You know, I haven't read Pearce's book yet, but I plan to one of these days. My understanding of his thesis is that his subtitle basically says it all - invasive species will be nature's salvation. I see things a bit differently, and take more of an applied ecology view on the matter. I do quite a bit of invasive species management myself, and I also do quite a bit of native species management...and I think this is one of the primary differences between my perspective and Pearce's. I'm an organic farmer by trade, so I deal with weeds all the time. Many of the 'worst' invasive species in my area are present on my property, and I'm involved with managing them on a long term basis. I've seen their populations decline as a result of this protracted management that has also served to build soil organic matter and replace the ecological functions that a single highly productive plant was serving with many similar plants (replacing Himalayan blackberry with raspberry, gooseberry, elderberry, and currant - lots of nectar, fruit, and habitat and quite a bit easier to manage in the long term).
While I believe that invasive species offer important insights into how an ecosystem is transforming, and my understanding of these transformations is influenced by acknowledging the extensive influence that people have had in shaping plant and animal communities. Nancy Turner at the University of Victoria in BC has done amazing work cataloguing the role of indigenous people in creating the biodiverse ecosystems that are now filled with what are considered native plants. And there's evidence these ecosystem-shaping effects from throughout North, Central, and South America, Australia, SE Asia, and Africa - everywhere that indigenous people have been classified 'hunter-gatherers.' There's a lot of interesting discussions to be had in this regard, but when it comes to invasive species, much of what we're seeing today is a direct result of the collapse of these management systems and a change in mindset about the nature of 'nature.' Many of the people who work with Dr. Turner and Dr. Kat Anderson in California believe that a lack of relationship and stewardship with the world that surrounds our immediate homes is leading to declines in biodiversity - the world is retreating from us because of our lack of attention. I think this perspective is extremely important to consider, because it reframes the focus on invasive species to a larger perspective of how we are relating to our home landscapes. How are we contributing to the proliferation of the native species that we ostensibly care so deeply about?
On my homestead, I've been tending my patches of camas, mariposa lily, fawn lily, tarweed, brodiaea, and 'wild' strawberry with the same attention that I lavish in my garden of (non-native) crop plants. I dig them, eat them, save seed from them, and spread the around in places I think they'll grow. I cut out and selectively graze blackberries from their midst. I also cut out douglas fir to give them light. I believe that if we started to conceive of our immediate environs as resources for our daily needs and see how our day to day lives affect the quality and availability of these resources, many things would start to shift socially, ecologically, and economically. Many interesting conversations to be had in this regard as well, but for me, this is a key piece of deciding how and when to manage invasive species - looking not just toward their eradication, but crafting clear goals and management plans for supporting what remains when and if they are moved along to their next iteration as
compost, mulch, or manure.