To KR Bluestem Home
Winter 1976, nearly all KR,
little bluestem is very red in evening sun.
Summer 2007, nearly all little bluestem,
limited KR (in red box).
Two views of fertile canyon area 30 years apart.

Competition between KR Bluestem (Bothriochloa ischaemum var. songarica) and Little Bluestem (Schizachyrium scoparium)

by Bob Harms  email-here
The two dominant grasses in the open areas of our land have always been KR bluestem (KR) and little bluestem. Initially, when the cattle were gone, the overgrazed bottomland was almost entirely KR, with little bluestem dominating the dry rocky slopes on both east and west sides of our valley. In the subsequent 3 decades I have not seen little bluestem ever replaced by KR. I am thus led to suspect overgrazing for its near demise in the greener valley pastures, and not competition with KR.

Although I did not originally document the status of our grasslands, I came to know both KR and little bluestem intimately by virtue of having to use a small hand mower to mow the yard area around our cabin as well as numerous long walking paths. Both grasses recovered quickly from mowing, little bluestem a bit more quickly. Over the years our landscape has changed in many ways, but the changes have been gradual and largely unnoticed. I was aware that old untouched areas of KR undergo a process of senescence, with the dry thatch apparently shading out new KR growth, and that in general KR was gradually being replaced by native grasses in shadier areas.

Most recently I have noticed a striking replacement of KR with little bluestem in all areas where they are adjacent, sunny or shady, mown or not. Since little bluestem has always dominated the slopes, the emerging picture often seems to indicate that it is flowing downhill into KR areas. The possibility that gravity has played a role in seed dispersal can't be ruled out, but the change is not restricted to slope areas. Until recently this has been a very slow process, but in recent years it seems to have accelerated — even in years with summer drought. During the extreme summer drought of 2006 — portions of our creek dried up for the first time — little bluestem clearly suffered, turning orange in mid summer, and produced only short culms (c. 2 feet tall) with little seed. But with return of abundant moisture during the record wet summer of 2007, the little bluestem has emerged with renewed vigor — late July culms are over 5 feet tall — and shows no signs of having retreated during the drought.

I had originally concluded that when mown, nothing could ever replace KR. But this has proven incorrect. Regularly mown KR areas are being infiltrated by little bluestem; e.g., along paths and in the yard.

Mown path with little bluestem, KR to the left, mostly little bluestem to the right.

I have not attempted to reduce KR, given that burning and mowing only create dense stands. But the recent spread of little bluestem in KR areas led me to suspect that one way to speed along the process might be to introduce little bluestem into areas of dense KR. To test this, in the fall of 2003 I did just this in 3 small plots. As of 2007 these plots appear to have held their own in spite of the 2006 drought, and will bloom for the first time. As the plants mature I hope to see some spread into surrounding KR.

Three plots with little bluestem introduced into KR areas.