This post was written by former Hubbard Fellow Sarah Lueder. In it, she shares the results of the second part of her independent project as a Fellow. (The other part was the terrific sunflower video she shared here back in February.) This second portion focuses on the roots of prairie plants and I think you’ll agree it’s a pretty great project. Enjoy!
A common theme of this blog is that when it comes to prairies, there’s more than meets the eye. We’ve grown up in a prairie-dismissive world, and to remedy the idea that not much happens in grasslands, we can get up close and see what’s happening beneath our very noses. Consciously noticing what’s going on around you can be highly rewarding, and can certainly help you become better acquainted with prairies. But, as I often forget when exploring, there’s a world equally as vast and potentially even more mysterious beneath our feet. One we typically only catch small glimpses of, if we are lucky.
Most of the biological activity in Great Plains Grasslands (around 60-90%) occurs out of sight, bolstered by two powerhouses: roots and soil organisms. Prairie plants show us again and again that they would rather grow down than grow up. On average, prairie grasses have 3-4 times more roots by weight than they do leaves and stems. This root to shoot ratio is ten times higher than a forest’s, occasionally landing prairies with the title “upside down forests.”
The reason for this is pretty simple: in prairie environments, it’s safer in the soil. When the weather is hot and dry, you can often go just a few hand widths down and find soil that’s cool and moist. This is why when things get stressful for prairie plants (because of drought, aboveground herbivore grazing, etc.), they transfer some or most of their resources from their leaves and stems into their roots and rhizomes. While to us aboveground-dwellers the plants can look dead, those who hedged their bets well live beneath the surface, patiently waiting for conditions to improve. And when they eventually do, the plants can put out new shoots, roots, and rhizomes.
Since the underground prairie is so impressive but we have a limited capacity to sense it, I wanted to create something that would shed a light on its (largely) unseen activity.
While talking one day with Greg Pec, a belowground prairie extraordinaire and professor at the University of Nebraska-Kearney, he mentioned that you could use window boxes (boxes with a glass pane on one side) to see roots grow. I latched onto this idea and decided to dig up a few different species, plant them in window boxes, and take pictures of them throughout the season.
One prairie plant I immediately wanted to grow was the emblematic big bluestem (Andropogon gerardii), a plant regarded for its impressive root depths. While digging up the plants, I mistook a barnyardgrass (Echinochloa crus-galli) for big bluestem, so one ended up in this box as well. (editor’s note: This error was not Sarah’s alone. The vaunted ‘Prairie Ecologist’ was the one that first spotted the grass and called it big blue.) The barnyardgrass roots exploded into activity, while big bluestem took to its new environment more slowly.
One reason for this could be because barnyardgrass is an annual, while big bluestem is a perennial, and annuals are generally more disturbance adapted. Barnyardgrass is also an allelopathic plant, which means it was potentially using chemicals to hamper the growth of big bluestem. These ideas are just guesses, but regardless, it looked to me like big bluestem’s growth was stifled by barnyardgrass (at least for a while) and I couldn’t help but feel a little defensive over big blue. Like some misbehaved party crasher, barnyardgrass showed up unannounced, took all the food, and trashed the place. My sincerest apologies to all those affected (big bluestem #1 & #2)… please know that I am taking this lesson in grass misidentification to heart.
When I initially transplanted all my plants into window boxes, I let them sit for about a week before I started moving them around and taking pictures of them. The idea was the roots would have a little time to establish, because they wouldn’t grow that much in a week, right? Turns out annual sunflowers are tenacious growers, and after a week they were already plunging their way down the box. They touched down to the bottom of the box in less than two weeks, leaving the goldenrods (below) in their dust as they crawled to the same depths over ten weeks. It appears that the sunflowers took the “live fast, die young” approach of the three, measuring up to their status as annuals who can grow well in highly disturbed environments.
Stiff goldenrod (Solidago rigida) is a perennial plant like big bluestem, and fittingly, they were less eager to immediately exploit every inch of their new space. Over the season it looked to me like they were in no hurry as they expanded into the soil. The goldenrod’s steady, even descent might have been because someone didn’t put in a rapidly growing, poison spewing competitor next to them. That is neither here nor there though. Over time this became my favorite window box to view because each time I checked there was new growth, without the competition-induced drama or boom-bust mania. It turns out slow and steady does win the race! At least the race to be my favorite window box.
Favorites aside, I would imagine tracking the root growth of any prairie plant would have left me with a similar sense of awe at the prairie underground, a place that remains a mystery to most of us. This small stint into the soil served as a glimpse into what takes place in prairies just out of our sight, with or without us noticing. Returning to this daily helped me re-confirm what we all already knew about prairies, time and time again… when it comes to prairies, there’s always more than meets the eye.
The Prairie Ecologist 