Contrasting effects of fire frequency on plant traits of three dominant perennial herbs from Chaco Serrano.

Fire frequencies are currently increasing in many regions a cross the world as a result of anthropic activities, affecting ecological processes and plant population dynamics. Fire can generate important changes in soil properties, altering nutrient dynamic sand there by plantg rowth. Here wean analyse fire frequency effects on soil quality and plant trait sof three native perennia lherbaceous plants (Cologania broussonetii, Desmodiumun cinatum and Rhynchosia edulis; Fabaceae) with the capacity for biological N2 fixation that resprouts and are abundant after fire in Chaco Serrano forests. Based on 22-year fire history, we assessed plant traits in sites with low and high fire frequencies along with unburned scenarios. We found significantly lower water content, nitrates and electrical conductivity in frequently burneds oils. As a result, the three species showed consistently lower leaf area and specific leaf area in both fire frequencies, implying lower growth rates in comparison to unburned sites. However, total leaf biomass was not affected by fire, leaf phosphorus concentration was higher in R. edulis in high fire frequency and leaf N concentration was twice as large in plants growing in sites of high fire frequencyi n C. broussonetii and R. edulis. Such an increase in N and phosphorus concentrations is likely a result of both their conservative use of resources and their biological N2 fixation capacity. To our knowledge, this is the first record of such contrasting fire effects observed consistently in three co-occurring species: while plant growth decreased with fire frequency, leaf nutritional traits remain unchanged or increased in frequently burned sites.Quality depleted and drier soils that result from in creased fire frequencies may not only affect trait variation at the intraspecific level but can also drive to a homogenization of the plant community, selecting species with particular combinations of morphologic a land functional traits.publishedVersio

El rol del herbario ACOR en la comunidad: colección, ciencia y educación.

Las colecciones representan un testigo imprescindible para la ciencia y un vehículo para arribar a posibles y adecuadas soluciones a los problemas de la comunidad. Los herbarios son el único documento de la vegetación sobre nuestro planeta que garantiza su conservación de manera permanente. Contienen la información indispensable para investigaciones en taxonomía, ecología, biogeografía, etnobotánica, anatomía, mejoramiento genético, biodiversidad agrícola, invasión de especies, fitopatología, aislamiento y síntesis de compuestos químicos orgánicos, entre otras. El herbario de la Facultad de Ciencias Agropecuarias, reconocido en el Index Herbariorum por su acrónimo ACOR, posee en la actualidad aproximadamente 20000 especímenes correspondientes a ejemplares recolectados en su hábitat natural en el centro de Argentina y a ejemplares de materiales cultivados en ensayos productivos o experimentales. Como parte de su organización merecen mencionarse las colecciones especiales de plantas forrajeras, malezas, plantas melíferas, plantas medicinales, muestras de drogas crudas comercializadas en Córdoba y plantas nativas con potencial ornamental. Durante los últimos años, los docentes, investigadores y becarios que trabajan en el herbario han centrado sus estudios en líneas de investigación relacionadas a sistemática, vegetación, etnobotánica, semillas, anatomía y morfología vegetal; han iniciado el proceso de ordenamiento y digitalización de los ejemplares con programas específicos; están desarrollando acciones que fortalecen el vínculo con instituciones educativas de los distintos niveles de enseñanza. Como respuesta a las demandas, por parte de la sociedad y en particular del sector agro-productivo, ofrece un listado de servicios a la comunidad, relacionados con la identidad y caracterización de especies vegetales. Tiene como objetivo general mantener y desarrollar una colección de la flora de la región central de Argentina con énfasis en de la flora de la provincia de Córdoba y de aquellas especies que son evaluadas en estudios botánicos y agronómicos que se llevan a cabo en ésta u otras institucionespublishedVersio

Cambios florísticos inducidos por la frecuencia de fuego en el Chaco serrano.

Las Sierras Chicas de Córdoba son el cordón montañoso con mayor frecuencia de fuego del centro de Argentina. Sin embargo, hasta el momento no se ha evaluado cuál es la respuesta de las comunidades de plantas del Chaco Serrano a los efectos de la frecuencia de fuego. En base a 23 años de historia de fuego, evaluamos la fisonomía de la vegetación, la riqueza y la composición de la comunidad de plantas vasculares en sitios no quemados, con baja y alta frecuencia de fuego en el distrito Chaqueño Serrano localizado en las Sierras Chicas de Córdoba. Encontramos que la frecuencia de fuego produce cambios en la estructura de la vegetación, en la riqueza y en la composición florística. Específicamente, observamos una disminución de la riqueza total de especies en sitios con un mayor número de eventos de fuego. Todas las formas de crecimiento mostraron una disminución de su riqueza a los efectos del fuego, a excepción de los graminoides que no mostraron cambios. Además, detectamos un cambio en la composición de especies entre los sitios quemados (ambas frecuencias) y los sitios no quemados, caracterizado por la emergencia de especies indicadoras que definen ambas condiciones. Estos resultados indican que el fuego es un fuerte proceso ecológico que estructura las comunidades vegetales, seleccionando especies con rasgos de historia de vida (i.e., rebrote y ciclo de vida) que confieren valor adaptativo a las nuevas condiciones ambientales que impone el régimen de elevada frecuencia de fuego.publishedVersio

El fuego en los ecosistemas argentinos

Este artículo pretende compartir con toda la sociedad parte del conocimiento científico desarrollado sobre nuestros ambientes propensos a incendios, tratando de responder varios aspectos desde la Ecología del Fuego. Para ello, se organiza el contenido en relación a cómo el régimen de fuego afecta las propiedades de los ecosistemas, los organismos que forman parte del mismo, y las interacciones bióticas.publishedVersionFil: Carbone, Lucas Manuel. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias; Argentina.Fil: Carbone, Lucas Manuel. Universidad Nacional de Córdoba. Instituto Multidisciplinario de Biología Vegetal (IMBIV); Argentina.Fil: Carbone, Lucas Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Instituto Multidisciplinario de Biología Vegetal (IMBIV); Argentina.Fil: Tavella, Julia. Universidad de Buenos Aires. Facultad de Agronomía. Cátedra de Botánica General; Argentina.Fil: Naval Fernández , María Cecilia. Universidad Nacional de Córdoba. Instituto de Altos Estudios Espaciales "Mario Gulich"; Argentina.Fil: Naval Fernández , María Cecilia. Comisión Nacional de Actividades Espaciales (CONAE). Instituto de Altos Estudios Espaciales "Mario Gulich"; Argentina.Fil: Bianchi, María Martha. Ministerio de Cultura. Instituto Nacional de Antropología y Pensamiento Latinoamericano (INAPL); Argentina.Fil: Bianchi, María Martha. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Argentina.Fil: Rodríguez, Juan M. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas (IIByT); Argentina.Fil: Rodríguez, Juan M. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Instituto de Investigaciones Biológicas y Tecnológicas (IIBYT); Argentina.Fil: Rodríguez, Juan M. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Centro de Ecología y Recursos Naturales Renovables Dr. R. Luti (CERNAR); Argentina.Fil: Marcora, Paula. Universidad Nacional de Córdoba. Instituto Multidisciplinario de Biología Vegetal (IMBIV); Argentina.Fil: Marcora, Paula. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Instituto Multidisciplinario de Biología Vegetal (IMBIV); Argentina.Fil: Longo, Silvana. Universidad Nacional de Córdoba. Instituto Multidisciplinario de Biología Vegetal (IMBIV); Argentina.Fil: Longo, Silvana. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Instituto Multidisciplinario de Biología Vegetal (IMBIV); Argentina.Fil: Urcelay, Carlos. Universidad Nacional de Córdoba. Instituto Multidisciplinario de Biología Vegetal (IMBIV); Argentina.Fil: Urcelay, Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Instituto Multidisciplinario de Biología Vegetal (IMBIV); Argentina.Fil: Jaureguiberry, Pedro. Universidad Nacional de Córdoba. Instituto Multidisciplinario de Biología Vegetal (IMBIV); Argentina.Fil: Jaureguiberry, Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Instituto Multidisciplinario de Biología Vegetal (IMBIV); Argentina.Fil: Landi, Marcos. Universidad Nacional de Córdoba. Instituto de Altos Estudios Espaciales "Mario Gulich"; Argentina.Fil: Landi, Marcos. Comisión Nacional de Actividades Espaciales (CONAE). Instituto de Altos Estudios Espaciales "Mario Gulich"; Argentina.Fil: Landi, Marcos. Universidad Nacional de Córdoba. Centro de Investigación y Estudios de Matemática (CIEM); Argentina.Fil: Landi, Marcos. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Centro de Investigación y Estudios de Matemática (CIEM); Argentina.Fil: Bravo, Sandra. Universidad Nacional de Santiago del Estero. Facultad de Ciencias Forestales; Argentina.Fil: Blackhall, Melisa. Universidad Nacional del Comahue. Instituto de Investigaciones en Biodiversidad y Medioambiente. Laboratorio Ecotono; Argentina.Fil: Blackhall, Melisa. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Instituto de Investigaciones en Biodiversidad y Medioambiente. Laboratorio Ecotono; Argentina

Peptide-MHC heterodimers show that thymic positive selection requires a more restricted set of self-peptides than negative selection

T cell selection and maturation in the thymus depends on the interactions between T cell receptors (TCRs) and different self-peptide–major histocompatibility complex (pMHC) molecules. We show that the affinity of the OT-I TCR for its endogenous positively selecting ligands, Catnb-H-2Kb and Cappa1-H-2Kb, is significantly lower than for previously reported positively selecting altered peptide ligands. To understand how these extremely weak endogenous ligands produce signals in maturing thymocytes, we generated soluble monomeric and dimeric peptide–H-2Kb ligands. Soluble monomeric ovalbumin (OVA)-Kb molecules elicited no detectable signaling in OT-I thymocytes, whereas heterodimers of OVA-Kb paired with positively selecting or nonselecting endogenous peptides, but not an engineered null peptide, induced deletion. In contrast, dimer-induced positive selection was much more sensitive to the identity of the partner peptide. Catnb-Kb–Catnb-Kb homodimers, but not heterodimers of Catnb-Kb paired with a nonselecting peptide-Kb, induced positive selection, even though both ligands bind the OT-I TCR with detectable affinity. Thus, both positive and negative selection can be driven by dimeric but not monomeric ligands. In addition, positive selection has much more stringent requirements for the partner self-pMHC

Post-2020 climate agreements in the major economies assessed in the light of global models

Integrated assessment models can help in quantifying the implications of international climate agreements and regional climate action. This paper reviews scenario results from model intercomparison projects to explore different possible outcomes of post-2020 climate negotiations, recently announced pledges and their relation to the 2 °C target. We provide key information for all the major economies, such as the year of emission peaking, regional carbon budgets and emissions allowances. We highlight the distributional consequences of climate policies, and discuss the role of carbon markets for financing clean energy investments, and achieving efficiency and equity

Leaf colour as a signal of chemical defence to insect herbivores in wild cabbage (Brassica Oleracea)

Leaf colour has been proposed to signal levels of host defence to insect herbivores, but we lack data on herbivory, leaf colour and levels of defence for wild host populations necessary to test this hypothesis. Such a test requires measurements of leaf spectra as they would be sensed by herbivore visual systems, as well as simultaneous measurements of chemical defences and herbivore responses to leaf colour in natural host-herbivore populations. In a large-scale field survey of wild cabbage (Brassica oleracea) populations, we show that variation in leaf colour and brightness, measured according to herbivore spectral sensitivities, predicts both levels of chemical defences (glucosinolates) and abundance of specialist lepidopteran (Pieris rapae) and hemipteran (Brevicoryne brassicae) herbivores. In subsequent experiments, P. rapae larvae achieved faster growth and greater pupal mass when feeding on plants with bluer leaves, which contained lower levels of aliphatic glucosinolates. Glucosinolate-mediated effects on larval performance may thus contribute to the association between P. rapae herbivory and leaf colour observed in the field. However, preference tests found no evidence that adult butterflies selected host plants based on leaf coloration. In the field, B. brassicae abundance varied with leaf brightness but greenhouse experiments were unable to identify any effects of brightness on aphid preference or performance. Our findings suggest that although leaf colour reflects both levels of host defences and herbivore abundance in the field, the ability of herbivores to respond to colour signals may be limited, even in species where performance is correlated with leaf colour

How much leaf area do insects eat? A data set of insect herbivory sampled globally with a standardized protocol

Herbivory is ubiquitous. Despite being a potential driver of plant distribution and performance, herbivory remains largely undocumented. Some early attempts have been made to review, globally, how much leaf area is removed through insect feeding. Kozlov et al., in one of the most comprehensive reviews regarding global patterns of herbivory, have compiled published studies regarding foliar removal and sampled data on global herbivory levels using a standardized protocol. However, in the review by Kozlov et al., only 15 sampling sites, comprising 33 plant species, were evaluated in tropical areas around the globe. In Brazil, which ranks first in terms of plant biodiversity, with a total of 46,097 species, almost half (43%) being endemic, a single data point was sampled, covering only two plant species. In an attempt to increase knowledge regarding herbivory in tropical plant species and to provide the raw data needed to test general hypotheses related to plant–herbivore interactions across large spatial scales, we proposed a joint, collaborative network to evaluate tropical herbivory. This network allowed us to update and expand the data on insect herbivory in tropical and temperate plant species. Our data set, collected with a standardized protocol, covers 45 sampling sites from nine countries and includes leaf herbivory measurements of 57,239 leaves from 209 species of vascular plants belonging to 65 families from tropical and temperate regions. They expand previous data sets by including a total of 32 sampling sites from tropical areas around the globe, comprising 152 species, 146 of them being sampled in Brazil. For temperate areas, it includes 13 sampling sites, comprising 59 species

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries