By Bill Kleiman, Project Director of Nachusa Grasslands, The Nature Conservancy
Have you planted seed into an already established prairie planting, trying to increase floral diversity? You had that warm hopeful feeling. Those tiny seeds in your hand soon to be germinating. New flowers blooming in your restoration.
Did what you plant ever show up? Most of us have examples of where the seed planted did eventually produce new populations, but more often we shrug when asked.
Way back in 2009 I had this study question: What is the best way to over-seed an already established prairie planting to increase its diversity? Below is the random block we set up with four treatments and a control. I explain the block below.
This was in an established prairie, with reasonable forb diversity, rather thick in warm season grasses. Look at the top row of cells. In cell A1 we worked up the prairie sod with a disc, then raked it with a harrow, and then seeded a rich and abundant mix of seed, well over 50 species at a heavy pounds per acre. Would this cell turn out the best?
In A2 we only added seed.
In A3 we harrowed, seeded, and then in mid-summer we sprayed with Poast grass herbicide. Would the grass herbicide set back the Indian grass and big bluestem and make space for our seed to grow?
A4 was the control with no seed added.
A5 we harrowed and seeded.
The B row and C row are the same setup but not in same order. This is called a Random Block study.
Below photo looks down at the block when we set it up. It was burned before we did anything. You can see the harrowed and disced cells.
Below is the disc in one of the cells. We worked up the prairie sod several inches deep.
Ten years later what do you think we see when we walk along this experimental block?
All the cells look the same to me. Elizabeth says she saw some subtle differences.
The experiment is ongoing. We are looking for a grad student to adopt this experiment and collect the vegetation data.
My takeaways on adding seed to established plantings is this:
It takes a long time for the seed planted to produce a noticeable sized plant. There are exceptions where plants show up in just a handful of years after addition, but you should expect a decade, or two decades, to get the establishment you want.
Yes, you should add seed to those prairie plantings. Many species you want to see in your restorations will not blow in, nor be dropped in by birds flying over, or carried in the fur of rabbits or deer or mice. It will be you planting the seed.
Patience is a prairie word.
Below are the experimenters in 2009: Susan Kleiman, 9 year old Leah K, and myself, Bill K. I coaxed Leah with promises of fun science. She is now 20 years old majoring in plant ecology.
We did three of these same blocks. More details here: https://www.nachusagrasslands.org/links–resources.html
If you want to see the seed list we planted look to planting 91 and 92 here: https://www.nachusagrasslands.org/planting-histories-in-chronological-order.html