Watching the Sandhills Bounce Back at the Niobrara Valley Preserve

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.

sunflowers and grass

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.

April 23

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.

bison

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.

wildflowers

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

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flowers

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.

Gr asshopper nymph

Grasshopper nymph on annual sunflower.

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antlion

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

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fence lizard

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.

bison calves

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

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bison bull

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…

Photo of the Week – April 11, 2013

Sometimes, you can see a lot by just sitting down.

I carved out some time in the field last Friday to collect data on poison hemlock in our research plots.  After finishing that, I had about half an hour before I needed to head back to the office, so I took my camera for a walk along the creek running through our Platte River Prairies.  Not having a particular agenda, I stopped to look at a tree that had been recently felled by beavers.

This tree, cut down by our local beavers, had sap seeping from the stump last week.  The Nature Conservancy's Platte River Prairies, Nebraska.

This tree, cut down by our local beavers, had sap seeping from the stump last week. The Nature Conservancy’s Platte River Prairies, Nebraska.

As I was admiring the patterns of tooth marks on the stump, I noticed an interesting-looking little fly hanging around.  As I watched, the fly started to feed on the sap that was oozing out of the tree.  Taking advantage of the fact that the fly was distracted by its meal, I managed to get a couple photos of it.

This fly seemed to be enjoying its meal enough that it didn't mind me sticking my lens in its face.

This fly seemed to be enjoying its meal enough that it didn’t mind me sticking my lens in its face.

Since I had time, I decided to sit and watch the fly for a bit.  Before long, another – different – fly came along.

A second fly joins the meal.

A second fly joins the meal.

One of my favorite statistics is that there are more than 37,000 species of flies in North America.  That seems an almost unfathomable diversity.  Taking that into account, I guess I shouldn’t have been surprised to see a third kind of fly arrive at the stump…

Fly #3.  A big green one.

Fly #3. A big one with blue and green stripes on its abdomen.

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A rear view of fly #3, showing the striped abdomen.

A rear view of fly #3, showing the striped abdomen.

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A tiny wasp (2mm long).

A tiny chalcidoid wasp was on the stump as well, though not feeding on sap (thanks to Mike Arduser for identifying it for me – Mike says they are a group of parasitic and important wasps).  The quality of this image isn’t very good – my excuse is that the wasp was BARELY 2mm LONG and I had to crop it quite a bit so you could even see it…

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A tiny red mite came ambling along...

A tiny red mite came ambling along too…  It was about the same size as the little chalcidoid wasp

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Fly #3 didn't like Fly #1 working over the same puddle of sap and lunged at it

Fly #3 apparently didn’t like Fly #1 working over the same puddle of sap.  This photo captures Fly #1 rearing back as Fly #3 lunged at it.

I wish I’d had more time to stick around; it would have been fun to catalog all the little critters that visited – or were living in – that beaver stump.  I also wish I would have gotten a shot of the little wolf spider hiding in the pile of wood chips at the base of the stump – it darted out and almost caught one of the flies when it landed nearby, but didn’t stick around for a photo.  Too fast for me…

I think my short time watching the beaver stump brings up a number of interesting points that I could focus on as the overall theme of this blog post.  I could focus on the odd side benefits provided by the work beavers do.  I could focus on the crazy diversity of life found on a single tree stump.  I could focus on the way creatures of all different kinds are able to take advantage of unexpected resources (like oozing tree sap) when they appear.

But I think the biggest point is this:  You can see and learn an awful lot by just sitting down and watching.