Prothonotary Warbler

Prothonotary Warbler

Sunday, 2 April 2017

Fire: a hot topic which often gets a bad rap

On Wednesday, March 26, 2017 a fire got started in the Point Pelee National Park (PPNP) marsh, the cause of which is as yet undetermined. I have my own theory, as do others. Regardless, the fire was allowed to burn itself out, with park staff and local firefighters successfully protecting the boardwalk. From some media reports, I believe the area burned was about 125 hectares.

Kory Renaud posted a few pics on his blog which you can see here.

There was lots of local media coverage, including social media, and it was interesting to read all the comments of concern in how horrible this was for the marsh and the wildlife. Of course it is encouraging to know that so many people have concerns for wildlife and natural areas. Unfortunately people have been programmed, it seems, to believe that fire in a natural area is always devastating.

Some people will remember the Smokey The Bear ads and posters, declaring that "Only you can prevent forest fires", or have seen other posters showing a firefighter rescuing little bambi from a forest burning in the background.


There is no question that fire can have a significant impact on a natural area. But it is imperative to remember that fire is a natural aspect of many natural areas, and in spite of the effects it might have on some species or individuals, contributes in a positive way to the overall health of the ecosystem.

Remember the fires of Yellowstone National Park in the late 1980s? It was initially declared a national disaster by the masses. Some people knew better. In short order, it was shown how critical periodic fire is to the broader ecosystem, and without it, future fires can be a lot more devastating. There were photos showing bison grazing peacefully in the meadows, while smoke lingered in the background. Wildlife in general were not nearly as alarmed as people were. The event which had so much attention provided an opportunity to inform the masses of how necessary, and beneficial, fire can be. (These next two images were not taken at the time of those fires.)
Bison resting at Yellowstone National Park


The same kind of thing has happened, albeit on a much smaller scale, with the recent fire at PPNP. There was a 'firestorm' of comments posted to various media, some of them which were quite concerned about how devastating it would be to wildlife, such as the recently emerging frogs and turtles. Supposedly the marsh would never be the same. Admittedly there is the possibility that a very small number critters might have been impacted, but far, far fewer than people might realize. And in reality, fire is an essential component to maintain healthy natural ecosystems, including marshes, certain types of forests and in prairie and savanna. In one sense, fire is perhaps more important nowadays in marshes than it was in decades gone by.

Let me explain.

One of the most common species of plants typically found in many marshes is cattail (Typha). Yet the cattail we see in our marshes these days is not the same cattail that used to dominate. The native species is Wide-leaved Cattail (Typha latifolia). Unfortunately there is a similar looking species that is native to Europe and Asia and arrived decades ago, known as Narrow-leaved Cattail (Typha angustifolia). The two of them hybridize, and the hybrid is known as Typha X glauca. Unfortunately both the non-native species and the hybrid are quite aggressive, and quickly dominate most marshes they occur in. They grow thicker and taller than the native cattail. A stand of cattail these days, is very dense, and has fewer benefits to wildlife than in days gone by.
A really healthy marsh which supports a greater diversity of plants and wildlife is referred to as a hemi-marsh, which really means that it is about half emergent vegetation such as cattail, and half mostly open water which may include things like water lilies floating on the surface. There are lots of edges, where the emergent vegetation and open water intersect, and that is the most critical area for many species of wildlife.
Virginia Rail using the edge

This first image shows a relatively healthy mix of open water and emergent vegetation at St. Clair NWA.

This next image shows what the south end of the Rondeau marsh looked like in the mid 1980s, where there was a good mix of emergent vegetation and open water. The amount of open water is exaggerated a bit, since I used a 24mm wide angle lens.
The areas that are open at the beginning of the year, may gradually get partially covered over by floating vegetation such as water lilies, and this provides shade for the water, making the metre or so depth of water below a more suitable temperature for fish, frogs, and millions of invertebrates, etc to survive in during the hot summer months. All of these creatures are essential for the survival of many other forms of aquatic life. For example the under surface of the lily pad is where some invertebrates such as snails attach. Birds such as rails, with their long toes, can walk on top of these lily pads and will turn up the pad to feed on the invertebrates.
The seeds of the lily pads as well as for many species of submergent pond weeds (Potamogeton species) are invaluable food sources for migrating waterfowl.

When the non-native cattail and hybrid cattail dominates, it steadily fills in the openings of a healthy marsh, suppressing the sub-mergent vegetation and making the area generally less beneficial to wildlife and other native plants. Many marshes today are dense, with very little open area amongst the cattail. This next photo shows a very dense stand of cattail, with the only open water actually not directly associated with the marsh, but is part of the deeper water of Rondeau Bay.


If a wetland is impounded, that is, surrounded by a dyke system and the water levels can be controlled via a pumping system, one can raise the water level to slow down the advance of these dense stands of cattail. The PPNP marsh is not impounded, with a dyke only at the north end, so it is subject to the natural fluctuation of water based on adjacent lake levels.

In lots of cases, the expanding stand of non-native cattail is not rooted to the ground; the roots and thatch build-up can create a dense floating mat of vegetation, sometimes a metre or more thick, which floats over water too deep for it to take root in. Fire, however, can reduce the thatch build-up and kill off the expanding edges of these floating mats, suppressing the expansion and giving the open areas of water a chance to survive. It also burns the buildup of dead plant material which has accumulated over many previous years, exposing the organic material at 'ground' level. The plants themselves, whether it be cattails or others, will for the most part not likely be harmed. They will survive, since the growing points have been underwater and thus have not burned. But the outer edges of these mats may be slowed down in their expansion.

As for the concern over wildlife: there are few, if any, birds nesting yet, so nests and young will not be affected. Adult birds can fly, so they can escape. Frogs and turtles, if they feel threatened, will simply go underwater until the fire has passed. And in reality, there were probably very few frogs or turtles in the dense stand of cattails....it was likely too dense for them to use. They were likely at the edges or in the open water basking on hummocks when the fire approached, so they could easily plop into the water and escape. Mammals such as muskrats will also be able to escape by going underwater.

Likely the only types of wildlife to be affected may be the larvae of certain species insects which may have overwintered in the stalk of the cattail.

As for the benefits of fire:
-it will likely open up the dense stand of cattail, making more edge around open water which is where most of the wildlife prefers; they can get out into the open water, yet if they feel threatened from avian predators such as a Northern Harrier (marsh hawk), can retreat to the denser vegetation;
-the surface of the now exposed organic matter will, for a few weeks, have some water on the surface or at least be moist, which will attract frogs as well as shorebirds and members of the heron and egret families;

 
-if there were muskrat houses in the cattail stand, they will be exposed and potentially be a nesting site for Black Tern, a species at risk ranked as Special Concern;

-an exposed muskrat house can also serve as a basking area, as well as a place to lay their eggs, of turtles, including the Endangered Spotted Turtle;
-where open water and emergent vegetation meets, reeds such as bulrushes (Scirpus sp) may grow, and this is a favourite spot for the Threatened Least Bittern to nest.

So please keep in mind that fire is natural and beneficial to ecosystems and wildlife. Take a walk on the boardwalk (no this isn't an advertisement for a Monopoly game :-) over the next few months and watch how the marsh and wildlife responds.




10 comments:

  1. Excellent post, Allen. Many places can certainly use a good fire, but unfortunately they are suppressed. With all the phragmites around anymore, there is potential for some rather large fires.
    I was at Point Pelee today and viewed the burn. Quite extensive, but I think a good thing in the end.

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    1. Thanks Blake. Those stands of Phragmites, which are even taller than the non-native cattail, can really cause much higher flame when it ignites.

      It will be interesting to watch the recovery of this burned area, and since it is so close to the boardwalk, should be easy to monitor.

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  2. A great read confirming what I have instinctively felt. Thank you for such a clear and well illustrated article about a topic close to my heart (wetlands).
    Love and blessings, Paula.

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    1. Hi Paula....thanks for your visit and comments. Wetlands need as much positive info as possible, don't they.

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  3. Good explanation. I didn't know about the non-native cattails.

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    1. Thanks, Furry Gnome....the non-native cattail issue doesn't get a lot of publicity so it is able to carry on doing its nasty stuff without recrimination. Trouble is, I don't think there is a lot that can be done anyway.

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  4. Great post Allen. Very informative!

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    1. Thanks, Kory, and I'm glad you had some pics on your blog to refer to.

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    2. Thanks for the great article. I am aware of "fire" being natures way of cleansing itself. Your explanation of how the wild life would escape the fire was excellent. Many points you made I would not have thought about. Siobhan

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    3. Hi Siobhan, thanks for checking this out and providing your comment. I'm glad you found it informative.

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