diurnal water potential change was negatively correlated with sapwood capacitance, indicating that lianas are highly reliant on conducting capability to maintain leaf water status, whereas trees relied more on stored water in stems to maintain leaf water status. Leaf nitrogen concentration was related to maximum leaf-specific hydraulic conductivity only for lianas suggesting that greater water transport capacity is more tied to leaf processes in lianas compared to trees. Our results are consistent with a trade-off between safety and efficiency of water transport and may have implications for increasing liana abundance in neotropical forests

Liana Competition with Tropical Trees Varies Seasonally but not with Tree Species Identity

Lianas in tropical forests compete intensely with trees for above‐ and belowground resources and limit tree growth and regeneration. Liana competition with adult canopy trees may be particularly strong, and, if lianas compete more intensely with some tree species than others, they may influence tree species composition. We performed the first systematic, large‐scale liana removal experiment to assess the competitive effects of lianas on multiple tropical tree species by measuring sap velocity and growth in a lowland tropical forest in Panama. Tree sap velocity increased 60% soon after liana removal compared to control trees, and tree diameter growth increased 25% after one year. Although tree species varied in their response to lianas, this variation was not significant, suggesting that lianas competed similarly with all tree species examined. The effect of lianas on tree sap velocity was particularly strong during the dry season, when soil moisture was low, suggesting that lianas compete intensely with trees for water. Under the predicted global change scenario of increased temperature and drought intensity, competition from lianas may become more prevalent in seasonal tropical forests, which, according to our data, should have a negative effect on most tropical tree species

Turgor loss point predicts survival responses to experimental and natural drought in tropical tree seedlings

Identifying key traits that can serve as proxies for species drought resistance is crucial for predicting and mitigating the effects of climate change in diverse plant communities. Turgor loss point (πtlp) is a recently emerged trait that has been linked to species distributions across gradients of water availability. However, a direct relationship between πtlp and species ability to survive drought has yet to be established for woody species. Using a manipulative field experiment to quantify species drought resistance (i.e., their survival response to drought), combined with measurements of πtlp for 16 tree species, we show a negative relationship between πtlp and seedling drought resistance. Using long-term forest plot data, we also show that πtlp predicts seedling survival responses to a severe El Niño-related drought, although additional factors are clearly also important. Our study demonstrates that species with lower πtlp exhibit higher survival under both experimental and natural drought. These results provide a missing cornerstone in the assessment of the traits underlying drought resistance in woody species and strengthen πtlp as a proxy for evaluating which species will lose or win under projections of exacerbating drought regimes.National Science Foundation DEB-1464866, DEB-1623775, DEB-184540

Lianas Suppress Seedling Growth and Survival of 14 Tree Species in a Panamanian Tropical Forest

Lianas are a common plant growth form in tropical forests, where they compete intensely with trees, decreasing tree recruitment, growth, and survival. If the detrimental effects of lianas vary significantly with tree species identity, as is often assumed, then lianas may influence tree species diversity and community composition. Furthermore, recent studies have shown that liana abundance and biomass are increasing relative to trees in neotropical forests, which will likely magnify the detrimental effects of lianas and may ultimately alter tree species diversity, relative abundances, and community composition. Few studies, however, have tested the responses of multiple tree species to the presence of lianas in robust, well‐replicated experiments. We tested the hypotheses that lianas reduce tree seedling growth and survival, and that the effect of lianas varies with tree species identity. We used a large‐scale liana removal experiment in Central Panama in which we planted 14 replicate seedlings of 14 different tree species that varied in shade tolerance in each of 16 80 × 80 m plots (eight liana‐removal and eight unmanipulated controls; 3136 total seedlings). Over a nearly two‐yr period, we found that tree seedlings survived 75% more, grew 300% taller, and had twice the aboveground biomass in liana‐removal plots than seedlings in control plots, consistent with strong competition between lianas and tree seedlings. There were no significant differences in the response of tree species to liana competition (i.e., there was no species by treatment interaction), indicating that lianas had a similar negative effect on all 14 tree species. Furthermore, the effect of lianas did not vary with tree species shade tolerance classification, suggesting that the liana effect was not solely based on light. Based on these findings, recently observed increases in liana abundance in neotropical forests will substantially reduce tree regeneration, but will not significantly alter tropical tree species diversity, relative abundance, or community composition

Influencias del paisaje, climatología y manejo agrícola sobre la biodiversidad asociada a viña: efectos sobre servicios ecosistémicos y sostenibilidad frente a cambio global (Proyecto BA C O)

Dentro de un contexto dominado por el cambio rápido y frecuente, es básico analizar sus efectos sobre la biodiversidad y los servicios ecosistémicos que ésta provee. El cultivo de la viña es uno de los sistemas agrícolas más antiguos de la región Mediterránea, con una interacción muy estrecha entre el manejo humano y el ambiente natural circundante. El proyecto BA C O pretende, desde un enfoque multidisciplinar, evaluar el papel del clima, paisaje y manejo sobre la biodiversidad y los servicios ecosistémicos asociados a viñedos. Se proponen los siguientes objetivos: i) caracterizar el paisaje, ambiente, clima y tipo de manejo de las principales explotaciones de vid; ii) evaluar la influencia del paisaje, ambiente y manejo en la biodiversidad de los viñedos y iii) estimar los servicios ecosistémicos que esta diversidad aporta. Se usarán tres escalas espaciales de resolución: a) Regional, considerando todos los viñedos y sistemas de manejo (convencional/ ecológico; variedades de uva) presentes en Andalucía; b) F inca, situadas en un gradiente altitudinal (proxi de Tª) y de paisaje, en las que se realizarán medidas de biodiversidad, servicios ecosistémicos, productividad, funcionalidad y sostenibilidad del viñedo frente a cambio global y c) Cepa, en las que se tomarán muestras de suelo, sarmientos, hojas, raíces, estado fisiológico, afectación por plagas, productividad y calidad. Los resultados esperamos que sirvan para: 1) mejorar predicciones y tomas de decisiones de gestión; 2) generar documentos de transferencia identificando las prácticas de manejo y uso agrícola más sostenibles que optimicen la conservación de los recursos naturales y los beneficios socioeconómicos y 3) el desarrollo de herramientas que permitan predecir efectos futuros derivados de cambio climático y de usos de suelo, así como su interacción y sus efectos sobre la biodiversidad, servicios ecosistémicos asociados y su capacidad de resiliencia.Dentro de un contexto dominado por el cambio rápido y frecuente, es básico analizar sus efectos sobre la biodiversidad y los servicios ecosistémicos que ésta provee. El cultivo de la viña es uno de los sistemas agrícolas más antiguos de la región Mediterránea, con una interacción muy estrecha entre el manejo humano y el ambiente natural circundante. El proyecto BA C O pretende, desde un enfoque multidisciplinar, evaluar el papel del clima, paisaje y manejo sobre la biodiversidad y los servicios ecosistémicos asociados a viñedos. Se proponen los siguientes objetivos: i) caracterizar el paisaje, ambiente, clima y tipo de manejo de las principales explotaciones de vid; ii) evaluar la influencia del paisaje, ambiente y manejo en la biodiversidad de los viñedos y iii) estimar los servicios ecosistémicos que esta diversidad aporta. Se usarán tres escalas espaciales de resolución: a) Regional, considerando todos los viñedos y sistemas de manejo (convencional/ ecológico; variedades de uva) presentes en Andalucía; b) F inca, situadas en un gradiente altitudinal (proxi de Tª) y de paisaje, en las que se realizarán medidas de biodiversidad, servicios ecosistémicos, productividad, funcionalidad y sostenibilidad del viñedo frente a cambio global y c) Cepa, en las que se tomarán muestras de suelo, sarmientos, hojas, raíces, estado fisiológico, afectación por plagas, productividad y calidad. Los resultados esperamos que sirvan para: 1) mejorar predicciones y tomas de decisiones de gestión; 2) generar documentos de transferencia identificando las prácticas de manejo y uso agrícola más sostenibles que optimicen la conservación de los recursos naturales y los beneficios socioeconómicos y 3) el desarrollo de herramientas que permitan predecir efectos futuros derivados de cambio climático y de usos de suelo, así como su interacción y sus efectos sobre la biodiversidad, servicios ecosistémicos asociados y su capacidad de resiliencia

Age-Associated Changes in Hearts of Male Fischer 344/Brown Norway F1 Rats

Aging is associated with left ventricular hypertrophy, dilatation, and fibrosis of the heart. The Fischer 344/Brown Norway F1 (F344/BNF1) rat is recommended for age-related studies by the National Institutes on Aging because this hybrid rat lives longer and has a lower rate of pathological conditions than inbred rats. However, little is known about age-associated changes in cardiac and aortic function and structure in this model. This study evaluated age-related cardiac changes in male F344/BNF1 rats using ECHO, gross, and microscopic examinations. Rats aged 6-, 30-, and 36-mo were anesthetized and two-dimensional ECHO measurements, two-dimensional guided M-mode, Doppler M-mode, and other recordings from parasternal long- and short-axis views were obtained using a Phillips 5500 ECHO system with a 12 megahertz transducer. Hearts and aortas from sacrificed rats were evaluated grossly and microscopically. The ECHO studies revealed persistent cardiac arrhythmias (chiefly PVCs) in 72% (13/18) of 36-mo rats, 10% (1/10) of 30-mo rats, and none in 6-mo rats (0/16). Gross and microscopic studies showed left ventricular (LV) dilatation, borderline to mild hypertrophy, and areas of fibrosis that were common in 36-mo rats, less evident in 30-mo rats, and absent in 6-mo rats. Aging was associated with mild to moderate decreases of LV diastolic and systolic function. Thus, male F344/BN F1 rats demonstrated progressive age-related (a) decline in cardiac function (diastolic and systolic indices), (b) LV structural changes (chamber dimensions, volumes, and wall thicknesses), and (c) persistent arrhythmias. These changes are consistent with those in humans. The noninvasive ECHO technique offers a means to monitor serial age-related cardiac failure and therapeutic responses in the same rats over designated time intervals

Pervasive and strong effects of plants on soil chemistry: a meta-analysis of individual plant ‘Zinke’ effects

Plant species leave a chemical signature in the soils below them, generating fine-scale spatial variation that drives ecological processes. Since the publication of a seminal paper on plant-mediated soil heterogeneity by Paul Zinke in 1962, a robust literature has developed examining effects of individual plants on their local environments (individual plant effects). Here, we synthesize this work using meta-analysis to show that plant effects are strong and pervasive across ecosystems on six continents. Overall, soil properties beneath individual plants differ from those of neighbours by an average of 41%. Although the magnitudes of individual plant effects exhibit weak relationships with climate and latitude, they are significantly stronger in deserts and tundra than forests, and weaker in intensively managed ecosystems. The ubiquitous effects of plant individuals and species on local soil properties imply that individual plant effects have a role in plant–soil feedbacks, linking individual plants with biogeochemical processes at the ecosystem scale

Desarrollo de un entorno integrado para un computador didáctico elemental, para la asignatura de Fundamentos de Informática del nuevo grado en Ingeniería de Tecnologías de Telecomunicación

El objetivo principal de este trabajo es la potenciación y mejora de la metodología docente en la asignatura de Fundamentos de Informática, asignatura obligatoria correspondiente al nuevo Grado en Ingeniería de Tecnologías de Telecomunicación de la Universidad de Granada. Para ello, se ha desarrollado un entorno integrado didáctico que engloba, en una sola aplicación, tanto el simulador como el ensamblador de un Computador Didáctico Elemental desarrollado en nuestro departamento, CODE-2, y que, además, incorpora un programa editor y un ensamblador en línea con el que el alumno puede visualizar directamente el código máquina generado por el código ensamblador que está escribiendo en tiempo real. De esta forma, conseguimos facilitar que los alumnos puedan adquirir los conocimientos necesarios para comprender el funcionamiento interno de un computador.Subvencionado parcialmente por el proyecto de Innovación Docente 10-22 de la Universidad de Granad

Solar Energy: Incentives to Promote PV in EU27

The growth in the use of renewable energies in the EU has been remarkable. Among these energies is PV. The average annual growth rate for the EU-27 countries in installed PV capacity in the period 2005-2012 was 41.2%. While the installed capacity of PV has reached almost 82 % of National Renewable Energy Action Plan (NREAP) targets for the EU-27 countries for 2020, it is still far from being used at its full potential. Over recent years, several measures have been adopted in the EU to enhance and promote PV. This paper undertakes a complete review of the state of PV power in Europe and the measures taken to date to promote it in EU-27. 25 countries have adopted measures to promote PV. The most widespread measure to promote PV use is Feed- in Tariffs. Tariffs are normally adjusted, in a decreasing manner, annually. Nevertheless, currently, seven countries have decided to accelerate this decrease rate in view of cost reduction of the installations and of higher efficiencies. The second instrument used to promote PV in the EU-27 countries is the concession of subsidies. Nevertheless, subsidies have the disadvantage of being closely linked to budgetary resources and therefore to budgetary constraints. In most EU countries, subsidies for renewable energy for PV are being lowered. Twelve EU-27 countries adopted tax measures. Low-interest loans and green certificate systems were only sparingly used

Woody lianas increase in dominance and maintain compositional integrity across an Amazonian dam-induced fragmented landscape

Tropical forest fragmentation creates insular biological communities that undergo species loss and changes in community composition over time, due to area- and edge-effects. Woody lianas thrive in degraded and secondary forests, due to their competitive advantage over trees in these habitats. Lianas compete both directly and indirectly with trees, increasing tree mortality and turnover. Despite our growing understanding of liana-tree dynamics, we lack detailed knowledge of the assemblage-level responses of lianas themselves to fragmentation, particularly in evergreen tropical forests. We examine the responses of both sapling and mature liana communities to landscape-scale forest insularization induced by a mega hydroelectric dam in the Brazilian Amazon. Detailed field inventories were conducted on islands created during reservoir filling, and in nearby mainland continuous forest. We assess the relative importance of variables associated with habitat fragmentation such as area, isolation, surrounding forest cover, fire and wind disturbance, on liana community attributes including abundance, basal area, diversity, and composition. We also explore patterns of liana dominance relative to tree saplings and adults ≥10 cm diameter at breast height. We find that 1) liana community composition remains remarkably similar across mainland continuous forest and islands, regardless of extreme area- and edge- effects and the loss of vertebrate dispersers in the latter; and 2) lianas are increasing in dominance relative to trees in the sapling layer in the most degraded islands, with both the amount of forest cover surrounding islands and fire disturbance history predicting liana dominance. Our data suggest that liana communities persist intact in isolated forests, regardless of extreme area- and edge-effects; while in contrast, tree communities simultaneously show evidence of increased turnover and supressed recruitment. These processes may lead to lianas becoming a dominant component of this dam-induced fragmented landscape in the future, due to their competitive advantage over trees in degraded forest habitats. Additional loss of tree biomass and diversity brought about through competition with lianas, and the concurrent loss of carbon storage, should be accounted for in impact assessments of future dam development