In The Nature Of Things: Language, Politics, and the Environment

7. Restoring Nature: Natives and Exotics

Chapter 7 Restoring Nature: Natives and Exotics John Rodman Three Cases The October 1988 issue ofFremontia, journal of the California Native Plant Society, carried three succinct articles on coastal dune restoration projects occurring in the 1980s, in addition to several notes and one letter on the control of various exotic (alien, nonnative) species of plants. The link, of course, is that the control, removal, and sometimes eradication of exotic species of plants and animals is the negative moment in the dialectic of ecological restoration, in complement to the positive moment of planting, reintroduction, and so on. But what does it mean to be an exotic, asdistinct from a native, and why is this important? In this first section the three texts are examined, not to evaluate the actual projects, but to raise questions about how we think and what we presuppose when we use the categories "native" and "exotic." The next section shifts the scene from the revegetation of coastal dunes to the defense of desert riparian areas against invasion by tamarisk.Throughout this chapter , the focus is primarily on plants, but the argument leads to a concern with larger ecological systems. It is not my intention to reduce the complex process of ecological restoration to the replacement of exotic by native species, but rather to focus on this particular aspect of ecological restora139 140 John Rodman tion, leaving the discussion of other problematic aspects to other times and places. Case 1 Andrea Pickart'sarticle, "Dune Revegetation at Buhne Point," describes the re-creation of a 20-acre sand spit in Humboldt Bay in northern California.1 The Buhne Point spit had eroded over the course of a century and finally washed out to sea in 1982, leaving a fishingvillage exposed to storm waves and flooding. Re-creation of the spit was undertaken as a state-of-the-art "shoreline erosion demonstration project" funded by Congress and carried out by the Army Corps of Engineers (sic) in collaboration with state and county governments. Until very recently,the state of the art for dealing with shoreline erosion consisted of building protective jetties and stabilizing the dunes by planting Ammophila arenaria, an introduced European beach grass. (One cause of the long-term erosion of Buhne Point,of course, was the construction of the Humboldt Bay jetties in 1899; like flood control dikes, jetties protect the immediate area and pass the problem along.) The new Buhne Point project continued the reliance on jetties, but, instead of seeding the newly imported sand with European beach grass, used instead a seed mix of plant species typical of the "dune mat" vegetation of the northern foredune community as it was found in its "most pristine" form on the Lanphere -Christensen Dunes Preserve, a 450-acre area located on the North Spit of Humboldt Bay,owned and managed by the Nature Conservancy. The Buhne Point project aimed not simply at creating a sand spit with stable dunes by revegetating with whatever would work, or even at restoring the sand spit as it had existed before the 1982 washout, but at creating a sand spit on the model of the best available paradigm of what a native foredune community was like. (The project director at Buhne Point was the manager of the Lanphere-Christensen Preserve, but I cannot fault her choice of models.) Subsequently,the Buhne Point project became a model used by the California Coastal Commission and by Oregon State Parks in cases where coastal development was permitted on the condition that disturbed dune areas be restored as a mitigation. The project manager's account does not suggest that revegetation with European beach grass would have been an ineffective way of stabilizing dunes. The defect of that approach was rather that "the spread of this introduced plant away from the stabilization sites was resulting in the dramatic loss of diverse natural communities." In short, the exotic plant was a threat to native plant communities—first, presumably, by replacing (or at least taking up space that could be occupied by) natives, and, second (and Restoring Nature: Natives and Exotics 141 apparently more important), by escaping the stabilization sites and invading various natural communities present in the region. Evidently, exotics are bad when they behave invasively; but, since what they do when they invade is to replace natives, we may suppose that the presence of an exotic is bad per se, and that invasive behavior compounds the...