Railway lines - a way to restore biodiversity

Jacek Kazimierczak

CEO of Lepidopterra

Used and especially disused railway lines have great potential in recreating the diversity of butterflies and moths. They offer sheltered, warm and sunny conditions with low vegetation. Europe has the highest density of railroads in the world, making it an excellent opportunity to use them as wildlife corridors. Butterflies can migrate along these lines quite undisturbed. The main challenges are insecticides, collisions with trains and poorly planed mowing.The railroads have been an interesting place for generations of entomologists. The Masłowski brothers, entomologists studying butterflies and moths in southern Poland, wrote in 1928: “Deilephila gallii Rott. [Bedstraw Hawkmoth]. Often in 2 generations: in May and August collected as caterpillars on the slopes of hills and railway embankments: February 17, 1922, August 2, 1920, July 7 and 18, 1918 (...)".

In 2015, the Italian Journal of Zoology published a scientific article entitled "Railway tracks can have great value for butterflies as a new alternative habitat", in which two Polish scientists, Dr. Konrad Karalus and Dr. Marek Bąkowski, proved that railways have a greater diversity of butterflies than forest clearings and degraded meadows. What's more, butterfly communities along the railroads proved to be more stable.

Why is this happening? One of the main conservation challenges is habitat fragmentation. Many well-protected and isolated populations appear to be safe but are in fact slowly degrading quantitatively as well as qualitatively in terms of gene diversity. These populations are more at risk than we think. Due to the limited gene pool, they become more sensitive and eventually disappear, even unnoticed. In Europe, about 40% of butterfly species live in isolated populations. Species that are less dependent on a particular habitat type or have a chance to migrate are less likely to become extinct.

"According to the European Biodiversity action plan for 2030, investing in and deploying green infrastructure should to be considered in planning and designing transport networks."

What do railroads have to do with it? First of all, they are linear, they also cross other railway tracks. They are relatively well protected from further anthropogenic impacts, such as land development. It is also important that the railway lines cross a variety of natural habitats, such as forests, meadows and wetlands. In themselves, they offer a very interesting artificial habitat. The southern slope of the railway embankment is a good substitute for xerothermic habitats, and ditches and lower sites offer a variety of wetland habitats. These railroads that are in the soil cutting offer sheltered and sunny conditions that can also be very attractive to some species.

So what's the catch? This is a certain risk for butterflies. In 2017, a team of scientists led by Luis Borda de Agua from the University of Lisbon published the book "Railway Ecology" in which they argue that railways have a different impact on wildlife than roads due to different traffic volumes and average speeds, but the problem remains same: possible collisions. There are no studies on butterfly-train collisions, not many studies on mammals or birds, in fact, but the conclusions seem to be the same in both cases. The benefits outweigh the losses for local rail lines, lower speed and traffic volumes and, of course, unused tracks.

Only collisions? Unfortunately not. Glyphosate and other herbicides can also affect butterflies, as well as poorly planned mechanical mowing. Although PKP Polskie Linie Kolejowe declares spraying only once a year, Deutsche Bahn and Swiss Federal Railways have announced that glyphosate and other weed control herbicides along railroad tracks will be phased out by 2025. How to protect caterpillars and their host plants from extinction? If we analyze the list of local species that we would like to protect, there is a certain regularity. Many species have a larval phase from May to August. They then begin to pupate and often hide underground or attach to stems. In the case of manual mowing, the risk is lower, but it is hard to imagine manually mowing 200 km of a railway line. Therefore, mosaic or selective mowing seems to be the solution. The track itself or the top of the embankment occupies a relatively small percentage of the total area. Then slopes and ditches can be well-designed ecosystems that do not require frequent intervention.

How to design an ecosystem? Consciously. After the first year of research, we know briefly what's out there. Which species should be supported. The list of plant species and their preferences are carefully planned together with our partners from Łąki Kwietne. We also identify invasive species that could undermine the entire project and eliminate them as much as possible. In winter, we agree our plans with the railroad site manager to avoid future conflicts in the event of earthworks and redevelopment. At the beginning of next year we are ready to sow and plant. Our partners ensure that the plants have optimal growth conditions. In the third and fourth year, we return to re-examine the area in order to prepare the final report. And if necessary, we offer additional sowing or pruning.

Does it actually work? Although there is not much experience in that field and we still gather experience, the biodiversity projects for railways which are now being implemented in Europe, like Biodiversity Action Plan for British rail network, proves it is a right direction. In 2018 Department for Transport commissioned an independent review of that approach to vegetation management. Also the International Union of Railways (UIC) developes solutions and practices to manage rail lineside in a way that can help halt and reverse the loss of biodiversity, and we are sure we are going to see much more in the near future.

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Rewilding as a concept is still relatively new in Europe, but it has long been a part of conservation strategies in other regions.

25 years later - what has changed?

Have you ever wondered if the loss of biodiversity is real or how much we have already lost? Let see how it all changed in Łódź, Poland!

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