Defeating Phragmites

Recently, Bay Journal published an article entitled: For Better or Worse, Invasive Phragmites is Here To Stay. As Phragmites is one of our “Dirty Dozen” invasive plants, we wanted to comment on this article. It marks a trend we see often now, the notion that we can come to an accommodation, that things are not as bad as all that, that these invasive plants have some redeeming qualities like carbon sequestration or shoreline hardening. The damage phragmites does to local ecosystems are extensive. It becomes an all but lifeless thicket of just that one plant interspersed with mosquito ditches.

We take the position that there are strategies through which phragmites can be defeated, using nature in effect to heal nature, and that these should become part of best practices in phragmites management. We know the type of habitat phragmites likes — let’s address that issue and take back our marshes and forested wetlands.


Phragmites As A Side Effect of Development

The main issue we need to address in phragmites management is development. Shoreline Development Drives Invasion of Phragmites australis and the Loss of Plant Diversity on New England Salt Marshes examines how phragmites,
opportunistically taking advantage of disturbed habitat, and fueled by the nitrogenous sources that come with development — fertilizer, wastewater, and road runoff — all fuel the growth of the phragmites. Logically then phragmites can be managed to the extent that the nutrient load in the surface water is not contributing to its growth, where the habitat is not disturbed.

Accepting Phragmites As Part of the Landscape Reflects a Broader Resignation

Looking around, it seems everyone is ready to throw in the towel on every invasive plant listed in our Dirty Dozen.

The Dirty Dozen

The challenge is monumental, granted, but we have to take the view that we are just getting started. These are all awful awful plants, and we didn’t really have to stop at twelve (and won’t). It is overwhelming, even as they overwhelm us! But we really can’t let that happen. We are only now recognizing the scope of the challenge that invasive plants and insect pose, and because Long Island is being overrun. At this time, we need a comprehensive approach to all these twelve of The Dirty Dozen — and then some — because this is in fact an existential crisis. Deal with one, deal with them all.

The Emerging Science of Environmental Management And Invasive Plant Control

Invasive plants need a toehold. They need disturbed habitat. Let’s address the problem at that level rather than assume disturbed habit is merely a fact of life along our coasts as they are developed. There needs to be an understanding of the natural infrastructure as we plan our human ones. Developers would do well to plan for invasive plant management today especially with the rampant spread of Japanese Knotweed, considered by some to be the worst invasive plant in the world. It’s roots can blast through seven feet of volcanic rock in Japan, and into building foundations. And it’s all over Long Island.

By comparison, Phragmites is just an endless lifeless eyesore. In any case, in ALL cases, we can’t afford to have our local environment succumb to these invasive plants. Our local wildlife depends on native habitat. Rest assured, there is ongoing research on each of these plants and many others, and on technologies to restore habitat.

The Future May Be Closer Than You Think

As an aspiring futurist, I can say with some certainty that all sorts of new methods of invasive plant control are emerging all the time. We’ve tried chemotherapy, but with toxic results. We need scalpels in the form of gene splicing, microbiology. It needs to be about restoring ecological balance, healing nature with nature. So the future ideally will be to some degree the past, putting back what should be there. So let’s get to it:

Phragmites Doesn’t Like Salt

Although Phragmites can tolerate salt spray, research has consistently found that it is typically outcompeted by Spartina grasses when the hydroperiod (length of time of inundation) of saltwater is long enough. Improving tidal exchange and saltwater residency in the marshes will go a long way towards shrinking the phragmites as the native spartina returns.

That means we don’t have to accept Phragmites as part of our permanent landscape.

Spartina in the background in the tidal zone,Phragmites in Foreground

In order to gain a competitive advantage, phragmites will build “islands” of land through litter fall and the process of soil accretion.  Increased sediment accretion rates follow an invasion by Phragmites, blocking natural tidal flows, which allows the phragmites to crowd out all else. The first strategy to combat phragmites is to restore natural tidal flows so that the salt water could infiltrate.

Throwing Shade at Phragmites

Phragmites is also shade intolerant.  A canopy consisting of native trees and shrubs can, therefore, keep phragmites populations to a minimum when present.  One may still find phragmites, but it will be sparse. See Environmental Limits on the Spread of Invasive Phragmites australis into Upland Forests with Marine Transgression  Ironically, when homeowners that own waterfront homes remove trees and shrubs for the sake of a view, they are often treated to 12-14 foot wall of phragmites instead.  

Phragmites on The Connetquot

No phragmites grows here in the shade of a tree:

Pragmites Being Shaded Out

We only recently learned that Black Willows, as a fast-growing, pioneer wetland species are excellent candidates to shade out phragmites. You just have to keep the phragmites stems off of the plants for a year or two until the willows break through the top of the phragmites. Pretty cool! The black willows are very thirsty!

So in sum, there is far too much that doesn’t belong here, and we shouldn’t underestimate the danger of normalizing these destructive plants. We need to be fighting for every square inch. These invasive plants destroy local food webs.

Frank Piccininni, with Marshall Brown

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