Last week, I helped arrange a tour of recently-burned oak woodlands at Indian Cave State Park, an eastern Nebraska site owned and managed by Nebraska Game and Parks Commission. Indian Cave State Park is one of very few deciduous woodlands in Nebraska that is managed with prescribed fire. The Nature Conservancy’s Rulo Bluffs Preserve is another, but while we started using fire back in the mid 1990′s, we’ve not been able to use it as consistently as we’d like. Seeing the results of four years of annual burning at Indian Cave State Park was a good incentive to keep trying to find ways to increase our burn frequency down at Rulo. You can read here about a fire we conducted at Rulo last year.
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Kent Pfeiffer (center) stands in a portion of woodland that has been burned four years in a row and points out some of the changes that have occurred over that time.
The tour was led by Gerry Steinauer (state botanist for Nebraska Game and Parks) and Kent Pfeiffer (Northern Prairies Land Trust), who have been leading the charge for woodland burning in eastern Nebraska. In addition to Kent and Gerry, and several other Game and Parks biologists, the tour group included staff from the Nebraska Forest Service and the Bureau of Indian Affairs.
We started by talking about why Game and Parks is implementing prescribed fire at Indian Cave State Park. Some of those reasons include:
- Fire topkills small understory trees and shrubs, and repeated fire can eventually kill them completely. Mature trees – especially oaks – are largely immune to even frequent fire, so they survive, keeping the canopy of the woodland intact. The end result of frequent fire is a more open woodland structure that promotes herbaceous plants such as grasses, sedges, and wildflowers of all kinds. Kent and Gerry are aiming for something around 80% canopy coverage of mature trees, with very few understory trees, so that as the sun moves across the sky, woodland plants receive a mixture of sun and shade off and on during the day. This keeps those woodland plants cool enough to survive, but gives them enough light to thrive. Since the majority of woodland species (plant and animal) live in the herbaceous community, maintaining a diversity of plant species at the ground layer is particularly important.
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A hiking trail used as a fire break for a recent prescribed fire. The woodland area to the left has not been burned (for many decades) and the area to the right was burned this spring. There is a dramatic visual difference between the two – primarily because the abundance of small trees and brush makes it impossible to see more than a few feet into the unburned area.
- Fire removes leaf litter, as well as understory brush, and allows more light to hit the woodland floor. This helps oak seedlings survive – a critical component of woodland ecosystems, because without that regeneration of oak trees, there will be no oaks to replace the mature trees as they die out.
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Frequent fires will promote the survival of these oak seedlings, which would otherwise stand no chance of growing into mature trees.
- In addition to the habitat and plant community benefits, there are benefits to human visitors as well. A woodland with an open understory is much more pleasant to walk through, making hunting, birding, or hiking easier and more fun. Kent talked about how much nicer the temperature is in burned oak woodlands on summer days because the open understory allows a breeze to come through and prevents the kind of stifling heat found in unburned woodlands. Plus, woodland burning suppresses poison ivy, which most hikers appreciate…
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Gerry Steinauer stands in an area of woodland that has been treated with frequent fire, as well as some “hack and squirt” herbicide treatments to help kill smaller diameter trees. Note how far you can see into the woods because of the open understory – and the abundance of plants growing on the woodland floor. Many of the smaller diameter trees in the photo are dead, but still standing (temporarily).
While those justifications are all good, Kent pointed out that there is a more comprehensive question that we need to answer in Nebraska. If we want to have oak woodlands 50 years from now, we have to make that decision now, and start changing the way we treat our current sites. Most oak woodlands in the state are essentially unmanaged. Another couple of decades of that kind of hands-off approach, and many of the mature oak trees will die without replacing themselves, allowing the current understory of hackberry, ash, white mulberry, and other tree species to become the new canopy. Those tree species don’t create leaf litter that can carry fire, so fire will no longer be a management option – meaning that it will be nearly impossible to create the kind of woodland habitat structure that birds and other woodland animals, as well as most plant species, depend upon. The forest will still support life, but it will be a dramatically different community than we have now. We have to decide as a society whether we value oak woodland enough to do what we know is necessary to maintain it into the future.
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An abundance of perennial sunflowers is typical of woodland plant communities in transition from a dense shady forest to an open woodland. Over time, the herbaceous layer on the forest floor will become much more diverse as other species, including grasses, sedges, orchids, and many more, increase in abundance.
Nebraska is a little late to the party in terms of burning oak woodlands. Other states like Missouri and Wisconsin (among others)have a strong record of utilizing fire to manage their woodlands. You can also read here about the innovative work Bill and Sybilla Brown are doing in Iowa. In those other places, the discussion revolves around how often to burn – not whether or not to burn in the first place. Here in Nebraska, we’ve seen a dramatic increase in the use of prescribed fire to manage grasslands over the last decade or two. Now we need to shift some of our attention to oak woodlands as well – and we need to do it before it’s too late.
Image may be NSFW.
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Image may be NSFW.Clik here to view.
