1. Metal mining in drylands generates waste tailings with high toxicity, physical instability, as well as water and thermal stresses that hamper their biological colonization. This limits the ...restoration of ecosystem functions that are essential to re-integrate these artificial micro-deserts within the landscape matrix. 2. We assessed the functional role of local nurse plant species and their traits to restore ecosystem functions related to soil fertility, soil microbial productivity and the reduction of abiotic stress. We sampled 30 metalliferous tailings in a mining district from semi-arid Spain to detect nurse plant species and quantify their ability to promote essential functions from their establishment on the barren substrate up to the adult stage. 3. We found 11 plant species acting as nurses out of 102 species able to colonize barren soils. Ten nurses further triggered a cascade of effects increasing soil fertility and microbial productivity and/or lowering soil abiotic stress. 4. Plant species with larger life-forms and longer periods of establishment since tailing abandonment contributed the most to the promotion of ecosystem functions. C4 plant species developing root systems with lower intensivity and depth:laterality ratios, as well as leaves with lower carbon:nitrogen ratios (C:N) induced a faster recovery of ecosystem functions. 5. Synthesis and applications. We propose a protocol for selecting key species to be used in restoration programmes based on their ability to restore ecosystem functions under extremely stressful conditions. We encourage combination of multiple target species with complementary traits in order to reinforce the rehabilitation of ecosystem functions.
Plant facilitation, an ecological interaction that benefits at least one species without harming the other, is increasingly used as a restoration tool. To restore degraded habitats under a ...facilitation framework, practitioners must correctly select both the benefactor (nurse) and the beneficiary (facilitated) species.
Based on community assembly and species coexistence theory, we propose selecting plant species that largely differ in a suite of functional traits so that competition is minimized and facilitation maximized due to functional complementarity. To apply this guideline in a pilot restoration experiment performed in metalliferous mine tailings in South‐Eastern Spain, we first built the plant–plant facilitative interaction network naturally occurring in a set of 12 tailings. After characterizing each species with 20 morphological and physiological traits, we verified that facilitative interactions were predominantly established between functionally distant species.
Then, we designed a sowing experiment combining 50 nurse‐facilitated species pairs separated by a wide range of functional distances. The success of seedling establishment significantly increased with the functional distance between the nurse and the facilitated plant species.
Synthesis and applications. We encourage the use of ecological facilitation together with trait‐based species selection to design restoration programmes based on the principle of increasing functional distance between target species. This method may not only promote the restoration of the plant cover but also impact paramount ecosystem functions, thus being an efficient low‐cost restoration practice in abiotically stressful ecosystems.
We encourage the use of ecological facilitation together with trait‐based species selection to design restoration programmes based on the principle of increasing functional distance between target species. This method may not only promote the restoration of the plant cover but also impact paramount ecosystem functions, thus being an efficient low‐cost restoration practice in abiotically stressful ecosystems.
Fire alters the structure and composition of above‐ and belowground communities with concurrent shifts in phylogenetic diversity. The inspection of postfire trends in the diversity of ecological ...communities incorporating phylogenetic information allows to better understand the mechanisms driving fire resilience. While fire reduces plant phylogenetic diversity based on the recruitment of evolutionarily related species with postfire seed persistence, it increases that of soil microbes by limiting soil resources and changing the dominance of competing microbes. Thus, during postfire community reassembly, plant and soil microbes might experience opposing temporal trends in their phylogenetic diversity that are linked through changes in the soil conditions. We tested this hypothesis by investigating the postfire evolution of plant and soil microbial (fungi, bacteria and archaea) communities across three 20‐year chronosequences. Plant phylogenetic diversity increased with time since fire as pioneer seeders facilitate the establishment of distantly related late‐successional shrubs. The postfire increase in plant phylogenetic diversity fostered plant productivity, eventually recovering soil organic matter. These shifts over time in the soil conditions explained the postfire restoration of fungal and bacterial phylogenetic diversity, which decreased to prefire levels, suggesting that evolutionarily related taxa with high relative fitness recover their competitive superiority during community reassembly. The resilience to fire of phylogenetic diversity across biological domains helps preserve the evolutionary history stored in our ecosystems.
Highlights • Healthy-life expectancy is shorter than life expectancy. • Frailty reflects vulnerability due to exhaustion of body systems. • Multimorbidity defines a synergy of two or more different ...individual diseases. • Both frailty and multimorbidity are predictors of disability and mortality.
Nurse plants drive the assembly of facilitated communities and commonly promote plant–soil feedbacks, and are thus recognized as key engineers in abiotically stressful ecosystems. The literature ...neglects; however, the role of the communities which benefit from the presence of the nurse as contributors to soil ecosystem functions. We hypothesized that the nurse and its beneficiaries synergistically enhance essential ecosystem functions mediated by soil microbiota.
To track how plant–plant facilitation impacts plant–soil feedbacks, we selected three nurse species in semi‐arid mine tailings and defined three microsites (open space, nurse canopy and nurse + facilitated canopy). In each microsite, we quantified 18 abiotic and biotic variables associated with four functions: reduction in climatic stress, reduction in edaphic stress, soil fertility and soil microbial productivity (decomposition and nutrient cycling).
Litter biomass increased from open spaces to the microsite beneath the nurses, and further beneath the nurses and their beneficiaries. Litter biomass was a good predictor of both the reduction in climatic stress and increase in edaphic stress (likely owing to metal bioaccumulation). We attributed increments in soil organics and heterotrophic respiration beneath the nurses and their beneficiaries, compared to nurses alone, to biomass effects through increased litter deposition. Variation in fertility and microbial productivity among microsites shaped by the nurses and their facilitated communities was attributed to both diversity and biomass effects. In particular, fertility was promoted beneath phenotypically diverse facilitated communities, as inferred from ten above‐ and below‐ground traits. However, microbial productivity increased at low levels of root biomass likely due to reduced plant–microbe competition for nutrients.
Synthesis. Our results show that facilitated plant communities sheltered by nurse species relieve local abiotic stress and promote plant–microbe interactions, both through biomass and biodiversity effects. These observations shift the conception of facilitated species from simple beneficiaries of the nurse's effects to co‐drivers of essential ecosystem functions.
Resumen
Las plantas nodriza actúan como especies clave ensamblando la comunidad vegetal y promoviendo las interacciones planta‐suelo en ecosistemas de alto estrés gobernados por facilitación. Sin embargo, habitualmente se ignora el papel adicional que la comunidad de especies facilitadas puede ejercer sobre las funciones ecosistémicas del suelo. En este trabajo hipotetizamos que la comunidad de plantas facilitadas contribuye sinérgicamente con la nodriza a la mejora de funciones ecosistémicas mediadas por la microbiota edáfica.
Para evaluar cómo la facilitación entre plantas promueve las interacciones planta‐suelo seleccionamos tres nodrizas en depósitos mineros con vegetación parcheada en ambientes semiáridos y definimos tres micrositios (claro, copa bajo nodriza y copa bajo nodriza con comunidad de facilitadas). Posteriormente, cuantificamos en dichos micrositios 18 variables abióticas y bióticas relacionadas con cuatro funciones principales: reducción del estrés climático, reducción del estrés edáfico, fertilidad edáfica y productividad microbiana (descomposición y ciclado de nutrientes).
La biomasa de hojarasca aumentó en el sentido claro < nodriza <nodriza con facilitadas, y fue un buen predictor de la reducción del estrés climático, aunque incrementó la concentración edáfica de algunos metales pesados. Observamos un incremento de la fertilidad y de la respiración heterotrófica en el micrositio nodriza con facilitadas con respecto a la nodriza, que atribuimos a un efecto del aumento en biomasa (biomass effect) promovido por una mayor deposición de hojarasca. La variabilidad en la fertilidad y productividad microbiana bajo la nodriza con facilitadas la atribuimos tanto a un efecto de la variación en biomasa como en diversidad (diversity effect). En particular, la fertilidad se incrementó en comunidades de facilitadas más diversas fenotípicamente (fenotipo medido a partir de 10 rasgos aéreos y subterráneos). Por el contrario, la productividad microbiana aumentó en micrositios nodriza + facilitada con una menor biomasa de raíces, probablemente debido a una menor competencia planta‐microorganismo por los nutrientes.
Síntesis. Nuestros resultados cambian la concepción de las especies facilitadas como meras beneficiarias de la presencia de una nodriza, para atribuirles un papel como promotoras de funciones ecosistémicas esenciales, mediadas por los efectos de la diversidad y biomasa sobre el estrés abiótico y las interacciones con la microbiota edáfica.
Our results show that facilitated plant communities sheltered by nurse species relieve local abiotic stress and promote plant–microbe interactions, both through biomass and biodiversity effects. These observations shift the conception of facilitated species from simple beneficiaries of the nurse’s effects to co‐drivers of essential ecosystem functions.
This article examines competitive balance in the group stage of the UEFA Champions League over the last two decades (1999/2000–2017/2018). Competitive balance is considered both before and after a ...competition. Have the groups been designed in such a way as to ensure similar levels of competitive balance ex ante? Have the demonstrated strengths (ex post competitive balance) of the different groups been similar over each season? What is the relationship between the competitive balance in the designed groups and that achieved in the same groups after the competition? Are the performance achieved in terms of ex post competitive balance similar to ex ante competitive balance levels? We found that, despite expectations, the groups' ex ante competitive balance was not homogeneous. Although ex ante competitive balance serves as a good predictor, on average, of ex post competitive balance, we observed significant differences at the levels of group and seasons. Therefore, it is possible to improve the design mechanism of the groups that make up the group stage of the champions so that they are composed homogeneously in terms of ex ante competitive balance.
Summary
Nitric oxide (NO) is a signalling molecule in eukaryotic and prokaryotic organisms. NO levels transiently boost upon induction of conidiation in Aspergillus nidulans. Only one pathway for NO ...synthesis involving nitrate reductase has been reported in filamentous fungi so far, but this does not satisfy all the NO produced in fungal cells. Here we provide evidence for at least one additional biosynthetic pathway in A. nidulans involving l‐arginine or an intermediate metabolite as a substrate. Under certain growth conditions, the addition of l‐arginine to liquid media elicited a burst of NO that was not dependent on any of the urea cycle genes. The NO levels were controlled by the metabolically available arginine, which was regulated by mobilization from the vacuoles and during development. In vitro assays with protein extracts and amino acid profiling strongly suggested the existence of an arginine‐dependent NO pathway analogous to the mammalian NO synthase. Addition of polyamines induced NO synthesis, and mutations in the polyamine synthesis genes puA and spdA reduced the production of NO. In conclusion, here we report an additional pathway for the synthesis of NO in A. nidulans using urea cycle intermediates.
Authorities in the economic field (European Commission and US Federal Trade Commission) focus on the level of market concentration and establish limits in order to promote competition. However, ...sports authorities do not seem to pay the same attention to competitive balance in the national leagues, given the results achieved in the major leagues and limited interventions and regulations in this area. How are the major European football leagues evaluated based on the limits set for market concentration in the United States or the European Union? Following this line, we undertook a comparative analysis using the distance to competitive balance index, whose range is the unit interval, and define it as a function in a metric space. The comparative analysis shows, as in other studies, the high and ever‐growing concentration of the results of these leagues over the past 25 years. With the European Commission and US Federal Trade Commission criteria, about one in three seasons would have been highly concentrated in the period analysed, and half in the last 10 seasons. Thus, it would seem reasonable that mechanisms that encourage competitiveness are considered.
This article augments the literature on the analysis of competitive balance, encompassing its measurement, comparisons across leagues and seasons, and ramifications for league management. Central to ...our examination is the notion of competitive balance, which is intimately tied to the concentration concept. This concept can be depicted as a dual metric—capturing both inequality and the number of competing teams. Historically, its magnitude has been gauged using standardised measures of inequality and concentration. Among these, the Herfindahl–Hirschman index and its subsequent refinements stand out. We employ the distance‐to‐competitive‐balance index, which, contingent upon the metric space chosen, qualifies either as an inequality or concentration measure. Our analysis spans the 2009/2010 to 2018/2019 seasons for both the Union of European Football Associations (UEFA) and South American Football Confederation (CONMEBOL) championships in the pre‐COVID‐19 era. We discern a tangible and significant correlation between the competitive equilibrium of leagues and the performance metrics of national teams. Both the disparities in strengths of teams and the number of participating teams emerged as paramount variables shaping this competitive balance. Further, we delineate the elasticities of competitive balance relative to these determinants. Our insights bear implications for designing football championship structures and delineating sports policies; thus, they are valuable for relevant sports governing bodies and federations. The strategic decision to enlarge team count vis‐à‐vis curtailing discrepancies in team competencies is nuanced, varying across federations and confederations. The Big Five European leagues display heightened sensitivity to inequality factors (with interventions such as financial fair play, salary caps or revenue distribution yielding pronounced effects), whereas for CONMEBOL, elasticity in relation to team count holds greater significance.
This paper presents the design, modeling and control of a fully actuated aerial robot for infrastructure contact inspection as well as its localization system. Health assessment of transport ...infrastructure involves measurements with sensors in contact with the bridge and tunnel surfaces and the installation of monitoring sensing devices at specific points. The design of the aerial robot presented in the paper includes a 3DoF lightweight arm with a sensorized passive joint which can measure the contact force to regulate the force applied with the sensor on the structure. The aerial platform has been designed with tilted propellers to be fully actuated, achieving independent attitude and position control. It also mounts a “docking gear” to establish full contact with the infrastructure during the inspection, minimizing the measurement errors derived from the motion of the aerial platform and allowing full contact with the surface regardless of its condition (smooth, rough, ...). The localization system of the aerial robot uses multi-sensor fusion of the measurements of a topographic laser sensor on the ground and a tracking camera and inertial sensors on-board the aerial robot, to be able to fly under the bridge deck or close to the bridge pillars where GNSS satellite signals are not available. The paper also presents the modeling and control of the aerial robot. Validation experiments of the localization system and the control system, and with the aerial robot inspecting a real bridge are also included.
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