View video in MPG format

Transcript:

Text:
Fire in the Forests
Part 3
Description:
Fire Communications Officer, Dave Verhulst walking along part of the Johnson Lake Trail.

Trees like Aspen and Lodgepole pine tend to die in fires, but it helps them to regenerate. Other trees in our forest are designed to survive fires. Trees like this – the big Douglas Fir. These trees have incredibly thick bark and it’s this thick bark that helps them to withstand low to moderate intensity fires.

Now, this douglas fir tree in particular, has another story to tell, come over this way and have a look.

Fire Communications Officer, Dave Verhulst, walks to the backside of the tree and points to a blackened portion of the tree devoid of bark.

This is a fire scar. As a fire moves through an area, sometimes it will burn a part of the tree and the rest of the tree is able to survive. It’s fire scars like these that have given us hints about what the fire cycle in this area has been like historically. So we can take a tree like this and if it falls over and dies...or we cut it down, we can have a good look at the cross section of the tree – it’s something we call a tree cookie.

Dave pulls a cross section of a tree trunk from his back pack.

When we are able to look at...a cross section of a tree, a tree with a fire scar will look like this. This tree is a lodgepole pine, but you can see here...this is the fire scar. So this tree was killed all the way around this part here, but survived in this section and it continued to grow. It grew for many, many more years... because we know when this tree was cut down, we can count back all of these different layers and years, all the way to the point when the fire was – in this case, the fire was in 1889.

Piecing together information we get from tree cookies like this and tree cookies like this one here,

Dave retrieves another tree cookie with multiple fire scars on it

we can get a better understanding of how often fires came through. In this case, this tree survived multiple fires –the first fire burned this part of the tree and this part of the tree and remarkably it continued to survive out this way, kept growing out to here and out to here as well and then a second fire and burned here; the tree survived in this direction and continued to grow until it got hit by another fire out here. So we know that fires came through in some cases, very frequently and those fires didn’t always kill the trees. As a matter of fact, the fire cycle in the Bow Valley is every 5 to 50 years.
So the next question fire researchers asked was: “where is the fire coming from?” Naturally, we tended to assume those fires were coming from lightning strikes, but if you have a look at lightning records here in Banff and how many fires tend to be lit by lightning in Banff, you’ll see that there isn’t a match.

Dave shows a picture with the boundaries of Banff, Yoho and Kootenay outlined in Yellow and lightning caused fires marked by red dots.

We did some research between 1961 and 1994 . Banff is this big area outlined in yellow here. The red dots indicate lightning caused fires and you can see that there are just not very many lightning caused fires in Banff. You get some out in BC and some out in the foothills of Alberta, but we’re in the lightning shadow here in the Rockies. We just don’t get a lot of thunderstorms that come through with lightning that would cause fires. So we started looking at other places, or other sources of information.

What we learned was that First Nations people started most of the fires that burned through this area historically. We know that from oral history records from the Siksaka as well as the Nakoda and we also can look at archaeological records as well. Looking at the hearth pits of First Nations people, we can see that 47% of the remains in those hearth pits was bison. Now, just think about that for a minute – look at the forest we have around Banff National Park today – is this the kind of place you can picture thousands of bison roaming? No...but that just tells you how much this place has changed over the years. It also tells you just how much First nations used fire in order to create a landscape that had the berries they liked to eat, that provided good travel corridors and that provided the food for bison, sheep and other animals that were staples in their diet.