wildfire | The Prairie Ecologist

I took our Hubbard Fellows up to the Niobrara Valley Preserve in north-central Nebraska last week. While we were there, I spent quite a bit of time in the east bison pasture, where the recovery of prairie plants from last year’s summer wildfire was in full swing.

Prairie grasses such as sand bluestem (front left) and many others were growing well across the bison pasture during the first growing season since last July’s wildfire.

The lush green growth was in strong contrast to the burned prairie’s appearance back in late April when only a few sedges and yucca looked alive – and both were being cropped short by hungry bison.

These sedges were about the only green in the bison pasture on April 23 of this year. Since the bison were mainly eating brown grass and hay all winter, anything green was pretty attractive.

We knew the prairie would survive the fire, but it was still good to see the quick strong growth after some nice rains this spring. The Preserve staff reduced the size of the east bison herd last year because more than 90% of the bison pasture had burned. The biggest concern was getting the bison through the winter with very little residual grass available to eat. With the help of a little fall growth and some supplemental hay, the bison survived just fine.

The bison are enjoying having a wide selection of green plants to choose from after a long winter of sparse brown grass.

The drought and wildfire definitely weakened the vigor of perennial plants in the prairie, and there is a flush of annuals and other short-lived plants taking advantage of that this year. Species such as goosefoot (an annual Chenopodium species), annual sunflower (Helianthus petiolaris) and six-weeks fescue (Vulpia octoflora) are abundant throughout the grassland. At the same time, however, perennial plants such as prairie wild rose (Rosa arkansana), spiderwort (Tradescantia occidentalis), cutleaf ironplant (Haploppus spinulosus), and many more are having a great year too.

Flower species such as cutleaf ironplant (left) and spiderwort (right) are coloring the sandhills in the burned bison pasture.

Goosefoot (the tall skinny light blue plants) and other annuals are abundant, but so are perennials such as wild rose (pink) and hairy puccoon (yellow).

Besides the bison, we saw numerous other creatures throughout the prairie. I wandered through the area where I’d seen sharp-tailed grouse displaying back in May, and flushed up a couple birds. Upland sandpipers, western meadowlarks, and lark sparrows were all over the place. Insects, of course, were easy to find too, including a number of species feeding on the pollen of the ubiquitous flowers.

Grasshopper nymph on annual sunflower.

Adult antlions were EVERYWHERE during my morning walk in the prairie. A few were feeding on the pollen of spiderwort flowers.

A lesser earless lizard (Holbrookia maculata) near a small sand blowout.

This spring brought a big new batch of bison calves, a testament to the toughness of the females, who were able to get through a hard winter of sparse brown grass and a little hay. There should be plenty to eat now – not only did the Preserve staff reduce the herd size to about 150 adults after the fire, they also increased the pasture size to about 10,000 acres. While the prairie grasses are still weak, that light stocking rate should give those plants plenty of opportunity to recover, depending upon the consistency of rainfall during the remainder of the season, of course. The staff will allow the herd size to grow again over the next few years, aiming for an eventual stocking rate of about 30 acres per animal.

This year’s bison calves looked as cute and healthy as always.

The big bulls looked healthy too…

In other news, the extent of erosion on the ridges where the pine woodland burned last year didn’t look any worse than the last time I was there. In addition to a lot of deciduous trees re-sprouting from their bases, we saw a fair number of oak trees with at least some leaves on last year’s branches – though it’s not clear whether they’ll actually survive long-term or not. Most importantly, we haven’t yet found any invasive plants moving into those burned woodland areas, which is good.

The burned woodlands will be significantly different – but fine – in the coming years. The prairies, however, have been able to absorb the impacts of the drought and wildfire without breaking stride.

It’s like they’ve done this before…

Spring is finally changing the color of The Nature Conservancy’s Niobrara Valley Preserve in north central Nebraska. After last summer’s wildfire and drought, much of the Preserve was barren and brown all winter. Now, the area has had several small rainfalls during the last couple months, followed by a hard 3 inch rain on May 19. That moisture has combined with the (finally) warming temperatures, and the Preserve is starting to look green again. I traveled up to the Niobrara last week and took some photos to share with those of you who are interested in the site’s recovery.

The headquarters of the Niobrara Valley Preserve with sandhills prairie behind. If it wasn’t for the ponderosa pine skeletons in the foreground, it would be difficult to know that a major wildfire had occurred last summer.

The sandhills prairie - as expected - is greening up very nicely. Many wildflowers are blooming, including this hoary vetchling (aka peavine or Lathyrus polymorphus).

The prairie in the sandhills – as expected – is greening up very nicely. Many wildflowers are blooming, including this hoary vetchling (aka peavine or Lathyrus polymorphus).

The recent big rain washed much of the remaining ash off the slopes north of the river. At the bottom of this photo, you can see the accumulation of the black goo that washed down. It was thick enough in some places that the road was closed while I was there last week.

One of the things we’ve been watching for and wondering about is soil erosion on the barren slopes – especially underneath formerly dense stands of pines and/or cedar trees. When I arrived at the preserve, several days after the big rain, the road along the river was closed because of an accumulation of black goo that had washed off the slopes above it. It was hard to tell, but it appeared to be mostly ash, mixed with some organic matter. Seeing that on the road, I was worried about what I’d find when I climbed the slopes.

A closer look at the black goo, seen here in a low pocket further up slope.

However, as I climbed the ridge north of the river, I was pleasantly surprised. There was some soil erosion, but much less than I’d expected. Green plants were popping up across the ridges, forming thicker carpets in areas where tree density had been lower.

Green plants dot the upper slopes, especially in places where pines and cedars grew less densely.

Annuals were abundant, including this Chenopodium species.

Many of the green plants were “weedy” annuals, taking advantage of the sudden lack of competition for light and moisture. However, numerous perennials were growing too – including leadplant, puccoons, skeleton weed, peavine, several species of grasses and sedges, and many more.

Perennial plants and shrubs were mixed in with the annuals. A the lower left of this photo is skunkbush sumac. Perennial grasses can be seen in the background.

This was about as bad as it got for soil erosion on the steep slopes, and I had to look for a while to find many examples like this. Rather than large scale slides or obvious losses of top soil, multiple rivulets formed in many places. In between the rivulets, however, perennial and annual plants were growing and helping to stabilize the remaining soil. The lightest colored steep bluffs are mostly devoid of soil, but were like that prior to the fire rather than as a response to it.

We have erosion pins in a number of places to help measure soil loss. The pins were installed in December and are being measured right now to see how much soil we’ve lost. The arrays of pins are located on a range of site types, varying in slope, aspect, and vegetation type. Additional erosion pin arrays will be installed in the coming weeks.

Most oak trees were resprouting from their bases. Oaks that had been burned less intensely hadn’t started their spring growth at all this year, so it’s still unknown whether some of those will be able to continue growing from the ends of their branches. Unburned oaks were leafing out, so we should see something from the “lightly” burned ones in the next couple of weeks.

For better or worse, deer tracks were common. Some of the oak resprouts were clearly being nipped back by deer and/or other wildlife, as were sedges and other green plants.

I don’t know what the future will hold for the Preserve, but I’m still optimistic. The sandhills and other prairies will clearly be fine. The woodlands will be slow to recover, but there are positive signs already. It’s hard to know how much erosion will occur or important that is. So far, even the most vulnerable slopes seem more resistant to erosion than I’d guessed they would be. Regardless, the Preserve is recovering, and will continue to be a beautiful place and important biological resource. And it’ll be very interesting to watch!

Other than steep slopes conifers were dense, the green up is well underway.

Other than steep slopes where conifers were dense, the green up is well underway.

The Prairie Ecologist

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

Tag Archives: wildfire

Watching the Sandhills Bounce Back at the Niobrara Valley Preserve

Wildfire Recovery at The Niobrara Valley Preserve – Spring Green Up