RESUMO
BACKGROUND: There is evidence that global anthropogenic climate change may be impacting floral phenology and the temporal and spatial characteristics of aero-allergenic pollen. Given the extent of current and future climate uncertainty, there is a need to strengthen predictive pollen forecasts. METHODS: The study aims to use CatBoost (CB) and deep learning (DL) models for predicting the daily total pollen concentration up to 14 days in advance for 23 cities, covering all five continents. The model includes the projected environmental parameters, recent concentrations (1, 2 and 4 weeks), and the past environmental explanatory variables, and their future values. RESULTS: The best pollen forecasts include Mexico City (R2(DL_7) ≈ .7), and Santiago (R2(DL_7) ≈ .8) for the 7th forecast day, respectively; while the weakest pollen forecasts are made for Brisbane (R2(DL_7) ≈ .4) and Seoul (R2(DL_7) ≈ .1) for the 7th forecast day. The global order of the five most important environmental variables in determining the daily total pollen concentrations is, in decreasing order: the past daily total pollen concentration, future 2 m temperature, past 2 m temperature, past soil temperature in 28-100 cm depth, and past soil temperature in 0-7 cm depth. City-related clusters of the most similar distribution of feature importance values of the environmental variables only slightly change on consecutive forecast days for Caxias do Sul, Cape Town, Brisbane, and Mexico City, while they often change for Sydney, Santiago, and Busan. CONCLUSIONS: This new knowledge of the ecological relationships of the most remarkable variables importance for pollen forecast models according to clusters, cities and forecast days is important for developing and improving the accuracy of airborne pollen forecasts.
Assuntos
Alérgenos , Previsões , Pólen , Pólen/imunologia , Previsões/métodos , Humanos , Mudança Climática , Modelos Teóricos , Monitoramento Ambiental/métodosRESUMO
We studied the diversity and abundance of the airborne fungal spores in the city of Thessaloniki, Greece, for two consecutive years. Air samples were collected at one rooftop station (at 30 m) and six near-ground stations (at 1.5 m) that differed in the size and composition of adjacent green spaces. The effects of meteorological factors on airborne fungal spore concentrations were also explored. Cladosporium spores were dominant everywhere in the air of the city. The total concentration of the airborne fungal spores at 30 m was 10 times lower than near the ground. Differences in concentration and composition were far less pronounced among near-ground stations. The attributes of the fungal spore season did not change in a consistent way among stations and years. Concentrations at the near-ground stations matched the grouping of the latter into stations of high, intermediate, and low urban green space. Minimum air temperature was the primary meteorological factor affecting spore abundance, followed by relative humidity. Airborne fungal spores are more homogeneously distributed in the air of the city, but their concentrations decrease more rapidly with height than pollen.
Assuntos
Meteorologia , Parques Recreativos , Febre , Grécia , Conceitos Meteorológicos , Esporos FúngicosRESUMO
The emergence of novel SARS-CoV-2 variants of concern (VOC), in late 2020, with selective transmission advantage and partial immunity escape potential, has been driving further evolution in the pandemic. The timing of mutational evolution and its limits are thus of paramount importance in preparedness planning. Here, we present a model predicting the pattern of epidemic growth including the emergence of variants through mutation. It is based on the SEIR (Susceptible, Exposed, Infected, Removed) model, but its equations are modified according to the transmission parameters of novel variants. Since more transmissible strains will drive a further increase in the number of cases, they will also lead to further novel mutations. As one cannot predict whether there is a viral mutational evolutionary limit, we model a cascade that could lead to hyper-exponential growth (HEG) involving the emergence of even more transmissible mutants that could overwhelm any systematic response. Our results are consistent with the timing, since the beginning of the pandemic, of the concurrent and independent emergence of the VOCs. The current dominance of the Delta variant and the need for additional public health measures indicates some of the risks of a possible HEG. We examine conditions that favor the expected appearance of similar variants, thus enabling better preparedness and more targeted research.
Assuntos
COVID-19 , SARS-CoV-2 , Humanos , Mutação , PandemiasRESUMO
The study is aimed at determining the potential spatiotemporal risk of the co-occurrence of airborne pollen and fungal spores high concentrations in different bio-climatic zones in Europe. Birch, grass, mugwort, ragweed, olive pollen and Alternaria and Cladosporium fungal spores were investigated at 16 sites in Europe, in 2005-2019. In Central and northern Europe, pollen and fungal spore seasons mainly overlap in June and July, while in South Europe, the highest pollen concentrations occur frequently outside of the spore seasons. In the coldest climate, no allergy thresholds were exceeded simultaneously by two spore or pollen taxa, while in the warmest climate most of the days with at least two pollen taxa exceeding threshold values were observed. The annual air temperature amplitude seems to be the main bioclimatic factor influencing the accumulation of days in which Alternaria and Cladosporium spores simultaneously exceed allergy thresholds. The phenomenon of co-occurrence of airborne allergen concentrations gets increasingly common in Europe and is proposed to be present on other continents, especially in temperate climate.
Assuntos
Alérgenos , Hipersensibilidade , Esporos Fúngicos , Pólen , Estações do Ano , Europa (Continente) , Cladosporium , Alternaria , Microbiologia do ArRESUMO
We studied the structure and diversity of the phyllosphere bacterial community of a Mediterranean ecosystem, in summer, the most stressful season in this environment. To this aim, we selected nine dominant perennial species, namely Arbutus unedo, Cistus incanus, Lavandula stoechas, Myrtus communis, Phillyrea latifolia, Pistacia lentiscus, Quercus coccifera (woody), Calamintha nepeta, and Melissa officinalis (herbaceous). We also examined the extent to which airborne bacteria resemble the epiphytic ones. Genotype composition of the leaf and airborne bacteria was analysed by using denaturing gradient gel electrophoresis profiling of a 16S rDNA gene fragment; 75 bands were cloned and sequenced corresponding to 28 taxa. Of these, two were found both in the air and the phyllosphere, eight only in the air, and the remaining 18 only in the phyllosphere. Only four taxa were found on leaves of all nine plant species. Cluster analysis showed highest similarity for the five evergreen sclerophyllous species. Aromatic plants were not grouped all together: the representatives of Lamiaceae, bearing both glandular and non-glandular trichomes, formed a separate group, whereas the aromatic and evergreen sclerophyllous M. communis was grouped with the other species of the same habit. The epiphytic communities that were the richest in bacterial taxa were those of C. nepeta and M. officinalis (Lamiaceae). Our results highlight the remarkable presence of lactic acid bacteria in the phyllosphere under the harsh conditions of the Mediterranean summer, the profound dissimilarity in the structure of bacterial communities in phyllosphere and air, and the remarkable differences of leaf microbial communities on neighbouring plants subjected to similar microbial inocula; they also point to the importance of the leaf glandular trichome in determining colonization patterns.
Assuntos
Microbiologia do Ar , Bactérias/genética , Biodiversidade , Ecossistema , Magnoliopsida/microbiologia , Folhas de Planta/microbiologia , Bactérias/classificação , Bactérias/crescimento & desenvolvimento , Bactérias/isolamento & purificação , DNA Bacteriano/análise , DNA Bacteriano/genética , Grécia , Magnoliopsida/classificação , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , RNA Ribossômico 16S/genética , Estações do Ano , Análise de Sequência de DNARESUMO
In the midst of a persistent pandemic of a probable zoonotic origin, one needs to constantly evaluate the interplay of SARS-CoV-2 (severe acute respiratory syndrome-related coronavirus-2) with animal populations. Animals can get infected from humans, and certain species, including mink and white-tailed deer, exhibit considerable animal-to-animal transmission resulting in potential endemicity, mutation pressure, and possible secondary spillover to humans. We attempt a comprehensive review of the available data on animal species infected by SARS-CoV-2, as presented in the scientific literature and official reports of relevant organizations. We further evaluate the lessons humans should learn from mink outbreaks, white-tailed deer endemicity, zoo outbreaks, the threat for certain species conservation, the possible implication of rodents in the evolution of novel variants such as Omicron, and the potential role of pets as animal reservoirs of the virus. Finally, we outline the need for a broader approach to the pandemic and epidemics, in general, incorporating the principles of One Health and Planetary Health.
RESUMO
Sustainable farming practices aim to replace agrochemicals with plant-based alternatives to increase productivity and soil quality. To evaluate the potential use of aromatic plants as soil amendments in tomato seedbeds, in a greenhouse experiment, we used spearmint, peppermint, and rosemary, separately, as soil amendments, in pots sown with tomato, and studied their effect on seedling growth, soil nutrients, and the soil nematode community in terms of trophic and functional structure, metabolic footprint, and genera composition. Non-amended soil was used in the control pots. We further explored the dynamics of the plant-soil-nematode interactions by using aromatic plants at different stages of decomposition (0, 28, and 56 days). Incorporating aromatic plants into the soil led to the proliferation of free-living nematodes, especially of the opportunistic kind, resulting in vigorous and enriched soil. This was more pronounced in the case of the spearmint and peppermint, which also increased the tomato growth. The high soil nutritional status and enhanced plant growth were most prominent when the aromatic plants were left for 28 days to decompose in the soil before sowing. Compared with the mint plants, the rosemary had similar, yet less intense, effects on the soil community, but completely inhibited the growth of the tomato seedlings. Therefore, it is not recommended for use as a soil amendment in tomato seedbeds.
RESUMO
Parietaria judaica (Urticaceae) grows abundantly in urban areas of the Mediterranean region. Its pollen is a major allergy source. We studied the species' distribution and abundance in and around Thessaloniki (Greece), pollen production and pollen season. We also examined how urban pollution affects pollen viability. Our ultimate goal was to obtain an estimate of the species' performance and ability to expand under different environmental conditions related to climate change. We mapped P. judaica and the other Urticaceae species. In a north- and a south-facing population, we recorded the progress of P. judaica flowering and estimated the pollen content per flower, shoot and surface unit. We concurrently assessed atmospheric circulation of Urticaceae pollen. We estimated P. judaica pollen viability and Cu, Pb and Zn concentrations in plants collected from sites differing in traffic intensity. P. judaica is the most abundant Urticaceae species in the area; its occurrence has increased dramatically over the last 100 years. Production of flowers is intense in spring and autumn. Flowering started 12 days earlier in the south-facing population in spring, and 3 days later in autumn. Pollen production was higher in spring and in the south-facing population. Flower and pollen production were positively correlated with the size of the plant and the flower, respectively. Copper and lead concentrations in plants were positively correlated with pollen viability, which was higher for plants collected from high-traffic sites. P. judaica has a high phenotypic plasticity; this is a feature that promotes success of expansive and invasive species. It is also well adapted to warm and polluted urban environments. The climatic change forecast for the Mediterranean region could provoke earlier, longer, and more pronounced flowering and, consequently, more P. judaica pollen in the air. In return, this would result in increased severity of Parietaria pollinosis.
Assuntos
Flores/fisiologia , Parietaria/fisiologia , Pólen/crescimento & desenvolvimento , Movimentos do Ar , Cidades , Mudança Climática , Flores/genética , Grécia , Espécies Introduzidas , Região do Mediterrâneo , Metais Pesados/análise , Parietaria/genética , Fenótipo , Pólen/metabolismo , Estações do AnoRESUMO
We study here how soil bacterial communities of different ecosystems respond to disturbances caused by enrichments with monoterpenes that are common essential oil constituents. We used fenchone, 1,8-cineol and α-pinene, and soils from phrygana, a typical Mediterranean-type ecosystem where aromatic plants abound, and from another five ecosystem types, focusing on culturable bacteria. Patterns of response were common to all ecosystems, but responses themselves were not always as pronounced in phrygana as in the other ecosystems, suggesting that these enrichments are less of a disturbance there. More specifically, soil respiration and abundance of the bacterial communities increased, becoming from below two up to 16 times as high as in control soils (for both attributes) and remained at high levels as long as these compounds were present. Bacteria that can utilize these three compounds as substrates of growth became dominant members of the bacterial communities in the enriched soils. All changes were readily reversible once monoterpene addition stopped. Bacteria with the ability to utilize these monoterpenes as carbon sources were found in soils from all ecosystems, 15 strains in total, suggesting a rather universal presence; of these, six could also utilize the organic pollutants toluene or p-xylene. These results suggest also potential novel applications of monoterpenes in combating soil pollution.
RESUMO
This study provides insight into changes in the features of tomato seedlings growing in soils enriched with spearmint, peppermint, or rosemary leaves and into changes in the microbial communities of these soils used as seedbeds; an organic amendment was also applied as a positive control. While the soil microbial community flourished in the presence of all three aromatic plants, tomato growth was inhibited or stimulated depending on the plant that was used. More specifically, phospholipid fatty acid (PLFA) analysis showed an increase in the total microbial biomass and in the biomass of all the groups examined, except for actinobacteria, and changes in the microbial community structure, with Gram-negative bacteria and fungi being favoured in the mint treatments, in which the microbial biomass was maximized. Seedlings from the rosemary treatment were entirely inhibited; they were at the open-cotyledon stage throughout the experiment. Seedlings from the mint treatments were the heaviest, longest, and had the highest chlorophyll content and photosynthetic yield. Metabolomic analysis showed metabolism enhancement associated with both growth and priming in seedlings from the mint treatments and disruption of metabolic pathways in those from the rosemary treatment. There is a great potential for applying these aromatic plants as soil amendments and as either biostimulants of plant growth or as herbicides.
RESUMO
Monitoring biodiversity is of increasing importance in natural ecosystems. Metabarcoding can be used as a powerful molecular tool to complement traditional biodiversity monitoring, as total environmental DNA can be analyzed from complex samples containing DNA of different origin. The aim of this research was to demonstrate the potential of pollen DNA metabarcoding using the chloroplast trnL partial gene sequencing to characterize plant biodiversity. Collecting airborne biological particles with gravimetric Tauber traps in four Natura 2000 habitats within the Natural Park of Paneveggio Pale di San Martino (Italian Alps), at three-time intervals in 1 year, metabarcoding identified 68 taxa belonging to 32 local plant families. Metabarcoding could identify with finer taxonomic resolution almost all non-rare families found by conventional light microscopy concurrently applied. However, compared to microscopy quantitative results, Poaceae, Betulaceae, and Oleaceae were found to contribute to a lesser extent to the plant biodiversity and Pinaceae were more represented. Temporal changes detected by metabarcoding matched the features of each pollen season, as defined by aerobiological studies running in parallel, and spatial heterogeneity was revealed between sites. Our results showcase that pollen metabarcoding is a promising approach in detecting plant species composition which could provide support to continuous monitoring required in Natura 2000 habitats for biodiversity conservation.
Assuntos
Biodiversidade , Código de Barras de DNA Taxonômico/métodos , Magnoliopsida/classificação , Metagenômica/métodos , Pólen/genética , Genoma de Planta , Magnoliopsida/genética , Magnoliopsida/fisiologia , MetagenomaRESUMO
We studied the effects of five monoterpenoids, viz. 1,8-cineole, fenchone, linalool, p-cymene and α-pinene, on the sciatic nerve fibers of the frog Rana ridibunda (Pallas, 1771) and compared them to that of lidocaine, a standard local anesthetic. The isolated sciatic nerve, with its perineurium intact, was placed in a three-chambered recording bath, which allowed us to monitor the compound action potentials (CAP), stable in amplitude, for over 2 days. The half-vitality time (IT(50)), which is the time required for the amplitude of the CAP to decrease to 50% of its control value, was 53.5 ± 0.9 h for a nerve incubated in normal saline at 26.0 °C. The IT(50) values for nerves incubated in saline with p-cymene, 1,8-cineole, or α-pinene, at 30.0 mM, were 19.9 ± 0.4, 32.9 ± 0.5, and 31.0 ± 0.3 hours, respectively. As the IT(50) value for 30.0 mM lidocaine, a standard local anesthetic, was 1.6 ± 0.3 min under the same conditions, these three compounds cannot be considered as having a local anesthetic effect. The IT(50) values for 30.0 mM linalool and fenchone were 5.7 ± 0.6 and 15.4 ± 1.1 min, respectively; they were significantly, but not markedly different from the respective value for lidocaine. These results combined with the fast inhibition of the CAP and its fast recovery after the removal of either linalool or fenchone indicate a local anesthetic activity of the two compounds. Linalool retained this activity even at lower concentrations of 15.0 and 7.5 mM. The local anesthetic effects of lidocaine and linalool were concentration-dependent; this was not the case for fenchone, which had a relatively strong local anesthetic activity at 30.0 mM, but was entirely inactive at 25.0 mM. On the basis of the effects of the five monoterpenoids on the electrophysiological properties of the sciatic nerve fibers of the frog, we conclude that, whereas 1,8-cineole, p-cymene and α-pinene cause only minor effects, linalool and fenchone exhibit acute local anesthetic activity.
Assuntos
Anestésicos/farmacologia , Monoterpenos/farmacologia , Óleos Voláteis/farmacologia , Nervo Isquiático/efeitos dos fármacos , Potenciais de Ação/efeitos dos fármacos , Anestésicos/química , Anestésicos/isolamento & purificação , Animais , Técnicas In Vitro , Monoterpenos/química , Monoterpenos/isolamento & purificação , Óleos Voláteis/química , Óleos Voláteis/isolamento & purificação , Rana ridibundaRESUMO
Understanding the mechanisms of pollen release and dispersion in the atmosphere is of high importance, not only for getting an insight on the patterns of movement of these biological particles that are necessary for plants' reproduction, but also because exposure to airborne pollen is a major concern for respiratory allergies worldwide. In this work, a synoptic circulation-to-environment classification method was adopted to elucidate the relationship between distinct atmospheric patterns and pollen levels for the 11 most abundant but also allergenic taxa in Thessaloniki, Greece, for the 15-year period 1987-2001. It was found that the NW1 depressional weather type is associated with the "low winter pollen season" and high levels of pollen from Carpinus spp., Corylus spp., Cupressaceae, Platanus spp., Pinaceae, Quercus spp. and Urticaceae. In contrast, the SW1 cyclonic type is linked to the "high spring-summer pollen season" and high levels of pollen from Oleaceae and Urticaceae. On the other hand, anticyclonic weather is associated with the "summer-autumn pollen season" and high levels of Poaceae and Chenopodiaceae pollen in the atmosphere. Regional transport of Alnus pollen is linked to a strong high-pressure system centered over Italy, giving light NE winds over northern Greece. These findings shed light to the synoptic climatology of airborne pollen in Thessaloniki and could feed early-warning systems for alerting vulnerable groups of the allergic population.
Assuntos
Pólen/química , Alérgenos , Monitoramento Ambiental , Grécia , Itália , Meteorologia , Estações do AnoRESUMO
Plant growth promoting rhizobacteria (PGPR) are able to provide cross-protection against multiple stress factors and facilitate growth of their plant symbionts in many ways. The aim of this study was to isolate and characterize rhizobacterial strains under natural conditions, associated with naturally occurring representatives of wild plant species and a local tomato cultivar, growing in differently stressed Mediterranean ecosystems. A total of 85 morphologically different rhizospheric strains were isolated; twenty-five exhibited multiple in vitro PGP-associated traits, including phosphate solubilization, indole-3-acetic acid production, and 1-aminocyclopropane-1-carboxylate deaminase activity. Whole genome analysis was applied to eight selected strains for their PGP potential and assigned seven strains to Gammaproteobacteria, and one to Bacteroidetes. The genomes harboured numerous genes involved in plant growth promotion and stress regulation. They also support the notion that the presence of gene clusters with potential PGP functions is affirmative but not necessary for a strain to promote plant growth under abiotic stress conditions. The selected strains were further tested for their ability to stimulate growth under stress. This initial screening led to the identification of some strains as potential PGPR for increasing crop production in a sustainable manner.
Assuntos
Secas , Raízes de Plantas/microbiologia , Rizosfera , Plantas Tolerantes a Sal , Solanum lycopersicum , Bacteroidetes/fisiologia , Gammaproteobacteria/fisiologia , Grécia , Solanum lycopersicum/crescimento & desenvolvimento , Solanum lycopersicum/microbiologia , Microbiota , Reguladores de Crescimento de Plantas/metabolismo , Plantas Tolerantes a Sal/crescimento & desenvolvimento , Plantas Tolerantes a Sal/microbiologia , Microbiologia do SoloRESUMO
BACKGROUND: The island of Crete is a biodiversity hotspot having 223 endemic vascular taxa (species and subspecies) as a result of its long isolation and the wide range of habitats it includes. We explore trends and patterns in the electronic trade of these unique genetic resources and in their involvement in wildlife tourism, the ways these two activities are performed and the associated potential threats on the plants' wild populations, and we also identify priority taxa requiring special attention. The main part of the study was conducted in 2016-2017 using English as a search language; an additional search was conducted in 2019 using German and French. RESULTS: We found e-commerce for 28 (13%) endemic taxa. These are traded by 65 nurseries from 14 countries, the UK primarily. Among the traded plants, 16 face extinction risk and/or are under protection status. Prices vary largely for the same taxon and form of sale. Lamiaceae is the family with the highest number of e-traded taxa, Tulipa bakeri is the most traded species, and the living plant is the commonest form of sale. Thirty-seven endemic taxa are advertised in the websites of travel agencies involved in wildlife tourism. Tulipa doerfleri is the most frequently encountered taxon in these websites, whereas Lamiaceae, Liliaceae and Orchidaceae are similarly represented. The additional search showed a very rapid increase in the e-trade of the Cretan endemis. CONCLUSION: The two examined markets are similar in that geophytes play a prominent role and Lamiaceae rank first among the represented plant families, but differ in several aspects: only 22.6% of the taxa detected are common in both, obedience to rules exhibited by travel agencies is not usually the case with nurseries, and potential threats to wild populations are estimated as considerably higher for the traded plants. Sixteen endemic taxa of Crete were identified as requiring special attention.
RESUMO
We explore how the phyllosphere microbial community responds to a very seasonal environment such as the Mediterranean. For this, we studied the epiphytic bacterial community of a Mediterranean ecosystem in summer and winter, expecting to detect seasonal differences at their maximum. With high-throughput sequencing (HTS), we detected the operational taxonomic units (OTUs) present in the phyllosphere and also in the surrounding air. The epiphytic community is approximately five orders of magnitude denser than the airborne one and is made almost exclusively by habitat specialists. The two communities differ considerably but Proteobacteria and Actinobacteria are dominant in both. Of the five most abundant phyllosphere OTUs, two were closely related to Sphingomonas strains, one to Methylobacterium and the other two to Rhizobiales and Burkholderiales. We found the epiphytic community to become much richer, more distinct, even and diverse, denser and more connected in summer. In contrast, there was no difference in the level of bacterial colonization of the phyllosphere between the two seasons, although there were seasonal differences for individual taxonomic groups: Firmicutes, Gemmatimonadetes and Chlroroflexi had a higher participation in summer, whereas the major Proteobacteria classes presented reverse patterns, with Betaproteobacteria increasing in summer at the expense of the prominent Alphaproteobacteria.
RESUMO
Airborne fungal spores are prevalent components of bioaerosols with a large impact on ecology, economy and health. Their major socioeconomic effects could be reduced by accurate and timely prediction of airborne spore concentrations. The main aim of this study was to create and evaluate models of Alternaria and Cladosporium spore concentrations based on data on a continental scale. Additional goals included assessment of the level of generalization of the models spatially and description of the main meteorological factors influencing fungal spore concentrations. Aerobiological monitoring was carried out at 18 sites in six countries across Europe over 3 to 21â¯years depending on site. Quantile random forest modelling was used to predict spore concentrations. Generalization of the Alternaria and Cladosporium models was tested using (i) one model for all the sites, (ii) models for groups of sites, and (iii) models for individual sites. The study revealed the possibility of reliable prediction of fungal spore levels using gridded meteorological data. The classification models also showed the capacity for providing larger scale predictions of fungal spore concentrations. Regression models were distinctly less accurate than classification models due to several factors, including measurement errors and distinct day-to-day changes of concentrations. Temperature and vapour pressure proved to be the most important variables in the regression and classification models of Alternaria and Cladosporium spore concentrations. Accurate and operational daily-scale predictive models of bioaerosol abundances contribute to the assessment and evaluation of relevant exposure and consequently more timely and efficient management of phytopathogenic and of human allergic diseases.
Assuntos
Microbiologia do Ar/normas , Poluentes Atmosféricos/análise , Alternaria/fisiologia , Cladosporium/fisiologia , Conceitos Meteorológicos , Esporos Fúngicos/isolamento & purificação , Poluentes Atmosféricos/imunologia , Poluição do Ar/análise , Alérgenos/análise , Alérgenos/imunologia , Alternaria/imunologia , Cladosporium/imunologia , Monitoramento Ambiental/estatística & dados numéricos , Europa (Continente) , Previsões , Modelos Estatísticos , Esporos Fúngicos/imunologiaRESUMO
BACKGROUND: Ongoing climate change might, through rising temperatures, alter allergenic pollen biology across the northern hemisphere. We aimed to analyse trends in pollen seasonality and pollen load and to establish whether there are specific climate-related links to any observed changes. METHODS: For this retrospective data analysis, we did an extensive search for global datasets with 20 years or more of airborne pollen data that consistently recorded pollen season indices (eg, duration and intensity). 17 locations across three continents with long-term (approximately 26 years on average) quantitative records of seasonal concentrations of multiple pollen (aeroallergen) taxa met the selection criteria. These datasets were analysed in the context of recent annual changes in maximum temperature (Tmax) and minimum temperature (Tmin) associated with anthropogenic climate change. Seasonal regressions (slopes) of variation in pollen load and pollen season duration over time were compared to Tmax, cumulative degree day Tmax, Tmin, cumulative degree day Tmin, and frost-free days among all 17 locations to ascertain significant correlations. FINDINGS: 12 (71%) of the 17 locations showed significant increases in seasonal cumulative pollen or annual pollen load. Similarly, 11 (65%) of the 17 locations showed a significant increase in pollen season duration over time, increasing, on average, 0·9 days per year. Across the northern hemisphere locations analysed, annual cumulative increases in Tmax over time were significantly associated with percentage increases in seasonal pollen load (r=0·52, p=0·034) as were annual cumulative increases in Tmin (r=0·61, p=0·010). Similar results were observed for pollen season duration, but only for cumulative degree days (higher than the freezing point [0°C or 32°F]) for Tmax (r=0·53, p=0·030) and Tmin (r=0·48, p=0·05). Additionally, temporal increases in frost-free days per year were significantly correlated with increases in both pollen load (r=0·62, p=0·008) and pollen season duration (r=0·68, p=0·003) when averaged for all 17 locations. INTERPRETATION: Our findings reveal that the ongoing increase in temperature extremes (Tmin and Tmax) might already be contributing to extended seasonal duration and increased pollen load for multiple aeroallergenic pollen taxa in diverse locations across the northern hemisphere. This study, done across multiple continents, highlights an important link between ongoing global warming and public health-one that could be exacerbated as temperatures continue to increase. FUNDING: None.
Assuntos
Alérgenos/análise , Aquecimento Global , Temperatura Alta , Pólen , Ásia , Europa (Continente) , América do Norte , Estudos Retrospectivos , Estações do AnoRESUMO
BACKGROUND: The abundant-centre hypothesis (ACH) assumes that a species becomes more abundant at the centre of its range, where the environmental conditions are most favorable. As we move away from this centre, abundance and occupancy decline. Although this is obvious intuitively, efforts to confirm the hypothesis have often failed. We investigated the abundance patterns of Campanula lingulata across its altitudinal range on Mt. Olympus, Greece, in order to evaluate the "abundant centre" hypothesis along an elevation gradient. Furthermore, we explored the species' presence and dynamics at multiple spatial scales. METHODS: We recorded flowering individuals during the summer months of 2012 and 2013 along a series of transects defined by paths. We investigated whether the probability of acquiring a larger number of individuals is larger toward the centre of its altitudinal distribution. We also calculated mean presence and turnover at different spatial scales that ranged from quadrats of 10 × 10 m2 to about 10 × 10 km2. RESULTS: We were able to identify an abundant centre but only for one of the years of sampling. During the second year, we noted a two-peak abundance pattern; with the first peak occurring at 650-750 m and the second at 1100-1300 m. Variability in the species-presence pattern is observed across a wide range of spatial scales. The pattern along the transect displays fractal characteristics, consistent with a dimension of 0.24-0.29. We found substantial changes of state between the 2 years at all resolutions. CONCLUSIONS: Our results do not contradict the ACH, but indicate that ecological distributions exhibit types of variability that make the detection of abundant centres more difficult than expected. When a random fractal disturbance is superimposed upon an abundant centre, we can expect a pattern in which the centre is difficult to discern from a single instance. A multi-resolution or fractal approach to environmental variability is a promising approach for describing this phenomenon.
RESUMO
The arbuscular mycorrhizal fungi (AMF) and the essential oils are both agents of sustainable agriculture, and their independent effects on the community of free-living soil microbes have been explored. In a tomato pot experiment, conducted in a sandy loam mixture, we examined the independent and joint effects of inoculation with the fungus Rhizophagous irregularis and the addition of Mentha spicata essential oil on the structure of the soil microbial community and the activity of soil enzymes involved in the N-cycle, during the pre-symbiosis phase. Plants were grown for 60 days and were inoculated with R. irregularis. Then pots were treated with essential oil (OIL) weekly for a period of a month. Two experimental series were run. The first targeted to examine the effect of inoculation on the microbial community structure by the phospholipid fatty acids analysis (PLFAs), and enzyme activity, and the second to examine the effects of inoculation and essential oil addition on the same variables, under the hypothesis that the joint effect of the two agents would be synergistic, resulting in higher microbial biomass compared to values recorded in singly treated pots. In the AMF pots, N-degrading enzyme activity was dominated by the activity of urease while in the non-inoculated ones by the activities of arylamidase and glutaminase. Higher microbial biomass was found in singly-treated pots (137 and 174% higher in AMF and OIL pots, respectively) compared with pots subjected to both treatments. In these latter pots, higher activity of asparaginase (202 and 162% higher compared to AMF and OIL pots, respectively) and glutaminase (288 and 233% higher compared to AMF and OIL pots, respectively) was found compared to singly-treated ones. Soil microbial biomasses and enzyme activity were negatively associated across all treatments. Moreover, different community composition was detected in pots only inoculated and pots treated only with oil. We concluded that the two treatments produced diverging than synergistic effects on the microbial community composition whereas their joint effect on the activity of asparaginase and glutaminase were synergistic.