I agree with David Stalling that the increase in exotic plants on Montana’s rangelands is distressing (see “War on weeds,” March 24, 2011). However, calling grassland conservation efforts the “war on weeds” and referring to exotic plants as “botanical barbarians” is naïve at best and may actually be fooling us into thinking we’re doing the right thing. In many cases the alarming increase in exotic plants is due to disturbance and unenlightened management, not evildoer plants. Thirty years ago, Richard Mack at Washington State University studied cheat grass and was one of the first to point out that grasslands west of the Great Plains did not evolve with herds of large herbivores and would be quickly converted to cheat grass under spring and summer grazing by domestic livestock. Tamarisk is replacing native cottonwoods across the semi-arid West not because it is so nasty and aggressive (it grows more slowly than cottonwood), but because man-made dams have decreased or eliminated the flood conditions required for cottonwood regeneration. In many cases exotic plants are not the big, bad villains; rather they are the messengers bringing the unfortunate news about our misguided stewardship.
We all agree that conserving native grasslands that provide a home for a diversity of wildflowers, birds, insects and animals is a laudable goal. Eradication of exotic plants through herbicide application and biological control is an important component of 21st Century grassland stewardship, but it is not the only or even the most important activity. Many articles in the scientific literature report that eliminating one exotic species via herbicide or biocontrol just results in domination by another exotic. Killing weeds and conservation are not the same thing. Our goal should be conservation. It’s always easier to have a well-defined enemy to vilify. The “war on weeds” gives us this enemy to focus on, and allows us to blame something other than ourselves for our problems. We do need to control exotic plants, but more importantly we need to pay more attention to how our own behavior contributes to our problems. Going to war is not the answer.