Awakening to the spirit and beauty of the northern Great Plains
Monday, March 29, 2010
Fire on the hills—two days of burning prairie
If there are ways to bind human desire to the longings within wildness, setting fire to grass is one of them. Yesterday and the day before, we burned several acres of grassland on our pasture at Cherry Lake, in the upper Indian Head Creek valley. The wind, snow and sun did most of the work, but we helped out with some fuel, a Bic lighter, two old brooms, and a small shovel. There were three of us: myself and Rob and Sylvie, one of the other two couples who share the land with us. Rob and Sylvie tending the burn
Rob, an ecologist with a lot of experience working on prescribed burns, showed us how to do our first small burn last May, using the standard range of precautions: a fireguard around the site, which we made by burning between two lines of grass that we mowed and soaked down; waterpacks with lots of water in reserve, a light wind, a careful plan. Everything under control, it took us the full day of work and another day of planning and preparation to burn that ¼ acre rectangle. fire running through a stand of wolf willow
Like most grass on the northern Great Plains, our pastures have not seen fire in a long time. Without the disturbance of fire now and then, woody growth takes over, changing grassland to shrubland unfit for many plants and creatures that will not tolerate shade or brushy growth of any kind. Under fire suppression and cattle grazing, native shrubs like wolf willow have begun to invade onto vast stretches of the mixed grass prairie and parkland, degrading the quality and biodiversity of native range. When we talk about burning our pasture, we focus on the wolf willow and smooth brome grass (an invasive non-native) that we would like to discourage.
At a recent community meeting where the three families got together to consider priorities for the coming summer season (Do we raise the water tank or install a pump? Bring in some topsoil or make do with what we have?), Rob said he had been thinking about this year’s plans to do some more burning and wondering if we might be better off firing the grass when the snow is still in the coulees and draws. That way we could let nature take care of the fireguard, because a grass fire at this time of year will stop when it hits snow. All we have to do is wait for a favourable wind during the period when the snow is gone from the hillsides but remains in the low areas. Some of us were heading to the land on the weekend and we would assess the burn opportunities then.
I left for the land on Saturday, planning to spend the day moving bluebird nest boxes. I see mountain bluebirds each spring but they never stay. A couple of my nest boxes raise tree swallows every summer, but most seem to become twig repositories for overzealous house wrens. Perhaps they are too close to treed areas. As well, a friend said that bluebirds like shorter grass than we have on our native prairie. Within minutes of arriving I saw a group of 4 male and two female bluebirds. One of them was checking out a nest box along the mowed area in our yardsite. That seemed auspicious so I began to install another box next to mowed grass. Just as I finished installing the last screws, I saw smoke coming from the crest of the hill northwest of the yard. Above the flames, I could see Rob and Sylvie standing watch. Rob at the first burn on Saturday
I ran up to the pasture and joined them. Rob decided the conditions were ideal so he got out his lighter and started up one hillside near last year’s burn. That afternoon we burned about two acres of grass, with remarkably little effort. The next day we got up, had breakfast, packed a lunch and headed up onto the pasture with new confidence that we could safely burn several more acres.
I learned more about the way fire behaves in those two days than I have in the rest of my life. One thing I never fully comprehended was how fire moves outward in all directions from the ignition point, expanding its periphery even against the wind until it meets something that won’t burn. Several factors affect the rate of the burn and its movement over the pasture, and of these wind is perhaps the most important of all. With a southwest wind of about ten or 12 kms per hour, the front of the fire zipped along rapidly right through the wolf willow and grass. The flanks of the burn, parallel to the direction of the wind, burned more slowly, creeping outward, and the rear of the fire, or “backburn,” moved slowest of all with small flames licking only a few inches from the ground. a headfire
Rob explained that slow moving fires, with longer residency, heat up the cambium in woody vegetation better so the back burn is likely to be more effective in killing the wolf willow, but it was the headfire that was most spectacular. After we lit a chosen segment of pasture, we sometimes walked behind the front of the fire on the burned area’s smoking ground where the fire had passed moments before, looking downwind toward the galloping head of the fire. It was like walking on a broad black, arrow with two straight flanks and a point all lit by fire. Whenever the headfire came to an uphill slope it would run even faster, especially where there was better fuel, taller grasses such as little bluestem.
If there were gaps in the snow banks encircling an area we wanted to burn, we used a small shovel to toss more snow across any areas where the fire might try to escape. Sylvie and I were on broom duty, wetting the straw in snow banks and then sweeping out any rear or flanking fires that tried to get past our snowguards. At one point, we had three separate regions burning over several acres, some of them meeting at narrow bridges of grass. I know that sounds careless, but with snow surrounding us, there was little that could go awry. backburn
The fire revealed things I had not seen on the pastures before: boulder fields that had been lost in tall grasses; a large harvester ant mound—the ants were not pleased, but their mound survived well and will soon be surrounded with green shoots of spring; and two burial mounds overlooking a coulee. harvester ants on top of their mound after the fire went through--click to enlarge and see the ants
Once the last headfire petered out, and we were down to one slow-moving backfire moving downslope on a line about twenty or thirty feet wide, Rob and Sylvie left me alone to watch the last flames die. I put my jacket down on the ground and laid back to rest. I thought about the rush of green that will come in the next few weeks, trying to guess what other surprises the fire will reveal. The western red lily is said to like fire. We have had a few blossoms some years but not many. Will this burn make a difference? How will the prairie crocuses fare. They bloom by mid-April and do best when there is little other cover around. Will a fire in March help or hurt them? me near the end of the second day of burning
And then I wondered about one fire-adapted beauty that has not been seen for more than a century in these parts. The small white lady’s slipper is a long-lost tallgrass species in this province, thanks to fire suppression. It’s not likely to show up just because we lit a fire, but I think a lot about this orchid because it was last seen more than a century ago somewhere near Indian Head, perhaps in the Qu’Appelle or in one of its tributaries. We have other tallgrass plants on the property and the kind of habitat and slopes where the small white lady slipper is said to grow in Manitoba.
The lady’s slipper takes thirteen years to come to maturity, and even then it would likely require soil mycorrhizal associations that this land may not have, but it never hurts to keep an eye out. Some of the deepest rewards of natural history come from faithfulness and watching out for the improbable and rare. The faith costs very little: in this case, an afternoon or two helping the wind to release energies that come from the inside of the sun. I can’t speak for our pastures, but, after a long winter, I feel restored and hopeful. an antler revealed by the fire