Polemochores in Kaluga Oblast: European plants brought in by the Wehrmacht

In the 1940s, Finnish botanists began recording plants in Finland that had never grown in those habitats, and, curiously enough, they were found at the sites where units of a foreign army had been stationed. For such plants, introduced into an ecosystem as a result of military action, a term of their own was coined: polemochores.

The polemochores of Russia are being studied by the biologist Natalya Mikhailovna Reshetnikova. She noticed, in particular, some unusual plants characteristic of Western Europe, located in undisturbed natural habitats and forest communities, which alien plants do not normally reach, along old abandoned roads. All these rare plants grew in clusters in remote parts of the Kaluga Region, neither spreading nor loosening their huddle, which never exceeded a few metres across.

Interestingly, alongside rare and relict plants that do occur in Russia after all, such as wood sanicle (Sanicula europaea), musk mallow, umbellate wintergreen, bearded bellflower and black pea, there were exclusively European plants: meadow oat-grass, spiked blown-grass, soft brome, the Mediterranean-Atlantic fine-leaved fescue (extremely rare in Russia), red fescue and dozens of other species.

Several features allowed these plants to be classed as polemochores. As a rule, these species do not spread beyond their zone of growth, yet their present location is cut off from the rest of their range by a wide margin. They are found along what were dirt roads in the war years, carrying heavy traffic, and only on territories temporarily occupied by the Germans, along the front line or in the rear of German formations, and only in the post-war period.

In 267 locations the researcher discovered 115 introduced species. Some of them are listed in the Red Data Book, and occasionally they turned up along old roads and in old manor estates, where they might have arrived in the nineteenth century.

What, precisely, was the mechanism by which polemochores reached new habitats? Chiefly, fodder. The Germans made extensive use of horses as draught animals, and there were millions of them. Making hay on the spot was difficult and at times impossible, and some units found themselves cut off from hay altogether. Imagine how critical that is in, say, a snowy winter, and under constant strain at that. The Germans made up the shortfall by bringing hay from every occupied European territory where it was plentiful, even resorting to air transport. By and large, it was horse dung that became the incubator for the polemochore species.

There were, of course, other mechanisms: seeds suspended in the mud and litter that gathered in vehicles and on equipment, seeds clinging to clothing and to animals' coats. Nor should we forget the deliberate sowing of their own seeds on airfields and in occupied territories, in the form of lawns and flowerbeds. One way or another, the traces of military action on our country's soil sprout to this day not only in the memory of the people but in the memory of nature, and, to all appearances, they will endure far longer than political history, and on a far greater scale.