Selected fragments of road corridors as environmental barriers

Abstract

In the case of the majority of roads built nowadays, the main environmental structural and functional effects include fragmentation of ecosystems and barriers to populations of many animal species. Specific objectives include the following: (a) to determine fragmentation of forest areas in the gminas which are traversed by selected transports routes and to define the role of these routes for an increasing landscape fragmentation; (b) to determine the number of traffic incidents involving animals by road categories, seasons, time of the day or night and distance from forest. For the detailed analyses six research areas were selected through which the selected road sections run: (a) A1 on section Pruszcz Gdanski–Grudziądz (operational since 2008) and DK91; (b) A4 on section Wroclaw–Opole (operational since 2003) and DK94; (c) DK8 on section Kudowa Zdroj–Wroclaw; (d) DK8 on section Augustow–Budzisko; (e) DK17 on section Garwolin–Kurow; (f) S8 on section Radzymin–Wyszkow. Data on traffic incidents which involved animals cover the years 2006–2012 and originate from the SEWIK database. The results obtained show that: (1) between 2006 and 2012 the number and percentage of incidents involving animals were increasing on a regular basis; (2) new roads (motorways and expressways) do not significantly enhance the value of formal landscape fragmentation indicators, but constitute tremendous physical barriers. It is proven, inter alia, by a visibly lower number and density (per 1 km of road) of incidents on these routes, compared to other roads; (3) there is no simple relation between landscape fragmentation and the number and location of forest patches on the one hand, and the total number of incidents and their distribution in space on the other; incidents involving animals take place mainly late in the evening and at night; (4) events occur more frequently 100 m away from the forest than at a distance of 100–200 m away, which may prove some preferences as to road crossing place selection by the animals; (5) incidents within built-up areas, especially during the daytime, have different seasonal pattern, in particular there are no pronounced minimum and maximum periods, which may prove that these incidents involve animals other than ungulates.