The Function of A Set-Aside Railway Bridge in Connecting Urban Habitats for Animals: A Case Study

Abstract

As elements of green infrastructure, railway embankments are important corridors in urban environments connecting otherwise isolated habitat fragments. They are interrupted when railways cross major roads. It is not known whether dispersing animals use railway bridges to cross roads. We examined the function of a set-aside iron-steel railway bridge crossing a 12 m wide road with high traffic density in Basel (Switzerland) for dispersing animals. We installed drift fences with traps on a single-track, 32 m long and 6 m wide railway bridge with a simple gravel bed, and collected animals daily for 9 months. We captured more than 1200 animals crossing the bridge: small mammals, reptiles and amphibians as well as numerous invertebrates including snails, woodlice, spiders, harvestmen, millipedes, carabids, rove beetles and ants. For some animals it is likely that the gravel bed, at least temporarily, serves as a habitat. Many animals, however, were apparently dispersing, using the bridge to cross the busy road. We found season- and daytime-dependent differences in the frequency the bridge was used. Our findings indicate an important function of a set-aside railway bridges for connecting urban habitats. As most animal dispersal was recorded during the night, railway bridges with no (or little) traffic during the night may also contribute to animal dispersal. As important elements of green infrastructure, set-aside railway bridges should be considered in future urban planning.

Ground-dwelling invertebrate diversity in domestic gardens along a rural-urban gradient: Landscape characteristics are more important than garden characteristics

“…Complementing our study with findings from other work on more mobile taxa in urban gardens, we suggest that garden owners can improve conditions for many species by increasing habitat diversity and implementing biodiversity-friendly management practices [ 120 ] and, for example, by replacing exotic plants with native species [ 31 ]. At a larger spatial scale, urban planners should consider the valuable contributions made by the mosaic of highly variable domestic gardens and need to promote the biodiversity therein by reducing urbanisation in the surroundings through measures like urban greenways increasing biological connectivity [ 12 , 13 , 20 ].…”

“…Beside carbon storage and sequestration, these elements of green infrastructure provide ecosystem services such as microclimate regulation, improved air quality, water flow regulation, as well as habitat, food and shelter for plants and animals and thereby increase urban biodiversity [14,15]. Certain elements of green infrastructure, such as greenways, also contribute to the connectivity of otherwise isolated open habitats or woodlots [16][17][18][19][20].…”

Biodiversity Conservation and Sustainable Urban Development

“…This Special Issue covers a broad geographical range, with contributions from Africa [17], Asia [18][19][20], Australia [21,22], Europe [23][24][25][26][27][28][29][30] and North America [31][32][33]. It explores a range of ecosystems in the urban realm, spans natural remnants such as forests [30,32], wetlands [18,21], and natural grasslands [17,22], traditional urban greenspaces including cemeteries [33], gardens [29,31], and, finally, novel urban ecosystems such as green roofs and constructed wetlands [20,26], built-up areas [23], railway bridges [24] and emerging forests on vacant land [27]. In combination, a wide range of socio-cultural and environmental settings are explored and discussed.…”

“…Several papers explore biodiversity in relation to diverse features of urban environments and address a range of animal groups [21,24,27,31,33] and plants [17,18,20,22,27,30,32], including some multi-taxa studies [24,26,27]. Other papers explicitly address urban environments as socio-ecological systems [19,22,25], or further methodological approaches in understanding the people-nature intersection in cities [23,28,29].…”

“…Biodiversity sensitive planning is also an important pathway to achieving conservation with sustainable development. While habitat fragmentation is a ubiquitous challenge in urban regions, Braschler et al [24] show in a case study of a set-aside railway bridge in Basel, Switzerland, that small-scale measures can make a useful contribution to addressing this challenge. They reveal that abandoned elements of the transportation infrastructure can help connect urban habitats for a range of animal taxa and should thus be integrated into urban biotope network schemes.…”