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.
Conditions 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.
Maintenance 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.
History 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.
Invasive species 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.
Causes There are three mechanisms that lead to invasive species being spread by the railway industry:
Commodity: when the goods carried by train are the invasive species, which can escape into the surrounding habitat. Stowaway: when the invasive species is inadvertently transported by train. Natural dispersion: when the species invades by an artificial corridor such as the railway verge. Railway verges, similarly to road verges, are typically regularly mowed and covered in herbicide by train companies. This creates an environment that is very different from the surrounding habitat, which could be a forest for example. Native species from the surrounding habitat are not adapted to this new habitat type, allowing generalist species and species who favor open environments to take root. These railway verges can extend for multiple kilometers without being interrupted, creating a corridor for species to disperse. Additionally, when constructing a new railway, vegetation is removed, soil is bared, and water is managed, creating ideal conditions for invasive plants to implant.
Impacts The impacts of invasive species are widespread. They modify communities and ecosystems making them more vulnerable to disruptions such as climate change. They can outcompete native species and cause their extinction. For humans, invasive species have a huge economic cost.
Management There are four main management categories to stop invasive species along railways: the do-nothing strategy, the management of the propagule supply, the management of environmental conditions, and the management of the invasive species populations. The do-nothing strategy is, as its name suggests, to not try to act against the invasive species. This strategy can be appropriate when the cost of management is very high or when a native species will likely overtake an invasive species in future successional stages of the railway verge. Managing the propagule supply can be done in many ways, planting or seeding the verge with native plants and using fire management to burn seeds of invasive species are two examples of this method. Changing the environmental conditions to prevent native species from implanting can be done through soil compaction for example. Removing the invasive species can be done by burning, using herbicides or mechanical removal. Removing new patches of the invasive species should be prioritized when this species spreads fast as this new patch can be a new source of dispersal. Creating barriers for the invasive species to stop spreading should be done for species with lower dispersion speeds. Management practices should always take into account native species to not harm them.
Impacts on local wildlife There are four main impacts on wildlife from railroads: wildlife mortality, the barrier effect, habitat fragmentation/loss, and disturbances.
Wildlife mortality
Wildlife-train collisions Wildlife species from smaller birds and mammals to deer and large mammals such as elephants may be killed in collisions with trains running on railway tracks. Studies on wildlife-train collisions have mostly been focused on moose and bear. These species are large and due to their size, are more likely to cause a financial impact when a train collides with them. They are also considered charismatic megafauna and keystone species in conservation efforts. More research is needed on the effects of railroads on smaller species.
Other causes of mortality Rail entrapment, wire strikes and electrocution are some of the other causes of mortality due to railways. Eastern box turtles can enter in between rails at the level crossings and be unable to escape once they are outside of the level crossing zone.
… excerpt ends here. Continue reading the full article.
