Rawinski and Malecki (1984): Purple Loosestrife is taking over! AHHH!! STOP IT!!! HORRIBLE PURPLE WEED!!!!
Government, environmental groups, people in general: Dude! It is purple and evil! (run about trying to kill purple loosestrife. Spend tons of money. Introduce non-native beetles to eat it. Generally go nuts.)
Hager and McCoy (1998): Umm... People? Have you actually READ Rawinski and Malecki's paper? It sucks. Basically, they just decided to hate on loosestrife because it is so purple and they noticed it everywhere.
Government, environmental groups, people in general: Lalalalala! I can't HEAR you! (keep spending lots of money trying to kill purple loosestrife)
Anderson (1995), Farnsworth and Ellis (2001), Houlan and Findlay (2004) : (Do a lot of actual research to see if loosestrife is hurting anything) Um... People? Like, Hager and McCoy were right, this loosestrife stuff doesn't seem to be that big of a deal. It just sits there being purple.
Government, environmental groups, people in general: Lalalala! I can't HEAR you! (keep spending lots of money trying to kill loosestrife)
Okay, so I'm being silly, but I started reading about purple loose strife because I wanted to use it as an example of what, exactly, invasive plants do to native species in areas they invade. Surprisingly (to me anyway), in the case of purple loosestrife, the answer seems to be... just about nothing. That's not the whole story – many other invasive species do a lot of damage (more about that in a future post) but it is shocking that so much money and time has been invested in killing purple loosestrife without good evidence that it is worth it. No less than three non-native species of insects have been introduced to the US just to eat the loosestrife. And what if those beetles start eating some other native plant as well?
The lesson I'm taking away from this is: While no invasive plant is good, many aren't all that damaging, and we need to make sure we invest the limited resources we have to save the environment on the issues and species that matter the most -- not just the ones which are easy to notice because they have bright purple flowers.
(Photo: from Urtica on flickr.)