Monday, November 10, 2008

Fire season begins

For the past week or so, following the front system that knocked all the oak leaves off the trees, the first order of business in the morning hasn't been making coffee, but consulting the fire weather forecasts.

Until today (when the relative humidity crept up to 51% in the lower Ozarks and rain moved into the Niangua Basin), grassy glades and restored woodlands throughout the Ozark Highlands could have burned. Of course, land managers have to make sure they're not going to smoke out neighboring towns so they can only burn when wind directions are conducive. The relative humidity needs to hover between 21-35% for results (though some burn when it's 19% and others when it's 42%). Winds can't be too high, either, during a prescribed fire and it would be truly swell if a puttering rain event moved into the area following the fire event. And this is all relevant only if the fuels are dry enough.

Furthermore, the fire prescription depends on one thing: meeting the desired condition of the land. If the humidity is too high and the wind sends fire creeping along, leaf litter may burn off. But a raging, stand-replacing headfire simply can't happen unless humidities are low, winds are high, and fuels are crispy. Oh, but good burn conditions only coalesce rarely in the fall. Experienced land managers can feel a good burn day in their bones, days when the leaves are dry enough, when the air feels crisp, when smoke columns from local chimneys don't go crazy the higher they rise. Before the responsible managers set fire to their woods or glades, they ask NOAA for an on-the-ground, immediate forecast. Check back here for listings of possible fire events in the western Ozark Highlands based on those forecasts. And see today that Laura (hopefully) burned off her glades!


cedrorum said...

I'm curious, does the natural fire history in Missouri occur at this time of year? Down here in the southeast it is typically mid April through August when lightening inspired fires normally occur. I don't know anything about the fire regime in Missouri.

Allison Vaughn said...

You know, naturally, fires occurred more during the growing season (think late August, early September) and in early spring (mid-March through April, say, 15th). In a lot of our areas, we try to burn in these fall windows of low humidities (mid November to about Dec. 15, otherwise, the says are too short and the fuels too wet) to mimic natural disturbance of fall burns. I've been to a lot of sites where they keep doing the same thing: early April fire. And lo and behold, they get the same results: high WSGs, low wildflowers. I respect the pine areas in the southeast where you burn during the growing season (just read a great paper out of Georgia on growing season fires and ground nesters, namely quail). It's sad that there are still groups in Missouri who don't fully understand fire-adapted community, so anytime we can get fire on the ground, it's success. I'm really pushing for more growing season fires on our grassy glades (dry rocky outcroppings, usually south facing, dominated by grasses and wildflowers, few trees. Called barrens in survey records) and woodlands. My friends in the Forest Service are really jealous of all the fire you guys put on the ground. We're way behind target in Missouri...