The magnetic signal from trunk bark of urban trees catches the variation in particulate matter exposure within and across six European cities.

Biomagnetic monitoring increasingly is applied to assess particulate matter (PM) concentrations, mainly using plant leaves sampled in small geographical area and from a limited number of species. Here, the potential of magnetic analysis of urban tree trunk bark to discriminate between PM exposure levels was evaluated and bark magnetic variation was investigated at different spatial scales. Trunk bark was sampled from 684 urban trees of 39 genera in 173 urban green areas across six European cities. Samples were analysed magnetically for the Saturation isothermal remanent magnetisation (SIRM). The bark SIRM reflected well the PM exposure level at city and local scale, as the bark SIRM (i) differed between the cities in accordance with the mean atmospheric PM concentrations and (ii) increased with the cover of roads and industrial area around the trees. Furthermore, with increasing tree circumferences, the SIRM values increased, as a reflection of a tree age effect related to PM accumulation over time. Moreover, bark SIRM was higher at the side of the trunk facing the prevailing wind direction. Significant relationships between SIRM of different genera validate the possibility to combine bark SIRM from different genera to improve sampling resolution and coverage in biomagnetic studies. Thus, the SIRM signal of trunk bark from urban trees is a reliable proxy for atmospheric coarse to fine PM exposure in areas dominated by one PM source, as long as variation caused by genus, circumference and trunk side is taken into account.

Phyllosphere bacterial communities in urban green areas throughout Europe relate to urban intensity.

The phyllosphere harbours a diverse and specific bacterial community, which influences plant health and ecosystem functioning. In this study, we investigated the impact of urban green areas connectivity and size on the composition and diversity of phyllosphere bacterial communities. Hereto, we evaluated the diversity and composition of phyllosphere bacterial communities of 233 Platanus x acerifolia and Acer pseudoplatanus trees in 77 urban green areas throughout 6 European cities. The community composition and diversity significantly differed between cities but only to a limited extent between tree species. We could show that urban intensity correlated significantly with the community composition of phyllosphere bacteria. In particular, a significant correlation was found between the relative abundances for 29 out of the 50 most abundant families and the urban intensity: the abundances of classic phyllosphere families, such as Acetobacteraceae, Planctomycetes, and Beijerinkiaceae, decreased with urban intensity (i.e. more abundant in areas with more green, lower air pollution, and lower temperature), while those related to human activities, such as Enterobacteriaceae and Bacillaceae, increased with urban intensity. The results of this study suggest that phyllosphere bacterial communities in European cities are associated with urban intensity and that effect is mediated by several combined stress factors.

Wild bee larval food composition in five European cities.

Urbanization poses threats and opportunities for the biodiversity of wild bees. At the same time, cities can harbor diverse wild bee assemblages, partly due to the unique plant assemblages that provide resources. While bee dietary preferences have been investigated in various studies, bee dietary studies have been conducted mostly in nonurban ecosystems and data based on plant visitation observations or palynological techniques. This data set describes the larval food preferences of four wild bee species (i.e., Chelostoma florisomne, Hylaeus communis, Osmia bicornis, and O. cornuta) common in urban areas in five different European cities (i.e., Antwerp, Belgium; Paris, France; Poznan, Poland; Tartu, Estonia; and Zurich, Switzerland). In addition, the data set describes the larval food preferences of individuals from three wild bee genera (i.e., Chelostoma sp., Hylaeus sp., and Osmia sp.) that could not be identified to the species level. These data were obtained from a Europe-level study aimed at understanding the effects of urbanization on biodiversity across different cities and cityscapes and a Swiss project aimed at understanding the effects of urban ecosystems in wild bee feeding behavior. Wild bees were sampled using standardized trap nests at 80 sites (32 in Zurich and 12 in each of the remaining cities), selected following a double gradient of available habitat at local and landscape scales. Larval pollen was obtained from the bee nests and identified using DNA metabarcoding. The data provide the plant composition at the species or genus level preferred by each bee. These unique data can be used for a wide array of research questions, including urban ecology (e.g., diversity of food sources along urban gradients), bee ecology (characterization of bee feeding preferences), or comparative studies on the urban evolution of behavioral traits between urban and nonurban sites. In addition, the data can be used to inform urban planning and conservation strategies, particularly concerning flower resources (e.g., importance of exotic species and, thus, management activities). This data set can be freely used for noncommercial purposes, and this data paper should be cited if the data is used; we request that collaboration with the data set contact person to be considered if this data set represents an important part of the data analyzed in a study.

Exploring multitrophic interactions in oilseed rape fields reveals the prevailing role of Carabidae.

In cropped fields, birds are often at the highest position in the food chain, feeding on pest arthropods and their intermediate predators in a process known as intraguild predation. The net effects of bird predation on phytophagous insect populations (feeding on plants) are difficult to predict without comprehensively describing prey-predator communities and their complex interplay. We sampled bird and arthropod communities in 30 oilseed rape fields in the spring of 2019 and 2020 in France. To assess the top-down control of arthropods by birds, we used a vertebrate exclusion experiment. Using a taxonomic and functional trait-based approach, we determined the direct and indirect influences of birds on arthropod predators and phytophagous insect populations in arable crops. We observed a negative relationship between the abundance of Carabidae and phytophagous insects but not with the other predator group suggesting the key role of Carabidae on phytophagous insects in agroecosystem. We found no statistical evidence of intraguild predation from birds toward intermediate predators. Despite the lack of overall effect of predator functional diversity on their prey, we highlighted the negative relationship between the functional complementarity (through functional evenness) of Carabidae and the abundance of phytophagous insects. This result suggests that functional complementarity between Carabidae species could help to reduce phytophagous insect populations. We analyzed the effect of agricultural practices on these multitrophic interactions, showing that pesticide intensity only had detrimental effects on Carabidae abundance, while the frequency of tillage did not affect the studied communities. Complementary indices used to depict communities are helpful to better understand the mechanisms underlying trophic relationships.

Any despot at my table? Competition among native and introduced bird species at garden birdfeeders in winter.

Garden bird feeding constitutes a massive provision of food that can support bird communities, but there is a growing concern it might favour the establishment of exotic species that could be detrimental to others. How bird species compete with novel species for this anthropogenic food resources needs to be assessed. Here, we investigated competition in wintering bird communities at garden birdfeeders. We evaluated whether - and how much - bird access to resources is hampered by the presence of putative superior competing species, among which the Rose-ringed parakeet, the most abundant introduced species across Europe. Using the nation-wide citizen science scheme BirdLab, in which volunteers record in real-time bird attendance on a pair of birdfeeders during 5-minute sessions, we tested whether i) cumulative bird presence time and richness at birdfeeders, and ii) species probability of presence at birdfeeders, were influenced by three large species (the Eurasian magpie, the Eurasian collared-dove, and the Rose-ringed parakeet). Additionally, we assessed whether the Rose-ringed parakeet occupied resources significantly more than others. Presence of the Rose-ringed parakeet or the Eurasian collared-dove similarly reduced community cumulative presence time at birdfeeders, but only the dove reduced community richness. Each of the three large species influenced the presence of at least one of the six smaller species that could be separately modelled, but effects varied in strength and direction. The Rose-ringed parakeet and the Eurasian collared-dove were among the three species monopolising birdfeeders the longest, substantially more than the Eurasian magpie. Our findings confirm the competitive abilities of the large species studied, but do not suggest that garden bird feeding may alarmingly favour introduced species with detrimental effects on native species. Given the variability of large species' effects on small passerines, direct and indirect interactions among all species must be examined to fully understand the ecological net effects at stake.

Effect of a 16-Day Altitude Training Camp on 3,000-m Steeplechase Running Energetics and Biomechanics: A Case Study.

The purpose of this study was to investigate the effect of a 16-day training camp at moderate altitude on running energetics and biomechanics in an elite female 3,000-m steeplechase athlete (personal best: 9 min 36.15 s). The 16-day intervention included living and training at 1,600 m altitude. A maximal incremental test was performed at sea level to determine the maximal oxygen uptake ( V ∙ O 2 max ). Before (pre-) and after (post-) intervention, the participant performed a specific training session consisting of 10 × 400 m with 5 hurdles with oxygen uptake ( V ∙ O 2 ), blood lactate, stride length and stride rate being measured. A video analysis determined take-off distance and landing around the hurdle (DTH and DLH), take-off velocity and landing around the hurdle (VTH and VLH), and the maximal height over the hurdle (MH). The results demonstrated that the mean V ∙ O 2 maintained during the ten 400 m trials represented 84-86% of V ∙ O 2 max and did not change from pre- to post-intervention (p = 0.22). Mean blood lactate measured on the 6 last 400-m efforts increased significantly (12.0 ± 2.2 vs. 17.0 ± 1.6 mmol.l-1; p < 0.05). On the other hand, post-intervention maximal lactate decreased from 20.1 to 16.0 mmol.l-1. Biomechanical analysis revealed that running velocity increased from 5.12 ± 0.16 to 5.49 ± 0.19 m.s-1 (p < 0.001), concomitantly with stride length (1.63 ± 0.05 vs. 1.73 ± 0.06 m; p < 0.001). However, stride rate did not change (3.15 ± 0.03 vs. 3.16 ± 0.02 Hz; p = 0.14). While DTH was not significantly different from pre- to post- (1.34 ± 0.08 vs. 1.40 ± 0.07 m; p = 0.09), DLH was significantly longer (1.17 ± 0.07 vs. 1.36 ± 0.05 m; p < 0.01). VTH and VLH significantly improved after intervention (5.00 ± 0.14 vs. 5.33 ± 0.16 m.s-1 and 5.18 ± 0.13 vs. 5.51 ± 0.22 m.s-1, respectively; both p < 0.01). Finally, MH increased from pre- to post- (52.5 ± 3.8 vs. 54.9 ± 2.1 cm; p < 0.05). A 16-day moderate altitude training camp allowed an elite female 3,000-m steeplechase athlete to improve running velocity through a greater glycolytic-but not aerobic-metabolism.

Tillage and herbicide reduction mitigate the gap between conventional and organic farming effects on foraging activity of insectivorous bats.

The increased use of pesticides and tillage intensification is known to negatively affect biodiversity. Changes in these agricultural practices such as herbicide and tillage reduction have variable effects among taxa, especially at the top of the trophic network including insectivorous bats. Very few studies compared the effects of agricultural practices on such taxa, and overall, only as a comparison of conventional versus organic farming without accurately accounting for underlying practices, especially in conventional where many alternatives exist. Divergent results founded in these previous studies could be driven by this lack of clarification about some unconsidered practices inside both conventional and organic systems. We simultaneously compared, over whole nights, bat activity on contiguous wheat fields of one organic and three conventional farming systems located in an intensive agricultural landscape. The studied organic fields (OT) used tillage (i.e., inversion of soil) without chemical inputs. In studied conventional fields, differences consisted of the following: tillage using few herbicides (T), conservation tillage (i.e., no inversion of soil) using few herbicides (CT), and conservation tillage using more herbicide (CTH), to control weeds. Using 64 recording sites (OT = 12; T = 21; CT = 13; CTH = 18), we sampled several sites per system placed inside the fields each night. We showed that bat activity was always higher in OT than in T systems for two (Pipistrellus kuhlii and Pipistrellus pipistrellus) of three species and for one (Pipistrellus spp.) of two genera, as well as greater species richness. The same results were found for the CT versus T system comparison. CTH system showed higher activity than T for only one genus (Pipistrellus spp.). We did not detect any differences between OT and CT systems, and CT showed higher activity than CTH system for only one species (Pipistrellus kuhlii). Activity in OT of Pipistrellus spp. was overall 3.6 and 9.3 times higher than CTH and T systems, respectively, and 6.9 times higher in CT than T systems. Our results highlight an important benefit of organic farming and contrasted effects in conventional farming. That there were no differences detected between the organic and one conventional system is a major result. This demonstrates that even if organic farming is presently difficult to implement and requires a change of economic context for farmers, considerable and easy improvements in conventional farming are attainable, while maintaining yields and approaching the ecological benefits of organic methods.

Improving the selection of focal species exposed to pesticides to support ecological risk assessments.

Risk assessment investigates the potential impacts of chemicals on non-target organisms. To assess the risk, ecotoxicologists study the responses of a panel of species to different substance exposure. Among the different parameters used to select indicator species (i.e. focal species), their frequency of occurrence is considered as the key parameter. Although species occurrence within a given habitat is easy to determine, we argue that it does not totally reflect the dependence of a species on a given habitat or its potential exposure to chemicals. In this study, we combined the occurrence of species with their habitat-specificity to identify focal species for risk assessment in cereals. We showed that ranking species by occurrence or by habitat-specificity produced different results, with generalist species ranking high in the occurrence list, and species with specialised habitats ranking high in the abundance list. Integrating frequency and abundance of species into one single indicator (the "Indicator Value") allows us to rank species with specialised habitats as high as generalist species in the top rank species list. Although habitat-specificity is an ecologically meaningful concept, it is largely overlooked in eco-toxicological risk assessment, despite the fact that specialists are good indicators of various environmental pressures. This method could be used extensively at different scales and could contribute to studies on risk assessment issue by (re)introducing ecological and population-level concepts and opening up new trait-based approaches.

Disentangling the role of environmental and human pressures on biological invasions across Europe.

The accelerating rates of international trade, travel, and transport in the latter half of the twentieth century have led to the progressive mixing of biota from across the world and the number of species introduced to new regions continues to increase. The importance of biogeographic, climatic, economic, and demographic factors as drivers of this trend is increasingly being realized but as yet there is no consensus regarding their relative importance. Whereas little may be done to mitigate the effects of geography and climate on invasions, a wider range of options may exist to moderate the impacts of economic and demographic drivers. Here we use the most recent data available from Europe to partition between macroecological, economic, and demographic variables the variation in alien species richness of bryophytes, fungi, vascular plants, terrestrial insects, aquatic invertebrates, fish, amphibians, reptiles, birds, and mammals. Only national wealth and human population density were statistically significant predictors in the majority of models when analyzed jointly with climate, geography, and land cover. The economic and demographic variables reflect the intensity of human activities and integrate the effect of factors that directly determine the outcome of invasion such as propagule pressure, pathways of introduction, eutrophication, and the intensity of anthropogenic disturbance. The strong influence of economic and demographic variables on the levels of invasion by alien species demonstrates that future solutions to the problem of biological invasions at a national scale lie in mitigating the negative environmental consequences of human activities that generate wealth and by promoting more sustainable population growth.

Reacción ocular de inclinación en infarto talámico / Ocular tilt reaction in thalamic infarct

La reacción ocular de inclinación, constituida por desviación ocular oblicua, torsión ocular e inclinación cefálica, parece que refleja una disfunción de la vía otolítica. También suele asociar alteración de la percepción subjetiva de la vertical. Este caso clínico muestra una reacción ocular de inclinación central por infarto talámico paramediano y mesecefálico rostral simultáneos (AU)

Ocular tilt reaction (OTR) includes skew deviation, eye torsion and head tilt. It is usually accompanied by a tilt in the subjective visual vertical. OTR seems to reflect an otolithic dysfunction. This case report shows an OTR of central origin as a result of simultaneous paramedial thalamic and mesencephalon rostral infarcts (AU)

[Ocular tilt reaction in thalamic infarct]. / Reacción ocular de inclinación en infarto talámico.

Ocular tilt reaction (OTR) includes skew deviation, eye torsion and head tilt. It is usually accompanied by a tilt in the subjective visual vertical. OTR seems to reflect an otolithic dysfunction. This case report shows an OTR of central origin as a result of simultaneous paramedial thalamic and mesencephalon rostral infarcts.

Human-related processes drive the richness of exotic birds in Europe.

Both human-related and natural factors can affect the establishment and distribution of exotic species. Understanding the relative role of the different factors has important scientific and applied implications. Here, we examined the relative effect of human-related and natural factors in determining the richness of exotic bird species established across Europe. Using hierarchical partitioning, which controls for covariation among factors, we show that the most important factor is the human-related community-level propagule pressure (the number of exotic species introduced), which is often not included in invasion studies due to the lack of information for this early stage in the invasion process. Another, though less important, factor was the human footprint (an index that includes human population size, land use and infrastructure). Biotic and abiotic factors of the environment were of minor importance in shaping the number of established birds when tested at a European extent using 50 x 50 km2 grid squares. We provide, to our knowledge, the first map of the distribution of exotic bird richness in Europe. The richest hotspot of established exotic birds is located in southeastern England, followed by areas in Belgium and The Netherlands. Community-level propagule pressure remains the major factor shaping the distribution of exotic birds also when tested for the UK separately. Thus, studies examining the patterns of establishment should aim at collecting the crucial and hard-to-find information on community-level propagule pressure or develop reliable surrogates for estimating this factor. Allowing future introductions of exotic birds into Europe should be reconsidered carefully, as the number of introduced species is basically the main factor that determines the number established.