invasive species

I learned a few new words today while on a trip down a research rabbit hole.

And as is so often the case, I can’t remember how I first got to the interesting blog, Cryptoforestry. But get there I did, and that’s when I fell down the hole.

The first word I learned is polemobotany, i.e. war botany. The study of fauna impacted during the course of military activity.

Greater Yellow-rattle (Rhinanthus serotinus), which rode into Sweden on German military trains during WWII.

In a book on invasive species, author James Carlton describes how there was little danger of any unintentional hitch hikers on caterpillar-treaded vehicles from central Europe surviving the trip to desert conditions in the Middle East during the 1991 Gulf War.

In contrast, the Australian military took steps to clean military vehicles on its tropical base in Darwin, Northern Territory, to prevent the introduction of invasive species to the similar environment of East Timor in 1999. Of course, the Australian military was part of a peacekeeping force, not an aggressive invader.

Wig knapweed (Centaurea phrygia subsp. phrygia), a WWII newcomer to Norway.

Another word I learned is related: polemochores, the followers, or seeds, of conflict. Coined at the end of the Second World War to denote alien plants introduced through war-related activities, this term refers to the tiny agents of polemobotany, the hitch hikers themselves, trespassing along with invasive forces, setting up camp and making themselves at home.

Unlike the invasive humans, however, polemochores would have to fall upon friendly ground to take root and thrive.

A further narrowing of the lens when it comes to polemochores led me to a couple of very specific types of botany study: hippochores. These are seeds introduced by horses and their foraging during the course of human conflict.

Heath rush (Juncus squarrosus), which invaded Finland during WWII

A further term, not nearly as official-sounding but just as interesting, is railroad botany: The botany of railroad tracks. Specifically, the botany of areas in which there are alien seeds transported by rail, particularly during conflict. This enlightening term was found in a 1979 paper titled Flora of the Railroads in St. Louis, Missouri by Viktor Mühlenbach, which someone kindly added to the Internet.

I found no specific terms referring to seed transportation by trucks, tanks, ships or boots during conflict, but I’m sure they exist.

Overgrown railroad tracks
Photo: Frank Dutton

I did, however, find a reference to ‘rubble fauna‘, the plants that established themselves in the rubble of bombed urban areas during WWII – rubble offering “warmer and drier conditions than natural habitats and (being) a suitable habitat for plants and animals from warmer regions of the world. Many plants that were previously rare became permanent members of the urban flora in war-damaged European cities.”

So many ways to describe inadvertent anthrobotany, the way in which we alter the world around us through our human activities and disputes.

Axolotl (Ambystoma mexicanum)
Source: National Geographic

I wonder what Charles Darwin would have had to say about the Mexican axolotl (Ambystoma mexicanum), a feather-gilled salamander sometimes jokingly referred to as the Darwin fish.

The axolotl once swam in abundant numbers in its only native habitat, the network of mountain lakes upon which Mexico City was eventually built. It was a food staple, it was considered useful as a medicinal for respiratory ailments, and Aztec legend held it to be a transformed god who had escaped the politics of fellow gods by transforming into a salamander and hiding among the reeds.

The axolotl is all but extinct in its native lakes, a victim of the usual suspects: pollution, water drainage, invasive species, and overfishing.

Outside its native habitat, the axolotl is one of the most studied creatures on the planet due to its strange longevity (up to 15 years) and its ability to regenerate almost all parts of its body, including parts of its brain. So the animals are bred and maintained for research, and are also popular in hobbyist fish tanks.

Efforts have been underway for years to protect the axolotl’s native environment, but at this point, the IUCN Red List only lists a few dozens of the salamanders living in the wild.

Tenochtitlan on Lake Texcoco Source: Tectonica

Tenochtitlan on Lake Texcoco, the site of the future Mexico City.
Source: Tectonica

It’s the 205th anniversary of Darwin’s birth today. In thinking about what Darwin might have thought about conservation efforts and endangered species lists, I came upon this quote by Peter Ward. Ward has compared human impact on the environment and world’s species to that of the presumed asteroid that led to the extinction of the dinosaurs, saying that this time, humans are the asteroid.

On this topic, he said, “If we were to go back about 63 million years ago and look at a very tiny rat-sized mammal that would give rise to all of the rest of the primates, it would be very difficult for us to say, Well, there is the future of intelligence on this planet. That tiny rat-sized creature would look anything but intelligent.

“The point, to me, is that species not only have an inherent value in the present day, but they have a future, that we cannot tell where the next global intelligence, if there’s going to be one, will come from. We do not know what species will give rise to some charismatic group, or some very important group. If we take the long view, the millions-of-years view, then we must not only think about species’ value, but future species’ value.”

Axolotl (Ambystoma mexicanum)

Darwin spoke of the success of species in terms of survival, but what would have made of the axolotl’s circumscribed type of survival.

And what would Darwin, who studied past extinctions but still lived in world where it must have been virtually unimaginable to envision the disappearance of the vast rainforest, the plentiful wildlife on land and on sea, the abundant amounts of fresh water, what would Darwin have had to say about whether the current wave of extinction could be considered a force of ‘natural selection’?

Charles Darwin (age 29)

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Horses, Railroads, Seeds and War

Darwin and the Long View