In Half 1 of this matter, I wrote concerning the uncomfortable scenario many prairie stewards discover ourselves in – that our grasslands are getting “shrubbier” and it’s more and more tough to stop that. As a result of the drivers for that change are largely past our management, it appears apparent that we have to begin pondering in another way about grassland administration.
There are nonetheless loads of grasslands the place we should always work to stop woody encroachment. Nevertheless, there are additionally a whole lot of prairies the place bushes or shrubs have already turn into a part of the group. In lots of different locations, it seems to be only a matter of time. It appears good for us to attempt to get forward of this and work out easy methods to handle woodier grasslands for biodiversity and productiveness.
Most of us haven’t centered a lot on easy methods to handle the peak and density of shrubs in our prairies as a result of we’ve been pondering largely about easy methods to repel them. Which means we have to begin experimenting, and shortly. My workforce has carried out a pair completely different discipline trials within the final couple years and I’m going to share some preliminary outcomes with you. I hope these outcomes will spur others to share their experiences and, extra importantly, ramp up their very own experimentation efforts.
Our first trials give attention to clonal deciduous shrubs (easy sumac and rough-leaved dogwood). We began with the speculation that if we may hit them twice (or extra) in the identical rising season, we’d get a number of years of suppressed peak and density consequently. This speculation was knowledgeable by useful conversations with folks like Dean Kettle on the Kansas Organic Survey and a number of other others.
Area Trial #1 – Easy Sumac at The Nature Conservancy’s Niobrara Valley Protect
In 2023, we handled plenty of easy sumac patches with remedies (usually together) that included prescribed hearth, mowing, and a non-lethal “burn-down” herbicide. The photographs proven right here illustrate what these sumac patches regarded like on June 16, 2025.
Fast abstract of preliminary outcomes:
- Mowing sumac in June and August actually diminished each the peak and density of stems, and that influence has continued for at the very least 2 years.
- An August mowing, adopted by a dormant season hearth (November, in our case), confirmed fairly related outcomes.
- June mowing adopted by herbicide in August appeared barely much less efficient than the above two remedies, however a lot better than any single therapy alone.
- June mowing adopted by a November hearth was the least efficient of all of the mixtures listed thus far, however nonetheless higher than a single mowing therapy.
- All single therapy purposes (June mowing, August mowing, November hearth) confirmed fast restoration inside two years.
Remedies had been utilized on June 13, August 9, and November 29, 2023. The photographs under present sumac patches with numerous therapy mixtures.
The herbicide we used contained the energetic ingredient Carfentrazone-ethyl, which disrupts cell membranes in leaves and basically defoliates crops. The hope was that it might act very like a prescribed hearth – injuring the shrubs with out killing them or any surrounding crops. We blended 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 utilized a heavy foliar spray.
We examined this on full-sized sumac crops in June, however the spray didn’t penetrate the cover nicely, and solely burned up the highest layer of leaves. It appeared to work a lot better in August as a follow-up therapy to resprouted sumac crops mowed in June.
As we’d hoped, we noticed no mortality of sumac or another crops from the herbicide therapy. As a substitute, it appeared to behave very like a prescribed hearth, in that it simply injured the shrubs. We’d anticipated it to do some momentary injury to surrounding vegetation as nicely, however noticed little or no proof of that.
My takeaway from the herbicide software was that it’s value extra testing, however appears much less efficient than mowing or hearth. In locations/conditions the place spraying could be possible, however mowing isn’t, it could be a good follow-up therapy to increase the impacts of prescribed hearth. Perhaps. We’ll see. Both manner, it didn’t appear to trigger any injury to the plant group across the sumac, which reinforces my curiosity in additional experimentation.
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Area Trial #2 – Tough-Leaved Dogwood at The Nature Conservancy’s Platte River Prairies
For a number of years now, I’ve been being attentive to fenceline variations and different proof that cattle grazing has potential to assist handle deciduous shrub peak and density. This spring (2024) we arrange a fast experiment to check that with rough-leaved dogwood. Cattle had been introduced into the unit in early June and shall be current by means of October (a part of our bigger open gate grazing experiment.)
Forty cow/calf pairs had been launched to a 49 acre pasture in late Could, 2025. In early July, they got one other 25 acres (along with the preliminary 49) and later this summer time, they’ll achieve entry to an extra 69 acres. The photographs under, although, had been all taken on June 10 – about 2 weeks after cattle had been introduced into the pasture. In different phrases, the grazing impacts proven under occurred fairly shortly after cattle had been introduced in. It’s not like they waited to graze dogwood leaves till they’d eaten every part else.
We arrange 4 remedies:
- Grazed (unmowed)
- Ungrazed (unmowed)
- Mowed/Grazed
- Mowed/Ungrazed
The peak of all dogwood stems included within the research was measured on April 22, 2025 and a few of these stems had been mowed instantly afterward. Small exclosures had been set as much as exclude grazing from some remedies.
Fast abstract of preliminary outcomes (as of June 16, 2025):
- Cattle are undoubtedly grazing the leaves of dogwood. Stems outdoors the exclosures regarded very ragged in comparison with ungrazed crops.
- Dogwood stems mowed in April had been being stored cropped off at only a few inches in peak.
- Dogwood stems mowed in April however excluded from grazing had already reached about 10-12 inches in peak by June 16.
This challenge is simply getting began, nevertheless it’s gratifying to see that cattle are grazing dogwood as we’d anticipated (see photographs under for additional affirmation). Probably the most promising outcome thus far is that the mowed dogwoods appear significantly engaging to cattle and we hope repeated grazing of these resprouting stems will result in a number of years of much-reduced development in comparison with stems within the different remedies. Time will inform, however we’re off to a very good begin.
My actual hope is that we are able to discover ways in which cattle grazing can play into our bigger efforts to handle shrub peak and density. For instance, burning each 4-5 years isn’t sufficient by itself to suppress shrub development. Nevertheless, burning adopted by a season of grazing on the regrowth of these shrubs may result in considerably diminished development over the subsequent a number of years. By the point the subsequent hearth comes by means of, these shrubs may not have grown very tall in any respect.
Now we have a number of expertise (and information) displaying that some sorts of cattle grazing can profit habitat heterogeneity with out lowering plant variety. If related grazing approaches can even suppress the peak and density of shrubs, that’ll be an enormous assist.
This (together with the sumac work above) is simply the beginning of an extended experimental path, however I’m excited by the early outcomes.
I’m sharing these very early leads to the hope that I can encourage others to do related experimentation. Please don’t interpret these preliminary findings as something greater than what they’re. We’re seeing some hopeful indicators, however have to observe these trials for extra years to see the longer-term impacts of what we’re making an attempt. We additionally have to drastically increase the remedies and mixtures to actually perceive what numerous choices can do.
Please assist! If you’re a land supervisor within the Central U.S. and have shrubs in your grassland, it might be terrific should you may check these or related approaches to managing shrub peak and density and report again. Simply as importantly, we want researchers to assist us study concerning the impacts of various levels of shrub peak and density on plant communities, pollinators and different invertebrates, birds, mammals, and rather more. That data shall be essential to land administration and assist inform us what to goal for.
As I stated within the first submit, the rise in woody crops in our grasslands doesn’t should be a disaster. It would simply be another issue we have to embody in the way in which we take into consideration managing prairies for numerous aims. If we ignore the difficulty till the shrubs have stuffed in and brought over, although, we’ll undoubtedly lose. Let’s not lose, okay?
