woodland | The Prairie Ecologist

We spent a long day at our Rulo Bluffs property last week. The site is at the very southeast corner of Nebraska, and includes about 450 acres of mostly oak/hickory woodland with prairie and savanna habitat on steep ridge tops. I’ve written before about our work to burn and thin the woodlands to open up the understory layer as a way to encourage higher plant diversity and better wildlife habitat. Last week, Nelson, our land manager, spent the entire day in a rubber-tracked skidsteer, shredding brush along ridges because we didn’t manage to get a fire done last fall or this spring. I got a few overhead photos of his work with our drone.

Nelso Winkel shredding brush with a skidsteer at The Nature Conservancy’s Rulo Bluffs Preserve, Nebraska. Using fire, thinning, and shredding, we are trying to allow more light to hit the ground in the woodland, which enhances oak tree regeneration, increases plant diversity, and improves habitat quality for many wildlife species.

This photo shows a ridge where we’ve been working for more at least 15 years to beat back brush with fire and mechanical treatments. Nelson didn’t have to shred this area this year because the brush is finally starting to give way to more herbaceous plants.

The second image above, taken with our drone, was interesting because it and others from the day showed a surprising number of large dead trees scattered across the property. We knew we were reducing the number of smaller diameter trees with our thinning and fire work, and that a few bigger trees were also dying, but couldn’t see the real scope of that without being in the air. (Couldn’t see the forest for the trees…) While we’re not trying to kill off a large number of big trees, losing some provides space for new oak trees to get started, and provides a number of other benefits – including habitat for the many species that live in standing dead timber. So, it wasn’t a shock or disappointment to see all the dead trees, it was just an interesting observation we couldn’t have gotten without the ability to get eyes up in the air.

My main job last week was to be on site in case Nelson ran into trouble with the skidsteer. (That makes it sound like I was there to help fix the skidsteer – nothing could be further from the truth. Nelson has more mechanical ability in his little finger than I could dream of. I was just there to go for help in case he rolled the thing down the hill or something.) While he was doing the real work, I tried to stay productive by pulling garlic mustard, scouting for invasive honeysuckle, and killing small trees with herbicide. I also managed to find a little time for some photography. Here are a few of the photos I took.

This is starting to look more like what we want the site to be. A strong herbaceous (non-woody) plant community, including sedges, grasses, and wildflowers, supports better wildlife diversity and also helps facilitate fire to maintain that open woodland character.

These paw paw trees were top-killed in our 2014 prescribed fire. they are regrowing from the base, but aren’t yet tall enough to suppress growth of other plants beneath them.

A small bur oak is fighting to establish itself on a prairie ridge as older oaks near the end of their lives. Both in the woodland and savanna portions of the site, this replacement process is critically important.

These beautiful metallic-looking flies were pretty abundant the day were at the site. I saw several in the clutches of spiders, but didn’t manage to photograph any of those.

A close-up photo of bur oak leaves.

I’m not sure what species of bug (and it is a true bug) this nymph is, but it sure was striking against the green leaves it was feeding on. I watched it repeatedly stick its long proboscis into this leaf as it moved across it.

Eastern redbud (Cercis canadensis) is a beautiful tree. Both its pink flower and leaves are very attractive. However, it is also one of the species we are trying to reduce the density of in the understory of the Rulo Bluffs woodland.

This beautiful little brown snake was about 10 inches long. I spotted it as it was making its way through one of the areas Nelson had just shredded.

There are a couple species of raspberries, or close relatives, at Rulo Bluffs, but I don’t know what species they are. This one was particularly beautiful the day we were there.

Because of its long distance from our shop and field headquarters, we never feel like we spend enough time working at Rulo Bluffs. It’s a beautiful site, and one of the best examples of oak woodland remaining in Nebraska. As with other oak/hickory woodlands, however, it requires active management in order to survive and regenerate. Without frequent fire, or substitutes such as thinning and shredding, the understory at Rulo Bluffs would become choked with small trees and shrubs, such as ironwood, dogwood, paw paw, and others. Those woody understory species block light from hitting the ground, prevent the establishment of new oaks, and choke out most grasses, sedges, and wildflowers. Eventually, if older oaks die without being replaced, these woodlands change into new communities, dominated by trees such as ash, hackberry, and others that don’t create leaf litter that can carry fire. At that point, restoring the oak/hickory woodland community, which supports a much larger diversity of plant and animal life, is nearly impossible.

…and that is why we keep trying to find time to head down to Rulo Bluffs. That, and it’s such a beautiful place.

I made a trip down to our Rulo Bluffs Preserve last week. I wanted to get down and see the results of the prescribed fire we conducted earlier this spring. We’re in a restoration mode at the site, trying to re-open the woodland and increase the amount of light hitting the ground. The day we burned the site this spring, the relative humidity was very low, so the fire was a little hotter and burned a higher percentage of the unit than we’d seen in previous burns. Killing small trees and brush with a nice hot fire was good for our objective. On the other hand, I worried a little that we might have cooked some of the bigger trees we wanted to keep.

Another panorama showing burned and unburned. This time, the burned area is to the left and the unburned to the right.

A panorama (four photos merged together) along the edge of the burn unit. The area burned this spring is to the left and the unburned is to the right.

Overall, I was very pleased with what I saw last week. The fire, combined with some recent “hack-and-squirt” herbicide treatments on smaller trees has done a great job of increasing the amount of light hitting the ground. At the same time, the majority of larger trees were still alive and leafing out, maintaining a fairly complete canopy – but one that allows for mottled light to hit the ground throughout the day. We hope to continue annual, or at least very frequent, fires for the next several years to set the woodland back on the trajectory we want. Then we may back off on the fire frequency a little. Eventual success will be measured by whether we see an increased abundance of wildflowers, sedges, and grasses on the woodland floor, and – more importantly – regeneration of oak trees, which is crucial for the survival of the woodland itself.

Here are some photos of this year’s spring fire, as well as what I found during my walk through the site last week.

Firebreaks for the fire were mostly created by using a power leaf blower to clear out a narrow trail. Nelson Winkel is shown here making a final pass around the breaks of the 100 acre burn unit. Other members of the crew followed behind, raking out any other debris that needed to be cleared from the breaks.

Anne Stine lights down a slope during the fire.

The fire burned a little more intensively than most woodland burns we've done at the site, but nothing like a prairie fire - though it burned pretty hot up some of the steeper draws, where leaf litter had accumulated and slopes helped drive the fire.

The fire burned a little more intensively than most woodland burns we’ve done at the site, but nothing like a prairie fire – though it got pretty hot as it went up some of the steeper draws where leaf litter had accumulated and slopes helped drive the fire. Crew members patrolled the narrow breaks constantly during the burn, checking the fire, raking leaves and sticks in, and looking for dead trees burning along the edge of the unit that might need to be taken down.

This multi-photo panorama shows the largest of the prairies at Rulo Bluffs, along with some of the woodland. The photo(s) were taken from our neighbor's pasture.

This stitched multi-photo panorama shows the largest of the prairies at Rulo Bluffs, along with some of the woodland. The photo(s) were taken from our neighbor’s pasture during the fire.

This area burned fairly completely but there were still small unburned patches here and there.

We were able to use ATVs to access some portions of the firebreaks, but others were too steep and/or narrow, and were accessible only on foot.

This panorama shows approximately the same area as Anne is shown lighting above. The right half of the photo was burned, the left was not. Note how much more open the burned area is.

This panorama shows approximately the same area as Anne was lighting in the earlier photo. The right half of this image was burned, the left was not. Note how much more open the burned area is.

Burned on the left, unburned on the right. Wood nettles seem to be having a banner year in both burned and unburned areas. I’m not sure why that is.

More wood nettles (and other plants) – this time on a southeast-facing slope that burned pretty hot. Note the dead (or at least top-killed) small diameter trees.

Wood nettles were most abundant on lower slopes. Higher up, mayapples, sanicle, and other plants were more common. Here, mayapples grow with little company. That will change as the plant community adjusts to an environment with more light availability. The fire wiped out this year’s crop of garlic mustard. Hopefully, maintaining a high fire frequency in coming years will help suppress that invader.

Here is a south-facing wooded slope that has a lot of bare ground. Again, this will change over time. Here, many of the small trees were dead prior to the fire (from the hack-and-squirt treatment.

Here is a south-facing wooded slope with a lot of bare ground. Again, this will change over time as light-loving plants colonize and spread. Here, many of the small trees were dead prior to the fire (from the hack-and-squirt treatment.

Columbine was blooming on north-facing slopes – mainly in places the fire skipped.

A close-up of columbine.

Yellow ladies slipper orchids seemed to weather the fire just fine. Of four populations we marked with GPS last year, I found all four and three of them were blooming. All had been in areas that burned.

Yellow ladies slipper orchids seemed to weather the fire just fine. I found all four of the plants we marked with GPS last year, and three of them were blooming. All four were in areas that burned.

The prairie (left) and neighbor's pasture (right) shown in the earlier photo during the fire. the prairie greened up very nicely, and the numerous dogwoods were knocked back (temporarily).

Here is the same prairie (left) and neighbor’s pasture (right) shown in an earlier photo (during the fire). The prairie looks vibrant, and numerous dogwoods were knocked back (at least temporarily).

Small prairie ridges were greening up very nicely. Most of the bur and black oaks in those areas appeared to escape the fire with little or no injury.

The small prairie ridges scattered across the preserve are greening up very nicely. Most of the bur and black oaks in those areas appeared to escape the fire with little or no injury.

This beautiful spreading bur oak was clearly thriving - as was the prairie around it.

This beautiful spreading bur oak was clearly thriving – as were the prairie plants around it. The top-killed shrubs will regrow, but frequent fires (and maybe some basal herbicide treatments) should keep them at bay.

The Prairie Ecologist

Essays, photos, and discussion about prairie ecology, restoration, and management

Tag Archives: woodland

A Day in the Bluffs

2014 Woodland Burning at the Rulo Bluffs Preserve