Sunday, July 25, 2010

Invasive species confusion confounds

Invasive species are everywhere. One man’s invasive species, feral animal, or weed is another one’s native plant, garden favorite or cherished pet. And even more troublesome are aggressive wandering opportunistic species that come with multiple uses for mankind. Kudzu, Pueraria montana (Lour.) Merr. var. lobata (Willd.) Maesen & S. Almeida, loose-strife, Lythrum salicaria L. and burdock, Arctium minus Bernh. were brought to North America for their medicinal, aesthetic and culinary uses. Kudzu, the invasive species, can provide a biofuel source, fiber for textiles, food through its starch content, forage and feed for cattle and other farm animals, pharmaceutical potential, arts and crafts, and a fragrant flower on a vine that could cover unsightly disturbances in landscape settings.  Purple loose-strife, an invasive species, has given the ornamental gardener a beautiful flower and garden workhorse that blooms through out the growing season oblivious to the damage of insects and diseases, withstanding a wide range of temperatures, and growing through flood and drought. Lesser burdock is also a medicinal and food source but interestingly enough gets classified as a weed rather than an invasive species.

The weed or invasive species question is a reflection of one’s point of view. If you are standing in a managed landscape, a garden or a farm, then a species that invades and reduce your harvest or your view, is a weed, and invader a pest to be removed. If you are standing in a natural area, park or wilderness than a species that comes in from other ecosystems, and is not native, is an invasive species that needs to be weeded, culled and removed. In both cases the best strategy is to detect the plant early and remove it at once. This is called is an Integrated Pest Management (IPM) strategy in managed landscapes and is called Early Detection and Rapid Response (EDRR) in natural landscapes. And while we are speaking about plants, the idea of perspective extends to animals. For example I have written about the third rail of invasive species issues, the feral cat (Are cats an invasive species - a wickedly inconvenient conversation), and I have also noted that the problem of invasive species context extends to insects too.

Invasive species are those that are transported by human activity easily and readily establish in new ecosystems. Taking advantage of our global trade they hitchhike on our human provided pathways. In this way they have spread with humanity across the earth. Mankind is perpetually disturbing or “plowing” the land. This chronic disturbance favors certain companion species that “travel” with us. Some of the species come with our knowledge and some come unbidden; the ability to survive and reproduce within a large range of conditions allow these invasive species to take advantage of and work with mankind’s grand disruption of local native or natural ecosystems.

It is easy to chastise ornamental gardeners for introducing new species of colorful plants that may escape or to rail against pet owners that discard over grown species into supposed natural recycling systems (Invasive issues and complicated species) The cost of mitigating the impact of invasive species has been calculated to be around 132 billion dollars) plants, animals, disease); the size of the nursery industry is approximately 140 billion dollars setting up a perfect storm of competing interests. However, things get more complicated when basic human need such as food or fuel is involved. We quickly forget that the major impetus behind kudzu and its spread was the search for a legume that could survive in the US southeast. The collision of desires that surround our pets and our interests, wants and needs clouds the issues of invasive species. Do we save the charismatic non indigenous swan (Wicked Invasive Swans) or save the native flora long the water’s edge? Considering the problems of invasive species is to take a look at our human activities and our place in the world. How will we resolve the conflict between our immediate needs versus our long term wants?

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