[Allergies in the light of global environmental changes]. / Allergien im Lichte globaler Umweltveränderungen.

BACKGROUND: The increase in allergies began worldwide with the onset of the Great Acceleration. Environmental pollution and climate change now threaten to cancel out decades of success in health research. OBJECTIVE: A summary of environmental influences is provided, which not only shows the significant increase in the prevalence of allergies worldwide but also that of noncommunicable diseases. The effects of the climate crisis on allergies and the multifactorial and interfunctional relationships with other environmental changes are described in detail. MATERIAL AND METHODS: In order to obtain an overview of the possible effects of global environmental changes on allergies, a wide range of literature was evaluated and the study results were prepared and summarized. RESULTS: A large number of allergens are influencing the human exposome on a daily basis. These allergens are triggered by environmental changes, such as air pollution in the ambient air and indoors, chemicals in everyday objects or residues in food. People are sensitized by the interaction of allergens and pollutants. CONCLUSION: The prevalence of allergies is stagnating in industrialized countries. This is probably just the calm before the storm. The accelerating effects of global warming could make pollen and air pollutants even more aggressive in the future. Urgent action is therefore needed to minimize environmental pollution and mitigate climate change.

Pollen production of downy birch (Betula pubescens Ehrh.) along an altitudinal gradient in the European Alps.

High-altitude environments are highly susceptible to the effects of climate change. Thus, it is crucial to examine and understand the behaviour of specific plant traits along altitudinal gradients, which offer a real-life laboratory for analysing future impacts of climate change. The available information on how pollen production varies at different altitudes in mountainous areas is limited. In this study, we investigated pollen production of 17 birch (Betula pubescens Ehrh.) individuals along an altitudinal gradient in the European Alps. We sampled catkins at nine locations in the years 2020-2021 and monitored air temperatures. We investigated how birch pollen, flowers and inflorescences are produced in relation to thermal factors at various elevations. We found that mean pollen production of Betula pubescens Ehrh. varied between 0.4 and 8.3 million pollen grains per catkin. We did not observe any significant relationships between the studied reproductive metrics and altitude. However, minimum temperature of the previous summer was found to be significantly correlated to pollen (rs = 0.504, p = 0.039), flower (rs = 0.613, p = 0.009) and catkin (rs = 0.642, p = 0.005) production per volume unit of crown. Therefore, we suggest that temperature variability even at such small scales is very important for studying the response related to pollen production.

Is Pollen Production of Birch Controlled by Genetics and Local Conditions?

Intraspecific genetic variation might limit the relevance of environmental factors on plant traits. For example, the interaction between genetics and (a-)biotic factors regulating pollen production are still poorly understood. In this study, we investigated pollen production of 28 birch (Betula pendula Roth) individuals in the years 2019−2021. We sampled catkins of eleven groups of genetically identical trees, which were partially topped, but of the same age and located in a seed plantation in southern Germany characterized by similar microclimatic conditions. Furthermore, we monitored environmental factors such as air temperature, characterized air quality (NO2, NOx and O3), and assessed potential solar radiation. We especially checked for differences between years as well as between and within clones and assessed the synchronicity of years with high/low pollen production. We present a robust mean for the pollen production of Betula pendula (1.66 million pollen grains per catkin). Our findings show temporal (H(2) = 46.29, p < 0.001) and clonal variations (H(4) = 21.44, p < 0.001) in pollen production. We conclude that synchronized high or low pollen production is not utterly site-specific and, in addition, not strictly dependent on genotypes. We suggest that appropriate clone selection based on application (seed plantation, urban planting) might be advantageous and encourage a long-term monitoring.