Spatial and temporal variation of light pollution in a highly structured nature reserve near Zürich
Constantin, L., 2020: Spatial and temporal variation of light pollution in a highly structured nature reserve near Zürich. Master thesis.
Constantin, L., 2020: Spatial and temporal variation of light pollution in a highly structured nature reserve near Zürich. Master Thesis ETHZ, D-USYS. Supervisors: PD Dr. J. Bolliger, Prof. Dr. F. Kienast.
Artificial lighting at night (ALAN) has adverse effects on biodiversity, and its distribution in the environment needs to be assessed. On the regional scale, I used satellite data to assess the exposure of nature reserves to ALAN across the canton of Zürich. To quantify the spatial and temporal variation of ALAN within the Katzensee nature reserve, two complementary methods were used: continuous monitoring using luxloggers and punctual monitoring using full-sphere photography.
The 13% brightest reserves from the canton suffer from 50% of the light pollution that occurs in nature reserves, while 68% of the reserves are lowly polluted. Brightness depends on proximity to settlement, whereby a small settlement within 1km can have the same light-pollution effect as a larger settlement at 5km.
The Katzensee is highly light-polluted. Some nights without moon were brighter than some with full moon, depending on the weather: clouds had an amplification factor of up to 12x. Weather is also the main driver for differences in spatial variation: In cloudy or clear sky conditions, brightness was constant over the whole area, and was mostly determined by light sources up to several km away. In partially cloudy or foggy conditions, the presence of close-by (within 800m) light sources was more relevant for the brightness.
Dark-buffer zones around nature reserves can protect them from light pollution. For such a buffer, care should be given to: (1) the average brightness resulting from lighting within 1 km, and (2) direct peaklights emissions such as from single streetlights or passing-by cars up to 500m away.