The other day I was walking along a trail in our local woodland park (a real treasure!) and I started to think about the concept of invasive species. An article in a city publication had mentioned how Buckthorn was being eradicated from this park as it was an “invasive species”. The park has huge gashes in the woods where the offending bushes have been ripped out and laid aside. Another part of the park has large expanses of Milkweed which is celebrated and touted as responsible for a commendation from a Monarch butterfly organization (Milkweed is a major food source for Monarchs). Ironically, some publications list the Milkweed as an invasive species!
Just as a plant can be a cherished wildflower or an offensive weed – it all seems to be in the eye of the human beholder.
Interestingly, the very next day, “The Current”, a CBC radio program, dealt with this whole issue of invasive species. It included interviews with Matt Chew of the Center for Biology and Society at Arizona State University and Dr. Jim Carlton a Professor of Marine Sciences at Williams College.
Matt Chew and 18 other scientists who have co-authored a recent article in the journal Nature, are challenging the pervasive view that we should declare all out war on so-called invasive species.
The article has been published on-line and I have not seen a statement that it can not be reproduced so excerpts are given below:
“Over the past few decades, 'non-native' species have been vilified for driving beloved 'native' species to extinction and generally polluting 'natural' environments. Intentionally or not, such characterizations have helped to create a pervasive bias against alien species that has been embraced by the public, conservationists, land managers and policy-makers, as well by as many scientists, throughout the world.”
“Increasingly, the practical value of the native-versus-alien species dichotomy in conservation is declining, and even becoming counterproductive. Yet many conservationists still consider the distinction a core guiding principle.”
“It wasn't until the 1990s that 'invasion biology' became a discipline in its own right… proponents of biodiversity preservation and ecological restoration commonly used military metaphors and exaggerated claims of impending harm to help convey the message that introduced species are the enemies of man and nature.”
“But many of the claims driving people's perception that introduced species pose an apocalyptic threat to biodiversity are not backed by data. Take the conclusion made in a 1998 paper that invaders are the second-greatest threat to the survival of threatened or endangered species after habitat destruction. Little of the information used to support this claim involved data, as the original authors were careful to point out. Indeed, recent analyses suggest that invaders do not represent a major extinction threat to most species in most environments — predators and pathogens on islands and in lakes being the main exception. In fact, the introduction of non-native species has almost always increased the number of species in a region.”
“Nativeness is not a sign of evolutionary fitness or of a species having positive effects. The insect currently suspected to be killing more trees than any other in North America is the native mountain pine beetle Dendroctonus ponderosae.”
“Most human and natural communities now consist both of long-term residents and of new arrivals, and ecosystems are emerging that never existed before. It is impractical to try to restore ecosystems to some 'rightful' historical state.”
I tend to agree, however I confess that I am not directly impacted by these species and so can afford a less biased view. But the more I read about eradication programs as well as restoration programs; e.g. the re-introduction of animals into areas where they have been driven out in the past (usually by humans) - for instance wolf recovery programs - the more I think all this management of nature needs to be stopped. Yes, let us curb our destructive habits and tread more lightly on the Earth but now trying to force it into a balance that we deem the proper one is only causing more grief.
On a somewhat related note, last Sunday while in these same local woods, I was delighted to find what I believe were Paper Wasps building a nest behind the glass of a large wooden sign at one entrance to the park. I watched them for quite some time and took many pictures (always trying to eliminate the darn glare from the glass). This nest was at eye-level and afforded me a glimpse into their lives without any danger of unintentionally inciting an attack because of the glass barrier. It was a great opportunity for learning.
Three days later I returned to check on their progress and all the wasps lay dead inside the sign. Some were still in the nest. It looked like a battle scene with all these brightly coloured warriors lying lifeless. I guess someone in the city park services determined that these animals were also to be destroyed.
I wonder if there will ever be an area close by where I can go to see unmanaged, unmassacred, unharassed wildlife.
I dedicate this blog post to the wasps.