I was back up at the Niobrara Valley Preserve last week to help with a roundup and sorting of the east bison herd (more on that later this week). While I was there, I was glad to see the prairies starting to green up again. It had been about three weeks since the wildfire, and the area had received an inch of rain one week prior to my visit.
Of all the areas of the Preserve that burned, I’m the least concerned about the sandhills prairie. We’ve done enough summer burning in the sandhills – as well as in sand prairie along the Platte River – that we know what to expect there. The only question is about how the drought will affect the recovery. Because many of the plants, especially those that had been grazed, were already dormant because of the drought, I’m guessing they’ll wait until next year to resprout. If that’s the case, we may see immediate greening mainly of those plants that had escaped grazing or that have particularly deep roots. Either way, next spring will bring recovery of the entire sandhills plant community. In the meantime, our east bison herd would appreciate it if enough plants greened up to keep them fed through the winter. We’ll see – some more rain would sure help.
In contrast to the prairies, the woodlands are not yet greening up. I’m not sure what to expect with pine trees – will the survivors start to put on new needles yet this fall? Or next year?
We have a lot more questions about what comes next. I’ve put out feelers to some colleagues who have been through similar wildfires to see if they can share some lessons that would help us be proactive. If anyone reading this has experience that could help us, I’d appreciate hearing from you as well. You can add comments to this post or contact me separately. Thanks!
Chris, I would suggest doing something about the erosion on those trails because if you don’t it will just keep getting worse. What you should do is fill the gully at certain intervals. Where the trail curves is often a good location. After filling the gully, lay a thick long log across the gully that extends out away from the curve of the trail. The log should be angled down slope slightly so the water flows down a 2 to 5 degree incline. This incline will allow water to be shunted away from the trail and into vegetated areas.
Others might suggest check dams. These create flat areas at intervals in the gully so sedment can drop out of the flowing water. These also work, but do not shunt the flowing water out of the gully like the method I mentioned above. The thickness of the log you use should be based on how much sediment you think will get trapped above it. If the area behind the log completely fills with sediment then high flows of water will go over the log instead of being directed into vegetated areas. Directing concentrated flows of water into vegetated areas is how you stop erosion.
“Directing concentrated flows of water into vegetated areas is how you stop erosion.”
While re-directing the flow can help reduce erosion (we never really stop it…) along the trail, it might just end up moving the problem. In addition to re-directing, it is important to spread the water so the volume and velocity flowing over any given location is reduced. Since plant-based solutions seem most appropriate to your situation, it is important that this vegetated area the water is redirected to has the right kind of plants.
– The plants will probably need to tolerate greater moisture than they have had in that location in the past.
– They will need to have sturdy stems that can tolerate the force exerted by the flowing water.
– There should be a large number of stems per area.
In areas of directed flow, clump-forming plants (many sedges and rushes, for example) will do a much better job of reducing erosion than single-stemmed plants. The multiple stems will break the flow across a wider area, reducing both the volume and velocity that each stem is exposed to and that each soil particle is exposed to – because to cut erosion, what we really need to do is reduce the force of the water to a point that it is unable to pick up and carry the soil.
“In addition to re-directing, it is important to spread the water so the volume and velocity flowing over any given location is reduced.”
This is true. To accomplish this I like to use partially buried curved logs to shunt the water off a trail. The top of the curved log allows for an incline that directs the flow away from the trail. This incline should be enough that sediment is not immediately deposited. If sediment is deposited in front of the log where it crosses the trail then the buildup will allow water to flow over the log. If water flows over the log and continues down the trail then the purpose has been defeated. The bottom of the curved log then creates a long level area for water to be distributed into vegetation. It is not a big problem if sediment gets deposited where the log is level because you want water to flow over the log in this area. The end of the curved log should slope up slightly so you are not directing a concentrated flow of water into vegetation. This upward curve at the end of the log is how you prevent “moving the problem” as Danelle mentioned. I like to use a log because I have found that trenches repeatedly need to have sediment removed to work correctly. The height added by the partially buried log helps alleviate problems that occur from sediment deposition.
I would not worry about using different plants than are located onsite for your purposes. The prairie grasses are superbly adapted for preventing erosion.
Now you know all my secrets :)
Chris, Here’s some good information.
Click to access 207_Trail_Decommission_v0311.pdf
I prefer to use long logs positioned at a slight downslope angle to shunt the water away instead of check dams with trenches to divert the water. However, both techniques are about the same.
The most important thing is to prevent trails from going down a “fall line.” These trails should be decommissioned and new trails that decend the slope sideways at about 5 degree grade should be created. If these trails have been created by buffalo then fencing would probably be the best option to prevent them from going straight down the slope.
Are there areas where cedar trees should be eliminated soon after they start to show green, or next spring, summer and fall – showing that they they were not killed by the fires?
Have chainsaw, and friends with chainsaws and will travel!
Chris, one question. How low was the soil moisture during this fire?
It’s a good question, but I don’t know the answer. The drought has been pretty severe, and many of the prairie plants had already gone into dormancy by the time the fire came through, so soil moisture was certainly low – I just don’t have any numbers.
Hello Chris, just came across your site from Ian Lunt’s site from south east Australia, a place you probably know, is prone to bushfires or wildfires as you northerners call it! About 5 years ago, a bushfire went through several hills including Pinus radiata plantation, Eucalyptus globulus plantation, native bush land and farm pastures. The pine trees are gone. Only a few seedlings along the edges. The mature trees never recovered. The blue gum was burnt to the ground but new shoots from perhaps lignotubers grew up and now the plantation looks like new again. I just thought it was an interesting contrast. The local gum trees reshoot from the burnt trunks and branches but the wattles all came up from seed, so the native bush regenerates fastest. Anyway, just an observation from a non ecologist!