Fungal and Bacterial Communities in Indoor Dust Follow Different Environmental Determinants.

People spend most of their time inside buildings and the indoor microbiome is a major part of our everyday environment. It affects humans' wellbeing and therefore its composition is important for use in inferring human health impacts. It is still not well understood how environmental conditions affect indoor microbial communities. Existing studies have mostly focussed on the local (e.g., building units) or continental scale and rarely on the regional scale, e.g. a specific metropolitan area. Therefore, we wanted to identify key environmental determinants for the house dust microbiome from an existing collection of spatially (area of Munich, Germany) and temporally (301 days) distributed samples and to determine changes in the community as a function of time. To that end, dust samples that had been collected once from the living room floors of 286 individual households, were profiled for fungal and bacterial community variation and diversity using microbial fingerprinting techniques. The profiles were tested for their association with occupant behaviour, building characteristics, outdoor pollution, vegetation, and urbanization. Our results showed that more environmental and particularly outdoor factors (vegetation, urbanization, airborne particulate matter) affected the community composition of indoor fungi than of bacteria. The passage of time affected fungi and, surprisingly, also strongly affected bacteria. We inferred that fungal communities in indoor dust changed semi-annually, whereas bacterial communities paralleled outdoor plant phenological periods. These differences in temporal dynamics cannot be fully explained and should be further investigated in future studies on indoor microbiomes.

Can we detect a nonlinear response to temperature in European plant phenology?

Over a large temperature range, the statistical association between spring phenology and temperature is often regarded and treated as a linear function. There are suggestions that a sigmoidal relationship with definite upper and lower limits to leaf unfolding and flowering onset dates might be more realistic. We utilised European plant phenological records provided by the European phenology database PEP725 and gridded monthly mean temperature data for 1951-2012 calculated from the ENSEMBLES data set E-OBS (version 7.0). We analysed 568,456 observations of ten spring flowering or leafing phenophases derived from 3657 stations in 22 European countries in order to detect possible nonlinear responses to temperature. Linear response rates averaged for all stations ranged between -7.7 (flowering of hazel) and -2.7 days °C-1 (leaf unfolding of beech and oak). A lower sensitivity at the cooler end of the temperature range was detected for most phenophases. However, a similar lower sensitivity at the warmer end was not that evident. For only ∼14 % of the station time series (where a comparison between linear and nonlinear model was possible), nonlinear models described the relationship significantly better than linear models. Although in most cases simple linear models might be still sufficient to predict future changes, this linear relationship between phenology and temperature might not be appropriate when incorporating phenological data of very cold (and possibly very warm) environments. For these cases, extrapolations on the basis of linear models would introduce uncertainty in expected ecosystem changes.

Neighbourhood and physical activity in German adolescents: GINIplus and LISAplus.

INTRODUCTION: Impact of neighbourhood on physical activity (PA) is under-investigated in European adolescents, and few studies have used objective data on both exposures and outcomes. Therefore we investigated the association between objectively measured neighbourhood characteristics and PA in 15-year-old German adolescents. METHODS: Study populations comprised of 688 adolescents residing in the urban Munich area and 504 from the rural Wesel area from the GINIplus and LISAplus birth cohorts. Neighbourhood was defined as a circular 500-m buffer around the residence. Greenness was calculated 1) as the mean Normalized Difference Vegetation Index (NDVI), and 2) as percent tree cover. Neighbourhood green spaces and sport and leisure facilities were defined as present or absent in a neighbourhood (data only available for Munich). Data on PA were collected from one-week triaxial accelerometry (hip-worn ActiGraph GT3X). Minutes of PA were classified into moderate-to-vigorous (MVPA), light and sedentary using Romanzini's et al. triaxial cutoffs, and averaged over the recording period. Activity diaries were used for differentiation between school and leisure (total minus school) PA. Area-specific associations were assessed by adjusted negative binomial regressions. RESULTS: In the Wesel area, residing in a neighbourhood with higher NDVI was associated with 9% more leisure MVPA among females and with 8% more leisure MVPA in rural dwellers. In the Munich area, residing in a neighbourhood with sport facilities was associated with 9% more leisure MVPA. The latter association was only significant in urban dwellers while neighbourhood leisure facilities increased MVPA in rural dwellers. Estimates were very similar when total MVPA was considered rather than solely leisure. CONCLUSION: There is indication that neighbourhood features could be associated with MVPA in German adolescents. However, different features seem to be important across sexes and in rural/urban settings, which need to be specifically addressed in future studies.

The effects of short- and long-term air pollutants on plant phenology and leaf characteristics.

Pollution adversely affects vegetation; however, its impact on phenology and leaf morphology is not satisfactorily understood yet. We analyzed associations between pollutants and phenological data of birch, hazel and horse chestnut in Munich (2010) along with the suitability of leaf morphological parameters of birch for monitoring air pollution using two datasets: cumulated atmospheric concentrations of nitrogen dioxide and ozone derived from passive sampling (short-term exposure) and pollutant information derived from Land Use Regression models (long-term exposure). Partial correlations and stepwise regressions revealed that increased ozone (birch, horse chestnut), NO2, NOx and PM levels (hazel) were significantly related to delays in phenology. Correlations were especially high when rural sites were excluded suggesting a better estimation of long-term within-city pollution. In situ measurements of foliar characteristics of birch were not suitable for bio-monitoring pollution. Inconsistencies between long- and short-term exposure effects suggest some caution when interpreting short-term data collected within field studies.

Does flower phenology mirror the slowdown of global warming?

Although recent global warming trends in air temperature are not as pronounced as those observed only one decade ago, global mean temperature is still at a very high level. Does plant phenology - which is believed to be a suitable indicator of climate change - respond in a similar way, that is, does it still mirror recent temperature variations? We explored in detail long-term flowering onset dates of snowdrop, cherry, and lime tree and relevant spring temperatures at three sites in Germany (1901-2012) using the Bayesian multiple change-point approach. We investigated whether mean spring temperature changes were amplified or slowed down in the past decade and how plant phenology responded to the most recent temperature changes. Incorporating records with different end points (i.e., 2002 and 2012), we compared differences in trends and inferred possible differences caused by extrapolating phenological and meteorological data. The new multiple-change point approach is characterized by an enhanced structure and greater flexibility compared to the one change point model. However, the highest model probabilities for phenological (meteorological) records were still obtained for the one change point (linear) model. Marked warming trends in the recent decade were only revealed for mean temperatures of March to May, here better described with one or two change point models. In the majority of cases analyzed, changes in temperatures were well mirrored by phenological changes. However, temperatures in March to May were linked to less strongly advancing onset dates for lime tree flowering during the period 1901-2012, pointing to the likely influence of photoperiodic constraints or unfulfilled chilling requirements. Due to the slowdown of temperature increase, analyses conducted on records ending in 2002 demonstrated distinct differences when compared with records ending in 2012. Extrapolation of trends could therefore (along with the choice of the statistical method) lead to distinctly different results and most recent data should be integrated in order not to over- or underestimate future phenological changes.

Urban phenological studies - Past, present, future.

Phenology is believed to be a suitable bio-indicator to track climate change. Based on the strong statistical association between phenology and temperature phenological observations provide an inexpensive means for the temporal and spatial analysis of the urban heat island. However, other environmental factors might also weaken this relationship. In addition, the investigation of urban phenology allows an estimation of future phenology from current information since cities with their amplified temperatures may serve as a proxy for future conditions. Nevertheless, the design of spatial compared to long-term studies might be influenced by different factors which should be taken into consideration when interpreting results from a specific study. In general, plants located in urban areas tend to flush and bloom earlier than in the countryside. What are the consequences of these urban-rural differences? This review will document existing findings on urban phenology and will highlight areas in which further research is needed.

High environmental ozone levels lead to enhanced allergenicity of birch pollen.

BACKGROUND: Evidence is compelling for a positive correlation between climate change, urbanisation and prevalence of allergic sensitisation and diseases. The reason for this association is not clear to date. Some data point to a pro-allergenic effect of anthropogenic factors on susceptible individuals. OBJECTIVES: To evaluate the impact of urbanisation and climate change on pollen allergenicity. METHODS: Catkins were sampled from birch trees from different sites across the greater area of Munich, pollen were isolated and an urbanisation index, NO2 and ozone exposure were determined. To estimate pollen allergenicity, allergen content and pollen-associated lipid mediators were measured in aqueous pollen extracts. Immune stimulatory and modulatory capacity of pollen was assessed by neutrophil migration assays and the potential of pollen to inhibit dendritic cell interleukin-12 response. In vivo allergenicity was assessed by skin prick tests. RESULTS: The study revealed ozone as a prominent environmental factor influencing the allergenicity of birch pollen. Enhanced allergenicity, as assessed in skin prick tests, was mirrored by enhanced allergen content. Beyond that, ozone induced changes in lipid composition and chemotactic and immune modulatory potential of the pollen. Higher ozone-exposed pollen was characterised by less immune modulatory but higher immune stimulatory potential. CONCLUSION: It is likely that future climate change along with increasing urbanisation will lead to rising ozone concentrations in the next decades. Our study indicates that ozone is a crucial factor leading to clinically relevant enhanced allergenicity of birch pollen. Thus, with increasing temperatures and increasing ozone levels, also symptoms of pollen allergic patients may increase further.

Can spatial data substitute temporal data in phenological modelling? A survey using birch flowering.

In addition to the evaluation of long-term series, the analysis of spatial gradients, such as urbanization gradients, may be helpful in assessing phenological responses to global warming. But are phenological responses of birch (Betula pendula Roth) assessed by temperature variations comparable over time and space and can spatially calibrated models predict long-term phenological data adequately? We calibrated and tested linear regression models and the process-based DORMPHOT model on phenological and temperature data sampled along an urbanization gradient in 2010 and 2011 in the German cities Munich and Ingolstadt (spatial data). Additionally, we analysed data from the German Meteorological Service for the period 1991-2010 (long-term data). The model comparison showed that the DORMPHOT model performed better than the linear model. Therefore, the importance of forcing and chilling sums as well as photoperiod, factors which were all considered in the DORMPHOT model, was evident. Models calibrated on spatial data produced good predictions of spatial data, but they were less adequate for predicting long-term data. Therefore, a time-for-space substitution might not always be appropriate. This finding was also confirmed by a comparison of temperature response rates. The rate of change in the spatial data (-4.4 days °C(-1)) did not match the changes observed in the long-term data (-1.9 days °C(-1)). Consequently, it is important not to generalize results derived from one specific study method, but their inherent methodological, spatial and temporal peculiarities have to be considered.

Nutrient status: a missing factor in phenological and pollen research?

Phenology ranks among the best ecosystem processes for fingerprinting climate change since temperature explains a high percentage of the interannual or spatial variation in phenological onset dates. However, roles of other environmental variables, such as foliar nutrient concentrations, are far from adequately understood. This observational study examined the effects of air temperature and 11 nutrients on spring phenology of Betula pendula Roth (birch) along an urban-rural gradient in Munich, Germany, during the years 2010/2011. Moreover, the influence of temperature, nutrients, and air pollutants (NO2 and O3) on the amounts of pollen and catkin biomass in 2010 was evaluated. In addition to the influence of higher temperatures advancing phenological onset dates, higher foliar concentrations of potassium, boron, zinc, and calcium were statistically significantly linked to earlier onset dates. Since flushing of leaves is a turgor-driven process and all the influential nutrients are involved in cell extension, membrane function, and stability, there might be a reasonable physiological interpretation of the observed association. The amounts of pollen were negatively correlated with temperature, atmospheric NO2, and foliar iron concentration, suggesting that these variables restrict pollen production. The results of this study suggested an influence of nutritional status on both phenology and pollen production. The interaction of urbanization and climate change should be considered in the assessment of the impact of global warming on ecosystems and human health.

The influence of altitude and urbanisation on trends and mean dates in phenology (1980-2009).

Long-term studies on urban phenology using network data are commonly limited by the small number of observation sites within city centres. Moreover, cities are often located on major rivers and consequently at lower altitudes than their rural surroundings. For these reasons, it is important (1) to go beyond a plain urban-rural comparison by taking the degree of urbanisation into account, and (2) to evaluate urbanisation and altitudinal effects simultaneously. Temporal phenological trends (1980-2009) for nine phenological spring events centred on the German cities of Frankfurt, Cologne and Munich were analysed. Trends of phenological onset dates were negative (i.e. earlier onset in phenology) for 96% of the 808 time series and significantly negative for 56% of the total number. Mean trends for the nine phenological events ranged between -0.23 days year(-1) for beech and -0.50 days year(-1) for hazel. The dependence of these trends and of mean dates on altitude and on the degree of urbanisation was explored. For mean dates, we demonstrated an earlier phenological onset at lower altitude and with a higher degree of urbanisation: altitude effects were highly significant and ranged between 1.34 days (100 m)(-1) (beech) and 4.27 days (100 m)(-1) (hazel). Coefficients for the log-transformed urban index were statistically significant for five events and varied greatly between events (coefficients from -1.74 for spruce to -5.08 for hazel). For trends in phenology, altitude was only significant for Norway maple, and no urban effects were significant. Hence, trends in phenology did not change significantly with higher altitudes or urbanised areas.