Eastern Iberian Peninsula Research Articles

Sea breeze thunderstorms in the eastern Iberian Peninsula. Neighborhood verification of HIRLAM and HARMONIE precipitation forecasts

In this study we investigated sea breeze thunderstorms with intense convective activity (i.e., heavy rainfall, hail and gusty winds) that occurred over the eastern Iberian Peninsula (Spain) and were missed by the operational HIRLAM model. We used two grid-spacing setups (5.0km and 2.5km) of the hydrostatic HIRLAM model, and the non-hydrostatic spectral HARMONIE suite (2.5km), to simulate isolated convection associated with sea breezes. The overall aim is to estimate the ability of these three experimental setups, in particular the HARMONIE model as the forthcoming operational numerical weather prediction in most European Weather Services, to correctly simulate convective precipitation associated with sea breezes. We evaluated high-resolution gridded precipitation forecasts from HIRLAM and HARMONIE suites for 15 sea breeze thunderstorms against high-density gridded raingauge measurements applying different neighborhood verification techniques. The results indicate that higher horizontal resolutions of HIRLAM and HARMONIE models succeeded in predicting the occurrence of these missed sea breeze thunderstorms, the HARMONIE suite being the most capable of providing good estimates of accumulated precipitation in convective events in terms of space and time. Advances in quantitative precipitation forecasting of locally driven convection could have practical applications for nowcasting dangerous sea breeze convective phenomena.

Helminths from the red-eared slider Trachemys scripta elegans (Chelonia: Emydidae) in marshes from the eastern Iberian Peninsula: first report of Telorchis attenuata (Digenea: Telorchiidae)

The present work describes the presence of a digenean in the red-eared turtle Trachemys scripta elegans (Wied-Neuwied, 1839) in marshes of the Valencian Community. The faeces and intestinal tract of 105 animals were examined. Only one helminth species was found and identified as the digenean trematode Telorchis atenuatta (Goldberger, 1911), present in the 7.6% of the animals analysed. This is the first report of the parasite in sliders from Spain. Although conclusions are preliminary due to the limited sampling, our results suggest that the presence of red-eared turtles in new habitats may increase the risk of introducing new microorganisms and new diseases with them, altering the sanitary status of the autochthonous terrapins Mauremys leprosa (Schweigger, 1812) and Emys orbicularis (Linnaeus, 1758).

Artificial dam lakes as suitable habitats for exotic invertebrates: Ostracoda ecology and distribution in reservoirs of the Eastern Iberian Peninsula

Reservoirs are the most common deep lakes in Spain, as a consequence of water needs and dry climate. Although these aquatic systems can play an important ecological role in such an area with few large natural lakes, they can also provide new habitats for exotic species, which can colonize ecosystems that native species have not explored yet. Here we present our results for a biannual survey of the ostracod fauna from 24 reservoirs in Xuquer River basin. We check which variables affect ostracod presence, test for differences between winter and summer assemblages, and compare our data with previous available ostracod records from the same river drainage network. Our results reveal that ostracod presence is positively related to high diversity of the invertebrate community and reservoir volume, and negatively with phosphorus concentration. Among the 22 species found, it is noteworthy the first Iberian record of Ilyocypris getica and the second European record of Candonocypris novaezelandiae . Ostracod assemblages significantly vary between summer and winter, and strong differences are found between ostracod communities of reservoirs and those from their connected rivers. Remarkably higher frequency of exotic species in the reservoirs confirms previous findings about the facilitation that artificial ecosystems confer to aquatic invasions.

Fishing Long-Fingered Bats (Myotis capaccinii) Prey Regularly upon Exotic Fish

The long-fingered bat Myotis capaccinii is a European trawling bat reported to feed on fish in several Mediterranean locations, but the ecological circumstances of this behavior have not yet been studied. To elucidate the importance of fishing in this bat's diet, we evaluated the frequency and seasonal variation of fish remains in 3,000 fecal pellets collected from M. capaccinii at a nursery roost in Dénia (Eastern Iberian Peninsula) in 2008, 2009, and 2010. Fish consumption occurred evenly throughout the year. All otoliths found in feces were identified as belonging to the surface-feeding fish Gambusia holbrooki. Measuring otoliths, we estimated that the mean size of consumed fish was significantly smaller than the mean measured for available fish, suggesting that the long-fingered bat's relatively small body may constrain its handling of larger prey. Of note, one bat had eaten 15 fish, showing that fish may be a locally or seasonally important trophic resource for this species. By capturing 15 bats and radio-tracking the four with the most fish remains in their droppings, we also identified fishing areas, including a single fishing ground comprising several ponds within a golf course. Ponds hold a high density of G. holbrooki, suggesting that the amount of fish at the water surface may be the principal factor triggering fishing. The observed six-fold increase in percentage of consumed fish across the study period may be related to recent pond-building in the area. We discuss whether this quick behavioral response is a novel feature of M. capaccinii or an intrinsic feature that has erupted and faded locally along the species' history.

The “Alluvial Mesovoid Shallow Substratum”, a New Subterranean Habitat

In this paper we describe a new type of subterranean habitat associated with dry watercourses in the Eastern Iberian Peninsula, the “Alluvial Mesovoid Shallow Substratum” (alluvial MSS). Historical observations and data from field sampling specially designed to study MSS fauna in the streambeds of temporary watercourses support the description of this new habitat. To conduct the sampling, 16 subterranean sampling devices were placed in a region of Eastern Spain. The traps were operated for 12 months and temperature and relative humidity data were recorded to characterise the habitat. A large number of species was captured, many of which belonged to the arthropod group, with marked hygrophilous, geophilic, lucifugous and mesothermal habits. In addition, there was also a substantial number of species showing markedly ripicolous traits. The results confirm that the network of spaces which forms in alluvial deposits of temporary watercourses merits the category of habitat, and here we propose the name of “alluvial MSS”. The “alluvial MSS” may be covered or not by a layer of soil, is extremely damp, provides a buffer against above ground temperatures and is aphotic. In addition, compared to other types of MSS, it is a very unstable habitat. It is possible that the “alluvial MSS” may be found in other areas of the world with strongly seasonal climatic regimes, and could play an important role as a biogeographic corridor and as a refuge from climatic changes.

Comparability of fish-based ecological quality assessments for geographically distinct Iberian regions

In this work we compare two Iberian and a pan-European fish-based methods to assess ecological quality in rivers: the Fish-based Index of Biotic Integrity for Portuguese Wadeable Streams (F-IBIP), the Mediterranean Index of Biotic Integrity (IBIMED) and the pan-European Fish Index (EFI+). The results presented herein were developed in the context of the 2nd phase of the Intercalibration Exercise (IC), as required by the Water Frame Directive (WFD). The IC is aimed at ensuring comparability of the quality boundaries among the different WFD assessment methods developed by the Member States for each biological quality element. Although the two national assessment methods were developed for very distinct regions of Iberia (Western and Eastern Iberian Peninsula) they share the same methodological background: both are type-specific and guild-based multimetric indices. EFI+ is a multimetric guild-based model, but it is site-specific and uses a predictive modelling approach. The three indices were computed for all sites included in the Iberian Intercalibration database to allow the direct comparison, by means of linear regressions, of the resulting three quality values per site. The quality boundary harmonization between the two Iberian methods was only possible through an indirect comparison between the two indices, using EFI+ as a common metric. The three indices were also shown to be responsive to a common set of human induced pressures. This study highlights the need to develop general assessment methods adapted to wide geographical ranges with high species turnover to help intercalibrating assessment methods tailored for geographically more restricted regions.

In situ genetic association for serotiny, a fire‐related trait, in Mediterranean maritime pine (Pinus pinaster)

Wildfire is a major ecological driver of plant evolution. Understanding the genetic basis of plant adaptation to wildfire is crucial, because impending climate change will involve fire regime changes worldwide. We studied the molecular genetic basis of serotiny, a fire-related trait, in Mediterranean maritime pine using association genetics. A single nucleotide polymorphism (SNP) set was used to identify genotype : phenotype associations in situ in an unstructured natural population of maritime pine (eastern Iberian Peninsula) under a mixed-effects model framework. RR-BLUP was used to build predictive models for serotiny in this region. Model prediction power outside the focal region was tested using independent range-wide serotiny data. Seventeen SNPs were potentially associated with serotiny, explaining approximately 29% of the trait phenotypic variation in the eastern Iberian Peninsula. Similar prediction power was found for nearby geographical regions from the same maternal lineage, but not for other genetic lineages. Association genetics for ecologically relevant traits evaluated in situ is an attractive approach for forest trees provided that traits are under strong genetic control and populations are unstructured, with large phenotypic variability. This will help to extend the research focus to ecological keystone non-model species in their natural environments, where polymorphisms acquired their adaptive value.

Higher β‐ and γ‐diversity at species and genetic levels in headwaters than in mid‐order streams in Hydropsyche (Trichoptera)

Summary The influence of local habitat characteristics and landscape barriers on the distribution of species and genetic diversity remains poorly known. We tested for differences in turnover and total diversity in aquatic insect assemblages among headwater and mid‐order reaches, two habitats presumably differing in their connectivity between catchments. The genus Hydropsyche (Trichoptera) includes 17 species in the eastern Iberian Peninsula and northern Morocco. Cytochrome c oxidase subunit I (cox1) gene was sequenced for Hydropsyche assemblages at 38 headwater sites and 12 mid‐order sites. Local species and intraspecific genetic diversity and differentiation among populations were measured. A total of 231 cox1 sequences resulted in 83 unique haplotypes that clustered into 19 genetic species entities. We find that α‐diversity did not differ between headwater and mid‐order habitats at species and genetic levels, but total species numbers and intraspecific genetic diversity (γ‐diversity) were higher for headwater than for mid‐order or lowland clades, due to greater turnover among sites (β‐diversity). The study revealed lineage‐specific evolutionary responses to different river zones, presumably because of differences in the strength of landscape barriers. The multispecies community genetic approach provides a comprehensive picture of diversity patterns in Hydropsyche, as it links habitat heterogeneity and dispersal limitations to genetic structure and lineage diversification.

<i>Centaurea stuessyi</i> (Compositae: Cardueae), a new species from the eastern Iberian Peninsula

Centaurea stuessyi is described as new to science from the eastern Iberian Peninsula, Spain. The range of this new species coincides with the zone of overlap of the ranges of two related species, C. antennata (subsp. antennata) and C. linifolia. The chromosome number found in the new species (2n = 44) reinforces its differences from C. linifolia (2n = 22) and C. antennata (2n = 22). The new species is compared with related species, and a description is given of its ecological preferences.

El proceso de filtración en los badlands del Este de la Península Ibérica : avances y retos

Badlands are geomorphological miniature laboratories that contributed to the landforms and geomorphological processes studies. Infiltration is a key process in the hydrological cycle because it manages the volume of surface water and thus the erosive processes. Studying the process of infiltration into badlands gain insight on both, the process of infiltration and on badland geomorphology, and the results can be extrapolated to other areas where the high losses of soil and water must be controlled. This paper presents a review of the research regarding the infiltration in the badlands from experiments developed in the last two decades in the badlands of eastern Iberian Peninsula. The use of rainfall simulation experiments and cylinder infiltrometers measurements has provided relevant information to determine the effects of parent material, seasonality, time and geomorphological position on the process of infiltration, and then on the runoff generation and soil loss. Despite the lack of vegetation cover, and low soil development, the process of infiltration is highly complex in the badland surfaces because they generate macroporos from cracks that favor water infiltration and thus the piping developement. In the absence of vegetation, is the parent material through the surface morphology (cracks) the dominant factor in the processes of infiltration. Topographical position is key to understand the geomorphological processes in areas of badlands because the pediments behave as simple transmitters of water and sediment coming from the slopes because of its small infiltrabilidad and lack of cracks. Cracks also explain why the seasonality in the infiltration capacity of the regolith is high. Thus, the infiltration process in badlands is characterised by a highly seasonal, temporal and spatial variability which is key on the geomorphological processes behaviour.

Population dynamics of an epibiont Ostracoda on the invasive red swamp crayfish Procambarus clarkii in a western Mediterranean wetland

Recently, the American entocytherid ostracod Ankylocythere sinuosa was discovered for the first time in Europe to inhabit widely distributed populations of the invasive American crayfish Procambarus clarkii in the Iberian Peninsula. Based on this finding, the aim was to describe the population dynamics of exotic entocytherids for the first time beyond their original area, and to analyse the main variables modulating temporal demographic patterns. We monitored a population of A. sinuosa and its host, P. clarkii, in the Pego-Oliva wetland (Eastern Iberian Peninsula) monthly for 1 year. Crayfish entocytherid loads strongly related to crayfish weight, moult-related exoskeleton hardening stage and water temperature. The proportion of earliest juvenile entocytherid instars, an indicator of recent hatching periods, also related to water temperature and conductivity. According to our results, the most important factors affecting entocytherid dynamics are individual crayfish moulting events, which diminish ostracod load, together with water temperature and ionic concentration, both influencing the life cycle of the exotic epibiont ostracod A. sinuosa.

SYNDROME-DRIVEN DIVERSIFICATION IN A MEDITERRANEAN ECOSYSTEM

Phylogenetic methods to detect lineage diversification have been traditionally used within a particular taxonomic clade, but rarely applied to detect local diversification. For understanding in situ diversification triggered by novel conditions it is necessary to focus on the time slice where such conditions occur. These new conditions may differentially affect the diversification rate of lineages with different morpho-functional syndromes. A prominent example of these processes occurs in the Mediterranean Basin, where climate arising along the Tertiary/Quaternary transition acted as an environmental filter. In this context, lineages with different syndromes (sclerophyllous and nonsclerophyllous) are hypothesized to have different local diversification rates after the rise of the Mediterranean conditions. We used macroevolutionary methods of time-dependent diversification on a calibrated local phylogeny accommodating topological and chronological uncertainty to test syndrome-driven diversification in Mediterranean shrublands from the eastern Iberian Peninsula. We found phylogenetic evidence of higher speciation associated with the nonsclerophyllous syndrome, although extinction rates were similar between syndromes. Consequently a syndrome-driven local diversification has occurred in shrublands under Mediterranean conditions. The results provide an example of how the integration of the environmental filter in a dated phylogeny may recreate the local history of lineages and help to explain assembly processes in Mediterranean ecosystems.

Physico-chemical analysis of Albian (Lower Cretaceous) amber from San Just (Spain): implications for palaeoenvironmental and palaeoecological studies

Amber from a Lower Cretaceous outcrop at San Just, located in the Eastern Iberian Peninsula (Escucha Formation, Maestrat Basin), was investigated to evaluate its physico-chemical properties. Thermogravimetric (TG) and Differential Thermogravimetric (DTG) analyses, infra-red spectroscopy, elemental and C-isotope analyses were performed. Physico-chemical differences between the internal light nuclei and the peripheral darker portions of San Just amber can be attributed to processes of diagenetic alteration that preferentially took place in the external amber border colonized by microorganisms (fungi or bacteria) when the resin was still liquid or slightly polymerized. δ13Camber values of different pieces of the same sample, from the nucleus to the external part, are remarkably homogeneous, as are δ13Camber values of the darker peripheral portions and lighter inner parts of the same samples. Hence, neither invasive microorganisms, nor diagenetic alteration changed the bulk isotopic composition of the amber. δ13C values of different amber samples range from -21.1‰ to -24‰, as expected for C3 plant-derived material. C-isotope analysis, coupled to palaeobotanical, TG and DTG data and infra-red spectra, suggests that San Just amber was exuded by only one conifer species, belonging to either the Cheirolepidiaceae or Aracauriaceae, coniferous families probably living under stable palaeoenvironmental and palaeoecological conditions.

Revision of Cestocampa Condé (Diplura, Campodeidae), with description of a new species from caves in the eastern Iberian Peninsula

Revision of Cestocampa Condé (Diplura, Campodeidae), with description of a new species from caves in the eastern Iberian Peninsula

Indicator species of broad-leaved oak forests in the eastern Iberian Peninsula

The degraded state, scattered distribution and substrate type of Quercus pyrenaica forests in eastern Spain make them a subject of particular interest, as well as a priority for conservation efforts. An extension of Dufrêne and Legendre's indicator value (IndVal) analysis was applied to one hundred relevés. This extension of the IndVal method allowed us, by considering the preference of species for combinations of relevé groups, to obtain those species that represent local, but also regional, characteristics (as a new practical use). Our objective was to identify the species that best indicate the main ecological features of these broad-leaved oak forests. The usefulness of our analysis was evidenced at two levels: local indicator species, showing the characteristic species of individual sites and including the presence of endemics in the area; and indicator species of combinations of two or more sites, reflecting the affinities or relationships between these scattered forests.Most singular forests showed a higher number of local indicator species. The indicator species of each site combination represent the main ecological traits shared by these groups – such as proximity to the coast, land uses or postglacial migration pathways – thereby defining their relationships. Indicator value analysis with site group combinations (Multipatt function) proved to be a useful tool for the identification of different species that could serve both to determine the local forest conservation status and aid in its preservation, as well as contributing to an understanding of the life history of larger territories.

New insights into the biogeography of south‐western Europe: spatial patterns from vascular plants using cluster analysis and parsimony

AbstractAimWe analysed the distributional pattern of the vascular flora of the Iberian Peninsula and Balearic archipelago using cluster and parsimony methods to delineate a biogeographical scheme for south‐western Europe and to compare the results with previous regionalizations. Additionally, we aim to identify areas of endemism.LocationSouth‐western Europe (Iberian Peninsula and the Balearic Islands).MethodsPattern analysis of a chorological dataset, consisting of the occurrences of 3041 vascular plant species in each of the 50 km × 50 km UTM cells of a grid covering Iberia and the Balearic Islands, was based on cluster analysis (unweighted pair‐group method using arithmetic averages; UPGMA) and parsimony analysis of endemicity (PAE). The Jaccard similarity index was used in the UPGMA, and the set of most parsimonious trees from the PAE were summarized in a 75% majority consensus tree.ResultsThe UPGMA dendrogram delineated two main branches in the study region: (1) an eastern area of six sectors including the Balearic Islands plus those regions of Iberia with basic substrates, and (2) a western area with three sectors comprising the regions with acidic soils. The majority rule consensus tree of 53 most parsimonious trees from PAE showed eight main clades similarly separating eastern Iberia plus the Balearic Islands with their basic substrates, from western Iberia with its acidic and basic substrates; in addition the PAE tree showed some previously undetected chorological patterns.Main conclusionsThe use of large and inclusive datasets allows for the recognition of different spatial patterns from those obtained using a limited number of endemic or indicator species. The analyses support some floristic regions previously recognized for Iberia, but not the classic Eurosiberian–Mediterranean division, and some transition territories. Our recognition of 19 areas of endemism consisting of two or more cells and 60 consisting of one cell in south‐western Europe is new.

Late Mesolithic burials at Casa Corona (Villena, Spain): direct radiocarbon and palaeodietary evidence of the last forager populations in Eastern Iberia

Current knowledge about the Mesolithic–Neolithic transition in the Central and Western Mediterranean European regions is deeply limited by the paucity of Late Mesolithic human osteological data and the presence of chronological gaps covering several centuries between the last foragers and the first archaeological evidence of farming peoples. In this work, we present new data to fill these gaps. We provide direct AMS radiocarbon dating and carbon (δ13C) and nitrogen (δ15N) stable isotope analysis were carried out on bone collagen samples of two single burials from the recently discovered open-air Late Mesolithic site of Casa Corona (Villena, Spain). The results shed new light on the chronology and subsistence patterns of the last Mesolithic communities in the Central Mediterranean region of the Iberian Peninsula. Radiocarbon results date the human remains and funerary activity of the site to 6059–5849 cal BC, statistically different from other Late Mesolithic sites and the earliest Neolithic contexts, and bridging the 500 yrs chronological gap of the Mesolithic–Neolithic transition from the area. Isotopic evidence shows that diet was based on terrestrial resources despite the proximity to the site of lagoon and marine ecosystems. This and previous isotope studies from the region suggest a lower reliance upon marine resources than for Atlantic and Cantabrian sites, although intra-regional patterns of neighbouring Mesolithic populations exhibit both fully terrestrial diets and diets with significant amounts of aquatic resources in them. We hypothesize that in the Central Mediterranean region of Spain the Late Mesolithic dietary adaptations imposed structural limits on demographic growth of the last foragers and favoured rapid assimilation by the earliest Neolithic populations.

Assessment of brown trout habitat suitability in the Jucar River Basin (SPAIN): Comparison of data-driven approaches with fuzzy-logic models and univariate suitability curves

The implementation of the Water Framework Directive implies the determination of an environmental flow (E-flow) in each running water body. In Spain, many of the minimum flow assessments were determined with the physical habitat simulation system based on univariate habitat suitability curves. Multivariate habitat suitability models, widely applied in habitat assessment, are potentially more accurate than univariate suitability models. This article analyses the microhabitat selection by medium-sized (10–20cm) brown trout (Salmo trutta fario) in three streams of the Jucar River Basin District (eastern Iberian Peninsula). The data were collected with an equal effort sampling approach. Univariate habitat suitability curves were built with a data-driven process for depth, mean velocity and substrate classes; three types of data-driven fuzzy models were generated with the FISH software: two models of presence–absence and a model of abundance. FISH applies a hill-climbing algorithm to optimize the fuzzy rules. A hydraulic model was calibrated with the tool River-2D in a segment of the Cabriel River (Jucar River Basin). The fuzzy-logic models and three methods to produce a suitability index from the three univariate curves were applied to evaluate the river habitat in the tool CASiMiR©. The comparison of results was based on the spatial arrangement of habitat suitability and the curves of weighted usable area versus discharge. The differences were relevant in different aspects, e.g. in the estimated minimum environmental flow according to the Spanish legal norm for hydrological planning. This work demonstrates the impact of the model's selection on the habitat suitability modelling and the assessment of environmental flows, based on an objective data-driven procedure; the conclusions are important for the water management in the Jucar River Basin and other river systems in Europe, where the environmental flows are a keystone for the achievement of the goals established in the European Water Framework Directive.

DNA analysis in charred grains of naked wheat from several archaeological sites in Spain

In the present work we attempt to recover endogenous ancient DNA from cereal grains preserved under different conditions: charred, partially charred and waterlogged. A total of 126 grains from naked wheat and 18 from barley from different sites on the Eastern Iberian Peninsula ranging from the beginning of agriculture in the region to the turn of the Common Era, were studied. Two different extraction protocols were used, a standard phenol–chloroform method and a silica-based DNA extraction procedure implemented for artificially charred seeds. Amplifications were directed to three markers: the large subunit of ribulose 1,5 biphosphate carboxylase (rbcL) and the microsatellite WCT12 in the chloroplast genome and the x and y subunits of the high molecular weight glutenin gene (Glu-1) in the nucleus. The first two were used to assess the preservation status of the samples, while with the third we tried to identify the wheat grains at species level. It was possible to obtain eleven positive amplifications in 8 partially charred seeds but only two amplifications of the Glu-1 gene from a single sample of the Early Bronze age were genome-specific. Different contamination sources were identified and reported. Cloning and alignment of sequenced clones showed a correspondence of the amplified fragment to modern wheat D genome haplotypes. This result suggests that the sample corresponds to hexaploid wheat (Triticum aestivum L.), thus being the first ancient DNA evidence to date for the cultivation of hexaploid wheat in the prehistoric agriculture of the Iberian Peninsula. Moreover, obtained results highlight contamination problems associated to the study of ancient archaeobotanical charred seeds suggest that the combination of a silica-based extraction method together with the amplification of specific targets is a good strategy for recovering endogenous ancient DNA from this kind of material.

The use of experimental data and their uncertainty for assessing ozone photochemistry in the Eastern Iberian Peninsula

Observation-based methods are useful tools to explore the sensitivity of ozone concentrations to precursor controls. With the aim of assessing the ozone precursor sensitivity in two locations: Paterna (suburban) and Villar del Arzobispo (rural) of the Turia river basin in the east of Spain, the photochemical indicator O3/NOy and the Extent-of-Reaction (EOR) parameter have been calculated from field measurements. In Paterna, the O3/NOy ratio varied from 0 to 13 with an average value of 5.1 (SD 3.2), whereas the averaged value for the EOR was 0.43 (SD 0.14). In Villar del Arzobispo, the O3/NOy ratio changed from 5 to 30 with a mean value of 13.6 (SD 4.7) and the EOR gave an averaged value of 0.72 (SD 0.11). The results show two different patterns of ozone production as a function of the location. The suburban area shows a VOC-sensitive regime whereas the rural one shows a transition regime close to NOx-sensitive conditions. No seasonal differences in these regimes are observed along the monitoring campaigns. Finally, an analysis of the influence of the measurement quality of NOy, NOx and O3 on the uncertainty of the O3/NOy ratio and the EOR was performed showing that the uncertainty of O3/NOy is not dependent on either its value or the individual values of O3 and NOy but just on the quality of O3 and NOy measurements. The maximum uncertainty is 26% as long as the combined uncertainties of O3 and NOy remain below the 7.5%. The case of the EOR is different and its uncertainty depends on both the value of the EOR parameter and the individual concentration values of NOy and NOx. The uncertainty of the EOR estimation can be very high (>200%) if the combined uncertainties of both NOy and NOx are high (>7.5%), or especially, if u(NOy) and u(NOx) differ considerably from each other (>3.5%).