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Invasive weed continues to spread along local shorelines and roadways

Burning Sensation: Invasive weed a growing fire risk for nature trail neighbours (PDF)

Taking on the mighty Phragmites australis

By: Mary Baxter, Morel Magazine

Controlling Phragmites at Wymbolwood Beach

By Lynn Short

The beaches along the Georgian Bay Shore in Tiny township are dynamic ecosystems. They are constantly changing with the shifting sands. The sand on the beach was formed during the last Ice Age about 10,000 years ago. Fluctuating water levels have been a natural phenomenon in the past so the beach ecosystem has adapted to this situation. The native plants that grow on the beach are especially adapted to this constant change.

When the water level is low, there are several species of plants that thrive in the sand. As the plants grow, they slowly modify the nutrient content of the sand to enrich the soil (sand) by the decomposition of the dead plant parts. This allows for even more plant growth. The tree line slowly advances towards the water. The role of the plants during low water periods is to hold the soil (sand) in place so that it does not blow away.

When the water level is high, the plants that were growing drown and disappear; however, their seeds remain in the sand and grow again when the water level goes down. The wave action holds the soil (sand) during the high water period.

The current very low water level on Georgian Bay, although not a natural phenomenon, has allowed for the growth of many native species along the beach. Unfortunately, a non-native plant species has invaded the shores of Georgian Bay. It has become a big problem along the shores and in the wetlands of the whole Great Lakes area. This plant is Phragmites australis or Common Reed. It originated from Eurasia.

Because Phragmites is not a native plant and has not evolved along with the native plants and animals, it does not have any productive role in the beach ecosystem. It is a very aggressive plant that spreads by sending out long runners across the surface and underground (rhizomes) as well as producing a huge number of seeds each year. Also, the plant produces a chemical that is released into the surrounding soil which inhibits the growth of other plants in its vicinity. We say that it is allelopathic. This contributes to its rapid spread on the beach. If left on its own, this plant will take over the entire beach area between the tree line and the water’s edge, crowding out all other native plant species. Without the native plant species, native animals (insects, frogs, turtles, birds) cannot inhabit the beach ecosystem either. Plant diversity contributes to animal diversity which results in a healthy ecosystem for all. Native plant species also contribute to the health of the water. During rainy periods, the plants act as a filter, cleaning the water before it enters the lake. Many of the native species have attractive flowers that enhance the beauty of our beaches, too!

Phragmites started to appear on Wymbolwood Beach about 15 years ago. No one knew much about it. The beach was changing with the dropping water levels and many plants were starting to grow where the water used to be. Phragmites began to establish colonies in the wet areas of the beach. It started to grow on my property.

At first, I watched it grow with interest, but, when it seemed to be taking over my beach, I decided that it was time to do some research and find out what this plant was. I learned that it was a nasty invasive non-native plant and decided that I did not want it on my property at all.

I tried various strategies to remove the plant and found that the most successful one was to cut the shoots off just below the soil surface while trying not to disturb the surrounding soil. I used a sharp spade to do this. This allowed the native species that were present to continue to grow undisturbed and stopped the Phragmites from being able to photosynthesize.

Photosynthesis is the process in the green parts of the plant by which the plant converts the sun’s energy into chemical energy (sugar) that it needs for growth. Without the capability of photosynthesis, the roots cannot grow. By continually removing the green shoots, the rhizomes eventually are depleted of energy and die. This strategy is not effective overnight. It requires persistence. It took about 4 years to get the established patch ofPhragmites on my property under control. Like any weed, it requires continued surveillance and removal of stray seedlings that regrow each spring. Once control is established, this actually takes very little time. Once I realized that it is possible to control Phragmites, I began encouraging my neighbours to remove their Phragmites and leave the native plants to grow. Many of them took on the project of controlling the plants on their property and have been successful. The remaining native plants slowly out-compete the Phragmites and keep the soil (sand) stable. SincePhragmites thrives best in disturbed soil, it is not easy for it to invade the areas of established native plants.

This is a letter that I received from a resident (a retired doctor) whose property is down the beach from mine and who has been working at controlling Phragmites for the past 3 summers.

“Thanks Lynn, I simply followed your advice! As I explained to my 8 year old grandson – this is an example of a ‘controlled clinical trial’ where different approaches to the problem are examined. Unfortunately, most medical strategies used in clinical trials do NOT have the same degree of effectiveness. For the past month, I have not been able to find more than a couple of stray pieces of Phragmites on our property. I am convinced that the key is to stop the energy source (photosynthesis) of the Phragmites before it gets established and allow the natural plant life to thrive. It takes only about five or ten minutes each time we come up to the cottage this year and the result is quite amazing (I agree!).
Thanks for your help with it.”

Some residents, although they would like to remove the plant from their property, found that digging out the established patch on their property was too daunting a task. For the past three summers, I have been organizing summer students on the beach who are hired by the individual residents to use the removal technique that I described above. We begin the removal of the plants in mid-July and continue until mid-August. Since we can only come to each property once, we strategically time the removal to do the most damage to the plant. The goal is to remove the shoots after most of the energy that was stored in the rhizomes the previous fall, is used up in this year’s growth and before the plant begins to flower. Removal of the shoots at this time prevents seed production and causes the plant to use its reserve energy to grow new shoots thus weakening the rhizomes. With time, the plant will become more sparse and easier to control.

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What is really exciting is that the properties that have had the plants removed this way are starting to show more plant diversity and the animals are returning. Below is a note that I received from a property owner who has been removing Phragmites for 3 years. The first year, the Phragmites on the property was so thick that it was difficult to walk through.

“Lynn, Yes, the beach is looking really nice – I was out yesterday late afternoon taking photos of the various flowers – quite an assortment – some very small and barely noticeable unless one is very low to the ground. We are amazed by the diversity of the plants and their beauty.”

The key to controlling the Phragmites on the beach is to be persistent about selectively removing the green shoots as often as is practical throughout the summer without disturbing the soil and to preserve the native species that are growing between the Phragmites shoots. Encouraging the native biodiversity of the beach will make it a much healthier place for all living things. We should be good stewards of our beach properties and preserve this special beach ecosystem for generations to come.