Invasives August Issue

In February 2000 President Clinton established the National Invasive Species Council. Agriculture secretary Dan Glickman, Commerce Secretary William Daley and Interior Secretary Bruce Babbitt were asked to work together on a plan to minimize the economic, ecological and human health impact of invasive plants and animals not native to the US. The executive order on Invasive Species directs federal agencies to prevent the introduction of invasive species, to control populations of such species in a cost-effective and environmentally sound manner, to monitor populations, restore native species, conduct research and promote public education on invasive species.

         The council is directed to prepare a plan within 18 months (of Feb. 2000) which will recommend goals and approaches for preventing the introduction and spread of invasive species which are costing the US $123,000 million a year. The council is also supposed to identify pathways by which invasive species enter the US and to design risk-assessment methods which are science-based.

         Nothing is mentioned in the executive order of a “white list” of acceptable species , however there are some who expect such a list to be presented to President Clinton in August. According to J.L.Hudson, “current law ‘black lists’ known harmful plants; everything el  se is permitted. Under the ‘white list’, everything is prohibited except what is on the list. J.L.Hudson has been distributing seeds for 27 years. His motto is “Preservation through dissemination” and his seeds are all open-pollinated so customers can collect their own seeds once they have gotten mature plants. He believes we are fast losing important species and that if plants must be proved safe before they are allowed to be sold, it will severely handicap small companies from distributing unusual seeds. He is afraid this will mean only large corporations will be able to prove safe and distribute unusual seeds. Because the corporate rule for profit is large quantities of few choices, far fewer varieties will be saved and gardeners’ current cornucopia of choices will be severely reduced and biological diversity will diminish.

         Another leader in the plant industry who is giving a lot of attention to the invasives issue is Dan Hinkley. He is co-owner of Heronswood Nursery, an avid plant explorer and is responsible for collecting and distributing one of the largest selections of unusual plants in the US. He has hired an internationally recognized authority on invasive plant species, Sara Reichard, to review his plant lists and recommend culling any that might become invasive. Hinkley is seeing how quickly human and other impacts are disturbing and destroying native plant communities. He asks, “ Do we choose to simply observe the gross annihilation of genetic diversity and do nothing, in order to preserve the tattered remains of our own backyard ecology?” He adds, “ We are slowing our introduction schedule to accommodate the process and voluntarily removing certain genera from production that have proven to be potentially hazardous.”

         On a more local level, I just read Boulder County Commissioner Ron Stewart quoted as saying, “We’re in the third year of a staggering growth rate—we’re adding a population the size of Louisville every 18 months.” This pressure is leading the commissioners to ask voters to approve tax money to buy more open space. What Open Space accomplishes besides keeping us from being boxed in by houses and more houses is that it preserves rare plants and plant communities, and the whole range of creatures they support. Besides the human population pressures, invasive species are reducing or threatening what Open Space is trying to preserve.

         I spoke recently with two employees of the City of Boulder Open Space Department, Lynn Riedel, plant ecologist and Laurie Deiter IPM Coordinator. Their duties include seeing to it that the rare plant and plant communities are preserved. They expressed to me that it was their love of nature and plants that got them into this work, but a lot of the time, they are just fighting invasive weeds. They told me that few people are around the wild areas enough to see the extent to which certain species are invasive.

         Just because a species like tansy is not invasive in dry areas doesn’t mean it isn’t invasive. For example, far off the roads tansy has gotten into wetland areas and is choking out native plants. They explained that because certain weeds have taken off so quickly, like Diffuse Knapweed, reasonable caution needs to be given to other new introductions. They are especially wary of some of the Plant Select introductions. Plant Select is a joint effort of Colorado State University and the Denver Botanic Garden that has promoted many great plants. However Lynn and Laurie are concerned that not enough time has been spent evaluating their potential invasiveness, and they would prefer that they weren’t given names that make them sound like natives. (“Colorado Gold” for a gazania from South Africa, for example) They would prefer that Coloradoans get to know and take pride in more of our own great native plants.

         On June 14 a weed tour of invasive ornamentals was organized by Adams and Boulder counties. The tour was led by Cindy Owsley of Boulder County Parks and Open Space Weed Management. The tour was useful in pointing out exactly what these weeds look like and especially in seeing their impacts on Open Space and parks. Cindy Owsley mentioned that defining and controlling invasive species is so complex that broad generalized approaches are less valid than a case-by-case approach.         The deeper we go into this subject of invasive plants, the richer and the more complex it becomes. Although few people are actually faced with the problems of invasives, it is both a federal and a local issue, which is costing us money and plant communities. However overreactions to these dangers could cost us in biodiversity and sustainable (Colorado-adapted) gardens. In the next issue we will look at Sarah Reichard’s model for evaluating invasiveness; we’ll see what defines a weed and we’ll interview Panayoti Kelaidis on the subject.