North Coast Chapter - CNPS
Invasive Exotics

Everyone's (finally) talking about weeds
by Andrea Pickart, Exotics Coordinator
[appx. Jan.99]

The recent issue of Fremontia is not the only publication to recently feature exotic species. In the past few months there have been prominent articles in both the L.A. Times and the S.F. Chronicle discussing this problem. Hopefully, this is a sign that the issue of invasive species is finally becoming mainstream. The lack of public awareness is one of the biggest hurdles to overcome in implementing solutions to this problem. As a Florida ecologist was quoted as saying in the Times article, when the average member of the public hears you saying that plants are going to destroy an ecosystem, they look at you "like you just fell out of a tree." After all, to the untrained eye, a natural area and open space are indistinguishable. Until you’ve seen the multi-colored beauty of dune mat in bloom, for example, you may find expanses of wind-blown European beachgrass quite appealing. And exotic plants are often quite beautiful in their own right, which is exactly why many of them were transported here to begin with.

The lack of public awareness of the invasion problem was recently highlighted in an article in the Natural Areas Journal. Two researchers handed out questionnaires to visitors to the Bodega Marine Laboratory—an audience that is presumably both well educated and perhaps even biologically oriented. Although most people were familiar with the term "weed", when queried, they listed plants like dandelion and crabgrass, and the majority (80%) listed gardens, yards, and lawns as the places that weeds grow.

So what are the ecological problems? A quick skim through the last Fremontia will likely leave you feeling depressed. If by any chance you found yourself cheered by the introductory article’s conclusion that the introduction of new weeds to California is slowing in recent years, remember that this refers just to the appearance of new weeds, not the problems posed by old ones. The replacement (through competition) of native plants by non-native species is alarming enough—resulting in significant loss of biodiversity, but in some ways it is the most superficial of the negative impacts of invasions. Many invasive species cause dramatic changes to basic ecosystem functions and processes. Yellow bush lupine, for example, causes enrichment of the soil by elevating nitrogen levels, and facilitates the invasion of many other weedy species, and even some native species that normally would not be found on the dunes. In these cases restoration becomes much more difficult than just removing the offending plant. Restorationists must try to turn back the clock by laboriously (and usually expensively) reversing these changes. Meanwhile, invasive species increase in area exponentially, so with every passing decade the problem multiplies. On the Humboldt Bay dunes, invasive species now comprise 83% of the non-forested dune vegetation, native dune mat only 17%. The advanced state of this problem has led those of us in the business of restoring dunes to consider drastic and sometimes unlikely solutions, such as the use of bulldozers to remove beachgrass. Solutions like these may be unpopular with the public, who equate bulldozers with development. Herein lies the need for education.

The North Coast Chapter has decided to make education the number one priority of its exotics program. Given the magnitude of our local invasion problems, the amount of on-the-ground work we can do is limited. We hope to optimize the contribution we can make by working with other entities, such as local municipalities and state agencies, to help focus them on priority species. Of special importance will be species that are new to the area and just beginning to invade. The early stages of invasion are when the problem can be dealt with most efficiently and economically. We will be featuring such efforts in upcoming issues of Darlingtonia. In the meantime, if you are aware of any "hotspots" of new invasives, please contact me at


Invasive Exotic Web Links


California Native Plant Society - North Coast Chapter
P.O. Box 1067 Arcata, CA 95518-1067

Last modified  12/31/10 01:51 EST