Railroad ecology

Railroad ecology or railway ecology is a term used to refer to the study of the ecological community growing along railroad or railway tracks and the effects of railroads on natural ecosystems. Such ecosystems have been studied primarily in Europe. Similar conditions and effects appear also by roads used by vehicles. Railroads along with roads, canals, and power lines are examples of linear infrastructure intrusions.

Railroad beds, like road beds, are designed to drain water away from the tracks, so there is usually a bed of rock and gravel resulting in fast drainage away from the tracks. At the same time, this drainage often accumulates in areas fairly near the tracks where drainage is poor, forming small artificial wetlands. These unnatural conditions combine to form different zones, some in which water is scarce, others in which water is abundant.

Railroad companies routinely clear cut and/or spray with herbicide any vegetation that grows too close to the tracks. This favors vegetation that is able to respond favorably to clearcutting, and/or resist herbicides. On overhead electrified railroad lines, clear cutting must be more extensive, vertically as well as horizontally, in order to prevent vegetation (especially tree limbs) from interfering with the pantographs on a moving train, breaking off and falling on the wires, or simply from arcing in proximity to high voltage transmission cables. The same vegetative selection processes described in the previous paragraph apply, but may additionally favor climbing vines due to the presence of catenary and transmission poles in addition to the wooden communications and signal pole lines which often exist(ed) along nonelectrified lines.

Historically, conditions along railroad beds were very different from today. Coal engines used to blanket the area with soot, favoring species adapted to these conditions (some of which only occurred naturally in volcanic areas). Newer engines produced a less remarkable environment, but many of the same plants have remained and adapted to this new environment.

Railway tracks (like roads and highways) are often colonized by non native invasive species. In North America, such species include trees such as Ailanthus altissima, Paulownia tomentosa, Siberian Elm, and Norway Maple, and invasive non woody plants such as Japanese Knotweed and Phragmites. The railway tracks provide corridors along which these species can spread and thrive, even when the surrounding areas might be less hospitable to them. Many invasive species have been known to be propagated by railways, these include: spotted knapweed, South African ragwort, Oxford ragwort, rat, mouse, ants, beetle, spider, and armadillo.

Railways and powerlines to supply electrical trains, like other linear infrastructures, divide habitats when built.

There are many different railway mitigation measures, most of them fit into two main categories: either to prevent animals from being on the tracks or reduce the barrier effect.

Structures already built into the railway infrastructure such as pipe culverts, box culverts, small access roads and bridges to cross rivers or valleys can offer safe passage underneath the railway for wildlife. Audio animal calls produced 30 seconds to 3 minutes before the arrival of a train increased the rate and the speed at which wildlife fled, with wildlife not habituating to these sounds.

Reducing train speed at mortality hotspots or during migration periods can help animals and train drivers see each other earlier, leaving more time for the animals to flee. Selective hunting and trapping near railways can reduce wildlife train collisions. This could be because railways are typically harder to access than roads or because roadkill is much more visible to the public, while wildlife train collisions are only visible to train drivers. Trains and railways are very different from road motor vehicles and roads themselves. Trains typically are on a singular track, they cannot swerve to avoid a collision and their capacity to slow down is very limited. Trains only come from one direction, while roads are normally bidirectional. Intervals between vehicles are much longer on railways than on roads. Only a singular train comes at a time, while many vehicles are on the same stretch of road at once, often on multiple lanes. Road traffic occurs more often during the daytime, while train traffic can be higher in nighttime. Trains cause more vibrations due to their weight and the interaction between tracks and wheels. There is a large proportion of electrical trains, leading to lower emissions near tracks than gas vehicles on roads. Trains can be much quieter than road vehicles. The size of the railway and its verge is normally much smaller than the size of a road and its verge. High speed trains can be much faster than road vehicles, and fencing is more common along these high speed train tracks.