Analysis of the Noise Pollution in the Bielański Forest NATURA 2000 Area in Light of Existing Avifauna (Warsaw, Poland)

There is no doubt that the NATURA 2000 network has been one of the most relevant tools for nature protection. However, the designated areas within the borders of large cities are subjected to many threats. Traffic noise takes on a very important role in this subject, posing the question of whether NATURA 2000 areas should be located in urban areas strongly affected by noise pollution. This particular topic was exposed and analysed at Bielański Forest NATURA 2000 (PLH140041), located in northern Warsaw, where changes in noise distribution for the years 2007–2017 were examined and described by two types of indicators (Lden and Lnight). The data sources used for the analysis were city road noise maps for 2007, 2012 and 2017. Additionally, sound intensity measurements were taken in two separate groups of hot-spots. The first of these comprised locations determined based on an inventory of avifauna; they represented different habitat types, and were characterized by the highest bird activity. The second group of hot-spots consisted of those designated along roads in order to identify the main sources of traffic noise. The obtained results confirmed the high noise-absorbing ability of the existing vegetation. The avifauna surveys covered 19 forest bird species. Five of them were considered to be the most valuable and rare elements of the local avifauna, whereas 14 appeared to be key species for the functioning of biocenosis and, at the same time, determine the uniqueness of the ecosystem. The study showed that the type of habitat rather than differences in noise levels determines the distribution and abundance of key species. Therefore, there is a necessity to focus on actions that guarantee the maintenance of the existing status in order to counteract habitat deterioration. The investigation confirmed the feasibility of creating these kinds of natural protected areas in large cities, despite their exposure to noise pollution