By Fred Pearce, author of The New Wild: Why Invasive Species Will Be Nature’s Salvation (Beacon Press, April 2015)
Alien species are taking over nature. Rogue rats, predatory jellyfish, suffocating super-weeds, snakehead fish wriggling across the land–all are headed for an ecosystem near you. These biological adventurers are travelling the world in ever greater numbers, hitchhiking in our hand luggage, hidden in cargo holds and stuck to the bottom of ships. Our modern, human-dominated world of globalized trade is giving footloose species many more chances to cruise the planet and set up home in distant lands. Some run riot, massacring local species, trashing their new habitats and spreading diseases.
We all like a simple story with good guys and bad guys, so the threat of invasive species invading fragile environments and causing ecological mayhem instantly gets our attention. For half a century, conservationists have been in the forefront of the battle to hold back the invasive tide. And as an environmental journalist, I have written my share of stories about the mayhem they can cause.
Some of it is true. But do we fear the invaders too much? Do zebra mussels, kudzu, salt cedar and the rest do as much damage as is claimed? And what about the thousands of other visitors who fit in without trouble? Is our fear of invasive species little more than green xenophobia? In my new book The New Wild: Why Invasive Species Will Be Nature’s Salvation (Beacon Press, 2015), I explore these questions.
Most of us don’t treat foreign humans as intrinsically dangerous. Yet the orthodoxy in conservation is to stigmatize foreign species in just that way. Native is good, and foreign is bad. I believe it is time for a rethink—time to consider whether invasive species can sometimes be the good guys, and whether nature’s go-getters are actually rebooting ecosystems corrupted by human activity.
In my search for answers, I found numerous places–from Puerto Rico to Hawaii, San Francisco Bay to the urban badlands of Europe–where biodiversity is increasing and nature is recovering, thanks to invasive species. And there are many more places where interlopers once regarded as arch environmental villains are now quite at home and causing no lasting harm. Just like most human migrants.
There is a scientific dogma about the badness of invasive species that lurks in often outdated and ill-founded ideas about how ecosystems work. We often think of life on Earth as being made up of complex and tightly-knit ecosystems like rainforests, wetlands and coral reefs that have an intrinsic balance. We see pristine nature as perfected and stable biological machines in which every species has evolved to occupy a unique niche. So, the theory goes, losing a key native species or gaining a disruptive invasive one could be disastrous. Conservationists have to man the barricades to keep out the interlopers and maintain nature’s balance.
But fewer and fewer ecologists believe that this is how nature actually works. New ecological thinking holds that the structure of nature is often random, transient and accidental, constantly being remade by fire, flood, disease–and the arrival of new species. It is neither fragile nor finely tuned. It is temporary, versatile, resilient, adaptable and in a constant state of flux with species coming and going, fitting in, adapting or losing out. When invaded by foreign species, most ecosystems don’t collapse, and few natives go extinct. Often, they prosper better than before.
My conclusion is that in a world profoundly changed by humans, nature’s desperadoes and stowaways are its survival strategy–its best chance of surviving our chainsaws and ploughs, our pollution and climate change. The successful spread of invasive species–even with humans lending a helping hand–is often a sign of nature’s dynamism, not its enfeeblement. A sign that nature is not done, but can bounce back. True environmentalists should be applauding the invasive species. The old wild is dead; welcome to the new wild.
FRED PEARCE is an award-winning author and journalist based in London. He has reported on environmental, science, and development issues from eighty-five countries over the past twenty years. Environment consultant at New Scientist since 1992, he also writes regularly for the Guardian newspaper and Yale University’s prestigious e360 website. Pearce was voted UK Environment Journalist of the Year in 2001 and CGIAR agricultural research journalist of the year in 2002, and he won a lifetime achievement award from the Association of British Science Writers in 2011. His many books include With Speed and Violence, Confessions of an Eco-Sinner, The Coming Population Crash, and The Land Grabbers.