Invasive and Introduced Plants and Animals: Human Perceptions and Approaches to Management is edited by two British academics. It is a collection of articles written by invasion biologists as well as scientists who are critical of invasion biology. It attempts to present the entire spectrum of opinion on the debate that is the primary subject of the Million Trees blog: “Our intention is to stimulate the reader to question ideas and received wisdom [about invasion biology], and to try to establish the interface between objective science and subjective sociocultural fashions and values.” (1) That is, the evaluation of invasion biology involves both science and public opinion.
Using both criteria, the authors evaluate conservation projects in their concluding chapter of the book: “We perceive that present approaches:
- Generally lack scientific rigour in their justification;
- Fail to inform and engage and call upon all stakeholders…;
- Rarely provide a holistic (for example, catchment wide) context or strategy;
- Almost always lack financial or human resources to be long-term effective;
- Have no realistic long-term targets, and if they do, no effective monitoring towards achievement…”
This evaluation of ecological “restoration” projects fits perfectly with our opinion of projects in the San Francisco Bay Area. These projects are not based on sound science. They are initiated behind the public’s back and are therefore rarely supported by the public. Most importantly, they are usually unsuccessful. Typically, the projects are far more destructive than constructive. We are losing the trees we value and the habitat needed by wildlife and in return we are usually left with barren, weedy messes.
Based on these shortcomings, the authors point to new approaches that address past failures.
Acknowledge ambiguity and change
First, we must accept that the distinction between native and exotic plants is often ambiguous and the distinction between plants that are harmful and those that are not is even less clear. Dividing up the natural world into good and bad, is a fool’s errand that does not acknowledge that such judgments are ultimately a matter of opinion.
How many times have we heard native plant advocates say, “I hate eucalyptus”? More often, they dress up their hatred in more valid arguments, such as eucalyptus is flammable, or they aren’t healthy, or they kill other plants or they aren’t useful to wildlife. Those who defend eucalyptus know that these accusations are not true or equally true of some native trees. Therefore, that argument can’t be resolved with facts because in the end there is a range of subjective opinion that can’t be changed with facts.
Secondly, we must accept that returning landscapes to prehistoric conditions is impossible. Nature moves forward, not back. Humans have fundamentally altered the environment and reversing those changes is not physically possible. If we have unrealistic goals for conservation projects, we can expect failures. When native plant gardens are installed on landfill that served as garbage dumps for decades (as they have been in the East Bay), we should not be surprised when they are unsuccessful.
Setting realistic goals
Ironically, the authors recommend larger projects rather than smaller projects. Because ecosystems are integrated, attempts to change only a segment of an integrated system are doomed to fail. The 1,100 acres of city-managed park land that have been designated as “natural areas” in San Francisco are chopped into 32 pieces, some as small as one-third of an acre. When non-native plants are eradicated, these tiny plots are quickly repopulated with the same weeds from adjacent areas. Sharp Park in Pacifica is the only “natural area” that may be capable of functioning as an ecosystem in the long-term because of its size and its relative physical isolation.
Letting the public decide
Finally, we must acknowledge that the alteration of our public lands is not a scientific decision. It is a public policy decision. In a democracy this means that the public must decide. In the vast majority of cases, the public has not been given the opportunity to make the decision because the managers of our public lands have been making these decisions for us. They do so by claiming that it is a scientific, not a public policy decision and that their expertise puts them in a position to impose their will on the public. The authors of the book we are reviewing today challenge this claim: “Yet in interventions conservation practice hides behind a veneer of pseudoscience and certainly challenges democratic processes.” Hear, hear!!! Thank you for this astute observation, which we see played out repeatedly in the San Francisco Bay Area.
The authors conclude with this advice to those who are responsible for ecological “restorations”: “It is important to recognize the subjectivity of decision-making processes, and the cultural and historical origins of many of today’s problem species.”
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(1) Invasive & Introduced Plants and Animals: Human Perspectives, Attitudes, and Approaches to Management, editors Ian Rotherham, Robert Lambert, Earthscan Publishing, London, Washington, DC, 2011.
Conservation Sense and Nonsense 
Thanks for this excellent article. Makes lotsa sense and I’d love to see it get plenty of publicity.
Whenever I read excellent postings like this one on MillionTrees, I want to send them to nativists I know–so many are in the Bay area– but then I realize that nothing will change their minds, even well researched, scientific facts. I feel sad that these native plant fanatics who dare to call themselves environmentalists can be so hateful to non-native trees and plants that are not invasive or harmful in any way.