Battle of Wills with a Non-native Plant

Looking off of my back deck today, it hit me yet again that fall is truly here as you can see by the picture to the right.  But that is not what this entry is about – I just had to share the fall colors.

Beaver Brook Meadow Foliage 2011

The other thing I noticed about this view and have continued to notice all summer was the absence of bright purple spiked flowers where there was such an abundance of them last year, as seen in the picture below to the left. I am not talking about the purple in the foreground which is actually one of one of my butterfly gardens, but the faint purple flowers visible in the background. Now, before you get me wrong this is not a bad thing. For my first two years here in the early summer my neighbors have seen me fiendishly pulling plants from the wetland, probably thinking that I either really dislike the color purple or otherwise have way too much time on my hands. Neither is the case.

Purple Loosestrife Meadow Buffer
Purple Loosestrife at Pond Buffer

The plant known commonly as purple loosestrife is an alien introduction from Europe, a 200 year-old escapee from the horticultural garden trade. As beautiful as it seems, it is far from ecologically benign. The species is just one of hundreds of introduced noxious plants that affect the physical and chemical character of our environment. Due to media coverage most people know that this plant is “bad” but don’t really understand the reasons behind that conclusion. In brief summary, when purple loosestrife aggressively moves into a wetland area (it likes wet feet) it changes the physical community by crowding out our native plants such as sedges, rushes and ferns. The plant has a very deep tap-root that allows it to quickly establish, giving it a significant advantage over native plants in instances of ground disturbance and over seedlings in the spring. This in turn effects preferable food sources and host breeding or nesting sites for many wildlife species including the marsh wren and the federally-listed endangered bog turtle. As it possesses a different scheduled life-cycle than our native plants it decomposes quickly in the fall (rather than in the early spring) which in turn alters the level of nutrients in the soil (Phosphorus), ultimately affecting the population balance of those little beneficial insect critters that are responsible for decomposition of plant material. All of these domino-like impacts change how the entire system biologically and chemically functions. Then, because it is negative and we are human, we compound the injury by spending hundreds of billions of tax dollars for repeated application of generally toxic herbicides (that wonderful tap-root also allows it to recover from herbicide application) that can’t discern between purple loosestrife and a native plant.  I sometimes equate it in my mind to an ecological pandemic.

So, you are probably asking yourself if it is so difficult to get rid of the plant what happened this year? Good question. Below, are pictures of that same buffer this summer. One of the very many reasons introduced plants from other geographical areas do so well in new locations is that the environment has not had enough time to evolve to provide the necessary check and balance, a natural enemy. I will talk more about this in one of my next posts. In an effort to jump-start this evolutionary process many state management agencies have brought in their own – enter the Galerucella spp. beetle, the devoted enemy of purple loosestrife in its homeland.

Mostly Absent Loosestrife 2011
Mostly Absent Loosestrife 2011
Galerucella Beetle Photo Credit: Donna Ellis UCONN

You see this little, very hungry, beetle has found its way here to Beaver Brook meadow from other experimental releases including one at the Chelmsford Conservation Land Trust Archer Meadowbrook Preserve. As a result, this mostly stunted, defoliated condition relects what the purple loosestrife looked like this summer (though I would like to give my hard work repeatedly pulling up plants before they flower some credit too, even if its not truly deserved).

Galerucella Beetle Damage 2011

Because of the damage caused by this leaf-eating beetle, many of the loosestrife plants were shorter than normal and never flowered thus making it much easier for me to remove the above-ground parts. Like I have done for the past 2 years I have removed the invader and replaced it with native selections such as joe-pye weed, swamp milkweed, boneset, sensitive fern, buttonbush, and sweet pepper-bush. If the pattern here is similar to other beetle introduction sites in Massachusetts and Connecticut, the beetle damage is just temporary. When the hungry critters have devoured so much of the loosestrife plant community that it can no longer maintain the current beetle population, the insects will move on to more densely-packed feeding areas in Chelmsford, or in neighboring towns. This will allow the plant an opportunity to rebound, but hopefully at a lower density than that which previously existed. But I am not worried, because little does this plant know I will be one step ahead of it and I am really STUBBORN.