Today’s post is written by Sarah Kennings. Sarah and her colleague Leah Zuschlag joined The Nature Conservancy as Hubbard Fellows in early February of this year. Their Fellowship will run 12 months and end at the end of January 2027. Sarah comes from Chelsea, Michigan, graduated from Michigan Tech University, and came into the fellowship with immense enthusiasm and energy, along with many talents. She and Leah have both been jumping into a wide range of activities, including fire training, leading volunteer work days, fixing fence, cutting trees, driving skid steers, attending conservation strategy meetings, and more. Sarah’s post below captures an evening near the end of her second month in Nebraska. Enjoy!
Sarah Kennings, left, with our other Hubbard Fellow, Leah Zuschlag.
Journal entry from 03/30/2026 – Settling into the Platte River Preserve
I roll over in my bed and check the time on my phone. 8:16 pm. It’s still barely light enough outside that I can go out to the garden to simply… exist. I pause the show I’m watching, grab my favorite flannel from the closet, leave my phone plugged in on the nightstand, slide on my sandals by the front door, and slip out of the house. The cool, evening air catches me off guard. It’s hot and stuffy in the house because me and Leah (my co-fellow) haven’t quite figured out the air conditioning yet and the windows like to stick.
I step through pools of cool evening air as I make my way out to the garden. “Just taking a peek,” I tell myself, “Check in on things.” There’s not much to check in on at the moment. We have stripped the garden back to square one, taken all the old garden infrastructure out, built a new compost bin, and mowed. It doesn’t look much like a garden at this point, but I get giddy thinking about the taste of tomatoes straight off the vine. I can’t wait. I’m beating myself up because I wore shorts. I’ve already found a tick on me from working in the garden before. I remember the feeling of something small tickling my back, ear, leg, head – you name it, I found a tick there – while I was trying to fall asleep in my tent in summers past. I sigh, kicking myself for the poor choice in clothing.
The clouds are putting on a show in the remnant light. Still some pink, but it’s mostly faded, yet there are a myriad of textures and shapes. The moon is behind me as I lean against a post. A waxing gibbous, shrouded in a thin layer of cloud that provides a halo effect. Both the moon and clouds are creeping slowly across the sky, one barely faster than the other. There is barely any wind to move the branches of the tree above me, which has little buds that have just burst in the past few days.
I pause and listen. A distant turkey gobbles and a dog down the road barks. The turkey is obviously taunting the fenced pup. The robins chirp and the mourning doves lament their usual tunes. A pigeon hums. I can hear small creatures moving amongst the brush. I assume rabbits and this one little chipmunk-looking thing that I’ve yet to identify (upon further review, it’s a thirteen-lined ground squirrel). I wonder where the black and white cat went that greeted us in the evenings when we first moved in. Coyotes yip and yelp from different directions. I bet they’re happy it’s spring now, too. The post is starting to bore into my back, but I don’t mind.
The black and white cat. Photo by Sarah Kennings
Look deeper. The sun is so far set that I can only see the outlined clumps of dead grasses, but not the individual stems. They’re silhouetted memorials. I turn and look across the street. Two little heads are bobbing around in a pasture, then disappear. Deer. I hear the low hum of a motor far in the distance and hope it doesn’t come too quickly. They sneak through the barbed wire and are taking their sweet time crossing the road. I rush them in my mind. Without one ounce of motivation, the deer make it across the road and jump the wire into the pasture closest to me. They are out for an evening mosey, just like myself. They walk about 20 yards away from me. I’m happy that it’s dark enough to provide me some camouflage, but they know something’s up. One by one, I can see them catch my scent and stare at me. They wiggle their ears, walk back and forth a little bit, then waddle away. I’m not a threat. I hear more crunching and more deer appear – a mother and fawn. The fawn is quite antsy while mom stays still, staring me down. More deer are further up on the hill, but they snort and trot off. She walks away but is diligent about checking my position every few steps. Up on the hill, she and her baby are just black silhouettes behind a dead clump of big blue stem.
A (different) sunset seen from near Sarah’s house on the Platte River Prairies. Photo by Sarah Kennings
If only I had brought my phone to take a picture, but this walk to the garden was a conscious decision to be free of devices and just exist. An attempt to feel more grounded in this new place and put down some of those deep, fibrous, prairie roots.
In Part 1 of this topic, I wrote about the uncomfortable situation many prairie stewards find ourselves in – that our grasslands are getting “shrubbier” and it’s increasingly difficult to prevent that. Because the drivers for that change are mostly beyond our control, it seems obvious that we need to start thinking differently about grassland management.
There are still plenty of grasslands where we should work to prevent woody encroachment. However, there are also a lot of prairies where trees or shrubs have already become part of the community. In many other places, it appears to be just a matter of time. It seems smart for us to try to get ahead of this and figure out how to manage woodier grasslands for biodiversity and productivity.
Most of us haven’t focused much on how to manage the height and density of shrubs in our prairies because we’ve been thinking mostly about how to repel them. That means we need to start experimenting, and quickly. My team has implemented a couple different field trials in the last couple years and I’m going to share some preliminary results with you. I hope those results will spur others to share their experiences and, more importantly, ramp up their own experimentation efforts.
Our first trials focus on clonal deciduous shrubs (smooth sumac and rough-leaved dogwood). We started with the hypothesis that if we could hit them twice (or more) in the same growing season, we might get multiple years of suppressed height and density as a result. This hypothesis was informed by helpful conversations with people like Dean Kettle at the Kansas Biological Survey and several others.
Field Trial #1 – Smooth Sumac at The Nature Conservancy’s Niobrara Valley Preserve
In 2023, we treated a number of smooth sumac patches with treatments (often in combination) that included prescribed fire, mowing, and a non-lethal “burn-down” herbicide. The photos shown here illustrate what those sumac patches looked like on June 16, 2025.
Quick summary of preliminary results:
Mowing sumac in June and August really reduced both the height and density of stems, and that impact has persisted for at least 2 years.
An August mowing, followed by a dormant season fire (November, in our case), showed pretty similar results.
June mowing followed by herbicide in August seemed slightly less effective than the above two treatments, but much better than any single treatment alone.
June mowing followed by a November fire was the least effective of all the combinations listed so far, but still better than a single mowing treatment.
All single treatment applications (June mowing, August mowing, November fire) showed quick recovery within two years.
June 16, 2025 Photo of smooth sumac that received no treatment in 2023. You can just barely see my spade in the center of the photo, with sumac looming well above it. This patch received a single prescribed fire treatment in November of 2023. If you look really closely, you can see just the handle of my spade. The sumac rebounded very well. This is similar to what both single mowing treatments (June and August) looked like by June 2025.
Treatments were applied on June 13, August 9, and November 29, 2023. The photos below show sumac patches with various treatment combinations.
This patch was mowed in June and August of 2023 and experienced a significant decrease in both height and density of stems (the slope in the background was untreated).August mowing followed by November fire also had a significant impact. June mowing followed by a November fire was better than any single treatment, but not nearly as effective as the other combinations.
The herbicide we used contained the active ingredient Carfentrazone-ethyl, which disrupts cell membranes in leaves and essentially defoliates plants. The hope was that it would act much like a prescribed fire – injuring the shrubs without killing them or any surrounding plants. We mixed 17.5 ml (0.7 ml/gal) of AIM herbicide and 47.5 oz (1.9 oz/gal) of crop oil in 25 gallons of water and applied a heavy foliar spray.
We tested this on full-sized sumac plants in June, but the spray didn’t penetrate the canopy well, and only burned up the top layer of leaves. It seemed to work much better in August as a follow-up treatment to resprouted sumac plants mowed in June.
The brown-leaved sumac plants on the right were mowed in June and the regrowth was sprayed with AIM herbicide in August. This photo was taken 1 week after spraying.
As we’d hoped, we saw no mortality of sumac or any other plants from the herbicide treatment. Instead, it seemed to act much like a prescribed fire, in that it just injured the shrubs. We’d expected it to do some temporary damage to surrounding vegetation as well, but saw very little evidence of that.
Here is the June 2025 photo of the sumac sprayed with AIM herbicide in June 2023. Height and density are both much reduced compared to untreated patches.
My takeaway from the herbicide application was that it is worth more testing, but seems less effective than mowing or fire. In places/situations where spraying might be feasible, but mowing isn’t, it might be a decent follow-up treatment to extend the impacts of prescribed fire. Maybe. We’ll see. Either way, it didn’t seem to cause any damage to the plant community around the sumac, which reinforces my interest in more experimentation.
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Field Trial #2 – Rough-Leaved Dogwood at The Nature Conservancy’s Platte River Prairies
For a few years now, I’ve been paying attention to fenceline differences and other evidence that cattle grazing has potential to help manage deciduous shrub height and density. This spring (2024) we set up a quick experiment to test that with rough-leaved dogwood. Cattle were brought into the unit in early June and will be present through October (part of our larger open gate grazing experiment.)
A fenceline photo showing grazed prairie on the left and ungrazed on the right. Note the height and density of the dogwood and plum on the ungrazed side.
Forty cow/calf pairs were introduced to a 49 acre pasture in late May, 2025. In early July, they were given another 25 acres (in addition to the initial 49) and later this summer, they’ll gain access to an additional 69 acres. The photos below, though, were all taken on June 10 – about 2 weeks after cattle were brought into the pasture. In other words, the grazing impacts shown below happened pretty quickly after cattle were brought in. It’s not like they waited to graze dogwood leaves until they’d eaten everything else.
We set up four treatments:
Grazed (unmowed)
Ungrazed (unmowed)
Mowed/Grazed
Mowed/Ungrazed
The height of all dogwood stems included in the study was measured on April 22, 2025 and some of those stems were mowed immediately afterward. Small exclosures were set up to exclude grazing from some treatments.
Quick summary of preliminary results (as of June 16, 2025):
Cattle are definitely grazing the leaves of dogwood. Stems outside the exclosures looked very ragged compared to ungrazed plants.
Dogwood stems mowed in April were being kept cropped off at just a few inches in height.
Dogwood stems mowed in April but excluded from grazing had already reached about 10-12 inches in height by June 16.
Grazed dogwood (left) and ungrazed dogwood (right, in the exclosure).Dogwood stems inside the triangle of red flags were mowed in late April and cattle are keeping them grazed off close to the ground.Dogwood mowed in April but excluded from grazing had grown 10-12 inches by June 16.
This project is just getting started, but it’s gratifying to see that cattle are grazing dogwood as we’d expected (see photos below for further confirmation). The most promising result so far is that the mowed dogwoods seem particularly attractive to cattle and we hope repeated grazing of those resprouting stems will lead to several years of much-reduced growth compared to stems in the other treatments. Time will tell, but we’re off to a good start.
My real hope is that we can find ways that cattle grazing can play into our larger efforts to manage shrub height and density. For example, burning every 4-5 years isn’t enough on its own to suppress shrub growth. However, burning followed by a season of grazing on the regrowth of those shrubs might lead to significantly reduced growth over the next several years. By the time the next fire comes through, those shrubs might not have grown very tall at all.
We have lots of experience (and data) showing that some kinds of cattle grazing can benefit habitat heterogeneity without reducing plant diversity. If similar grazing approaches can also suppress the height and density of shrubs, that’ll be a huge help.
This (including the sumac work above) is just the start of a long experimental path, but I’m excited by the early results.
A cow grazing dogwood on July 2, 2025Even the calves are working on the dogwood.
I’m sharing these very early results in the hope that I can encourage others to do similar experimentation. Please don’t interpret these preliminary findings as anything more than what they are. We’re seeing some hopeful signs, but need to follow these trials for more years to see the longer-term impacts of what we’re trying. We also need to greatly expand the treatments and combinations to really understand what various options can do.
Please help! If you are a land manager in the Central U.S. and have shrubs in your grassland, it would be terrific if you could test these or similar approaches to managing shrub height and density and report back. Just as importantly, we need researchers to help us learn about the impacts of different degrees of shrub height and density on plant communities, pollinators and other invertebrates, birds, mammals, and much more. That information will be crucial to land management and help tell us what to aim for.
As I said in the first post, the increase in woody plants in our grasslands doesn’t have to be a catastrophe. It might just be one more factor we need to include in the way we think about managing prairies for various objectives. If we ignore the issue until the shrubs have filled in and taken over, though, we’ll definitely lose. Let’s not lose, ok?
The Prairie Ecologist 