In 1941, North America contained a wide diversity of ecosystems and human cultures. Today, the landscape is more homogeneous. Most of the prairie is gone, replaced by large areas of monocultures of corn, wheat, and soybeans. The eastern forests have largely been replaced by concrete jungles, which have spread across the rest of the continent as well. Whole cultures have disappeared. Whole species are going extinct at an alarming rate.
Other changes have occurred as well. The replacement of diverse ecosystems with monocultures and concrete has been accompanied by disturbances that create new habitats. As people have moved around, they have carried with them —sometimes unwittingly, sometimes purposely —plants and animals from their former homes. When the habitat suits the new species, they move in.
When these new inhabitants interfere with what we want to do, we call them “pests” or “weeds.” There has been a lot of attention recently to weeds that seem to be especially difficult to manage, particularly those that have become established in “natural” or managed ecosystems.
Are these species “invasive?" Or are they opportunists taking advantage of disturbed ecosystems? When, if ever, should we mount campaigns to eradicate these species in their adopted homes? David Pimentel, PhD argues that alien weeds pose serious problems for agricultural and natural ecosystems. Virginia Daley and Fritzi Cohen argue that humans have always been assisting the spread of plants wherever they moved, and that the current hype over “invasive plants” is an excuse to mount chemical warfare campaigns. Either way, toxic chemicals are not the answer—in fact, they pose greater threats than the problems they are meant to solve. Read this Harper's Magazine article for an interesting take on Monsanto, glyphosate, and the war on invasive species.
There are many other approaches to managing problem vegetation that have proved to be successful. As can be seen in the following descriptions of other approaches, successful land management needs to consider the whole system.
As transportation corridors for plant and animal invasives carried by traveling vehicles, highways cross geologic barriers that previously prevented the spread of species. Consequently transportation corridors and are a factor s in the spread of and loss of natural habitat, the top two drivers of declining biodiversity.
Every year, millions of miles of roads, utility lines, railroad corridors and other types of rights-of-way (ROWs) are treated with herbicides to control the growth of unwanted plants. However, public concern over the use of dangerous and inadequately tested pesticides has resulted in an increasing effort over the last decade to pass state laws and local policies requiring notification of pesticide use, restrictions on application types and implementation of least-toxic and organic approaches to vegetation management. For more information on what your town can do read Beyond Pesticides’ “The Right Way to Vegetation Management.”
An example of a community fighting these pesticide uses is Cape Cod. After four years of relying on non-toxic mechanical controls to clear weeds on rights-of-way across Cape Cod, the Massachusetts-based power company Nstar (nowcalled Eversource) announced that it would begin using herbicides again in 2013. All 15 Cape Cod towns have signed a no-spray resolution in 2011 and 2013, requesting NStar to use non-chemical means to defoliate transmission line easements, citing concerns for pesticide drift into the ground and surface water. Yet, despite extensive local opposition to the spraying, and evidence of the efficacy of organic land management to control weeds, NStar has refused to seriously consider alternative methods to spraying toxic herbicides.
Read Beyond Pesticides’ comments to the Massachusetts Department of Agriculture Resources (MDAR) on NStar’s 2014 spray plan.