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Friday, April 18, 2014

Spring Burn 2014: how successful was it?

There's always a certain amount of agonizing as burn seasons approach. Will we get an excellent fire that will do all the good we hope for? Or might various things go wrong?

What follows are photos - not of flames - but of the ecosystem after the burn - and some thoughts on what these images mean. 

Checking out a controlled burn at Somme Prairie Grove on April 7, 2014.
No fire on the path because there was no fuel there. 
The burn here looks fairly complete, as the main fuels were warm-season grasses and oak leaves - both "born to burn."
But elsewhere there are different stories.

Here's our first concern. A hot fire on a good burn day would have burned these logs. A good thing? Or not?

For the ecosystem, burning up these acres of jumbled trunks would be a plus. Almost all of these are (recently over-abundant) invasive trees that were killed by previous fires (or girdled by us stewards long ago). Natural oak woodlands burn so often that most downed wood is consumed. This kind of ecosystem is not adapted to lots of trunks lying helter skelter. 

Yet the practical challenges for resource managers are also a concern. For the burn crews, it would be a plus to get rid of all these logs. But if the fire had been hotter, most of the logs would have caught, and (with current Cook County Forest Preserve burn practices) they'd all have to be extinguished before the burn crew got to go home and rest up for the next day.  

Notice that some of these logs here have previously been cut into sections. Long before the burn, they should have been carried to a bonfire to get them out of the way, but we ran out of time when we last worked here. The stewards try to do as much of this "fuel reduction" as we can, because otherwise the burn crews may be reluctant to choose this needy site on the best burn days. Yet cleaning up all those logs is a lot of work for us, and while we're doing that, other needs go unmet. 
Here's a related issue. Though they may be hard to see, a few feet behind the somewhat charred red oak (front tree) are three bur oaks, each about 3" in diameter (one to the left and two to the right).
They all have dead limbs leaning against them and are a bit charred. The middle one rises out of the main helter skelter in the mid upper right. Bur oak was the main tree in this savanna area, but this species is poorly represented among young trees here now, because in the decades before restoration, there'd been too much shade, which bur oak can't survive. Thus we want to give extra protection to the now-too-rare young burs during this "remedial restoration" period. We ought to have cut the mess of fuel away from those young trunks, so they would get big enough to be pillars of this community in a few decades. The red oak with the blackened trunk in the middle left of this photo is much less adapted to fire. It's likely to burn out in time given the frequent conflagrations needed to maintain a bur oak savanna. Oak savanna is the community that the conservation-priority species of plants and animals depend on at this site. 

Another goal is the restoration of hazelnut, formerly a major shrub of the savannas and oak woodlands. Loss of native shrubs is a major problem for community structure and for some rare animal and plant species. The barely visible green fence protects young hazels from the deer (that would otherwise eat every one, at their current levels of overpopulation). The ground around this pampered patch was raked mostly free of fuel before the fire, protecting the young stems from burning. In time, with sufficient "remedial" help, the hazel populations should build up enough to both feed the deer and burn off naturally from time to time. But without help, they were almost gone. Before we started protecting and replanting them, we had watched them dwindle to only a few sprigs left on the entire site. At Somme Woods, across the street, they're now entirely gone.

This hazel clump didn't fare so well. Despite a narrow raked break, the fire got through and burned every stem. It will have to start again from its roots. Why did we fail? There are too many tasks, and two few stewards. Perhaps someone will read this and take over some of the hazel and young oak protection?

This patch around two scarlet oaks didn't burn. It was perhaps a bit too wet and the fuel too meager. Is this is a spot where the hazels would do better? We're hard at work planting what hazel nuts we can rescue from the squirrels in various areas that seem to have potential. 

Yet way too many areas didn't burn. In this "mesic intermediate" patch, a thin sprinkling of savanna herbs struggles to out-compete the invasive species. Rare natural ecosystem components would win out if burned frequently enough, but if the site is burned only on days mild enough that the downed logs won't catch, these areas will never recover. 

Savannas consist of a mosaic of: 
  • "open to the sun" prairie-like patches, 
  • "closed" woodland-like patches, and 
  •  in-between, the "intermediate." 

We started to realize this when we noticed that we needed "open," "intermediate," and "closed" seed mixes to get good results in savanna restoration. The "open" patches are easy to restore, as they burn readily from their "prairie grasses." The "closed" patches burn somewhat readily thanks to the oak leaves. The "intermediate" (and most distinctive of the savanna) patches are the hardest to burn, until the natural vegetation robustly re-establishes. Unburned patches like this won't benefit from this year's fire. Such areas will tend increasingly to become ever-less-burnable stands of tall goldenrod, briars, and young brush. 

Why didn't this patch of woods burn? Usually the problem areas are the "intermediate" ones - because they lack the dense prairie grasses and oak leaves, our best fuels. But here the trees are mostly ash, box elder, and cherry (all invasive in unburned oak woods). When brushy, the trunks and branches can burn explosively during extreme burn conditions (when we wouldn't have a controlled burn). But the leaves of these trees are adapted more to rot than burn, so this year's rather cool fire skipped this area too. 
As we walked the site, studying the results, we agonized over what to do with the downed wood. Then - we saw smoke in the distance. Is there a problem? 

That's when we found exactly what the burn crew had wanted to avoid. They put a lot of work into extinguishing any burning trees they find. This dead ash must have been imperceptibly smoldering. Now it's out-and-out burning. 

Is this tree a danger? 
We'll keep an eye on it while we do our other monitoring. 

This sedge was partly burned. Sedges are a critical part of the ecosystem. Have we damaged it? Our answer is "no." We've seen this before. It will be lush and luscious in a few weeks. The species of the savanna are adapted to fire.

When we return to that burning ash tree, it has fallen and continues to burn. Do we put in a call for the fire crew, or would we be wasting their time?
Stepping back, it's easy to see that all the fuel around this smoker has been burned. Perhaps it would concern people if it could be seen from the road. But it's certainly safe.

Returning the next morning, we find it entirely consumed. A ghost log. If there was more understanding and support from the public, this is what would happen to all those helter skelter piles of dead invasives. Then subsequent burning would be easier and better.

During our last burn at Somme Prairie Grove, in fall 2011, this vegetated pond was dry, and the whole pond area burned. But spring burns are different from fall burns. Today the water has chorus frogs singing. Every kind of fire helps the savanna, a little or a lot.
In the long run, we're looking forward to "pyro-diversity" - all kinds of fires occurring as they would have - when nature ran the show. In the meantime, we staff and volunteers will work to heal the ecosystem as best we can. 
Comments and questions very welcome.


  1. Since the quick burning fuels have all been consumed by the controlled burn, why don’t the stewards return later on a day that has extremely good fire conditions and ignite all those dead logs lying around the preserve?

    Your problem with areas not getting burned because of invasive species is more challenging. I think the best way to deal with this problem is to control the exotic invasive species like buckthorn or Asian honeysuckles. Basal bark application to control buckthorn would be best if native species might be released by the removal of this invasive species. I have trouble killing Asian honeysuckles with herbicide. I tend to pull out the entire root of Asian honeysuckles when possible. In areas with tall goldenrod I suggest sowing seeds of common dodder to reduce the dominance of the aggressive but native tall goldenrod. If you control the invasive species then the natives should be able to rebound creating the fuel needed to burn these areas.

    I think it is good to have some brambles present. The wild raspberries are a preferred winter food for rabbits and other rodents. However, I think the recent appearance of coyotes has been the reason that rabbits are now so uncommon in our preserves. The lack of rabbits has probably contributed to the over abundance of brambles. In ecology change typically has unpredictable and cascading results.


    1. 1. James, thanks for the thoughtful comments. We do burn up logs on dry days, but we throw them into piles first. They burn much quicker that way. Log lying on the ground sometimes burn for many days, and it's too time-consuming to stand guard over them, as required.
      2. I agree about the value of brambles (and roses and natural shrub thickets). These will all burn with a hot fire - and then come back - which seems to be part of their natural ecology.

    2. I have been thinking about what you said above and I have more comments. When logs are piled they will still take many days to burn. By piling the logs you are actually making the time for the pile to complete combustion longer. Although a pile burns hotter, the fire consumes so much oxygen that after a certain point only the surface burns. The FPCC rule is you can leave a brush pile once there is no flame. I don't see any flame on your burning log. I think by piling the logs you are just making more work for volunteers and altering the habitat. Plants that prefer burn scars would have more habitat if logs were burned where they fell instead of getting burned in centralized piles. The heating the soil experiences from a burning log is considerably different that what the soil experiences from a brush pile burn. A number of plants do not grow in burn scars themselves, but only on the edges. By piling the logs you are actually reducing the habitat for these plants. This may be the reason a number of these burn scar edge plants are rare.

  2. 7 April Spring 2014 Burn at Grove: Was it successful?
    Mistaken assertions.
    1) “A hot fire …would have burned these logs.” I have never seen a fire consume (burn to ash) as much as a third of the logs on the ground. Logs on the ground can be ignited by fires (even cool ones), but a small (<20%) percentage of logs are ignited even in fires that are out of prescription.
    2) “burning up these …jumbled trunks would be a plus”. Many organisms utilize down wood (=logs). Snake and salamander hide under the down wood and many insects have life stages that are dependent on down wood. Fungi live in log and the decay of wood is essential for the survival of many native fungi.
    3) “Natural oak woodlands burn so often that most downed wood is consumed”. This is not true based on my observations of Miller Woods (IN), Conrad Savanna (IN), Iroquois Co Conservaytion Area (IL), Burnham Savanna (IL) and numerous other sites. I have studied deadwood at Cranberry Slough in 2 plots. A snag averages 6 years from death to becoming a log and a mature oak (>25cm dbh) last an average of over 25 years before disappearing. Using the average life span of an oak as 180 years about a sixth of the oaks in a healthy forest should be dead. Snag are important for many birds and log are also important for many ‘mature’ forest species.
    4) The rules of agencies are based on what minimizes the number of complaints that they receive and other human considerations. Don’t try to manipulate words to make those rules seem what is natural.
    5) It is good to protect small trees and it is hard to get the time to do all one would like. I feel plums and some other subcanopy species are even more important than oaks.
    6) I visited Cedar Creek MN about 12 years ago. At that time the site had areas that were burned at various frequencies (# of times in last 29 years). I was surprised to find the most frequently burned site (17 times in 29 years) was dominated by hazel and brambles in the understory. Many woodies (hazel, Rubus and Amorpha among them) flourish growing as herbaceous species (ie from below ground each year). I have no idea of the deer situation at Cedar Creek. Deer are often so abundant in counties that prevent hunting that all woody recruits are consumed, so no shrubs or trees are able to produce seed. Top killing hazel should not kill the individual usually.
    7) Wild fires are diverse and not all natural fires burn all patches of the ground. The diversity of burn intensities is part of creating habitat heterogeneity. In the case where one is trying to replace ash and cherry with oaks the difficulty of burning is significant if the patches are large. I do not think ‘intermediate” is a feature of actual natural areas though there are patches that don’t burn in most fires, but I don’t think such patches become ‘ever-less-burnable’.
    8) A burning tree within a burnt area is a very low danger to spread fire, but it is something that people notice and will call-in. Once when I was sitting feet away from a burning brush pile with a water pack a horse back rider told me they told me they were going to call in the fire. People do what they think is useful or what they want to do regardless of what an intelligent analysis suggests.
    9) What you have shown (you should number/label your pictures if you are serious about comments) happens to some logs (or snags in the case you have shown) during prescribed fire or wild fire, but it happens rarely. It is uncommon that more than 10% of the logs burn to ash. I have never seen a majority of deadwood converted to ash unless people deliberately piled the deadwood in stacks.
    10) Study patterns in the most natural areas available. Use them as a model to mimic nature are your own site. Don’t try to fight nature, but understand it and use its flow/knowledge to make your own efforts more efficient.
    Dennis Nyberg

    1. I agree with most of what Dennis has said except the part about 'intermediate' not being a feature of actual natural areas. I have also noticed the phenomena to which Stephen is referring. I have always considered these ‘intermediate’ areas to be tension zones between competing woodlands and prairies species. I think the fighting between woodland and prairie species leaves a void that gets more thickly filled by species like buckthorn or tall goldenrod. Although the following is not based on actual observations, I tend to think of these areas as DMZ’s for the different mycorrhizae found in woodland or prairie. However, it could be some allelopathy of the native plants themselves which makes these zones open for colonization by buckthorn and tall goldenrod. Regardless of the mechanism, I have also observed this phenomenon. I just do not know what causes it.

    2. Dennis, thanks for the good comments. I agree with most of them, with qualifications.

      Not only does fire not kill the hazel roots, but a healthy hazel clump can grow back six feet high in the first season after a fire. The problem for our hazel is the combination of fire and deer. Many of our hazel clumps that are unprotected by deer fencing grow only a few inches tall in the year after a fire.

      I agree that most fires, even on good days, burn only a portion of the downed logs. But when our burns were sometimes hotter, downed logs were probably one tenth as many as there are now. I find it hard to believe that this is natural for an oak woods or savanna.

      Oak ecosystems evolved over millions of years. Before human-ignited fires, "extreme fire" (by today's standards) was probably most common for the average piece of ground, because these are the fires that would have spread fastest (and thus covered the most ground). We can't have those kinds of fires today, but we should consider the implications when we try, as you recommend, to work with nature rather than fighting her, or him, or it.

    3. I actually think both Stephen and Dennis have good points about the downed logs. There is nothing better in oak woodlands than big old downed oak tree logs. However, the picture Stephen has given shows logs in an area that appears to have been more prairie like before fire was eliminated from the site. I think Stephen has a good point that these logs would not have been an original component of this location. So the dilemma seems to be "What to do about it?" Personally, chain sawing and moving these logs looks like a lot of work. I think it would be less work for everybody if the burn crew uses a leaf blower to clear around these logs until the logs have decomposed. Given that the site only gets burned every couple of years the burn crew should only have to blow the leaves from around these logs a few times.


  3. Comment from John Marlin by email:

    I tried to respond to your post, but it kept trying to use my daughter's school login.

    Here is my post:

    Steve I have the same concerns at Blackpartridge. After thinning the ash, maples and cherries in the uplands we had a burn two weeks ago and it it was spotty in the cleared areas with a lack of oak leaves and native vegetation. I have been seeding in silky and Canadian wild rye, bottle brush grass, festuca obtusia, wood reed, penn sedge, carex rosa and the fox tailed sedges.
    While I understand these grasses job is to hold the leaves in place for a Fall burn, there were very few leaves in place on the slopes in the Spring to carry the fire through the intermediate and open areas on the site. As I was reading your post I was wondering if seeding in poverty oats would be a good idea as it is good at carrying fire, but do not know how it would be with other natives growing with it or would it create a monoculture as I only see it growing in poor soils and not richer areas.
    I also remember being at the Oak Woodlands Conference in Springfield, MO and touring a post oak woodland and savanna and there being patches of northern drop seed, little blue stem, big blue stem and Indian grass growing in clumps in the intermediate areas with many native plants.

    1. John, I'm doing pretty much what you are. Fortunately, most of the sites I work on already have poverty oats, and that species seems to "work well with others." In sites that have been seriously degraded (which, sadly, is most of them), many people recommend seeding in a full diversity of species that would have been there, especially the more conservative ones. They'll work out their own healing processes.

    2. John, I have seen Agastache, Actinomeris, and Scrophularia grow tall and lush for fire 1-2 years after seed. These are frequent associates of many the species you mentioned in your seed mix, and can compete in degraded situation.

      Stephen, thanks for the post. It was quite a spectacle (enhanced by my own exhaustion) to see a cohort cutting down a flamebrand of a 20" dbh snag under the dark sky and quarter moon this spring. Mop up near womped the crew at Wampum Woods.

      Great comments all around, lots to think about.

    3. I would suggest holding back on the Actinomeris unless the area has no natural area value. I was told this species was introduced to Bluff Spring Fen. I have seen where it has taken over a large area resulting in the disappearance of a state listed species.