Saturday, November 17, 2012

Burn at Somme Prairie Grove - Quick Report

November 14, 2912

Top priorities were three high quality wetlands. 
For months the overall weather has been dry, dry, dry. 
This was our first opportunity to burn our best wetlands in three decades.

Here is the Swale Pond? Can a pond go up in smoke? More on that later. But first, note the difference between backfire and headfire. With 20-foot flames, the headfire is running with the wind, partly obscured by smoke. Can you see the backfire? It’s creeping towards us, mostly one-foot flames barely visible above the dried sedges.

But those twenty-foot flames are heading toward an oak grove. Should we worry about what will happen when that wall of fire hits the trees?

No need to worry. Oak woods fires are different from wetland fires. Here the head fire (on the right) isn’t much bigger than the backfire. This woods burn is a cool one, because we had a bit of snow a day earlier. The oak leaves, lying flat, are still damp. In contrast, dead grasses are surrounded by moving air and have dried out quickly. Especially today, the low fire in the bur oak woods won’t hurt the oak trunks.

Where oaks stand in the grassland, it’s a different story. Scarlet oaks, like the ones in the background, keep their leaves all winter and have thin bark on their trunks.

This scarlet oak looks like the Bible’s burning bush. Even such a mild back-burn through thin fuel torched this one. But don’t feel bad for it. A scarlet oak loves to burn. It’s a “fire tree” that wouldn’t be able to compete here at all without combustion clearing the competition from time to time. It will re-sprout vigorously and grow bigger each year, until some future fire clears the competition and gives it a new start, once again.

The big tree here is a cottonwood. This species survives the burn by growing in ponds. Though dry now, the pond that this cottonwood stands in had too little fuel to start the tree on fire.

A dead, dry tree lying in the grass is another story. This year, the old hulk of a huge downed cottonwood finally met its maker.

In the foreground, believe it or not, we’re looking at another seasonal wetland, the Pothole Pond, which is knee-deep in spring when we usually burn. In the spot where I stand to take this photo, teal and wood ducks swim among chorus frogs and blue-spotted salamanders in April and May. The fuel that’s burning here is a plant called “floating manna grass.” In spring it floats. Now it burns.

The Swale Pond is an older, more mature, more vegetated wetland and has denser fuel.  Here the head-fire is just starting. [swale fire early]

Though deeper than the Pothole Pond, the denser fuel makes a much hotter fire.

The entire pond burned in just a couple of minutes. This is probably the first time since the reign of the Potawatomi that this wetland and its rare, fire-dependent plants have burned.

The black towers here are made by tussock sedge. A great diversity of wetland plants thrive here - some of them very rare and fire dependent. We can’t wait to watch the ecology respond to this too-long-overdue burn in the years ahead.

Here in the uplands, the tussocky bumps are made by dropseed grass. Notice the burned stems of shrubs. If this area burns frequently, the shrubs will be suppressed, and an open grassland will thrive.

But what happened here? On the edge of the Swale Pond, the fire just went out when where the grasses thinned at the edge of our biggest shrubland, the Bird Thicket. Without the fuel of either grasses or oak leaves, this thicket would burn only under extreme conditions. Patches of unburned ground are part of the “pryo-diversity” that makes for ecological diversity.

To a steward, getting the burn successfully done is a great relief and a great pleasure. Though fire is dramatic and beautiful in itself, the main beauty will be the unfolding of the flowers, shrubs, trees, birds, butterflies and all the biodiversity of rare nature that will thrive here yet more bountifully in 2013, thanks to this invigorating fire. 


Many thanks to the people who made this fire effective and safe: 
especially John McCabe who manages the fire program 
of the Forest Preserve District of Cook County 
and Patrick McCrae who led a hard-working crew 
from Pizzo and Associates (an ecological restoration company 
that did this work under contract with the FPD).


orchidartist said...


Mary Lou Mellon said...

Well done! I can hardly wait to see what this area looks like next year.

Anonymous said...

Floating Manna Grass? Ugh, someday I'll learn the difference between all those grasses. That should be my next project since Barbara Wilson helped me learn many of the Carex.

You should be prepared for a possible influx of invasives next year. The natives need fire, but the darn RCG likes it too.

I'm glad to see more of that cottonwood getting burned up. It seems a little more disappears every time a burn occurs.