Responsible Gardening and A Rare Lecture Opportunity

If you have read my previous posts, then you know of my personal war with one of several invasive and non-native plant or animal species in my backyard here in Chelmsford. I would like to think that I am not alone in this endeavor, either locally or regionally. So far I am not disappointed by my on-line excursions.

If you are interested in gardening for wildlife, butterfly gardens, plant or wildlife ecology or are just beginning to develop an inkling of interest in this topic I strongly recommend you take advantage of a rare opportunity to hear one of my top-list authors and a well respected scientist, Doug Tallamy (Bringing Nature Home: How You Can Sustain Wildlife with Native Plants)  lecture this Wednesday night (October 5, 2011) in Carlisle, MA.  The event is being sponsored by the Carlisle Conservation Foundation, Susan Zielinski Natural Science Fund, and Carlisle Conservation Commission and will begin at 7 pm at Corey Auditorium in the Carlisle Public School.

As many gardeners undoubtedly do, I use my garden as an expression of what is attractive to me as an individual. Also, as I have a strong interest in nature and ecology I seek to do the right thing while expressing myself in this artistic way. I want what I put in my garden to function in sync with the natural environment. Mr. Tallamy who is also a renowned entomologist (insect ecologist) at University of Delaware provides abundant scientific documentation to support that alien plant introductions generally do not have a productive ecological relationship with our environment. This is because they often have different characteristics such as leaf chemistry, time to maturity, or time to bud and flower. What this means is even though they are phisically present in our natural environment, they are not contributing or giving back energy to the system the way a native plant would (just taking it away).

We, as gardeners, do have a choice. Now, more than ever before native alternatives to invasive horticultural varieties can be found.  However, if you are not familiar with the horticulture trade or with these alternatives, it is easy to be overwhelmed and led in the wrong direction by a well-intentioned nursery worker, or even, a less than well-meaning individual who just wants to make money.

Hybrid variety of a native columbine species

For example, not all native plants are created equal. Some so-called native plants are actually naturalized alien plants from other countries.

Alien and Introduced Queen Anne's Lace - Invasive in some New England States

Some nurseries will push these plants as “native” or alternatives to invasive plants. Some plants are cultivar varieties (genetically altered) of our natives which may not possess identical or even similar traits to the native variety, depending upon what it was “crossed” with.

These plants will often be touted in their descriptions as “pest tolerant,” “a caterpillar may eat the foliage occasionally,” “deer resistant,” “disease free,” “mostly allergy free,” good for naturalizing, etc. What a description like this tells me is that the plant does not possess a substantial ecological benefit and it is not contributing much in terms of food to native insects, which are the base of our regional food chain. Any of the descriptions I listed above would be a BIG “red flag” in my book.

As an example, a lot of the statements above will often be found if you search for traits of the common butterfly bush (Buddleia davidii or Buddleia x weyeriana). Now, you are saying wait a minute, isn’t the butterfly bush good because it attracts butterflies? Well let me, and some of my favorite online sources, enlighten you. The butterfly bush is a butterfly magnet and I can often find many butterflies on it during the summer season where they seek the very abundant and nectar-rich flowers which bloom almost constantly from spring to fall. Tallamy’s research shows “not one species of butterfly in North America can use Buddleia as a larval host plant.” In particular, a large number of butterfly species are very plant-specific and will only use 1 or 2 plant types to deposit their eggs and provide food for their hatching larvae (think milkweed and the monarch butterfly folks). Without the presence of a particular plant, you cannot have a particular butterfly. Therefore, without larval host plants you cannot have any butterflies. Taken to the next logical step, if everyone is following horticulture and nursery recommendations to create a butterfly garden with the butterfly bush as its anchor plant, butterfly diversity (number and variety of butterfly species) will undoubtedly continue to decline as we raze additional natural land to build even larger suburban homes and replace these sites with sterile turf lawns.

Alien and Invasive Butterfly Bush - Buddlei Davidii

Now, here’s another little tidbit for you. The butterfly bush is considered invasive in over 25 North American states, including Massachusetts, Connecticut and Rhode Island – that is if you go by the U.S. Department of Agriculture Plants Database. I can honestly say that I personally have not had any experience with this plant’s invasive tendencies but I have heard of other wetland scientists that have. It is not currently listed on our Massachusetts Prohibited Plant list and it also has not been evaluated (as far as I know) for noxious tendencies by the Massachusetts Invasive Plant Advisory Group. Other organizations, including the National Park Service, Audubon, and other state and governmental organizations have it on their “Invasive Watch List,” or have outright banned the sale of the plant. It is considered prolifically invasive in Zones 6 and 7 (Mid-Atlantic States such as PA and VA) as well as the Northwest.  It is on the “Most Invasive” species list of the Pacific Northwest Exotic Pest Plant Council. In this region it is extremely invasive in disturbed natural areas such as burn sites and along large streams such as the Willamette River. It has been a huge problem in England, where it is considered one of the top 20 noxious weeds, infesting large tracts of disturbed land 50 years after it was introduced in those areas.

USDA Plants Database - Buddleia Invasive Representation in U.S.

You see every plant has a niche or a microhabitat which it prefers. I for one am not completely knowledgeable about this plant and what its preferred microhabitat may look like (I am NOT a botanist). But I can hazard some broad assumptions (thinking aloud folks…don’t read in more than that) based upon its noxious nature elsewhere.

For example it appears to respond well to fluctuating wet environments where it spreads predominantly by very abundant seedlings. It likes riparian corridors and floodplains, especially such sites that have experienced some level of disturbance. The fact that it likes burn sites AND wet areas could reveal an interesting relationship with nutrient cycling on low pH sites (cold, wet or acidic sites) or the timing of availability of elements critical for plant growth following a disturbance (Nitrogen or Phosphorus).  For example inorganic Nitrogen can be made available through bacterial fixation following a burn event and is often considered a valuable post-fire nutrient source. Another byproduct of fire to consider might be potash (Potassium in a water-soluble form)  The time it took to infest U.K. sites makes me wonder how long the seeds remain viable in the seed bank once they are deposited there?

Research on the Buddleia problem in the U.K. by Oregon State University has revealed that seeds from the plant require a long time to develop and release from the plant. Similarly, U.K. researchers have discovered that flower heads from a previous summer do not release seed until dry weather occurs the following spring. This could be very useful information. It is also possible that climate fluctuations or microclimate condition is sigificant. For example, does PA or VA normally have a dry spring (did we in MA have a dry spring in 2010)? In addition, practical application of this info suggests that pruning all of the spent blossoms from the butterfly bushes in the fall prior to full development of the seed could potentially limit release of the seed to native environments (possibly a best management practice?). Well at this point I am starting to ramble and very loosely hypothesizing with nothing to back it up. Needless to say, I have begun removing the butterfly bush from my gardens.

I think that Carole Sevilla-Brown in her Ecosystem Gardening Blog says it best. We have been down this road before with many of our currently-listed and most noxious invasive plants. She highlights the Bradford pear, purple loosestrife, and multi-flora rose. These are just a drop in the proverbial plant bucket. It is pretty clear that the Horticulture Trade has not learned from past mistakes. The industry’s on-going attempt to create a sterile form of butterfly bush is like déjà vu of the failed attempts at purple loosestrife sterility. If we don’t learn from our past mistakes we will be doomed to repeat them over, and over, and over again. Gee, even the mouse in the maze learns from repetition and will eventually find the cheese…

Anyway, if you have an interest and are able to find time to attend Tallamy’s lecture in Carlisle, I hope to see you there.

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.