Die Wirkung meteorologischer Faktoren auf die Populationsdynamik von Ixodes ricinus : Methodische Erkenntnisse und Problemanalyse

Schon lange ist bekannt, dass und teilweise auch wie meteorologische Parameter wie z.B. die Temperatur oder relative Luftfeuchte Einfluss auf die Lebensprozesse der Zecke nehmen. Laboruntersuchungen lassen hier klare Schlüsse zu. Felduntersuchungen zum Einfluss dieser Parameter auf die Populationsdichte der Zecke hingegen liefern bis dato aus verschiedenen Gründen noch unbefriedigende Ergebnisse. Diese Problematik wird zunächst an bisherigen Forschungskonzepten erläutert. Anhand in-situ gemessener, kontinuierlicher Daten wird die starke Divergenz zwischen den Bedingungen am Waldboden, wie sie die Zecke in ihrem Lebensraum erfährt, und den meteorologischen Daten, die bisher für Untersuchungen eingesetzt wurden, aufgezeigt. ... mehr Verschiedenste meteorologische Parameter wurden dafür kontinuierlich und an verschiedenen Stellen in den Waldstandorten gemessen, in denen auch Zecken gefangen wurden.

Background: Ecological field research on the influence of meteorological parameters on a forest inhabiting species is confronted with the complex relations between measured data and the real conditions the species is exposed to. This study highlights this complexity for the example of Ixodes ricinus. This species lives mainly in forest habitats near the ground, but field research on impacts of meteorological conditions on population dynamics is often based on data from nearby official weather stations, or occasionally, in situ measurements. In addition, studies use very different data approaches to analyze comparable research questions. ... mehrThis study is an extensive examination of the methodology used to analyze the impact of meteorological parameters on Ixodes ricinus and proposes a methodological approach that tackles the underlying complexity.
Methods: Our specifically developed measurement concept was implemented at 25 forest study sites across Baden-Württemberg, Germany. Meteorological weather stations recorded data in situ and continuously between summer 2012 and autumn 2015, including relative humidity measures in the litter layer and different heights above it (50 cm, 2 m). Hourly averages of relative humidity were calculated and compared with data from the nearest official weather station.
Results: Data measured directly in the forest can differ dramatically from conditions recorded at official weather stations. In general, data indicate a remarkable relative humidity decrease from inside to outside the forest and from ground to atmosphere. Relative humidity measured in the litter layer were, on average, 24% higher than the official data and were much more balanced, especially in summer.
Conclusions: The results illustrate the need for, and benefit of, continuous in situ measurements to grasp the complex relative humidity conditions in forests. Data from official weather stations do not accurately represent actual humidity conditions in forest stands and the explanatory power of short period and fragmentary in situ measurements is extremely limited. However, it is still an open question to what kind of meteorological data are necessary to answer specific questions in tick research. The comparison of research findings was hindered by the variety of information provided, which is why we propose details for future reporting.