Burns are a major management tool in prairie and savanna restoration,
and we plan them carefully. One rule is that vacation is out
during the fall and spring burn seasons. You can't decide you
are going to burn when you feel like it. You have to burn when
conditions are right. You also have to ensure that when those
conditions are right, a burn crew will be available.
Fall 2006
Burn season is when the vegetation is dormant and involves
both fall and spring burns. The season begins in the fall as
soon as the oak leaves have fallen and the herbaceous groundlayer
has died back. Depending on the year, this can be late October
through middle November, although we have burned as late as
December. This year we did our first fall burn on Halloween
(31 October 2006), but the weather changed during the burn,
so that burn coverage was spotty.
9 November was an outstanding day for controlled burns. We
burned three planted prairies and did some interior lighting
on the savanna burn that we had done on Hallowe'en. The weather
in October had been wet and highly variable. There was a change
in the weather pattern in late October, and since then there
had been no rain. Also, we had lots of sun, and the temperature
was unseasonally warm. The past few days had been sunny, with
low humidity. On burn day, the temperature was 68-70 F and the
relative humidity was 28-32%. The wind was out of the west gusting
to 14 mph.
We had a crew of 8, five contracted and three
volunteers. We assembled at 9 AM and got everything ready: water,
drip torch fuel, rakes, our Kawasaki Mule with 65 gallon pumper
unit. We did three burns: a small burn in what we call the Cabin
Prairie, followed by the Barn Prairie
and the Valley Prairie.
We could have burned all three of these prairies
in the spring, but we had a particular reason for burning now.
All three of these prairies had patches of a cool-season grass
that we wanted to get rid of. By burning in the fall, we gave
the "bad" grass a chance to get started early, well
before any warm-season (prairie) plants were above ground. In
the spring the whole prairie was treated with the herbicide
glyphosate, when the bad grasses were about 4 inches tall. Since
the prairie plants were not above ground, they are not be affected
by the herbicide. We have used this technique before with excellent
results. (The spraying was done by the local agricultural co-op.)
Spring 2007
The spring weather was especially challenging
for controlled burns. Although this later became one of the
coldest springs on record, Monday March 26 set a record high!
Fortunately, the planets were properly aligned and that was
the day we were able to burn our south-facing slope.
Although the humidity was a little high early
in the day, it promised to drop and the temperature was to increase.
By 11:00 AM, the temperature was in the upper 70s and the relative
humidity about 50%. With the sun shining, and with good fuel
on the south slope, all systems were go. We ate an early lunch
and started lighting at 12 noon.
The plan was to make a black line next to the
upper fire break, then flank fires to the middle, and light
along the middle from one end to the other. The purpose was
to have a head fire of the areas where fuel was less flamable,
and a back fire on the areas (mainly the lower prairie slope),
where the fuel was hot and flashy. Everything worked like a
charm, and we finished the whole burn (10 acres) in less than
two hours.
By using a primarily backing fire to keep the
flames low, we avoided any chance of low-hanging branches catching
on fire. Mop-up, often a problem for us with all the oak trees,
was simple. Coverage was close to 100%. Since brush had recently
been cut and treated on this whole slope, we are expecting good
things this growing season!
That day, National Weather Service reported, the
temperature reached a record high of 81 F. Who knew that this
tropical weather was to be followed by two weeks of unusually
cold weather.
We waited patiently for the opportunity to burn
our savanna areas. Since we "had" to get these areas
burned so that we could plant (we had bags of seeds hanging
in the barn), we suffered through the two weeks of cold weather.
The problem was that heavy rains after 26 March had made the
fuel in the savannas unburnable. We needed a good spell of dry
weather, preferably with some warmth. Although the warmth never
came, we did have a long spell of dry weather, accompanied by
very strong winds which really dried out the savannas.
On 9 April we burned about 32 acres of savanna
and planted prairie. Most of the savanna areas burned were ones
in which we had carried out intensive brush control this past
winter.
Our strategy (which frankly involved a modicum
of luck) was to burn as large amount as possible when the weather
was suitable and the burn crew was available. For the 9 April
burn we had three experienced volunteers, two interns, and four
paid contractors. We had two ATV's with pumper units, a full
sized pickup truck with pumper unit, three drip torches (we
could have used four or five), and six backpack water tanks.
Although the weather never warmed above 45 F,
the cloud layer gradually dissipated and by mid afternoon we
had full sun. Since the wind was out of the west, we started
at the east side of Toby's Prairie, burned all of this, and
then burned the White Oak Savanna (Unit 12A). This was followed
by the burn of the lower part of Unit 11 and all of Unit 18.
After we finished this, we burned the Pocket Prairie. With the
wind out of the west, the east side of the Pocket Prairie burned
up into Unit 20, stopping at our woods road. Once Unit 20 was
finished, we burned Unit 21, starting at Pleasant Valley Road.
Since our property line was on the east side of Unit 21, we
had to wetline this whole line, using two pumper units in ATV's,
one starting at the top, the
other at the bottom. Once we finished Unit 21 we burned
Unit 19, a long, narrow unit on top of the ridge. This was a
unit we had spent a lot of time clearing brush this past winter,
and it was important that we got it burned. It burned very well,
and we ended for the day at 4:30 PM. A great day!
On 16 April favorable weather made it possible
for us to burn most of the north woods (Units 14 and 15 and
a major part of 16) for the first time since October 1999. Around
1 PM we burned the quarry and Unit 14 with a crew of 5. At 4
PM our contractor came with three more people. We had a light
wind out of the northwest, relative humidity about 30%, and
a temperature in the upper 60's F. Since the whole top ridge
(and almost everything else) was already burned, this was a
very safe burn. We had already put in a fire break along the
east side of the property, from the top of the ridge to County
F, thus ensuring that the small house on County F was safe.
The whole burn was conducted as a headfire from County F. Since
the fuel was almost exclusively oak leaves, the fire front moved
slowly up hill. The whole burn was finished before dark. Since
some areas had not burned as well others, the next day Kathie
and I returned and lighted some of these areas. We had almost
100% covereage in Unit 14 and the quarry, about 70% coverage
in Unit 15, and around 30% coverage in Unit 16. (Unit 16 is
a lot shadier and moister than Unit 15.)
Despite the challenging burn weather, we burned
more this year (fall 2006/spring 2007) than we had ever burned
before! The map below shows the areas burned. My rough estimate
of area covered this burn year (fall/spring) is 92 acres.
