Invasive Species – a Question of Harm

    Invasive species are a problem. But deciding where they are a problem leads us to questions of when they area problem and to whom they prove to be a problem. An invasive species is "an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health." according to the United States Invasive Species Definition Clarification and Guidance White Paper submitted by the Definitions Subcommittee of the Invasive Species Advisory Committee (ISAC) and approved by ISAC on April 27, 2006. Setting aside for a moment the definitional debate about natives versus non native and the role of dead white Europeans in the introduction and cultivation of non indigenous species, we are left with the challenge of determining the meaning of harm.
    Because everyone knows what harm is when it impacts him or her personally and immediately, scant attention is paid to what is actually meant in the realms of politics and opinion. In my soon to be published book on invasive species certification policy, I write that "[h]arm is subject to interpretation, and there are differing schools of thought about harm and acceptable risk. For some the issue is how much harm from [an invasive or introduced species] is acceptable, while for others, the principle question is how much harm is avoidable." Harm in the context of invasive species and invasion biology as well as ecosystem services, "…can mean general harm to public welfare or it can be specific harm to the consumer or to the industry."

    Quantification of the harm from invasive species is the point of departure for all conversation, debates, regulations and legislation. In essence there are "two views that are diametrically opposed at the critical point of how one assesses harm, and until this is understood it is impossible to reach consensus." So the actual debate revolves around how much harm and therefore what level of risk is achievable and acceptable.[1]
The idea of harm, and its accompanying level of risk acceptance, colors any discussion about forms of control and regulation. For some of us there is a feeling that we should try to reduce the harmful impacts of invasive species as close to zero as possible, while others think that perhaps given all the other needs of mankind that there is an upper boundary or threshold of acceptable minimal impact that can be accepted. This divergence is a problem in setting standards for management of invasive species for the closer one tries to get to a zero risk the closer the cost go to infinity.

    Related to the identification of an acceptable level of harm is the problem of externalization of costs onto the natural systems. When we transport anything from one ecosystem to another, we do so because there is a human demand behind the movement of the product. If this product becomes an invasive species or a vector (a means of transport) for an invasive species and in the words of my friend and blogger John Waugh and the costs of that activity is not internalized, we are faced with deciding between our short terms needs and our long term choices.

    To put all this in perspective, how much destruction or alteration of a natural system are we willing to pay to prevent? How much damage or impact will the running bamboo that I plant on my land cause to surrounding landscapes? How much impact will the seed from my puple loosestrife have on biological diversity in my ecosystem? How bad could the accidental release of one snakehead into a storm water management pond really be in the big scheme of things? How many new species can be introduced into an ecosystem before it is no longer viable as a self sustaining system? How bad novel ecosystems are and what impact will they have on our quality of life tomorrow, and how will we assess this impact?

    The problem framed by these questions is all about you and me and our individual needs and wants right now. They do not address the cost to our grandchildren. In effect our troubling answer is to transfer the costs to a murky future. When we allow a historic human structure to decay and disappear we deny something of cultural value to the future. It cannot be recovered, pnly vaguely remembered a little while. If you cannot touch it, sense it, work with it, it becomes part of the past drifting in to musty memory. When we willingly allow the loss of species and their habitat we deny the future its turn to be a part of a greater whole. Loss is part of the grand equation of life, but loss due to direct immediate human action is a choice.

    These questions assume a certainty of the immediate that is allusive and in most cases illusive. Our by now automatic resort to science wherein we expect concise clear absolute answers simply brings us to Bertrand Russell's observation that "[e]verything is vague to a degree you don't realize till you have tried to make it precise."[2]


[1] Thompson, J. P. (2011). Certified: Feasibility of Audit-Based Certification to Prevent Invasive Plant Pests in the Nursery Industry. Washington: Northeast Midwest Institute. 112 pp +xii
[2] Russell, B. The Philosophy of Logical Atomism