Book Review: “Invasion Biology” by Mark A. Davis, Oxford University Press
The topic of “invasive species” has been hot since the late 1990s, but the public’s understanding of the science behind it is woefully superficial. I ascribe much of this to the media, which, through hundreds of stories in print, online and on TV, has painted an overly-simplistic, black and white narrative about villains we must make war on. A lot of blame can be laid on the word “invasive” itself, a totally loaded term that can really only have negative connotations.
So people can be forgiven for not knowing that the scientific field of “invasion biology” is far more nuanced, and is in fact “currently distinguished more by debate and controversy than consensus.”
That characterization is a quote from Mark A. Davis from his book, “Invasion Biology.” Davis was a biology professor at Macalester College in St. Paul, Minnesota, for over three decades and has authored fifty plus articles, mostly in the field of invasion biology. “Invasion Biology” is a textbook-like tome that cites in excess of 1000 papers from the scientific literature in its attempt “to review and reflect on the approaches, finding, controversies and conclusions” of the field, with an emphasis on the previous decade. From the outset, it’s clear that nothing is entirely settled in the field, and what’s more, that its direction has been changing in ways that the public has been unaware of so far.
Davis writes that since the late ’90s:
“some scholars, both within and outside the field of ecology, were beginning to challenge the dichotomous and normative perspectives that had come to dominate invasion biology [and that] at the same time, some ecologists began to dispute the traditional notion that introduced species pose an inevitable threat to local and regional bioverdiversity.”
This is a far cry from the sentiment of “native = good, non-native = bad” that’s so often repeated as gospel these days. As it turns out, that’s not at all a claim of the science of invasion biology, which, if it’s going to describe anything negatively, it will only be that very narrow subset of non-native species that manage to establish, spread and have some impact. The vast majority of non-native species do no such thing; in fact, 99% fail to do so, according to the most widely accepted figure in invasion biology (though that figure might be lower for animals and higher for plants).
“Invasion Biology” is not light reading for a general audience. Davis says: “My intended primary audience for this book includes students, researchers, land managers, and science writers, although I believe that policy makers and general citizens would find certain portions of the book interesting and informative as well.”
In that list, I might aspire to be as high up as “science writer” given all my environmental writing the last twenty years, but I found the book challenging to read. Though the main text is only about 200 pages long (followed by 40 pages of references), it took me over a week to get through it. I had to look up a fair amount of vocabulary, and re-read some sections in order to comprehend them. This book was definitely a brain stretcher, which felt great.
Davis divides the work into three main sections. The first, “The Invasion process,” includes the chapters, “Dispersal,” “Establishment,” “Persistence & Spread,” “Evolution,” and “Understanding and predicting invasions: an Integrated Approach.”
The second part, “Impacts and Management,” is split between “Impacts of invasions” and “Management of invasive species.”
The final part, “Reflections,” is the least dense in terms of science-speak, and is more philosophical in nature. It’s divided into “Framing biological invasions,” “Researching invasion biology,” and “Disciplinary challenges” with a “Conclusion.” This is the most readable section, even if it’s a bit “inside baseball” in some places.
I’m not going to try to sum up any of this. If the subjects interest you, I recommend you dive in yourself. Some people might only be drawn to the hard science of the first two sections, where he details the work and discussion around subjects like the diversity-invasibility hypothesis. For others the “Reflections” might hold the most appeal. It’s almost like two books in one.
The strongest impression I was left with is that invasion biology is a complex field that’s in a state of flux, and doesn’t look to settle down any time soon. Our understanding of ecology as a whole–and of fields related to invasion biology such as succession ecology and gap/patch dynamics–is still far from being able to explain everything we are observing, or even of being able to describe and measure it adequately.
I found the book quite refreshing, especially since I am a life-long plant lover who has never been comfortable with the hateful rhetoric dished out on “invasive” plant species by too many folks, especially on polarized social media platforms.
Look for what I learned from “Invasion Biology” to be rolled into the book that Nikki Hill and I are currently finishing up on the topic of invasive plants, working title: “Stop Shooting the Messengers,” an update of our 2018 zine, “The Troubles of ‘Invasive’ Plants,” which you can download for free here.