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There is an ongoing unprecedented loss in insects, both in terms of richness and biomass. The usage of pesticides, especially neonicotinoid insecticides, has been widely suggested to be a contributor to this decline. However, the risks of neonicotinoids to natural insect populations have remained largely unknown due to a lack of field-realistic experiments. Here, we used an outdoor experiment to determine effects of field-realistic concentrations of the commonly applied neonicotinoid thiacloprid on the emergence of naturally assembled aquatic insect populations. Following application, all major orders of emerging aquatic insects (Coleoptera, Diptera, Ephemeroptera, Odonata, and Trichoptera) declined strongly in both abundance and biomass. At the highest concentration (10 µg/L), emergence of most orders was nearly absent. Diversity of the most species-rich family, Chironomidae, decreased by 50% at more commonly observed concentrations (1 µg/L) and was generally reduced to a single species at the highest concentration. Our experimental findings thereby showcase a causal link of neonicotinoids and the ongoing insect decline. Given the urgency of the insect decline, our results highlight the need to reconsider the mass usage of neonicotinoids to preserve freshwater insects as well as the life and services depending on them.
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Organismos Acuáticos , Ecosistema , Insectos , Insecticidas , Neonicotinoides , Tiazinas , Animales , Pruebas de ToxicidadRESUMEN
Climate change impacts on freshwater ecosystems and freshwater biodiversity show strong spatial variability, highlighting the importance of a global perspective. While previous studies on biodiversity mostly focused on species richness, functional diversity, which is a better predictor of ecosystem functioning, has received much less attention. This study aims to comprehensively assess climate change threats to the functional diversity of freshwater fish across the world, considering three complementary metrics-functional richness, evenness and divergence. We built on existing spatially explicit projections of geographical ranges for 11,425 riverine fish species as affected by changes in streamflow and water temperature extremes at four warming levels (1.5°C, 2.0°C, 3.2°C and 4.5°C). To estimate functional diversity, we considered the following four continuous, morphological and physiological traits: relative head length, relative body depth, trophic level and relative growth rate. Together, these traits cover five ecological functions. We treated missing trait values in two different ways: we either removed species with missing trait values or imputed them. Depending on the warming level, 6%-25% of the locations globally face a complete loss of functional diversity when assuming no dispersal (6%-17% when assuming maximal dispersal), with hotspots in the Amazon and Paraná River basins. The three facets of functional diversity do not always follow the same pattern. Sometimes, functional richness is not yet affected despite species loss, while functional evenness and divergence are already reducing. Other times, functional richness reduces, while functional evenness and/or divergence increase instead. The contrasting patterns of the three facets of functional diversity show their complementarity among each other and their added value compared to species richness. With increasing climate change, impacts on freshwater communities accelerate, making early mitigation critically important.
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Cambio Climático , Ecosistema , Animales , Biodiversidad , Agua Dulce , PecesRESUMEN
The increasing application of synthetic fertilizer has tripled nitrogen (N) inputs over the 20th century. N enrichment decreases water quality and threatens aquatic species such as fish through eutrophication and toxicity. However, the impacts of N on freshwater ecosystems are typically neglected in life cycle assessment (LCA). Due to the variety of environmental conditions and species compositions, the response of species to N emissions differs among ecoregions, requiring a regionalized effect assessment. Our study tackled this issue by establishing regionalized species sensitivity distributions (SSDs) of freshwater fish against N concentrations for 367 ecoregions and 48 combinations of realms and major habitat types globally. Subsequently, effect factors (EFs) were derived for LCA to assess the effects of N on fish species richness at a 0.5 degree × 0.5 degree resolution. Results show good SSD fits for all of the ecoregions that contain sufficient data and similar patterns for average and marginal EFs. The SSDs highlight strong effects on species richness due to high N concentrations in the tropical zone and the vulnerability of cold regions. Our study revealed the regional differences in sensitivities of freshwater ecosystems against N content in great spatial detail and can be used to assess more precisely and comprehensively nutrient-induced impacts in LCA.
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Ecosistema , Nitrógeno , Animales , Peces/fisiología , Agua Dulce , Calidad del Agua , BiodiversidadRESUMEN
While wild pollinators play a key role in global food production, their assessment is currently missing from the most commonly used environmental impact assessment method, Life Cycle Assessment (LCA). This is mainly due to constraints in data availability and compatibility with LCA inventories. To target this gap, relative pollinator abundance estimates were obtained with the use of a Delphi assessment, during which 25 experts, covering 16 nationalities and 45 countries of expertise, provided scores for low, typical, and high expected abundance associated with 24 land use categories. Based on these estimates, this study presents a set of globally generic characterization factors (CFs) that allows translating land use into relative impacts to wild pollinator abundance. The associated uncertainty of the CFs is presented along with an illustrative case to demonstrate the applicability in LCA studies. The CFs based on estimates that reached consensus during the Delphi assessment are recommended as readily applicable and allow key differences among land use types to be distinguished. The resulting CFs are proposed as the first step for incorporating pollinator impacts in LCA studies, exemplifying the use of expert elicitation methods as a useful tool to fill data gaps that constrain the characterization of key environmental impacts.
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Conservación de los Recursos Naturales , Animales , Conservación de los Recursos Naturales/métodos , Alimentos , Estadios del Ciclo de VidaRESUMEN
To prevent the non-acceptable effects of agrochemicals on arable fields, Environmental Risk Assessment (ERA) aims to assess and protect against a wide range of risks due to stressors to non-target species. While exposure to stress is a key factor in ERA models, exposure values are difficult to obtain and rely on laboratory studies with often debatable relevance to field situations. To improve intake estimates, data from realistic field-based scenarios are needed. We developed calibration curves relating known seed numbers of up to 20 onion and carrot seeds consumed by wild-caught wood mice (Apodemus sylvaticus) to the seed DNA content in the feces. Based on these inferred quantitative relationships, a field trial was run to determine seed intake in a natural setting using realistic levels of seed spillage. Onion DNA was detected in the fecal samples of the wood mice caught in the field, which resembled a seed intake of up to 1 onion seed. No intake of carrot seeds was detected. This is the first-ever study to quantify seed intake in a realistic field scenario using a DNA-based analysis, showing that accurate seed intake estimates can be obtained. Our approach can help to improve risk assessment models through its minimally-invasive and accurate assessment of seed intake by ERA representative and non-target species, which would otherwise be undetectable with traditional methods. Our novel approach and its results are highly relevant to studies of food intake and diet composition for basic and applied research alike.
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Mamíferos , Murinae , Animales , Ratones , Heces/química , ADN , Medición de Riesgo , SemillasRESUMEN
Some commonly reported trait-trait relationships between species, including the leaf economic spectrum (LES), are regarded as important plant strategies but whether these relationships represent plant strategies in reality remains unclear. We propose a novel approach to distinguish trait-trait relationships between species that may represent plant strategies vs those relationships that are the result of common drivers, by comparing the direction and strength of intraspecific trait variation (ITV) vs interspecific trait variation. We applied this framework using a unique global ITV database that we compiled, which included 11 traits related to LES, size and roots, and observations from 2064 species occurring in 1068 communities across 19 countries. Generally, compared to between species, trait-trait relationships within species were much weaker or totally disappeared. Almost only within the LES traits, the between-species trait-trait relationships were translated into positive relationships within species, which suggests that they may represent plant strategies. Moreover, the frequent coincidental trait-trait relationships between species, driven by co-varying common drivers, imply that in future research, decoupling of trait-trait relationships should be considered seriously in model projections of ecosystem functioning. Our study emphasizes the importance of describing the mechanisms behind trait-trait relationships, both between and within species, for deepening our understanding of general plant strategies.
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Ecosistema , Hojas de la Planta , Fenotipo , Plantas/genéticaRESUMEN
BACKGROUND AND AIMS: While trait-based approaches have provided critical insights into general plant functioning, we lack a comprehensive quantitative view on plant strategies in flooded conditions. Plants adapted to flooded conditions have specific traits (e.g. root porosity, low root/shoot ratio and shoot elongation) to cope with the environmental stressors including anoxic sediments, and the subsequent presence of phytotoxic compounds. In flooded habitats, plants also respond to potential nutrient and light limitations, e.g. through the expression of leaf economics traits and size-related traits, respectively. However, we do not know whether and how these trait dimensions are connected. METHODS: Based on a trait dataset compiled on 131 plant species from 141 studies in flooded habitats, we quantitatively analysed how flooding-induced traits are positioned in relation to the other two dominant trait dimensions: leaf economics traits and size-related traits. We evaluated how these key trait components are expressed along wetness gradients, across habitat types and among plant life forms. KEY RESULTS: We found that flooding-induced traits constitute a trait dimension independent from leaf economics traits and size-related traits, indicating that there is no generic trade-off associated with flooding adaptations. Moreover, individual flooding-induced traits themselves are to a large extent decoupled from each other. These results suggest that adaptation to stressful environments, such as flooding, can be stressor specific without generic adverse effects on plant functioning (e.g. causing trade-offs on leaf economics traits). CONCLUSIONS: The trait expression across multiple dimensions promotes plant adaptations and coexistence across multifaceted flooded environments. The decoupled trait dimensions, as related to different environmental drivers, also explain why ecosystem functioning (including, for example, methane emissions) are species and habitat specific. Thus, our results provide a backbone for applying trait-based approaches in wetland ecology by considering flooding-induced traits as an independent trait dimension.
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Ecosistema , Inundaciones , Metano , Hojas de la Planta , Fenómenos Fisiológicos de las Plantas , Plantas/genéticaRESUMEN
Decision support tools such as life cycle assessment (LCA) increasingly aim to account for impacts on biodiversity. While taxonomic measures like species richness have been implemented, they do not fully grasp the impacts on ecosystem functioning. Functional diversity, derived from the species' traits, is more representative of ecosystem processes. This study provides a framework for developing characterization factors for functional diversity as affected by land use. It exploits the large databases on plant traits and species composition that have recently become available and allow bringing biodiversity impact assessment to the next level. Three functional diversity indices therein describe different aspects of functional diversity, namely richness, evenness, and divergence. Applying our framework to Germany as a proof of concept, we show significant losses in functional plant diversity when converting natural forests to agricultural land use. Consistently across different forests and agricultural systems, functional richness decreases steeply and functional divergence moderately upon occupation. In contrast, functional evenness exhibits opposite trends. The resulting characterization factors are likely to be representative of temperate regions. The framework is flexible and applicable to larger scales and other impact categories. As such, it facilitates harmonizing biodiversity impact assessments and better represents ecosystem functioning by incorporating functional diversity.
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Biodiversidad , Ecosistema , Bosques , Alemania , PlantasRESUMEN
Plant species diversity in Eurasian wetlands and grasslands depends not only on productivity but also on the relative availability of nutrients, particularly of nitrogen and phosphorus. Here we show that the impacts of nitrogen:phosphorus stoichiometry on plant species richness can be explained by selected plant life-history traits, notably by plant investments in growth versus reproduction. In 599 Eurasian sites with herbaceous vegetation we examined the relationship between the local nutrient conditions and community-mean life-history traits. We found that compared with plants in nitrogen-limited communities, plants in phosphorus-limited communities invest little in sexual reproduction (for example, less investment in seed, shorter flowering period, longer lifespan) and have conservative leaf economy traits (that is, a low specific leaf area and a high leaf dry-matter content). Endangered species were more frequent in phosphorus-limited ecosystems and they too invested little in sexual reproduction. The results provide new insight into how plant adaptations to nutrient conditions can drive the distribution of plant species in natural ecosystems and can account for the vulnerability of endangered species.
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Adaptación Fisiológica , Fósforo/deficiencia , Fósforo/metabolismo , Plantas/metabolismo , Biodiversidad , Conservación de los Recursos Naturales , Especies en Peligro de Extinción , Extinción Biológica , Nitrógeno/metabolismo , Hojas de la Planta/metabolismo , Haz Vascular de Plantas/metabolismo , Plantas/anatomía & histología , ReproducciónRESUMEN
Our ability to understand and predict the response of ecosystems to a changing environment depends on quantifying vegetation functional diversity. However, representing this diversity at the global scale is challenging. Typically, in Earth system models, characterization of plant diversity has been limited to grouping related species into plant functional types (PFTs), with all trait variation in a PFT collapsed into a single mean value that is applied globally. Using the largest global plant trait database and state of the art Bayesian modeling, we created fine-grained global maps of plant trait distributions that can be applied to Earth system models. Focusing on a set of plant traits closely coupled to photosynthesis and foliar respiration-specific leaf area (SLA) and dry mass-based concentrations of leaf nitrogen ([Formula: see text]) and phosphorus ([Formula: see text]), we characterize how traits vary within and among over 50,000 [Formula: see text]-km cells across the entire vegetated land surface. We do this in several ways-without defining the PFT of each grid cell and using 4 or 14 PFTs; each model's predictions are evaluated against out-of-sample data. This endeavor advances prior trait mapping by generating global maps that preserve variability across scales by using modern Bayesian spatial statistical modeling in combination with a database over three times larger than that in previous analyses. Our maps reveal that the most diverse grid cells possess trait variability close to the range of global PFT means.
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Ecosistema , Plantas , Carácter Cuantitativo Heredable , Ambiente , Geografía , Modelos Estadísticos , Dispersión de las Plantas , Análisis EspacialRESUMEN
Microplastics attract widespread attention, including for their potential to transport toxic chemicals in the form of plasticisers and associated hydrophobic organic chemicals, such as polybrominated diphenyl ethers (PBDEs). The aims of this study were to investigate how nylon (polyamide) microplastics may affect PBDE accumulation in snails, and the acute effects of nylon particles and PBDEs on survival, weight change and inherent microbiome diversity and community composition of the pond snail Lymnaea stagnalis. Snails were exposed for 96â¯h to BDEs-47, 99, 100 and 153 in the presence and absence of 1% w/w nylon microplastics in quartz sand sediment. No mortality was observed over the exposure period. Snails not exposed to microplastics lost significantly more weight compared to those exposed to microplastics. Increasing PBDE concentration in the sediment resulted in an increased PBDE body burden in the snails, however microplastics did not significantly influence total PBDE uptake. Based on individual congeners, uptake of BDE 47 by snails was significantly reduced in the presence of microplastics. The diversity and composition of the snail microbiome was not significantly altered by the presence of PBDEs nor by the microplastics, singly or combined. Significant effects on a few individual operational taxonomic units (OTUs) occurred when comparing the highest PBDE concentration with the control treatment, but in the absence of microplastics only. Overall within these acute experiments, only subtle effects on weight loss and slight microbiome alterations occurred. These results therefore highlight that L. stagnalis are resilient to acute exposures to microplastics and PBDEs, and that microplastics are unlikely to influence HOC accumulation or the microbiome of this species over short timescales.
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Éteres Difenilos Halogenados/metabolismo , Lymnaea/efectos de los fármacos , Microbiota/efectos de los fármacos , Microplásticos/toxicidad , Contaminantes Químicos del Agua/metabolismo , Animales , Carga Corporal (Radioterapia) , Exposición a Riesgos Ambientales/análisis , Retardadores de Llama/análisis , Retardadores de Llama/metabolismo , Retardadores de Llama/toxicidad , Éteres Difenilos Halogenados/análisis , Éteres Difenilos Halogenados/toxicidad , Lymnaea/metabolismo , Lymnaea/microbiología , Nylons/toxicidad , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/toxicidadRESUMEN
Hundreds of nonphotosynthetic mycoheterotrophic plant species cheat the arbuscular mycorrhizal symbiosis. Their patchy local occurrence suggests constraints by biotic and abiotic factors, among which the role of soil chemistry and nutrient status has not been investigated. Here, we examine the edaphic drivers predicting the local-scale distribution of mycoheterotrophic plants in two lowland rainforests in South America. We compared soil chemistry and nutrient status in plots where mycoheterotrophic plants were present with those without these plants. Soil pH, soil nitrate, and the interaction between soil potassium and nitrate concentrations were the best predictors for the occurrence of mycoheterotrophic plants in these tropical rainforests. Mycoheterotrophic plant occurrences decreased with a rise in each of these predictors. This indicates that these plants are associated with low-fertility patches. Such low-fertility conditions coincide with conditions that potentially favour a weak mutualism between plants and arbuscular mycorrhizal fungi according to the trade balance model. Our study points out which soil properties favour the cheating of arbuscular mycorrhizal networks in tropical forests. The patchy occurrence of mycoheterotrophic plants suggests that local soil heterogeneity causes the stability of arbuscular mycorrhizal networks to vary at a very small scale.
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Micorrizas/fisiología , Bosque Lluvioso , Simbiosis/fisiología , Modelos Lineales , Análisis de Componente Principal , Suelo , Microbiología del SueloRESUMEN
Electronic and electrical equipment contains over 1000 different substances, including metals. During informal e-waste recycling some of these substances such as metals, are released into the environment causing environmental pollution. This study assessed the impact of different informal e-waste recycling activities (burning, dismantling, and repairing) on metal concentrations in top soils and various dust. A comparative cross-sectional study design was adopted to assess metal concentrations in top soils and in various dust samples from multiple e-waste recycling sites. Metal concentrations at e-waste recycling sites were compared to the concentrations at control sites in three study locations in Nigeria (Lagos, Ibadan, and Aba). In the three study locations, mean metal concentrations at the e-waste recycling sites exceeded the concentrations at the control sites and the Nigerian standard guideline values by 100â¯s to 1000â¯s times. Burning sites showed the highest pollution level, followed by dismantling sites, then repair sites. Our findings show serious environmental and public health concerns. The metal concentrations were also higher than levels reported in other studies at the same locations in Nigeria, indicating that the situation is worsening. This study provides scientific evidence for an urgent need to develop effective strategies to strengthen enforcement of existing e-waste regulations in Nigeria.
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Residuos Electrónicos , Metales , Reciclaje , Contaminantes del Suelo , China , Estudios Transversales , Polvo , Monitoreo del Ambiente , Metales/análisis , Nigeria , Suelo , Contaminantes del Suelo/análisisRESUMEN
BACKGROUND: Despite the large volume of e-waste recycled informally, the prevalence of work-related injuries among e-waste workers is unknown. Therefore, this study assessed the prevalence, patterns and factors associated with occupational injuries among e-waste workers in the informal sector in Nigeria. METHODS: This cross-sectional study adopted a multistage sampling method to select 279 respondents from three cities (Ibadan, Lagos and Aba) in Nigeria. A questionnaire was used to obtain information on sociodemographics, work practices and injury occurrences from the respondents in 2015. The data were analysed using descriptive statistics and standard logistic regression. RESULTS: We found high injury prevalence of 38% and 68% in 1-2 weeks and 6 months preceding the study, respectively. The most common injuries were cuts (59%). Injuries were mainly caused by sharp objects (77%). The majority (82%) of the injuries occurred on the hands/fingers. Despite the high occurrence of injury, only 18% of the workers use personal protective equipment (PPE) and 51% of those that use PPE got at least an injury in 1-2 weeks and 88% got at least an injury in 6 months preceding the study. The factors associated with injury in 1-2 weeks were job designation and the geographical location, while the factors associated with injury in 6 months were job designation, geographical location and age. CONCLUSIONS: There is a high prevalence of injury and low use of PPE among the e-waste workers in Nigeria. Occupational injury can be reduced through health education and safety promotion programmes for e-waste workers.
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Residuos Electrónicos , Promoción de la Salud/métodos , Salud Laboral/estadística & datos numéricos , Traumatismos Ocupacionales/epidemiología , Administración de la Seguridad , Adulto , Estudios Transversales , Femenino , Conocimientos, Actitudes y Práctica en Salud , Humanos , Sector Informal , Masculino , Nigeria/epidemiología , Traumatismos Ocupacionales/prevención & control , Equipo de Protección Personal/estadística & datos numéricos , Prevalencia , Administración de ResiduosRESUMEN
Daphnia magna were exposed to two pesticides in the presence or absence of microplastics (300 000 particles ml-1 1⯵m polystyrene spheres) and to microplastics alone. The pesticides were dimethoate, an organophosphate insecticide with a low log Kow, and deltamethrin, a pyrethroid insecticide with a high log Kow. Daphnia were exposed to a nominal concentration range of 0.15, 0.31, 0.63, 1.25, 2.5, 5â¯mgâ¯l-1 dimethoate and 0.016, 0.08, 0.4, 2, 5 and 10⯵gâ¯l-1 deltamethrin. Exposure to polystyrene microplastics alone showed no effects on Daphnia magna survival and mobility over a 72â¯h exposure. In the dimethoate exposures, mobility and survival were both affected from a concentration of 1.25â¯mgâ¯l-1, with effects were seen on mobility from 28â¯h and survival from 48â¯h, with greater effects seen with increasing concentration and exposure time. In deltamethrin exposures, survival was affected from a concentration of 0.4⯵gâ¯l-1 and mobility from a concentration of 0.08⯵gâ¯l-1. Effects of deltamethrin on mobility were seen from 5â¯h and on survival from 28â¯h, with greater effects on survival and mobility seen with increasing concentration and exposure time. Contrary to expectations, pesticide toxicity to Daphnia magna was not affected by the presence of microplastics, regardless of chemical binding affinity (log Kow). This therefore suggests that polystyrene microplastics are unlikely to act as a significant sink, nor as a vector for increased uptake of pesticides by aquatic organisms. CAPSULE: Polystyrene microplastics are unlikely to act as vector for increased uptake of pesticides by aquatic organisms.
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Daphnia/efectos de los fármacos , Plaguicidas/toxicidad , Plásticos/toxicidad , Poliestirenos/toxicidad , Contaminantes Químicos del Agua/toxicidad , Animales , Organismos Acuáticos , Dimetoato/toxicidad , Nitrilos/toxicidad , Piretrinas/toxicidad , Pruebas de Toxicidad AgudaRESUMEN
Contents 653 I. 654 II. 657 III. 659 IV. 661 V. 662 VI. 663 VII. 665 665 References 665 SUMMARY: Biological decomposition and wildfire are connected carbon release pathways for dead plant material: slower litter decomposition leads to fuel accumulation. Are decomposition and surface fires also connected through plant community composition, via the species' traits? Our central concept involves two axes of trait variation related to decomposition and fire. The 'plant economics spectrum' (PES) links biochemistry traits to the litter decomposability of different fine organs. The 'size and shape spectrum' (SSS) includes litter particle size and shape and their consequent effect on fuel bed structure, ventilation and flammability. Our literature synthesis revealed that PES-driven decomposability is largely decoupled from predominantly SSS-driven surface litter flammability across species; this finding needs empirical testing in various environmental settings. Under certain conditions, carbon release will be dominated by decomposition, while under other conditions litter fuel will accumulate and fire may dominate carbon release. Ecosystem-level feedbacks between decomposition and fire, for example via litter amounts, litter decomposition stage, community-level biotic interactions and altered environment, will influence the trait-driven effects on decomposition and fire. Yet, our conceptual framework, explicitly comparing the effects of two plant trait spectra on litter decomposition vs fire, provides a promising new research direction for better understanding and predicting Earth surface carbon dynamics.
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Incendios , Fenómenos Fisiológicos de las Plantas , Hojas de la Planta/fisiología , Plantas/anatomía & histologíaRESUMEN
Many exotic species have little apparent impact on ecosystem processes, whereas others have dramatic consequences for human and ecosystem health. There is growing evidence that invasions foster eutrophication. We need to identify species that are harmful and systems that are vulnerable to anticipate these consequences. Species' traits may provide the necessary insights. We conducted a global meta-analysis to determine whether plant leaf and litter functional traits, and particularly leaf and litter nitrogen (N) content and carbon: nitrogen (C : N) ratio, explain variation in invasive species' impacts on soil N cycling. Dissimilarity in leaf and litter traits among invaded and noninvaded plant communities control the magnitude and direction of invasion impacts on N cycling. Invasions that caused the greatest increases in soil inorganic N and mineralization rates had a much greater litter N content and lower litter C : N in the invaded than the reference community. Trait dissimilarities were better predictors than the trait values of invasive species alone. Quantifying baseline community tissue traits, in addition to those of the invasive species, is critical to understanding the impacts of invasion on soil N cycling.
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Especies Introducidas , Ciclo del Nitrógeno , Hojas de la Planta/fisiología , Carácter Cuantitativo Heredable , Nitratos/análisis , Fijación del Nitrógeno , Compuestos Orgánicos/análisis , Suelo/química , Especificidad de la EspecieRESUMEN
The maximum photosynthetic carboxylation rate (Vcmax ) is an influential plant trait that has multiple scaling hypotheses, which is a source of uncertainty in predictive understanding of global gross primary production (GPP). Four trait-scaling hypotheses (plant functional type, nutrient limitation, environmental filtering, and plant plasticity) with nine specific implementations were used to predict global Vcmax distributions and their impact on global GPP in the Sheffield Dynamic Global Vegetation Model (SDGVM). Global GPP varied from 108.1 to 128.2 PgC yr-1 , 65% of the range of a recent model intercomparison of global GPP. The variation in GPP propagated through to a 27% coefficient of variation in net biome productivity (NBP). All hypotheses produced global GPP that was highly correlated (r = 0.85-0.91) with three proxies of global GPP. Plant functional type-based nutrient limitation, underpinned by a core SDGVM hypothesis that plant nitrogen (N) status is inversely related to increasing costs of N acquisition with increasing soil carbon, adequately reproduced global GPP distributions. Further improvement could be achieved with accurate representation of water sensitivity and agriculture in SDGVM. Mismatch between environmental filtering (the most data-driven hypothesis) and GPP suggested that greater effort is needed understand Vcmax variation in the field, particularly in northern latitudes.
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Dióxido de Carbono/metabolismo , Modelos Biológicos , Fotosíntesis , Carácter Cuantitativo Heredable , Ciclo del Carbono , Internacionalidad , Desarrollo de la Planta , Análisis de Componente Principal , Estaciones del Año , TemperaturaRESUMEN
Variation and tradeoffs within and among plant traits are increasingly being harnessed by empiricists and modelers to understand and predict ecosystem processes under changing environmental conditions. While fine roots play an important role in ecosystem functioning, fine-root traits are underrepresented in global trait databases. This has hindered efforts to analyze fine-root trait variation and link it with plant function and environmental conditions at a global scale. This Viewpoint addresses the need for a centralized fine-root trait database, and introduces the Fine-Root Ecology Database (FRED, http://roots.ornl.gov) which so far includes > 70 000 observations encompassing a broad range of root traits and also includes associated environmental data. FRED represents a critical step toward improving our understanding of below-ground plant ecology. For example, FRED facilitates the quantification of variation in fine-root traits across root orders, species, biomes, and environmental gradients while also providing a platform for assessments of covariation among root, leaf, and wood traits, the role of fine roots in ecosystem functioning, and the representation of fine roots in terrestrial biosphere models. Continued input of observations into FRED to fill gaps in trait coverage will improve our understanding of changes in fine-root traits across space and time.
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Bases de Datos Factuales , Raíces de Plantas/fisiología , Ecología/métodos , Ecosistema , Raíces de Plantas/anatomía & histologíaRESUMEN
Are the hyperdiverse local forests of the western Amazon undergoing changes linked to global and local drivers such as climate change, or successional dynamics? We analyzed local climatic records to assess potential climatic changes in Yasuní National Park, Ecuador, and compared two censuses (1995, 2012) of a palm community to assess changes in community structure and composition. Over 17 years, the structure and composition of this palm community remained remarkably stable. Soil humidity was significantly lower and canopy conditions were significantly more open in 2012 compared to 1995, but local climatic records showed that no significant changes in precipitation, temperature or river level have occurred during the last decade. Thus, we found no evidence of recent directional shifts in climate or the palm community in Yasuní. The absence of changes in local climate and plant community dynamics in Yasuní contrasts with recent findings from eastern Amazon, where environmental change is driving significant changes in ecosystem dynamics. Our findings suggest that until now, local forests in the northwest Amazon may have escaped pressure from climate change. The stability of this rich palm community embedded in the hyperdiverse Yasuní National Park underlines its uniqueness as a sanctuary for the protection of Amazonian diversity from global change impacts.