Prairie recovery after sumac eradication

In 2012 I published some photos of a well-known prairie that had become over-run with smooth and staghorn sumac (Rhus spp.). One of these photos is shown here. See this link for further details.

Sumac infestation of the prairie. Photo taken Oct. 2012.

It was unfortunate that this prairie was allowed to become invaded, but recent work shows that it was not too late to save it.

In the late fall/early winter of 2014 the large patch shown was mowed. Soon after mowing all the cut stems were treated with Garlon 4 in oil, using backpack sprayers. This major job took several days, but at least came at the time of year when no other work on this prairie was needed.

Upon returning to the prairie this year I was gratified to see how well it was recovering!

The same area in July 2015. The species diversity is quite high.

The same prairie in mid August 2015. Lots of warm-season grasses

Sumac root sucker killed by foliar spray with Garlon 3A

Although the prairie is coming back, the sumac has not been idle. This species, like many other clonal species, exhibits the phenomenon of root suckering. Dormant buds among rhizomes still alive underground are activated and send up new shoots. Early in the season, when the prairie vegetation was not too lush and would not be damaged, these root suckers were killed by foliar spray with Garlon 3A. Later in the summer, when prairie plants have occupied most of the land, it is difficult to spray sumac resprouts without damaging good plants. At that time of year, the sumac stems are killed by basal bark treatment with Garlon 4 in oil.

Where have all these prairie plants come from? The photo below shows what the land looked like in 2012. The sumac infestation was so dense that the ground underneath was almost completely barren. 

The soil under the dense sumac stand is barren; Oct 2012

The reasonable conclusion is that buried throughout were living roots and dormant buds of the prairie plants that had originally been present. As soon as the sumac was eliminated, these "good" plants were released, sent up new shoots, and recolonized the site. Note that this is not colonization from a seed bank. Although there were certainly viable seeds at the site, the plants that came up were not seedlings, but vigorous shoots from dormant buds. 

Which prairie plant species? The grasses (Indian grass, big bluestem) are certainly survivors. White wild indigo was very visible in July and obviously had not come from seed.

Unknown is how long prairie plants will remain alive buried underneath a stand of woody plants. This would seem like a good research study!