It’s sunflower season at the Platte River Prairies. Stiff sunflower is winding down its flowering, but Maximilian and sawtooth sunflowers are going crazy, especially in some of our newer restored prairies. During a brief period of good photography light this week, I grabbed some photos of sunflowers from both the ground and the air.
There are several interesting things to see in the above photo (you can click on these images to get better views of them). First, while this land was formerly cropland, we did some excavation work before our recent seeding projects and recreated slough wetlands (old river channels). In fact, if you look at the first aerial photo, which shows a broader view, you can see how our restored sloughs match up with the sloughs in the foreground of that photo (below the yellow) which run through unplowed prairie. These prairies are on alluvial soil laid down long ago by the Platte River and the old river channels and sandbars now host their own individual prairie plant communities. In the restored areas, you can see the ‘sandbars’ we recreated from the spoil removed during the excavation of the wetlands as we tried to produce a similar diversity of soil and plant community types.
Second, you can see the abundance of yellow sunflowers, especially in the more recently planted (and ungrazed this year) part of the site. A lot of that yellow is Maximilian sunflower (Helianthus maximiliani), but on this mesic to wet-mesic prairie, there is also a lot of sawtooth sunflower (H. grosseserratus), and stiff sunflower (H. pauciflorus) on the drier areas. Common annual sunflower (H. annuus) is also present – especially in small patches where perennial grasses and forbs haven’t yet fully established. Other plants chipping into the yellow color include several species of goldenrod, a couple Silphiums, and various others.
The left side of the photo shows a restoration that is three years older, but the lack of abundant yellow isn’t due to age as much as to this year’s management. Cattle have been grazing that area at a moderate intensity all season. They are creating lots of small ‘grazing lawns’ where big bluestem, especially, is grazed almost to the ground. But there are also lots of taller patches of grass scattered around. The cows have also been nipping at the sunflowers all season, keeping most plants to waist height or shorter. They’ve also cropped off quite a few of the flowers. Flower abundance is a lot higher in reality than this aerial photo shows, but the grazing definitely affected the height and density of sunflower plants – just as we’d hoped.
Finally, on the right half of the photo, you can also see the varying density of yellow across the prairie. That’s driven by soil, not by anything we did during the seeding process. There are some areas where forbs, and especially perennial sunflowers, are really abundant, and other places where grasses are much more dominant. Even where sunflowers are pretty thick, they’re far from a monoculture, but they’re pretty dang thick.
The more scarce yellow in the grazed area to the left hints at some of the impacts of grazing, but the story is pretty complex. If this site follows the pattern we see in most of our restored prairies, our ‘shifting mosaic‘ approach to grazing will affect the relative abundance of prairie plants quite a bit over the next decade or so. Those big sunflowers will become less visually dominant (smaller, less vigorous plants), and somewhat less abundant, as will big grasses like big bluestem, indiangrass, and prairie cordgrass. Many other plant species will become more abundant around those plants, increasing overall plant diversity. It should be fun to watch.
Late August and early September are very yellow periods in our prairies. The big sunflowers and goldenrods are all going strong, and joined by other less abundant flowering species. Those plants are loaded with pollinators and herbivorous insects that are feeding on the flowers and other parts of the plants. Tiny predators are all over too, chipping away at the abundance of the other invertebrates.
Our newer restorations definitely have the most dramatic yellows. Longer-established sites, especially those that have had years of fire and grazing treatments, tend to have less concentrated yellow, but only because the overall diversity of plants is higher. Patches of sunflowers don’t appear as big monocultures in those older sites, but instead blend into the broader matrix of plant species that make up the plant community. There’s still plenty of yellow, but it’s mixed in with lavenders, whites, blues, and the other flower colors produced by plants that benefit from management that prevents a few species from becoming dominant. Those older prairies might look less striking from the air, but they’re healthy and diverse and literally buzzing with life.
I could look at that first photo for hours. This is one of my favorite sunflowers, but I rarely get to see it in such numbers.
The photos of Maximilian sunflower (Helianthus maximiliani) were beautiful. A spectacular tall prairie forb.
But here in northern Ohio, (those of us who know) view this species with some alarm. First, it’s not native in the tallgrass prairies in Ohio. The very few herbarium specimens of it from the state are misidentifications.
About 20 years ago a large, several-acre prairie creation at a state wildlife area was planted with a seed mixture of prairie seeds from Missouri. The mixture included this sunflower.
But by the third year, the entire planting was essentially a monoculture of this perennial sunflower. Everything else was in decline or gone. The lesson was learned: don’t ever plant this species in Ohio. Here, it’s an alien aggressive invader, with no useful role in Ohio’s tallgrass prairies.
What’s the problem? The plant is natural and most appropriate in prairie states west of Ohio. What’s the problem here in the Buckeye state with it?
Two factors at play. The first is that cultivars or ecotypes planted in Ohio originate in more arid regions to the west. Ohio doesn’t have droughts. We get >40 inches of rain virtually every year, evenly spread out through all seasons. Consequently, western ecotypes or cultivars planted here are able to grow to their biological maximum, never hindered by dry-soil periods. This sunflower thrives, to excess, in Ohio’s moist soils.
But, coupled with that problem, on top of it, is the species allelopathy; it’s production, in its roots, of abscisic acid. When exuded in large amounts, which happens when the plant has ample, consistent soil moisture, abscisic acid is allelopathic; it kills or suppresses the growth of adjacent plants of other species. Hence, the monoculture in a season or two. All of that works for the species in areas to the west, where periods of dry soil moisture and aridity naturally suppress the over-growth of the plant. In Ohio, the plant is able to fully exploit its allelopathic powers to dominate in prairie plantings.
The lesson? Local and regional ecotypes are important. Don’t try to bring in to local prairie plantings otherwise nice, well-regarded, or “good” species that are not genetically adapted, selected for local conditions.
This sunflower isn’t the only “really fine” prairie species that is brought into Ohio, but fails or is inappropriate. I won’t list out the dozen or so other species that, likewise, should be kept to the west — even though they are authentically good prairie plants. Out there; not in Ohio.
And, we have some stunning prairie forbs (wildflowers) that our prairie friends in the states to the west don’t get to experience. None of those, either, should be moved to the west. Too dry, etc.
The wrong plant in the wrong place can become a problem, yes.
Do you have any problems with Solidago canadensis and/or Lupinus polyphyllus in restored prairies?
These imported garden plants have become very aggressive and difficult to get rid of here in northern Europe, especially on disturbed soil. Loved by bumble bees but not any good for the local flora.
Interesting as allways. Thank You for the great work!
Another great post, as always. We purchased an overgrazed, but never plowed farm in SE Oklahoma, and changed the management. We’ve seen 207 species of native prairie grasses and forbs return from what was in the soil. The bottom lands have lots of remnant Swamp Sunflower, but no sunflowers have emerged on higher ground. So, we’ve planted a good bit of H. maximilani, and also some H. pauciflorus, H. mollus, there. All should be adapted to our sandy soils, and are known for their aggressiveness. Many plants have come up, but nearly all wither away before flowering. For the very few that have come up and bloomed multiple years, the whole plant tends to disappear suddenly (in the absence of grazing). Gophers? Deer? – we don’t know. On the other hand, common sunflower has done really well when planted together with the failed perennial sunflowers. Any ideas or tips on how to get perennial sunflowers established?
Hi Ian, it’s always good to hear about your restoration project. I don’t know the answer, of course, but my best guess is that you don’t yet have the soil conditions you need for those perennial sunflowers. I wonder if they are able to germinate, but then don’t have the soil nutrition or other properties to survive when stressed? My best advice is to continue appreciating and encouraging the plants that do seem adapted to the soil you have and allow them to pave the way for others down the road. It might be quite a while (longer than our lifetimes) before the site gets to the point where some missing plant species will be able to rejoin the community, but that doesn’t mean you can’t foster a diverse and important community in the meantime.
If chemical/artificial fertilizers and herbicides, pesticides etc. have been used on the land then you have a long lasting problem.
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